Effects of SA priming (0.25 & 0.5mM) on germination percentage (after 48 hrs) & germination rate of rice under varying concentrations of Cr (0, 25, 50 & 100μM). The data represented as mean value of observations (n=3) ± SE. 

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... leaf material (100mg) was taken with 0.1g catalyst mixture (CuSO 4 , FeSO 4 and K 2 SO 4 ) and heated with 2ml conc. H 2 SO 4 in Kjeldhal digestion tubes for 2hrs and then transferred to titration unit of Micro-Kjeldhal apparatus for titration process. At the end, the nitrogen content was determined by the formula recommended by Pellet & Young (1980). Proline Determination Chlorophyll Determination and glycinebetaine and of of Nitrogen carotenoid ions (Na content: analysis: + , K content: + and Nitrogen Proline Ca The +2 & content content method Cr): was The was of determined determined Lichtenthaler contents of ions by by & slightly using were Wellburn, determined the modified Micro-Kjeldahl (1985) by method slightly was of apparatus. used modifying Bates for et Dry al., the the (1973). leaf determination method material of Fresh Awan (100mg) of leaf chlorophyll & sample Salim was taken (1997). (100mg) and with carotenoids Well was 0.1g powdered homogenized catalyst pigments dry mixture leaf by in 3.5% (CuSO extraction material 4 sulphosalicylic , (25mg) FeSO with 4 methanol and was K heat 2 acid SO and digested 4 ) and and absorbance heated with centrifuged. conc. with was found H 2ml 2 SO In 4 conc. with 1ml and supernatant, hydrogen UV-visible H 2 SO 4 in peroxide Kjeldhal spectrophotometer 1ml of in acid a digestion 2:1 ninhydrin ratio at (v/v). tubes three was After for added wavelengths: 2hrs digestion, followed and each 666, then by transferred 1ml sample 653 of and glacial was 470nm. to diluted titration acetic with The acid unit 20ml and chlorophyll of Micro-Kjeldhal deionized. heated at “a, 100oC Ion b” contents apparatus for and 1hr. (Na total The for + , titration mixture carotenoids K + and was Ca process. +2 then ) contents were At extracted analyzed the were end, with determined by the 2ml flame nitrogen toluene photometer. by content and formula proline was Cr determined was content suggested determined was by by Lichtenthaler determined the spectrophotometrically formula by & method Wellburn, recommended of (1985). Garraaud at 520nm by Pellet et from al., & Young upper (1996). colored (1980). First dry phase leaves after samples toluene of extraction. 100mg were L-Proline heat standard digested by curve acid was mixture used of for sulfuric comparing acid and sample nitric values. acid. The digested ash content was suitably diluted with deionized water to 20ml volume in all treated samples and used further for atomic absorption spectrophotometer. Proline and glycinebetaine analysis: Proline content was determined by slightly modified method of Bates et al., (1973). Fresh leaf sample (100mg) was homogenized in 3.5% sulphosalicylic acid and centrifuged. In 1ml supernatant, 1ml of acid ninhydrin was added followed by 1ml of glacial acetic acid and heated at 100oC for 1hr. The mixture was then extracted with 2ml toluene and proline was determined spectrophotometrically at 520nm from upper colored phase after toluene extraction. L-Proline standard curve was used for comparing sample values. Glycinebetaine was extracted by mechanical shaking finely ground-dried samples of leaves with deionized water for 24hrs. Glycinebetaine contents were determined spectrophotometrically after reaction with KI-I 2 at 365 nm and dissolving in 1-2, dicholoroethane (Grieve & Grattan, 1983). Final amounts were calculated from standard curve of glycinebetaine. Total soluble sugar and proteins: Total soluble sugar content was analyzed by phenol-sulphuric acid method of Dey et al., (1990) with slight modification by using 50mg fresh sample. Absorbance values were determined at 485nm wavelength. D-Glucose was used to make standard curve for determination of sample total sugar values. Total soluble protein was determined by following the method of Bradford (1976) by using Comassie G-250 as protein binding dye. Final amount of protein was calculated from standard curve obtained from bovine serum albumin. Statistical analysis: All the data was analyzed by the statistical software IBM SPSS v.20, presented as mean of triplicates and with standard error bars. Seed germination : Germination pattern of both the rice varieties Basmati-385 and Shaheen Basmati showed variations under the 0.25 & 0.50mM SA priming and at Cr stress treatments. Germination percentage (GP) decreased in both the varieties under increasing Cr stress (Fig.1). Maximum GP (100%) under non stress conditions was observed after 48hrs of interval in control (hydroprimed) and SA primings in B-385 variety while in SB, 100% GP was noted at SA 0.50mM priming treatment. In both varieties Cr stress treatments reduced the GP as the stress was increased and lowest GP of 57% and 50% were recorded at 100μM of stress in B-385 & SB respectively. In SA treatments, GPs were higher in comparison to respective stress treatments. Germination rate (GR) (1/t 50 ) i.e. the time required for 50% seeds to germinate was also lowered in both the varieties under varying Cr stresses (Fig. 1). Maximum GR was noted in control and SA priming treatments. Reduction in GR was prominent at 25, 50 and 100μM Cr stress in B385 and SB; however, with SA priming obvious elevations in GR were noted Seedling vigor : In both varieties, for SA priming treatments and control the root and shoot lengths improved sufficiently while gradual reduction in lengths were observed under increasing concentrations of Cr (Fig. 2). In B385, lowest root length was ~4cm under 100μM stress and 3.9cm in SB. SA priming alone and under stress had improved lengths at respective Cr concentrations. Same pattern was seen in shoot length measurements. SA priming prominently improved shoot lengths and the highest values 9.35 & 6.15cm at 0.50mM for B-385 and SB were noted. Under stress condition, shoot length decreased significantly. The fresh and dry biomass of roots and shoots decreased significantly but SA treatments were effective enough in alleviation of stress and helped in development of fresh and dry biomass as presented in Figs. 3 & 4. Cell membrane injury: Cell membrane injury elevated prominently with increase in Cr stress for B-385 and SB in comparison to control and SA priming treatments (Fig. 5). Significant elevation of cell injury was noted at 100μM stress of 57.8 and ~60μS/cm 2 as compared to control values of 24μS/cm 2 and 25μS/cm 2 in B-385 and SB respectively. SA showed a positive response in tolerating the damaging effects of Cr. Photosynthetic pigments: Chlorophyll and carotenoids contents decreased largely with increasing concentration of Cr. In control the chlorophyll a, b and carotenoids values were 6.7, 9.2 and ~660mg/g respectively which reduced to 0.72, 1.2 and 63 mg/g at 100μM Cr stress in B- 385. Same results pattern were observed in SB (Fig. 6). The SA priming under the subjected stress parameters showed higher values of photosynthetic pigments revealing the SA protective role during stress. Total Nitrogen : Total leaf nitrogen content in both varieties was higher in control and SA seed primed plants but the contents was lowered in stress conditions i.e. 1.19, 0.91 & 0.63 g/g in B-385 and 1.26, 0.9 & 0.63 g/g in SB at 25, 50 and 100μM Cr stresses respectively as presented in Fig. 8. SA primed treatments had higher N content at different Cr stress with respect to the stress applied to non SA primed rice plants. B-385 was more responsive to SA priming than SB under Cr toxicity. Ion contents: Considerable variations were observed in content of ions in leaves (Na + , K + and Ca 2 ) for rice plants treated under Cr stress. Under stress conditions, the content of Na + , K + and Ca 2+ ions decreased in both the varieties but with priming approach the ions contents were affected as in stress circumstances (Fig. 7). At 100μM Cr stress, lowest values of Na + , K + and Ca 2+ ions noted in B-385 and SB were 10 & 9.33ppm, 18 & 18.66ppm and 7.66 & 5.33ppm respectively. Chromium content: The increase in chromium content of leaves of both varieties was significant with the elevation of Cr stress as observed from Fig. 9. In control and SA priming, very low Cr content was detected i.e. ~0.012ppm for both varieties while the highest values were 1.7 and 2.0 ppm in100μM stress for B-385 and SB respectively. SA priming treatments under stress had lowered the Cr level to some extent while SB accumulated more Cr than B-385 at 100 μM ...