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Citation: Loconsole, D.; Sdao, A.E.;
Cristiano, G.; De Lucia, B. Different
Responses to Adventitious
Rhizogenesis under Indole-3-Butyric
Acid and Seaweed Extracts in
Ornamental’s Cuttings: First Results
in Photinia x fraseri ‘Red Robin’.
Agriculture 2023,13, 513.
https://doi.org/10.3390/
agriculture13030513
Academic Editor: Peter A. Roussos
Received: 29 December 2022
Revised: 16 February 2023
Accepted: 18 February 2023
Published: 21 February 2023
Copyright: © 2023 by the authors.
Licensee MDPI, Basel, Switzerland.
This article is an open access article
distributed under the terms and
conditions of the Creative Commons
Attribution (CC BY) license (https://
creativecommons.org/licenses/by/
4.0/).
agriculture
Article
Different Responses to Adventitious Rhizogenesis under
Indole-3-Butyric Acid and Seaweed Extracts in Ornamental’s
Cuttings: First Results in Photinia x fraseri ‘Red Robin’
Danilo Loconsole * , Anna Elisa Sdao, Giuseppe Cristiano and Barbara De Lucia
Department of Soil, Plant and Food Sciences (Di.S.S.P.A.), University of Bari, “Aldo Moro”, Via Amendola 165/A,
70126 Bari, Italy
*Correspondence: danilo.loconsole@uniba.it; Tel.: +39-080-544-30-39
Abstract:
Fraser’s photinia ‘Red Robin’ (Photinia x fraseri Dress, Rosaceae family) is an important
primary ornamental landscaping species with optimal hedge or screen effects and low maintenance,
but it is difficult to root when propagated by cuttings, although high concentrations of phytohormones
are used to optimize rhizogenesis. To our knowledge, there is currently no feasible enhanced method
for photinia vegetative propagation through stem cuttings, using seaweed extract-based biostimulants
as root promoters. Given the economic importance of the species, this research aims to assess the
effects of indole-3-butyric acid (IBA) and seaweed extract-based stimulators on the quality of photinia
‘Red Robin’ cuttings, in terms of rooting indicators and ground and aboveground agronomic features.
The treatments applied were different concentrations of commercial rooting stimulators compared
to an untreated control: C0: distilled water; Rhizopon AA: 1% IBA (R1); Kelpak
®
: 2 mL L
−1
(K2);
Kelpak
®
: 3 mL L
−1
(K3); Goteo
®
: 2 mL L
−1
(G2); Goteo
®
: 3 mL L
−1
(G3). The first results showed
different responses to adventitious rhizogenesis under IBA and both seaweed extract treatments. At
70 DAC (days after cutting), the seaweed extract stimulated the production of over 80% of cuttings
with callus; at 240 DAC, the percentage of rooted cuttings treated under R1 was the highest = 34.3%;
the worst results were obtained by both biostimulant treatments at the highest doses: K3 = 21.3%
and G3 = 20.7%. Furthermore, R1 produced 3.07 roots per cutting, which was 50% higher than the
average of all other treatments. The applications of Kelpak
®
and Goteo
®
biostimulants, at both
concentrations, resulted in an inhibition of root length with values below the untreated control.
Rooted cuttings under R1 showed the highest ground (0.35 g) and aboveground (0.47) dry value.
Neither seaweed extract, Kelpak
®
or Goteo
®
, at different concentrations, improved both the ground
and above-ground weights of rooted cutting, compared to the untreated control, indicating that
these natural products are not suitable for Fraser’s photinia ‘Red Robin’ propagation using this
methodology. The overall quality of cuttings in IBA treatment was the strongest, with 1%, being
the optimum concentration. Further research must be conducted to propose effective agronomic
protocols by investigating application methods, doses and number of applications, and to clarify the
biochemical and molecular mechanisms of action of these seaweed extracts.
Keywords:
Ascophyllum nodosum; auxin; biostimulants; cutting; Ecklonia maxima; ornamental plants;
quality rooted cutting; root architecture; vegetative propagation
1. Introduction
Nowadays, one of the critical challenges to address is increasing global agricultural
production and crop quality, through reducing the impact of agriculture on ecosystems [
1
,
2
].
Increasing the quality and yield of crops, maintaining agroecosystems, reducing chemical
substances, increasing nutrient uptake and use efficiencies, and stimulating the plant’s
natural defense, must be the major goals [
3
–
5
]. The quality of propagation material is
one of the most important factors for increasing the productivity of any ornamental crop.
Agriculture 2023,13, 513. https://doi.org/10.3390/agriculture13030513 https://www.mdpi.com/journal/agriculture
Agriculture 2023,13, 513 2 of 15
Several authors have dealt with defining the quality of the propagation material from
a genetic, sanitary and agronomic point of view. From a genetic point of view, quality
is related to the endogenous content of auxins [
6
]. Sanitary quality is characterized by
the absence of parasites and pathogens [
7
]; the agronomic quality of a rooted cutting is
based on the morphological features of the aerial parts and adventitious roots, which
influence health, vigor and uniformity [
8
,
9
]. A high number of very fine roots, which
are essential for continuous access to water and nutrients, can help the plant withstand
transplant shock, increasing survival and plant growth [
10
]. A multitude of internal
and environmental factors affect the production of adventitious roots. Among the internal
components, phytohormones, particularly auxins, have the most significant impact. Natural
(indole-3-butyric acid, IBA) and synthetic auxins (naphthalene acetic acid, NAA), applied
exogenously to cuttings [
11
], play a key role in generating adventitious roots [
12
,
13
] and
balanced shoots in ornamental species that are recalcitrant to clonal propagation, due to
a low concentration of endogenous auxins [
10
,
14
–
22
]. Commercial products based on
indole-3-butyric acid (IBA), such as Rhizopon, are one of the most widely used exogenous
sources of auxin and they can be delivered to cuttings in talc or dissolved in alcohol to be
used as a quick dip [
23
]. The most recent literature has expanded the research on other
natural substances with rooting activity such as biostimulants [
24
–
26
]. Biostimulants are
defined as “product stimulating plant nutrition processes, independently of the product’s
nutrient content, with the sole aim of improving one or more of the following characteristics
of the plant or the plant rhizosphere: (a) nutrient use efficiency; (b) tolerance to abiotic
stress; (c) quality traits; (d) availability of confined nutrients in soil or rhizosphere” [27].
Seaweed-extract based biostimulants [
28
], particularly from the brown alga Ascophyl-
lum nodosum (L.) Le Jolis [
29
,
30
], commonly used in the agriculture industry, have been
observed to be beneficial for plants because of the cell signaling activity of some molecules,
such as polysaccharides [
24
,
31
,
32
], polyphenols, peptides, carotenoids [
33
], betaines [
34
],
and macro- and micronutrients. Moreover, phytohormones (e.g., auxins, gibberellins and
cytokinins), found in seaweed extracts, accelerate metabolism and development [
35
,
36
],
as well as other hormone-like substances [
37
–
39
]. Among the numerous commercial bios-
timulants, Goteo
®
(Goteo—Goactiv, UPL, Cesena, Italy), a biologically active filtrate called
GA142, from the seaweed A. nodosum, is a source of polysaccharides, vitamins, auxins and
cytokinins [
40
,
41
]. A previous study carried out by Loconsole et al. [
42
] proved that Goteo
®
improved the aerial and root quality traits of ornamental cuttings at a dose of 3 mL L
−1
in wild sage, with a greater number of roots, better growth traits, root morphologies and
carbohydrate content compared to IBA. Moreover, in glossy Abelia, the same authors [
42
]
suggested the application of a 1 mL L
−1
concentration of Goteo
®
to obtain high-quality
rooted stem cuttings.
The biostimulant Kelpak
®
(Kelp Products Ltd., Cape Town, South Africa), an extract
of brown seaweed, in particular Ecklonia maxima (Osbeck) Papenfuss, stimulates the growth
and enlargement of the root system, due to the very high auxin-to-cytokinin ratio. This
leads to a better absorption and translocation of macro- and microelements [
43
]. Moreover,
the research carried out by Szabớet al. [
44
] on Prunus ‘Marianna’ showed that application
of the Kelpak
®
biostimulant resulted in the highest rooting rate and increased the fresh
weight of cuttings during rooting compared to the control. Finally, Traversari et al. [
45
]
observed that the application of Kelpak
®
improved both rooting percentage and root
biometric parameters on two rose cultivar cuttings, proving that a sustainable replacement
of synthetic products used for rooting promotion is possible and desirable.
Red-tip photinia (Photinia x fraseri Dress.), a hybrid from P. serrulata Lindl. x P. glabra
Thunb. Maxim., belonging to the Rosaceae family and discovered at the Fraser Nursery
in Birmingham (AL, USA) around 1940, is an evergreen shrub. It is probably the most
popular hedging plant of the last 20 years with great ornamental value; it has young red
foliage and heads of long-lasting creamy flowers in late spring [
46
] and is widely used
in the design of green areas [
47
]. Used by landscape designers as a low maintenance
hedge or screen that provides spring interest, it attracts pollinating insects with its nectar
Agriculture 2023,13, 513 3 of 15
and the larvae of some species of Lepidoptera feed on its leaves. However, despite its
important role in floriculture, this species is considered difficult to propagate [
48
]; although
high concentrations of phytohormones are used to optimize rhizogenesis [
49
], limiting
its commercial use [
47
]. P. x Fraseri ‘Red Robin’ differs from the species in that the young
shoots are a particularly strong red color and it is particularly robust.
Despite many studies having illustrated the value of seaweed extracts in promoting
growth, quality and yield when applied to the plant or rhizosphere in the production of
cereals, fruit, vegetables and ornamental plants [
50
–
52
], their use in vegetative propagation
by cutting has not been thoroughly investigated in terms of the current bibliography
[53–56]
.
To our knowledge, there is currently no feasible enhanced method for vegetative prop-
agation of P. x fraseri ‘Red Robin’ through stem cuttings by applying algae extracts as
root promoters.
Given the economic importance of the species, this research aims to assess the effects
of IBA and seaweed extract-based stimulators on the quality of photinia cuttings, in terms
of rooting indicators and ground and aboveground agronomic features.
2. Materials and Methods
2.1. Rooting Environment
The experiment was conducted in a commercial greenhouse for propagation, located
in Apulia, southern Italy (4054
0
19.1” N, 1718
0
21.4” E; 66 m a.s.l.), covered in an ethylene-
vinyl acetate film with a net that provided 50% shading, from 4 March to 30 October 2021
(240 days after cutting, DAC). The greenhouse’s environmental conditions during the
experiment included: air temperatures that ranged from 12
◦
C at night to 27
◦
C during the
day; seedbeds heated from the bottom during the winter; and misting for 60 s every 20 min
(with droplets of an average size of 100
µ
m) from 8 a.m. to 6 p.m. during the summer
period. The mist duration and interval varied in spring-autumn-winter months 2021.
2.2. Mother Plants and Cuttings
P. x fraseri ‘Red Robin’ stock mother plants were grown in open fields and regularly
pruned to prevent flowering. Twenty mother plants were randomly selected. From each
mother plant, ninety median and semi-hardwood stem cuttings were taken. Each cutting
was selected for its uniformity, vigor, lack of disease, trueness to type, and a length of 4 cm
with three nodes, removing the basal leaves and maintaining two leaves per cutting, with
an average above-ground fresh mass of 0.73 g and an average total leaf area of 4.63 cm2.
2.3. Rooting Promoters and Cutting Propagation
Cuttings were rooted using three different commercial rooting promoters: auxins were
applied in the form of commercially available rooting powder: Rhizopon AA (identified
as R), at 1% IBA (Sigma, St. Louis, MO, USA), directly to the bases of cuttings; the
concentration was chosen according to previous studies that observed how high doses of
IBA improve the quality of rooted cuttings. For example, refs. [
57
,
58
], have achieved the
best results with 0.8%, while Bonamino and Blazich [
49
] have applied IBA at 1%. Kelpak
®
(identified as K), is composed of 34% (w/w)E. maxima extract 11.16 mg L
−1
auxin and
0.031 mg L
−1
cytokinin (with a auxin:cytokinin ratio of 360:1), alginates (1.5 L
−1
), amino
acids (total 441.3 mg 100 g
−1
), mannitol (2261 mg L
−1
), neutral sugars (1.08 g L
−1
), and
small amounts of macroelements (N 0.09%, P 90.7 mg kg
−1
, K 7163.3 mg kg
−1
, Ca 190.4 mg
kg
−1
, Mg 337.2 mg kg
−1
, Na 1623.7 mg kg
−1
) and microelements (mean composition: Mn
17.3 mg kg−1
, Fe 40.7 mg kg
−1
, Cu 13.5 mg kg
−1
, Zn 17.0 mg kg
−1
, B 33.0 mg kg
−1
) [
43
,
59
].
The (producer’s) recommended dose is 10 mL L
−1
before transplanting and the same
dose three times after transplanting (7 days between each treatment); the dose chosen
in our experiment was 2 and 3 mL L
−1
respectively because they were applied by foliar
application and not by drenching. Goteo
®
(Goteo—Goactiv, UPL, Italy) (identified as G) is
a liquid formulation used as a source of auxins, cytokinins, polysaccharides and vitamins.
GA142 is supplemented by the company with organic mineral fertilizers (w/v): 13% P
2
O
5
,
Agriculture 2023,13, 513 4 of 15
5% K
2
O and 1.3–2.4% organic matter. In terms of concentration, the company recommends
a 0.1% solution (1 mL L
−1
) for vegetable crops, while ornamental plants are not specified.
Previous experiments, from Gajc-Wolska [
60
] and Matysiak [
61
], suggested 3 to 4 treatments
with 0.2% solution (2 mL L−1) every 2 weeks to accelerate root regeneration.
On 4 March 2021, plastic trays with 100 holes and a diameter of 3.5 cm were sanitized
using a fresh chlorine solution, which consisted of one part bleach (5.25 percent sodium
hypochlorite) to nine parts water for a final strength of 0.5%. They were then stuffed with
paper tubes that contained the substrate, a combination of brown and blonde peat and
perlite (v:v= 80:20; pH 5.0–6.0; organic carbon, 35%; organic nitrogen, 0.8%; organic matter,
85%) (Jiffy
®
Products International BV, Toul, France). They were then saturated with water
and cuttings were put two centimeters deep into the substrate.
2.4. Experimental Design
The experiment, started on 4 March, consisted of six treatments, each in three replica-
tions, each replication containing 100 cuttings.
The treatments applied were different concentrations of rooting stimulators compared
to an untreated control:
•C0: distilled water;
•R1: Rhizopon AA, 1% IBA;
•K2: 2 mL L−1;
•K3: 3 mL L−1;
•G2: 2 mL L−1;
•G3: 3 mL L−1.
IBA was applied directly to the bases of cuttings (10 mm) in the form of Rhizopon AA,
the commercially available rooting powder. Before the application, the cutting base was
wetted with distilled water.
Starting from 4 March, the Kelpak
®
and Goteo
®
solutions were sprayed with a hand
sprayer every two weeks until they ran off the leaves of the cuttings, a total of 4 times. The
treatment was always applied at the same time (9 a.m.) and the mist system stopped before
the application, to prevent the solution being washed out by water.
The treatment design was a randomized complete block design of 18 experimental
units (6 concentrations ×3 replicates).
Experimental analysis was conducted at the Floriculture and ornamental plants labo-
ratory of the Department of Soil, Plant and Food Sciences, at the University of Bari.
2.5. Callus Initiation and Rooting Formation
At 70 DAC (13 May), callus initiation and rooting formation was investigated, sam-
pling 24 cuttings per treatment (eight cuttings per replicate). The counting method was
used to quantify the callus production rate and rooting percentage; gross morphological
changes in the base of the stem cutting were captured using a Nikon SMZ800N microscope
with a Nikon DS-Fi1 camera (Nikon Corporation, Tokyo, Japan) and Nis Elements 4.0 digi-
tal software at a resolution of 96 dpi. A cutting was considered rooted if it had at least one
primary root ≥1 mm long; the unrooted cutting percentage was also evaluated.
On 13 May, 12 June (at 100 DAC) and 30 October (at 240 DAC), the callused (number of
cuttings that produced calli/total number of cuttings
×
100%) cuttings and rooted (number
of rooted cuttings/total number of cuttings tested
×
100%) cuttings percentages were
recorded for twelve randomly chosen cuttings per treatment (four cuttings per replicate).
At 240 DAC, the cutting survival percentage was also monitored. Percentage data were
subjected to arcsine square root transformation before ANOVA analysis. At 240 DAC, the
number of cuttings with 1, 2, 3, 4, 5 and 6 roots and the average root number per cutting for
each treatment were recorded.
Agriculture 2023,13, 513 5 of 15
2.6. Roots Architecture
Twelve rooted cuttings from each treatment (four cuttings per replicate) at 240 DAC
were sampled, and the morphology of the adventitious rooting system was examined. Each
rooted cutting was cleaned, and the roots, leaves, and stems were separated. Water and a
soft brush were used to gently wash out the rooting substrate. An Epson v700 Perfection
(Japan) scanner was used to scan the roots at a resolution of 400 dpi. For the evaluation of
total root length, root surface area, root diameter, number of root tips, forks, and crossings,
the images were subsequently analyzed using image analysis software (WinRHIZO v. 2005b,
Regent Instruments Inc., Québec, QC, Canada, www.regentinstruments.com accessed on
29 December 2022).
2.7. Ground Biomass
At 240 DAC, root fresh and dry weights (g) were measured on twelve rooted cuttings
per treatment (four cuttings per replicate): fresh samples were dried in a thermo-ventilated
oven at 70 ◦C until it reached a constant mass.
2.8. Aboveground Quality Features
At 240 DAC, the same samples analyzed for root parameters were recorded for aerial
growth traits. Three new and fully opened leaves were sampled for analyzing the chloro-
phyll index (SPAD) (Konica Minolta Chlorophyll Meter SPAD-502 Plus, Solna, Sweden).
The number of leaves per cutting was counted and the total leaf area per rooted cutting
was measured with a leaf area meter (Delta-T; Decagon Devices, Pullman, WA, USA).
Aboveground (leaves + stems) fresh and dry weights (g) were measured: samples were
dried in a thermo-ventilated oven at 70 ◦C until it reached a constant mass.
2.9. Statistical Analysis
The effects of various rooting promoters doses on rooting performance and morpho-
logical features were examined using a one-way analysis of variance (ANOVA).
All the above data analyses were performed using SAS version 9.3 statistical software
(SAS, 1999); treatment means were separated by the SNK (Student-Newman–Keuls) test
(p≤0.05).
3. Results
Table 1shows the percentage values of callus, rooted and unrooted cuttings at 70 DAC.
A higher percentage of callused cuttings was observed with both seaweed extracts (K and
G) at different concentrations compared to the IBA—Rhizopon treatment (R1) and the
control. The percentage of callused cuttings was 84.3% on average in both the seaweed
extracts, greater than 1.3 and 1.4 times compared to the control and the R treatment. The
rooted cutting percentage was significantly higher in the R1 treatment (29.2%) followed
by the G3 treatment (16.7%); the C0, K2, K3 and G2 treatments recorded the lowest rooted
cutting percentage values, with no differences between them. The same table shows that
the highest value of unrooted cuttings was found in the control (average 33.3%), while the
cuttings treated with G3 all had calli or roots.
Figure 1is a microscope image: we can see, on the left (a), the production of callous
tissue in the G2 treated cutting; on the right (b), the adventitious root in the R1 treated
cutting. Table 2shows the callused and rooted cutting percentage at 100 and 240 DAC. At
100 DAC, the greatest callused cutting percentage values were obtained in the untreated
control and Goteo
®
at the highest dose. The R1 application resulted in 51% fewer callused
cuttings compared to the control; the same trend was found at 240 DAC. Furthermore, K3
and G3 showed a lower production of callused cuttings, compared to the corresponding
lower dose of the same biostimulant (K3: 11.3%; G3: 10.3%; K2: 18.0%; G2: 15.3%). The
same Table 2shows that, at 100 and 240 DAC, the percentage of rooted cuttings treated
under R1 was statistically the highest (25% at 100 DAC and 34.3% at 240 DAC), with
an increase of 15.5% compared to the control at 240 DAC. At 100 DAC, treatments with
Agriculture 2023,13, 513 6 of 15
biostimulants showed the lowest values of rooting compared to IBA. At 240 DAC, the
worst results were obtained by both biostimulant treatments at the highest doses, with no
statistically significant differences between them (K3 = 21.3% and G3 = 20.7%).
Table 1.
Callused, rooted and unrooted cutting (%) at 70 DAC in P. x fraseri ‘Red Robin’ influenced by
rooting promoters concentration (RPC).
RPC Cuttings (%)
Callused Rooted Unrooted
C0 66.7 ±4.2 b 0.0 ±0.0 c 33.3 ±4.2 a
R1 58.3 ±4.0 c 29.2 ±3.0 a 12.5 ±0.0 b
K2 87.5 ±0.0 a 0.0 ±0.0 c 12.5 ±0.0 b
K3 83.3 ±4.2 a 0.0 ±0.0 c 16.7 ±4.2 b
G2 83.3 ±4.2 a 0.0±0.0 c 16.7 ±4.2 b
G3 83.3 ±4.2 a 16.7 ±4.2 b 0.0 ±0.0 c
In columns, different letters indicate significant differences within parameters (S.N.K. test, p≤0.05; mean ±SD,
n= 3) C0: untreated control; R1: Rhizopon AA (1% IBA); K: Kelpak
®
; G: Goteo
®
; K2: 2 mL L
−1
; K3: 3 mL L
−1
;
G2: 2 mL L−1; G3: 3 mL L−1.
Agriculture 2023, 13, x FOR PEER REVIEW 6 of 16
Table 1. Callused, rooted and unrooted cutting (%) at 70 DAC in P. x fraseri ‘Red Robin’ influenced
by rooting promoters concentration (RPC).
RPC
Cuttings (%)
Callused
Rooted
Unrooted
C0
66.7 ± 4.2 b
0.0 ± 0.0 c
33.3 ± 4.2 a
R1
58.3 ± 4.0 c
29.2 ± 3.0 a
12.5 ± 0.0 b
K2
87.5 ± 0.0 a
0.0 ± 0.0 c
12.5 ± 0.0 b
K3
83.3 ± 4.2 a
0.0 ± 0.0 c
16.7 ± 4.2 b
G2
83.3 ± 4.2 a
0.0± 0.0 c
16.7 ± 4.2 b
G3
83.3 ± 4.2 a
16.7 ± 4.2 b
0.0 ± 0.0 c
In columns, different letters indicate significant differences within parameters (S.N.K. test, p ≤ 0.05;
mean ± SD, n = 3) C0: untreated control; R1: Rhizopon AA (1% IBA); K: Kelpak®; G: Goteo®; K2: 2
mL L−1; K3: 3 mL L−1; G2: 2 mL L−1; G3: 3 mL L−1.
Figure 1 is a microscope image: we can see, on the left (a), the production of callous
tissue in the G2 treated cutting; on the right (b), the adventitious root in the R1 treated
cutting. Table 2 shows the callused and rooted cutting percentage at 100 and 240 DAC. At
100 DAC, the greatest callused cutting percentage values were obtained in the untreated
control and Goteo® at the highest dose. The R1 application resulted in 51% fewer callused
cuttings compared to the control; the same trend was found at 240 DAC. Furthermore, K3
and G3 showed a lower production of callused cuttings, compared to the corresponding
lower dose of the same biostimulant (K3: 11.3%; G3: 10.3%; K2: 18.0%; G2: 15.3%). The
same Table 2 shows that, at 100 and 240 DAC, the percentage of rooted cuttings treated
under R1 was statistically the highest (25% at 100 DAC and 34.3% at 240 DAC), with an
increase of 15.5% compared to the control at 240 DAC. At 100 DAC, treatments with bi-
ostimulants showed the lowest values of rooting compared to IBA. At 240 DAC, the worst
results were obtained by both biostimulant treatments at the highest doses, with no sta-
tistically significant differences between them (K3 = 21.3% and G3 = 20.7%).
Figure 1. On the left (a) the production of callous tissue in G2 treated cutting; on the right (b) the
adventitious root in R1 treated cutting.
Figure 1.
On the left (
a
) the production of callous tissue in G2 treated cutting; on the right (
b
) the
adventitious root in R1 treated cutting.
Table 2.
Callused and rooted cutting (%) at 100 and 240 DAC in P. x fraseri ‘Red Robin’ influenced by
rooting promoters concentration (RPC).
RPC Cuttings (%)
Callused Rooted
100 DAC 240 DAC 100 DAC 240 DAC
C0 33.0 ±1.1 a 13.7 ±0.7 bc 7.7 ±0.7 d 29.7 ±1.4 b
R1 16.0 ±1.0 d 3.3 ±0.3 e 25.0 ±1.0 a 34.3 ±0.9 a
K2 30.0 ±1.0 b 18.0 ±1.1 a 12.0 ±1.0 bc 25.0 ±0.6 c
K3 29.0 ±1.0 bc 11.3 ±0.7 cd 13.3 ±1.3 b 21.3 ±0.7 d
G2 27.3 ±0.9 c 15.3 ±0.9 b 14.3 ±1.3 b 27.0 ±1.0 bc
G3 34.0 ±0.6 a 10.3 ±0.9 d 9.0 ±1.6 cd 20.7 ±0.9 d
In columns, different letters indicate significant differences within parameters (S.N.K. test, p≤0.05; mean ±SD,
n= 3
) C0: untreated control; R1: Rhizopon AA (1% IBA); K: Kelpak
®
; G: Goteo
®
; K2: 2 mL L
−1
; K3: 3 mL L
−1
;
G2: 2 mL L−1; G3: 3 mL L−1.
Agriculture 2023,13, 513 7 of 15
Table 3shows, at 240 DAC, the number of rooted cuttings per treatment with a different
number of roots, between 1 and 6. Treatment with IBA positively influenced the number of
cuttings with 3, 4, 5 and 6 roots.
Table 3.
Cuttings (no.) with 1, 2, 3, 4, 5 and 6 roots at 240 DAC in P. x fraseri ‘Red Robin’ influenced
by rooting promoters concentration (RPC).
RPC Rooted Cuttings (No.)
1 Root 2 Roots 3 Roots 4 Roots 5 Roots 6 Roots
C0 13.7 ±0.7 a 7.0 ±0.6 a 4.3 ±0.3 b 3.7 ±0.3 a 1.0 ±0.0 b 0.0 ±0.0 c
R1 7.0 ±0.6 c 7.0 ±1.0 a 8.7 ±0.3 a 4.3 ±0.3 a 3.0 ±0.6 a 4.3 ±0.3 a
K2 10.3 ±0.7 b 7.3 ±0.3 a 4.3 ±0.3 b 1.7 ±0.3 b 1.0 ±0.0 b 0.4 ±0.3 bc
K3 9.7 ±0.3 b 5.3 ±0.3 a 2.7 ±0.3 c 2.0 ±0.0 b 1.0 ±0.0 b 0.7 ±0.3 bc
G2 14.0 ±0.6 a 6.3 ±0.3 a 2.0 ±0.6 c 4.0 ±0.6 a 0.7 ±0.3 b 0.0 ±0.0 c
G3 10.4 ±0.7 b 5.7 ±0.7 a 2.3 ±0.3 c 1.3 ±0.3 b 0.0 ±0.0 b 1.3 ±0.3 b
In columns, different letters indicate significant differences within parameters (S.N.K. test, p≤0.05; mean ±SD,
n= 3
) C0: untreated control; R1: Rhizopon AA (1% IBA); K: Kelpak
®
; G: Goteo
®
; K2: 2 mL L
−1
; K3: 3 mL L
−1
;
G2: 2 mL L−1; G3: 3 mL L−1.
Data on root morphological features are provided in Tables 4and 5. In Table 4, at
240 DAC, the statistically highest value of number of roots per cutting was obtained in
the treatment carried out with the R1 application (3.07 roots per cutting). This was 50%
higher than the average of all other treatments, which do not have statistically significant
differences between them. The same table shows that the greatest root length development
was obtained in cuttings treated with Rhizopon, compared to the other treatments; the
applications of Kelpak
®
and Goteo
®
biostimulants at both concentrations resulted in an
inhibition of root length with values below the untreated control. The same trend was
recorded for the surface area.
Table 4.
Root morphological traits: roots number (no.), length (mm), surface area (mm
2
) and average
diameter (mm), at 240 DAC in P. x fraseri influenced by rooting promoters concentration (RPC).
RPC Roots (No.) Length (mm) Surface Area
(mm2)Diameter (mm)
C0 2.0 ±0.04 b 133.0 ±1.1 b 23.8 ±0.9 b 0.60 ±0.01 a
R1 3.1 ±0.07 a 162.1 ±7.1 a 33.9 ±0.9 a 0.73 ±0.02 a
K2 2.1 ±0.10 b 54.9 ±3.0 cd 12.5 ±0.4 c 0.67 ±0.02 a
K3 2.1 ±0.05 b 51.1 ±2.3 d 11.8 ±0.6 c 0.66 ±0.01 a
G2 1.9 ±0.08 b 67.6 ±4.0 cd 14.5 ±0.1 c 0.70 ±0.02 a
G3 2.0 ±0.07 b 72.2 ±7.0 c 16.3 ±0.2 c 0.73 ±0.01 a
In columns, different letters indicate significant differences within parameters (S.N.K. test, p≤0.05; mean ±SD,
n= 3
) C0: untreated control; R1: Rhizopon AA (1% IBA); K: Kelpak
®
; G: Goteo
®
; K2: 2 mL L
−1
; K3: 3 mL L
−1
;
G2: 2 mL L−1; G3: 3 mL L−1.
Table 5.
Root morphological traits: root tips (no.), forks (no.) and crossing (no.), at 240 DAC in P. x
fraseri influenced by rooting promoters concentration (RPC).
RPC Root
Tips (No.) Forks (No.) Crossings (No.)
C0 330 ±7.0 b 755 ±12.5 b 99 ±1.8 b
R1 677 ±5.6 a 1215 ±7.7 a 114 ±3.8 a
K2 217 ±1.1 c 326 ±6.3 e 25 ±1.1 e
K3 225 ±6.7 c 298 ±5.5 e 30 ±1.5 e
G2 226 ±3.8 c 459 ±7.9 d 38 ±0.6 d
G3 340 ±8.7 b 621 ±13.3 c 49 ±1.7 c
In columns, different letters indicate significant differences within parameters (S.N.K. test, p≤0.05; mean ±SD,
n= 3
) C0: untreated control; R1: Rhizopon AA (1% IBA); K: Kelpak
®
; G: Goteo
®
; K2: 2 mL L
−1
; K3: 3 mL L
−1
;
G2: 2 mL L−1; G3: 3 mL L−1.
Agriculture 2023,13, 513 8 of 15
Table 5shows the average number of tips, forks and crossings at 240 DAC. Cuttings
treated with R1 showed a 105% increase in tips compared to the untreated control and G3.
The K2, K3 and G2 treatments were equal to each other and below the control, by an average
of 32%. Regarding the number of forks and crossings (Table 5), the highest value was
obtained with cuttings treated with Rhizopon, +61% forks and +15% crossings compared
to the control; the cuttings treated with the biostimulants at the different concentrations
obtained lower values than the control.
Data on fresh and dry ground weights are provided in Table 6: rooted cuttings under
R1 show the highest, and statistically different, dry value (0.35 g) compared to the other
treatments, resulting in +40% in comparison to the control.
Table 6.
Ground fresh and dry weights (g) per cutting, at 240 DAC in P. x fraseri influenced by rooting
promoters concentration (RPC).
RPC Ground Weights (g)
Fresh Dry
C0 0.81 ±0.07 ab 0.25 ±0.09 b
R1 0.97 ±0.02 a 0.35 ±0.01 a
K2 0.47 ±0.02 c 0.15 ±0.01 c
K3 0.72 ±0.02 b 0.23 ±0.01 b
G2 0.81 ±0.07 ab 0.24 ±0.01 b
G3 0.65 ±0.03 b 0.18 ±0.01 c
In columns, different letters indicate significant differences within parameters (S.N.K. test, p≤0.05; mean ±SD,
n= 3
) C0: untreated control; R1: Rhizopon AA (1% IBA); K: Kelpak
®
; G: Goteo
®
; K2: 2 mL L
−1
; K3: 3 mL L
−1
;
G2: 2 mL L−1; G3: 3 mL L−1.
Table 7shows the aboveground morpho-biometric features: no statistically significant
differences were found between the treatments, in terms of the number of leaves per cutting
and chlorophyll index. At 240 DAC, the statistically highest value of leaf area per cutting
was obtained in the treatment carried out with the R1 application (27.9 cm
2
); K3 and G3
were similar to the control, with lower values compared to R1. The worst performances
were observed in the K2 and G2 treatments.
Table 7.
Above-ground morpho-biometric traits: leaves per cutting (no.), leaf area (mm
2
)
and chlorophyll index (SPAD), at 240 DAC in P. x fraseri influenced by rooting promoters con-
centration (RPC).
RPC Leaves per Cutting
(No.)
Chlorophyll Index
(SPAD)
Leaf Area per Cutting
(cm2)
C0 3.7 ±0.7 a 570 ±13.7 a 22.0 ±1.2 b
R1 4.7 ±0.3 a 530 ±11.9 a 27.9 ±0.8 a
K2 3.3 ±0.3 a 533 ±15.0 a 18.1 ±0.3 c
K3 4.0 ±0.6 a 554 ±2.91 a 21.9 ±0.9 b
G2 3.3 ±0.3 a 529 ±20.4 a 18.4 ±0.4 c
G3 4.0 ±0.6 a 582 ±11.6 a 22.3 ±1.4 b
In columns, different letters indicate significant differences within parameters (S.N.K. test, p≤0.05; mean ±SD,
n= 3
) C0: untreated control; R1: Rhizopon AA (1% IBA); K: Kelpak
®
; G: Goteo
®
; K2: 2 mL L
−1
; K3: 3 mL L
−1
;
G2: 2 mL L−1; G3: 3 mL L−1.
Table 8showed that the aboveground dry weight was significantly influenced by
treatments: the rooting effect under IBA (R1) was higher than that under the control
and K3.
Agriculture 2023,13, 513 9 of 15
Table 8.
Aboveground fresh and dry weights (g) per cutting, at 240 DAC in P. x fraseri influenced by
rooting promoters concentration (RPC).
RPC Above-Ground Weights (g)
Fresh Dry
C0 1.11 ±0.14 a 0.40 ±0.09 b
R1 1.29 ±0.13 a 0.47 ±0.11 a
K2 0.99 ±0.11 a 0.35 ±0.04 bc
K3 1.11 ±0.09 a 0.39 ±0.08 b
G2 0.96 ±0.08 a 0.33 ±0.08 c
G3 1.04 ±0.06 a 0.35 ±0.03 bc
In columns, different letters indicate significant differences within parameters (S.N.K. test, p
≤
0.05;
mean
±
SD,
n= 3
) C0: untreated control; R1: Rhizopon AA (1% IBA); K: Kelpak
®
; G: Goteo
®
; K2: 2 mL L
−1
;
K3: 3 mL L−1; G2: 2 mL L−1; G3: 3 mL L−1.
4. Discussion
Calkins [
62
] reported that Fraser’s photinia is an important primary ornamental land-
scaping species with optimal hedge or screen effects and low maintenance, but it is difficult
to root when propagated by cuttings. Given the economic importance of the species in the
ornamental industry, this research aims to assess the effects of IBA and algae extract-based
stimulators on the quality of photinia cuttings, in terms of rooting indicators and ground
and aboveground agronomic features. Vegetative propagation by cuttings has numer-
ous advantages, one of which is to provide more uniform and agronomically superior
commercial plantlets than those obtained by heterozygous seeds [
63
]. First results show
different responses to adventitious rhizogenesis under in-dole-3-butyric acid and seaweed
extract treatments. The application of exogenous auxin and cytokinin stimulates callus
differentiation in various species [
64
]. Several studies showed that an intermediate ratio of
auxin and cytokinin promotes callus induction, while a high ratio of auxin-to-cytokinin or
cytokinin-to-auxin induces root and shoot regeneration, respectively [
65
]. Plants of Ara-
bidopsis thaliana treated with a biostimulant extracted from A. nodosum showed an increase
in cytokinin-like responses, suggesting a contribution in the cytokinin-like activity of the
extracts’s compounds [
66
]. From our results obtained at 70 DAC, it would appear that the
seaweed extracts stimulated the production of over 80% of cuttings with callus (Figure 1,
Table 1). Comparing this result to IBA (R1), it can be observed that this, in contrast, obtained
the highest rooting percentage (Table 1). Furthermore, it would appear that the conspic-
uous production of callus tissue prevents the adventitious rooting of photinia cuttings,
representing a structural obstacle to the emission of adventitious roots. Our preliminary
results agree with Monder et al. [
67
]: in the rhizogenesis of the ‘Hurdal’ rose, the authors
showed that an increase in rooting percentage was only strictly connected to a decrease in
the percentage of cuttings with calli only. Callus overgrowth in photinia could be an unfa-
vorable phenomenon for fast rhizogenesis. Conversely, Costa et al. [
68
] in Rosa ‘Madelon’
and Fouda and Schmidt [69] in Rosa rugosa stem cuttings found that the new parenchyma
tissue (callus) precedes root initiation. Martins et al. [
70
] showed an inverse relationship
between rooting and callus formation for olive tree cuttings. In our study, the application of
IBA (R1) improved the rooting percentage at 240 DAC (Table 2) and the number of cuttings
with six roots (Table 3), as compared to the untreated control and seaweed extracts. In our
experimental conditions, the application of IBA at the concentration of 1 gL
−1
produced
33% of rooted cuttings, while Bonaminio and Blazich, [
49
] in 1983, found that 5000 and
10,000 mg L
−1
of IBA solutions applied to the terminal, semi-hardwood cuttings of Fraser’s
photinia, promoted rooting more effectively than the control, and increased rooting percent-
age significantly (100 and 93%). Cutting success, entailing quality AR formation with high
rooting percentage, depends on numerous factors, such as cutting type, environmental
conditions, nutritional levels of the stock plant, rooting medium and phytohormone ap-
plication [
17
,
71
,
72
]. IBA has been reported to increase
in vivo
adventitious root formation,
overall quality and uniformity of roots in many ornamental species [
73
–
82
]. Untreated stem
Agriculture 2023,13, 513 10 of 15
cuttings (C0) were also able to root, but with a lower rooting percentage, in comparison to
IBA-treated cuttings, possibly due to the presence of stored carbohydrates and endogenous
auxin contents in the cuttings [
83
]. Until now, no research has compared the morphological
quality of adventitious roots treated with different IBA and seaweed extract concentrations
in Fraser’s Photinia cuttings. To improve plant performance and provide protection against
the deleterious effects of numerous abiotic stressors, several amendments such as bios-
timulators and bioelicitors have been used [
84
]. The favourable impact of using seaweed
extracts as natural regulators has resulted in better crop growth and production [
85
,
86
]. In
our experimental conditions, neither K nor G biostimulants, at different concentrations,
increased the rooting percentage (Table 2) and the root architecture (Figure 2, Tables 4and 5)
compared to the IBA treatment. On the contrary, previous studies have shown the efficacy
of biostimulants in promoting rhizogenesis. For example, the use of a 40% concentrated
A. nodosum extract increased the rooting of Passiflora actinia by about 10% [
87
]. Even if
unsuccessful, our results in the treatments with biostimulants agree with those of Traversari
et al. [
45
] on rose rhyzogenesis: cuttings treated with Phylgreen, a commercial biostimulant
made from A. nodosum, through a low temperature mechanical extraction, had low values
of both survival rate and root biometric parameters. Since biostimulating effects are clearly
species-specific and product-specific, results regarding one biostimulant or one species
only do not directly apply to another biostimulant or another plant species [
51
,
88
,
89
]. In
our study, both Kelpak
®
and Goteo
®
negatively affected root length, surface area and
diameter compared to IBA and the control (Table 4). On the contrary, positive effects of
Goteo
®
on rooting were reported for Physocarpus opulifolius [
75
], Hydrangea paniculata [
90
],
Ornithogalum arabicum [
91
] and rose [
58
]. In Fraser’s Photinia, both Kelpak
®
and Goteo
®
at
different concentrations decreased the number of root tips, forks and crossings compared
to the IBA treatment (Table 5). Based on these findings, the overall development and
morphology of Photinia cuttings treated with Kelpak®and Goteo®were inhibited.
Agriculture 2023, 13, x FOR PEER REVIEW 11 of 16
Figure 2. Root architecture in P. x fraseri ‘Red Robin’ influenced by application of rooting promoters
concentration.
Seaweed extracts often stimulate and accelerate cell division, elongation, differentia-
tion and protein synthesis [37,92]; Makhaye et al. [93] have verified the potential stimula-
tory effect of biostimulants (especially Kelpak®) on the germination of A. esculentus seeds.
The application of biostimulants based on seaweed extracts in our experiment did not
positively influence the number of leaves, chlorophyll index (SPAD) and leaf area index
(Table 7). These results are in disagreement with that found in Lantana camara, Abelia x
grandiflora [42] and Cornus alba ‘Aurea’ and ‘Elegantissima’ [94]. Our preliminary results
(Tables 6 and 8) disagree with Ratore et al. [95], Kocira et al. [96], Gajc-Wolska et al. [60]
and Caccialupi et al. [97] who obtained a positive effect, by applying seaweed extracts, on
plant growth, development and yield. Our results agree with Francke et al. [41], who ex-
hibited a lower yield of shallots than that of the control (4%) by applying Goteo biostim-
ulant. The limited information available in the literature does not allow further discussion
of this biostimulant since contrasting results were observed in Fraser’s photinia ‘Red
Robin’ cuttings with respect to other investigated species. The overall quality of cuttings
in the IBA treatment was the strongest, with 1000 mg L−1 being the optimum concentra-
tion, according to studies by Quan et. al. [98].
5. Conclusions
In conclusion, the main outcomes of this study can be summarized as follows: we sug-
gest that the use of 1% IBA (Rhizopon AA), compared to an untreated control, may be ben-
eficial to ornamental nursery farmers wishing to produce Fraser’s photinia ‘Red Robin’
quality cuttings with a well-developed root system and, therefore, capable of achieving
rapid establishment at transplantation. On the contrary, neither seaweed extract, Kelpak® or
Figure 2.
Root architecture in P. x fraseri ‘Red Robin’ influenced by application of rooting promoters
concentration.
Agriculture 2023,13, 513 11 of 15
Seaweed extracts often stimulate and accelerate cell division, elongation, differentia-
tion and protein synthesis [
37
,
92
]; Makhaye et al. [
93
] have verified the potential stimulatory
effect of biostimulants (especially Kelpak
®
) on the germination of A. esculentus seeds. The
application of biostimulants based on seaweed extracts in our experiment did not positively
influence the number of leaves, chlorophyll index (SPAD) and leaf area index (Table 7).
These results are in disagreement with that found in Lantana camara,Abelia x grandiflora [
42
]
and Cornus alba ‘Aurea’ and ‘Elegantissima’ [
94
]. Our preliminary results (Tables 6and 8)
disagree with Ratore et al. [
95
], Kocira et al. [
96
], Gajc-Wolska et al. [
60
] and Caccialupi
et al. [
97
] who obtained a positive effect, by applying seaweed extracts, on plant growth,
development and yield. Our results agree with Francke et al. [
41
], who exhibited a lower
yield of shallots than that of the control (4%) by applying Goteo biostimulant. The limited
information available in the literature does not allow further discussion of this biostimulant
since contrasting results were observed in Fraser’s photinia ‘Red Robin’ cuttings with
respect to other investigated species. The overall quality of cuttings in the IBA treatment
was the strongest, with 1000 mg L
−1
being the optimum concentration, according to studies
by Quan et. al. [98].
5. Conclusions
In conclusion, the main outcomes of this study can be summarized as follows: we
suggest that the use of 1% IBA (Rhizopon AA), compared to an untreated control, may be
beneficial to ornamental nursery farmers wishing to produce Fraser’s photinia ‘Red Robin’
quality cuttings with a well-developed root system and, therefore, capable of achieving
rapid establishment at transplantation. On the contrary, neither seaweed extract, Kelpak
®
or Goteo
®
, at different concentrations, improved root percentage and architecture, and
ground and above ground weights of rooted cutting, compared to the untreated control.
This result indicates that these natural products are not suitable for Fraser’s photinia ‘Red
Robin’ propagation using this methodology. Further research must be conducted to propose
effective agronomic protocols by investigating application methods, doses and number of
applications, and to clarify the biochemical and molecular mechanisms of action of these
seaweed extracts.
Author Contributions:
Conceptualization, B.D.L. and G.C.; methodology, B.D.L., G.C. and D.L.;
software, G.C.; data curation, B.D.L., G.C. and D.L.; writing—original draft preparation, B.D.L., G.C.,
D.L. and A.E.S.; writing—review and editing, B.D.L., G.C., D.L. and A.E.S.; funding acquisition,
B.D.L. All authors have read and agreed to the published version of the manuscript.
Funding:
This research was funded by Regione Puglia (Italy) MIS. 16—Cooperazione—sottomisura
16.2—Sostegno a progetti pilota e allo sviluppo di nuovi prodotti, pratiche, processi e tecnologie.
Grant number B79J20000140009. Agreement “Transfer of protocols for quarantine and harmful
organisms and for the selection of sanitary materials improved for the Apulian nursery-ProDiQuaVi”
project (“Trasferimento di protocolli per organismi da quarantena e nocivi e per la selezione di
materiali sanitariamente migliorati per il vivaismo pugliese (B79J20000140009)” realizzato nell’ambito
del PSR 2014–2020—Regione Puglia MIS. 16—Cooperazione—sottomisura 16.2—Sostegno a progetti
pilota e allo sviluppo di nuovi prodotti, pratiche, processi e tecnologie—Avviso pubblico approvato
con DAG n. 194 del 12/09/2018, in Italian). Paper no. 3.
Institutional Review Board Statement: Not applicable.
Data Availability Statement:
No new data were created or analyzed in this study. Data sharing is
not applicable to this article.
Acknowledgments:
The authors thank Vivai Capitanio (Monopoli, BA, Italy) and Giovanni Fanizzi
for technical support in the field and the materials used in the experiments. The authors thanks
Claudia Ruta and Patrick Angelo Guarini for providing huge help in microscope image acquisition.
Conflicts of Interest: The authors declare no conflict of interest.
Agriculture 2023,13, 513 12 of 15
References
1.
Del Buono, D. Can biostimulants be used to mitigate the effect of anthropogenic climate change on agriculture? It is time to
respond. Sci. Total Environ. 2020,751, 141763. [CrossRef] [PubMed]
2.
Davydov, R.; Sokolov, M.; Hogland, W.; Glinushkin, A.; Markaryan, A. The application of pesticides and mineral fertilizers in
agriculture. In MATEC Web of Conferences; EDP Sciences: Les Ulis, France, 2018; Volume 245, p. 11003. [CrossRef]
3.
Costa, J.A.V.; Freitas, B.C.B.; Cruz, C.G.; Silveira, J.; Morais, M.G. Potential of micro algae as biopesticides to contribute to
sustainable agriculture and environmental development. J. Environ. Sci. Health B 2019,54, 366–375. [CrossRef] [PubMed]
4.
Singh, N.; Joshi, E.; Sasode, D.S.; Dangi, R.S.; Chouhan, N. Soil fertility, macro and micro nutrient uptake and their use efficiencies
under integrated nutrient management in groundnut (Arachis hypogaea L.). Int. J. Chem. Stud. 2020,8, 1983–1987. [CrossRef]
5.
Neely, C.; Bourne, M.; Chesterman, S.; Kouplevatskaya-Buttoud, I.; Bojic, D.; Vallée, D. Implementing Agenda 2030 in Food and
Agriculture: Accelerating Policy Impact through Cross-Sectoral Coordination at the Country Level; Food and Agricultural Organization
of The United Nations: Rome, Italy, 2017.
6.
Blakesley, D.; Chaldecott, M.A. The role of endogenous auxin in root initiation: Part II. Sensitivity and evidence from studies on
transgenic plant tissues. Plant Growth Regul. 1993,13, 77–84. [CrossRef]
7. Gidoin, Y. Innovation to quality in the horticulture industry: Feedback from a CEO. Acta Hortic. 2019,1245, 1–10. [CrossRef]
8.
Song, S.J.; Ko, C.H.; Shin, U.S.; Oh, H.J.; Kim, S.Y.; Lee, S.Y. Successful stem cutting propagation of Patrinia rupestris for horticulture.
Rhizosphere 2019,9, 90–92. [CrossRef]
9.
Gallegos-Cedillo, V.M.; Diánez, F.; Nájera, C.; Santos, M. Plant Agronomic Features Can Predict Quality and Field Performance:
A Bibliometric Analysis. Agronomy 2021,11, 2305. [CrossRef]
10.
Loconsole, D.; Cristiano, G.; De Lucia, B. Image Analysis of Adventitious Root Quality in Wild Sage and Glossy Abelia Cuttings
after Application of Different Indole-3-Butyric Acid Concentrations. Plants 2022,11, 290. [CrossRef]
11. H ˛ac-Wydro, K.; Flasi´nski, M. The studies on the toxicity mechanism of environmentally hazardous natural (IAA) and synthetic
(NAA) auxin—The experiments on model Arabidopsis thaliana and rat liver plasma membranes. Colloids Surf. B Biointerfaces
2015,130, 53–60. [CrossRef]
12.
Gonin, M.; Bergougnoux, V.; Nguyen, T.D.; Gantet, P.; Champion, A. What Makes Adventitious Roots? Plants
2019
,8, 240.
[CrossRef]
13.
Abu-Zahra, T.R.; Al-Shadaideh, A.N.; Abubaker, S.M.; Qrunfleh, I.M. Influence of auxin concentrations on different ornamental
plants rooting. Int. J. Bot. 2013,9, 96–99. [CrossRef]
14.
Zheng, L.; Xiao, Z.B.; Song, W.T. Effects of substrate and exogenous auxin on the adventitious rooting of Dianthus caryophyllus L.
Hortic. Sci. 2020,55, 170–173. [CrossRef]
15.
Babaie, H.; Zarei, H.; Nikdel, K.; Firoozjai, M.N. Effect of different concentrations of IBA and time of taking cutting on rooting,
growth and survival of Ficus binnendijkii ‘Amstel Queen’ cuttings. Not. Sci. Biol. 2014,6, 163–166. [CrossRef]
16.
Bryant, P.H.; Trueman, S.J. Stem anatomy and adventitious root formation in cuttings of Angophora, Corymbia and Eucalyptus.
Forests 2015,6, 1227–1238. [CrossRef]
17.
Lei, C.; Fan, S.; Li, K.; Meng, Y.; Mao, J.; Han, M.; Zhao, C.; Bao, L.; Zhang, D. iTRAQ-based proteomic analysis reveals potential
regulation networks of IBA-induced adventitious root formation in apple. Int. J. Mol. Sci. 2018,19, 667. [CrossRef]
18.
Hartmann, H.T.; Kester, D.E.; Davies, F.T.; Geneve, R.L. Plant Propagation: Principles and Practices; Prentice Hall: Hoboken, NJ, USA, 2002.
19.
Erci¸sli, S.; E¸sitken, A.; Anapali, O.; ¸Sahin, U. Effects of substrate and iba-concentration on adventitious root formation on
hardwood cuttings of rosa dumalis. Acta Hortic. 2005,690, 149–152. [CrossRef]
20.
Ribeiro, M.M.; Collado, L.M.; Antunes, M.A. The influence of indole-3-butyric-acid in Prunus laurocerasus vegetative propagation.
Acta Hortic. 2008,885, 277–283. [CrossRef]
21.
Grigoriadou, K.; Sarropoulou, V.; Krigas, N.; Maloupa, E. Vegetative and
in vitro
propagation of the medicinal and ornamental
plant Astragalus suberosus subsp. Haarbachii (Fabaceae). Eur. J. Hortic. Sci. 2022,87, 1–9. [CrossRef]
22.
Cano, A.; Sánchez-García, A.B.; Albacete, A.; González-Bayón, R.; Justamante, M.S.; Ibáñez, S.; Pérez-Pérez, J.M. Enhanced
conjugation of auxin by GH3 enzymes leads to poor adventitious rooting in carnation stem cuttings. Front. Plant Sci.
2018
,9, 566.
[CrossRef] [PubMed]
23.
Shiri, M.; Mudyiwa, R.M.; Takawira, M.; Musara, C.; Gama, T. Effects of rooting media and indole-3-butyric acid (IBA)
concentration on rooting and shoot development of Duranta erecta tip cuttings. Afr. J. Plant Sci. 2019,13, 279–285. [CrossRef]
24.
Bulgari, R.; Franzoni, G.; Ferrante, A. Biostimulants application in horticultural crops under abiotic stress conditions. Agronomy
2019,9, 306. [CrossRef]
25.
Cuadrado, C.J.L.; Pinillos, E.O.; Tito, R.; Mirones, C.S.; Gamarra Mendoza, N.N. Insecticidal properties of capsaicinoids and
glucosinolates extracted from Capsicum chinense and Tropaeolum tuberosum.Insects 2019,10, 132. [CrossRef] [PubMed]
26.
Campobenedetto, C.; Mannino, G.; Beekwilder, J.; Contartese, V.; Karlova, R.; Bertea, C.M. The application of a biostimulant
based on tannins affects root architecture and improves tolerance to salinity in tomato plants. Sci. Rep. 2021,11, 354. [CrossRef]
[PubMed]
27.
EU. Regulation of the European Parliament and of the Council Laying Down Rules on the Making Available on the Market of EU
Fertilising Products and Amending Regulations (EC) No 1069/2009 and (EC) No 1107/2009 and Repealing Regulation (EC) No
2003/2003. Off. J. Eur. Union
2019
,62, 1–114. Available online: https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=OJ:L:
2019:170:TOC (accessed on 3 June 2022).
Agriculture 2023,13, 513 13 of 15
28.
Ali, O.; Ramsubhag, A.; Jayaraman, J. Biostimulant properties of seaweed extracts in plants: Implications towards sustainable
crop production. Plants 2021,10, 531. [CrossRef]
29.
Ertani, A.; Francioso, O.; Tinti, A.; Schiavon, M.; Pizzeghello, D.; Nardi, S. Evaluation of seaweed extracts from Laminaria and
Ascophyllum nodosum spp. As biostimulants in Zea mays L. using a combination of chemical, biochemical and morphological
approaches. Front. Plant Sci. 2018,9, 428. [CrossRef]
30.
Shukla, P.S.; Mantin, E.G.; Adil, M.; Bajpai, S.; Critchley, A.T.; Prithiviraj, B. Ascophyllum nodosum-based biostimulants: Sustainable
applications in agriculture for the stimulation of plant growth, stress tolerance, and disease management. Front. Plant Sci.
2019
,
10, 655. [CrossRef]
31.
Afonso, N.C.; Catarino, M.D.; Silva, A.; Cardoso, S.M. Brown macroalgae as valuable food ingredients. Antioxidants
2019
,8, 365.
[CrossRef]
32.
Franzoni, G.; Cocetta, G.; Prinsi, B.; Ferrante, A.; Espen, L. Biostimulants on Crops: Their Impact under Abiotic Stress Conditions.
Horticulturae 2022,8, 189. [CrossRef]
33.
Hrólfsdóttir, A.Þ.; Arason, S.; Sveinsdóttir, H.I.; Gudjónsdóttir, M. Added Value of Ascophyllum nodosum Side Stream Utilization
during Seaweed Meal Processing. Mar. Drugs 2022,20, 340. [CrossRef]
34.
Battacharyya, D.; Babgohari, M.Z.; Rathor, P.; Prithiviraj, B. Seaweed extracts as biostimulants in horticulture. Sci. Hortic.
2015
,
196, 39–48. [CrossRef]
35.
Zhang, X.; Ervin, E.H. Impact of seaweed extract-based cytokinins and zeatin riboside on creeping bent grass heat tolerance. Crop
Sci. 2008,48, 364–370. [CrossRef]
36.
Wang, Y.; Fu, F.; Li, J.; Wang, G.; Wu, M.; Zhan, J.; Chen, X.; Mao, Z. Effects of seaweed fertilizer on the growth of Malus hupehensis
Rehd. Seedlings, soil enzyme activities and fungal communities under replant condition. Eur. J. Soil Biol.
2016
,75, 1–7. [CrossRef]
37.
Stirk, W.A.; Rengasamy, K.R.R.; Kulkarni, M.G.; van Staden, J. Plant Biostimulants from Seaweed. In The Chemical Biology of Plant
Biostimulants; John Wiley & Sons, Ltd.: Hoboken, NJ, USA, 2020; pp. 31–55. ISBN 978-1-119-35725-4.
38.
Kulkarni, M.G.; Rengasamy, K.R.R.; Pendota, S.C.; Gruz, J.; Plaˇcková, L.; Novák, O.; Doležal, K.; Van Staden, J. Bioactive molecules
derived from smoke and seaweed Ecklonia maxima showing phytohormone-like activity in Spinacia oleracea L. New Biotechnol.
2019,48, 83–89. [CrossRef]
39.
Petropoulos, S.A. Practical Applications of Plant Biostimulants in Greenhouse Vegetable Crop Production. Agronomy
2020
,10,
1569. [CrossRef]
40.
Stepowska, A. Effects of GA 142 (Goëmar Goteo) and GA 14 (Goëmar BM86) extracts on sweet pepper yield in non-heated
tunnels. In Solanaceous Crops; Zbigniew, T.D., Ed.; Editorial House Wie’s Jutra: Warsaw, Poland, 2008; p. 45.
41.
Francke, A.; Majkowska-Gadomska, J.; Kaliniewicz, Z.; Jadwisie
´
nczak, K. No Effect of Biostimulants on the Growth, Yield and
Nutritional Value of Shallots Grown for Bunch Harvest. Agronomy 2022,12, 1156. [CrossRef]
42.
Loconsole, D.; Cristiano, G.; De Lucia, B. Improving Aerial and Root Quality Traits of Two Landscaping Shrubs Stem Cuttings by
Applying a Commercial Brown Seaweed Extract. Horticulturae 2022,8, 806. [CrossRef]
43.
Lötze, E.; Hoffman, E.W. Nutrient composition and content of various biological active compounds of three south African-based
commercial seaweed biostimulants. J. Appl. Phycol. 2016,28, 1379–1386. [CrossRef]
44.
Szabó, V.; Sárvári, A.; Hrotkó, K. Treatment of stockplants with biostimulators and their effects on cutting propagation of Prunus
marianna‘GF 8-1’. Acta Hortic. 2011,923, 277–281. [CrossRef]
45.
Traversari, S.; Cacini, S.; Nesi, B. Seaweed Extracts as Substitutes of Synthetic Hormones for Rooting Promotion in Rose Cuttings.
Horticulturae 2022,8, 561. [CrossRef]
46.
Gilman, G.F.; Watson, D.G. Photinia
×
fraseri—Fraser Photinia. Fact Sheet ST-447. 1994. Available online: https://hort.ufl.edu/
trees/PHOFRAA.pdf (accessed on 1 November 2022).
47.
Larraburu, E.E.; Apóstolo, N.M.; Llorente, B.E. Anatomy and morphology of photinia (Photinia
×
fraseri Dress)
in vitro
plants
inoculated with rhizobacteria. Trees 2010,24, 635–642. [CrossRef]
48.
Dirr, M.A. Tolerance of Leyland Cypress and Red-Tip Photinia to Soil and Foliar Applied Sodium Chloride. J. Environ. Hortic.
1990,8, 154–155. [CrossRef]
49.
Bonaminio, V.P.; Blazich, F.A. Response of Fraser’s photinia stem cuttings to selected rooting compounds. J. Environ. Hortic.
1983
,
1, 9–11. [CrossRef]
50.
Khan, W.; Rayirath, U.P.; Subramanian, S.; Jithesh, M.N.; Rayorath, P.; Hodges, D.M. Seaweed extracts as biostimulants of plant
growth and development. J. Plant Growth Regul. 2009,28, 386–399. [CrossRef]
51.
Paradikovi´c, N.; Tekli´c, T.; Zeljkovi´c, S.; Lisjak, M.; Špoljarevi´c, M. Biostimulants research in some horticultural plant species—A
review. Food Energy Secur. 2019,8, e00162. [CrossRef]
52.
Kisvarga, S.; Farkas, D.; Boronkay, G.; Neményi, A.; Orlóci, L. Effects of Biostimulants in Horticulture, with Emphasis on
Ornamental Plant. Agronomy 2022,12, 1043. [CrossRef]
53.
Cardoso, J.C.; Vendrame, W.A. Innovation in Propagation and Cultivation of Ornamental Plants. Horticulturae
2022
,8, 229.
[CrossRef]
54.
Monder, M.J.; Kozakiewicz, P.; Jankowska, A. Anatomical structure changes in stem cuttings of rambler roses induced with plant
origin preparations. Sci. Hortic. 2019,255, 242–254. [CrossRef]
55.
Pacholczak, A.; Nowakowska, K.; Mika, N.; Borkowska, M. The effect of the biostimulator Goteo on the rooting of ninebark stem
cuttings. Folia Hortic. 2016,28, 109–116. [CrossRef]
Agriculture 2023,13, 513 14 of 15
56.
Pacholczak, A.; Nowakowska, K. The Effect of Biostimulators and Indole-3-Butyric Acid on Rooting of Stem Cuttings of Two
Ground Cover Roses. Acta Agrobot. 2020,73, 1. [CrossRef]
57.
Hammo, Y.H.; Kareem, B.A.; Salih, M.I. Effect of planting date and IBA concentration on rooting ability of stem cutting of Fraser’s
Photinia (Photinia x fraseri). IOSR J. Agr. Vet. Sci. 2013,5, 51–54. [CrossRef]
58.
Hasan, N.S.; Hammo, Y.H. Influence of IBA and media on rooting percentage and growth of semi-hardwood cuttings of red-tip
Photinia plant (Photinia x fraseri). J. Duhok Univ. 2021,24, 114–119. [CrossRef]
59.
Stirk, W.A.; Tarkowská, D.; Tureˇcová, V.; Strnad, M.; Van Staden, J. Abscisic acid, gibberellins and brassinosteroids in Kelpak
®
, a
commercial seaweed extract made from Ecklonia maxima. J. Appl. Phycol. 2014,26, 561–567. [CrossRef]
60.
Gajc-Wolska, J.; Kowalczyk, K.; Nowecka, M.; Mazur, K.; Metera, A. Effect of organic-mineral fertilizers on the yield and quality
of endive (Cichorium endivia L.). Acta Sci. Pol. Hortorum Cultus 2012,11, 189–200.
61. Matysiak, K.; Kaczmarek, S.; Kierzek, R.; Kardasz, P. Effect of seaweeds extracts and humic and fulvic acids on the germination
and early growth of winter oilseed rape (Brassica napus L.). J. Agric. Eng. Res. 2010,55, 28–32.
62.
Calkins, M. The Sustainable Sites Handbook: A Complete Guide to the Principles, Strategies, and Best Practices for Sustainable Landscapes;
John Wiley & Sons: Hoboken, NJ, USA, 2012; Volume 39.
63.
Lustosa Sobrinho, R.; Zoz, T.; Finato, T.; Oliveira, C.E.d.S.; Neto, S.S.d.O.; Zoz, A.; Alaraidh, I.A.; Okla, M.K.; Alwasel, Y.A.;
Beemster, G.; et al. Jatropha curcas L. as a Plant Model for Studies on Vegetative Propagation of Native Forest Plants. Plants
2022
,
11, 2457. [CrossRef]
64.
Ikeuchi, M.; Sugimoto, K.; Iwase, A. Plant Callus: Mechanisms of Induction and Repression. Plant Cell
2013
,25, 3159–3173.
[CrossRef]
65.
Skoog, F.; Miller, C.O. Chemical regulation of growth and organ formation in plant tissues cultured
in vitro
.Symp. Soc. Exp. Biol.
1957,11, 118–130.
66.
Khan, W.; Hiltz, D.; Critchley, A.T.; Prithiviraj, B. Bioassay to detect Ascophyllum nodosum extract-induced cytokinin-like activity
in Arabidopsis thaliana. J. Appl. Phycol. 2011,23, 409–414. [CrossRef]
67.
Monder, M.J.; Kozakiewicz, P.; Jankowska, A. The Role of Plant Origin Preparations and Phenological Stage in Anatomy Structure
Changes in the Rhizogenesis of Rosa “Hurdal”. Front. Plant Sci. 2021,7, 12. [CrossRef]
68.
Costa, J.M.; Heuvelink, E.; Pol, P.A.; Put, H.M.C. Anatomy and morphology of rooting in leafy rose stem cuttings and starch
dynamics following severance. Acta Hortic. 2007,751, 495–502. [CrossRef]
69.
Fouda, R.A.; Schmidt, G. Histological changes in the stems of some Rosa species propagated by leafy cuttings as affected by IBA
treatments. Acta Agron. Hungar. 1994,43, 265–275.
70.
Martins, M.; Gomes, A.F.G.; da Silva, É.M.; da Silva, D.F.; Peche, P.M.; Magalhães, T.A.; Pio, R. Effects of anatomical structures
and phenolic compound deposition on the rooting of olive cuttings. Rhizosphere 2022,23, 100557. [CrossRef]
71.
Li, S.W.; Xue, L.; Xu, S.; Feng, H.; An, L. Mediators, genes and signaling in adventitious rooting. Bot. Rev.
2009
,75, 230–247.
[CrossRef]
72.
Della Rovere, F.; Fattorini, L.; D’Angeli, S.; Veloccia, A.; Falasca, G.; Altamura, M.M. Auxin and cytokinin control formation of the
quiescent centre in the adventitious root apex of Arabidopsis. Ann. Bot. 2013,112, 1395–1407. [CrossRef]
73.
Blazich, F.A. Chemicals and Formulations Used to Promote Adventitious Rooting. In Adventitious Root Formation in Cuttings;
Davis, T.D., Haissig, B.E., Sankhla, N., Eds.; Dioscorides Press: Portland, OR, USA, 1988; pp. 132–149.
74.
Carpenter, W.J.; Cornell, J.A. Auxin application duration and concentration govern rooting of Hibiscus stem cuttings. J. Am. Soc.
Hort. Sci. 1992,117, 68–74. [CrossRef]
75.
Iapichino, G.; Arnone, C.; Bertolino, M.; AmicoRoxas, U. Propagation of three Thymus species by stem cuttings. Acta Hort.
2006
,
723, 411–413. [CrossRef]
76.
Sabatino, L.; D’anna, F.; Iapichino, G. Cutting type and IBA treatment duration affect Teucrium fruticans adventitious root quality.
Not. Bot. Horti Agrobot. Cluj Napoca 2014,42, 478–481. [CrossRef]
77.
Kashefi, M.; Zarei, H.; Bahadori, F. The Effect of Indole Butyric Acid and the Time of Stem Cutting Preparation on Propagation of
Damask Rose Ornamental Shrub. JOP 2014,4, 237–243.
78.
Pacholczak, A. The effect of the auxin application methods on rooting of Physocarpus opulifolius Maxim. cuttings. Propag.
Ornam. Plants 2015,15, 147–153.
79.
Zhang, L.; Wang, S.; Guo, W.; Zhang, Y.; Shan, W.; Wang, K. Effect of Indole-3-Butyric Acid and rooting substrates on rooting
response of hardwood cuttings of Rhododendron fortune Lindl. Propag. Ornam. Plants 2015,15, 79–86.
80.
Kaviani, B.; Gholami, S. Improvement of Rooting in Forsythia
×
intermedia Cuttings by Plant Growth Regulators. JOP
2016
,6,
125–131.
81.
Sabatino, L.; D’Anna, F.; Iapichino, G. Improved Propagation and Growing Techniques for Oleander Nursery Production.
Horticulturae 2019,5, 55. [CrossRef]
82.
Kashyap, U.; Chandel, A.; Sharma, D.; Bhardwaj, S.; Bhargava, B. Propagation of Jasminum parkeri: A Critically Endangered
Wild Ornamental Woody Shrub from Western Himalaya. Agronomy 2021,11, 331. [CrossRef]
83.
Dick, J.M.; Leakey, R.R.B. Differentiation of the dynamic variables affecting rooting ability in juvenile and mature cuttings of
cherry (Prunus avium). J. Hortic. Sci. Biotechnol. 2006,81, 296–302. [CrossRef]
84.
Sikorska, A.; Gugała, M.; Zarzecka, K.; Doma ´nski, Ł.; Mystkowska, I. Morphological Features of Winter Rape Cultivars Depending
on the Applied Growth Stimulators. Agriculture 2022,12, 1747. [CrossRef]
Agriculture 2023,13, 513 15 of 15
85.
Chanthini, K.M.-P.; Senthil-Nathan, S.; Pavithra, G.-S.; Asahel, A.-S.; Malarvizhi, P.; Murugan, P.; Deva-Andrews, A.; Sivanesh, H.;
Stanley-Raja, V.; Ramasubramanian, R.; et al. The Macroalgal Biostimulant Improves the Functional Quality of Tomato Fruits
Produced from Plants Grown under Salt Stress. Agriculture 2023,13, 6. [CrossRef]
86.
Sujeeth, N.; Petrov, V.; Guinan, K.J.; Rasul, F.; O’Sullivan, J.T.; Gechev, T.S. Current Insights into the Molecular Mode of Action
of Seaweed-Based Biostimulants and the Sustainability of Seaweeds as Raw Material Resources. Int. J. Mol. Sci.
2022
,23, 7654.
[CrossRef]
87.
Gomes, E.N.; Vieira, L.M.; Tomasi, J.D.C.; Tomazzoli, M.M.; Grunennvaldt, R.L.; Fagundes, C.D.M.; Machado, R.C.B. Brown
seaweed extract enhances rooting and roots growth on Passiflora actinia Hook stem cuttings. Ornam. Hortic.
2018
,24, 269–276.
[CrossRef]
88.
Toscano, S.; Ferrante, A.; Branca, F.; Romano, D. Enhancing the Quality of Two Species of Baby Leaves Sprayed with Moringa
Leaf Extract as Biostimulant. Agronomy 2021,11, 1399. [CrossRef]
89.
Kapczy´nska, A.; Kowalska, I.; Prokopiuk, B.; Pawłowska, B. Rooting Media and Biostimulator Goteo Treatment Effect the
Adventitious Root Formation of Pennisetum ‘Vertigo’ Cuttings and the Quality of the Final Product. Agriculture
2020
,10, 570.
[CrossRef]
90.
Nowakowska, K.; Pacholczak, A. Effect of the biopreparation “Goteo” on rooting of Hydrangea stem cuttings (Hydrangea
paniculata siebold Limelight and Vanille Freise® Renhy). Propag. Ornam. Plants 2017,17, 126–133.
91.
Salachna, P.; Zawadzinska, A.; Piechocki, R.; Wilas, J. Propagation of arabian star flower (Ornithogalum arabicum L.) by twin scales
using seaweed extracts. Folia Pomeranae Univ. Technol. Stetin. 2014,310, 105–112.
92.
Aremu, A.O.; Makhaye, G.; Tesfay, S.Z.; Gerrano, A.S.; Du Plooy, C.P.; Amoo, S.O. Influence of Commercial Seaweed Extract
and Microbial Biostimulant on Growth, Yield, Phytochemical Content, and Nutritional Quality of Five Abelmoschus esculentus
Genotypes. Agronomy 2022,12, 428. [CrossRef]
93.
Makhaye, G.; Aremu, A.O.; Gerrano, A.S.; Tesfay, S.; Du Plooy, C.P.; Amoo, S.O. Biopriming with seaweed extract and microbial-
based commercial biostimulants influences seed germination of five Abelmoschus esculentus genotypes. Plants
2021
,10, 1327.
[CrossRef]
94.
Pacholczak, A.; Szydło, W.; Jacygrad, E.; Federowicz, M. Effect of auxins and the biostimulator AlgaminoPlant on rhizogenesis
in stem cuttings of two dogwood cultivars (Cornus alba ‘Aurea’ and ‘Elegantissima’). Acta Sci. Pol. Hortorum Cultus
2012
,11,
93–103.
95.
Rathore, S.; Chaudhary, D.; Boricha, G.; Ghosh, A.; Bhatt, B.; Zodape, S.; Patolia, J. Effect of seaweed extract on the growth, yield
and nutrient uptake of soybean (Glycine max) under rainfed conditions. S. Afr. J. Bot. 2009,75, 351–355. [CrossRef]
96.
Kocira, A.; Lamorska, J.; Kornas, R.; Nowosad, N.; Tomaszewska, M.; Leszczy´nska, D.; Kozłowicz, K.; Tabor, S. Changes in
biochemistry and yield in response to biostimulants applied in bean (Phaseolus vulgaris L.). Agronomy 2020,10, 189. [CrossRef]
97.
Caccialupi, G.; Caradonia, F.; Ronga, D.; Ben Hassine, M.; Truzzi, E.; Benvenuti, S.; Francia, E. Plant Biostimulants Increase the
Agronomic Performance of Lavandin (Lavandula x intermedia) in Northern Apennine Range. Agronomy
2022
,12, 2189. [CrossRef]
98.
Quan, J.; Ni, R.; Wang, Y.; Sun, J.; Ma, M.; Bi, H. Effects of Different Growth Regulators on the Rooting of Catalpa bignonioides
Softwood Cuttings. Life 2022,12, 1231. [CrossRef]
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