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SCREENING OF RABI SORGHUM GENOTYPES UNDER VARIED MOISTURE REGIMES FOR
PHYSIOLOGICAL PERFORMANCE AND ADAPTABILITY TO DROUGHT STRESS
Abstract ID: IC-T4-030
Brahmesh Reddy B R*, Kiran B O, Somanagouda B Patil, Ashwathama V H
Department of Plant Physiology, University of Agricultural Sciences, Dharwad
Correspond ing author: b r a h m eshcph@y a h o o . c o m
Abiotic stresses, in particular, drought and heat, are
the significant factors limiting the crop yield in arid and semi-arid
regions, where sorghum is an essential component of the cropping
systems. Much of the impact due to stress results from an effect on
crucial physiological processes such as canopy temperature
Introduction
•Understand the effects of drought stress on canopy temperature
•Test the hypothesis that cooler canopy can be used to screen
sorghum plants are exposed to drought stress.
Objectives
•Experimental site: AICRP on Sorghum at the RARS, Vijayapura using
18 rabi sorghum genotypes in both irrigated and stressed conditions.
•Gas-exchange parameters:LI - 6800 portable infrared gas analyzer
(LI-COR Biosciences, Lincoln, NE, USA). The observations were
recorded at soft dough stage between 10:00 and 14:00 IST.
•Canopy temperature: An infrared thermocouple was used to record
the canopy temperatures which was placed at one meter height from
the top most leaf of that particular genotype. The canopy temperature
depression is the difference between the canopy temperature and the
ambient air temperature.
Phule Anuradha (16.30 µmol/m2/s) and RSV 1876 (16.22 µmol/m2/s)
achieved highest photosynthetic rate under the stressed regime. Similar
trend was observed with transpiration rate and stomatal conductance.
The lowest canopy temperature was achieved by RSV 1876 (34.5 ℃)
followed by Phule Anuradha (34.6℃).
CRS 99 had the highest canopy depression of 2.2℃followed by RNTN-
13-39 showing 2.1℃of depression in the irrigated regime. Similarly, in the
stressed regime, genotype RSV 1876 because of having lowest canopy
temperature resulted in highest canopy temperature depression of 1.7℃
followed by Phule Anuradha with 1.6℃depression
The correlation was observed between the canopy temperature
depression and the grain yield [RSV 1876 (53.65 g) and Phule Anuradha
(52.09 g)] produced under the water stressed condition.
The canopy temperature serves as a
physiological screening parameter and
genotype with cooler canopy can be considered
as drought tolerant or can be promoted for
stricter screening and evaluation
33.90
34.10
34.30
34.50
34.70
34.90
35.10
35.30
35.50
35.70
33.90
34.10
34.30
34.50
34.70
34.90
35.10
35.30
35.50
35.70
RSV 1850 RSV 1876 RSV 1945 RSV 2371 CRS 89 CRS 93 CRS 95 CRS 98 CRS 99 VJP 2704 VJP 2705 RNTN-13-39 RNTN-14-1 RNTN-14-2 RNTN-14-3 M-35-1 P. Suchitra P. Anuradha
Canopy Temperature (℃)
Canopy Temperature (℃)
Graph 1. Canopy Temperature in Irrigated and Stressed regime
Irrigated Stressed
0.0
0.5
1.0
1.5
2.0
2.5
0.00
1.00
2.00
3.00
4.00
5.00
6.00
RSV 1876 P. Anuradha CRS 99 RNTN-13-39
Relationship between the Transpiration rate (E), Stomatal conductance (GSW) and Canopy temperature
epression (CTD)
E CTD GSW
Plates
Summary
A A F S - 2 0 2 2
22- 2 4 A u g u s t 2 0 2 2
U n i v e r s i t y o f A g r i c u l t u r a l S c i e n c e s ,
B a n g a l o r e
Methods
The differences between the irrigated and stressed regime
Assimilation rate
37%
Transpiration rate
32%
Stomatal Conductance
36%
Results
The water stress resulted significant reduction in photosynthetic rate
and maintaining higher net photosynthetic rate under the water stress
condition is a sign of tolerance to drought in drought stress (Rajarajan et
al., 2021). In view of this research the genotypes RSV 1876 and Phule
Anuradha can be considered as drought tolerant, given that they both
possess highest transpiration rates under the drought stress.
Rajarajan et al. (2021) suggested that higher transpiration rate might
make the genotype’s internal plant system cooler by relieving the plant’s
heat. The lower stomatal conductance associated with higher
transpiration rate is said to have higher transpirational efficiency. In
reference to this statement, it can be said that the genotypes RSV 1876
and Phule Anuradha gain highest transpirational efficiency among the
genotypes under this study. A strong significant negative correlation of
canopy temperature with the gas exchange parameters specially the
transpiration rate (-0.96**) signifies that the canopy temperature is
determined by the water vapor escaping the leaf surface.
Discussion
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