Physiological and molecular responses to high temperature in chickpea (Cicer arietinum L.)
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Date
2013
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CCSHAU
Abstract
The present investigations were carried out on two chickpea (Cicer arietinum L.) genotypes viz. ICCV 92944 and HC 5 to test their tolerance against high temperature. High temperature stress was given by manipulation of sowing dates under field conditions i.e. normal sown (10th November, 2010) and late sown (14th December, 2010) during 1st year and normal sown (NS) (11th November, 2011) and late sown (LS) (16th December, 2011) during 2nd year. The sampling was done as the temperature rises above 30°C at reproductive phase at 4, 8, and 12 days after exposure (DAE) and the control sampling was done the temperature below 30°C.
High temperature adversely affected plant water status of both the genotypes. The water potential and osmotic potential of leaf became more negative with increased period DAE to high temperature and relative water content of leaf declined significantly at all samplings. A sharp rise in proline content i.e. from 1.79 to 22.62 (μ mol g-1 DW) and 2.05 to 15.53 was noticed in leaves of genotype ICCV 92944 and HC 5, respectively. TSC content also increased. The MDA content increased from 22.68 to 39.26 (μ mol g-1 DW) with increase period of DAE to high temperature. MDA and H2O2 content were estimated to be highest in leaves of HC 5 than ICCV 92944. With the increasing period DAE to high temperature relative stress injury (%) was increased, with a minimum in ICCV 92944 (29.52%) than in HC 5 (46.13%). At 12 DAE, ICCV 92944 and HC 5 possessed 11.25% and 30.67% lower total chlorophyll, respectively. However, genotype ICCV 92944 maintained comparatively higher photosynthetic pigments as compared to HC 5. The ratio of chlorophyll a:b and chlorophyll a: carotenoid were increased i.e. from 10.23 to 12.73 and 2.56 to 4.49, respectively upon increasing DAE, with maximum in ICCV 92944 (12.24 and 3.79) and minimum was in HC 5 (11.18 and 3.30), respectively. The maximum CSI (%) was observed in ICCV 92944 (76%) as compared to HC 5 (59.59%) at 12 DAE. At 12 DAE maximum Fv/Fm, SPAD and less CTD values i.e. 0.69, 54.77, -3.56, respectively were recorded in ICCV 92944 and minimum i.e. 0.60, 49.20, -2.95, respectively were in HC 5 genotype. High temperature stress induced the antioxidant defense system by increasing the specific activity of antioxidant enzymes (SOD, CAT, POX, APX, GR, GPX and GST) in concomitant with increase in ascorbate and glutathione content in both the genotypes, but they could not overcome the increase in H2O2 content.
There was a significant reduction in pollen viability (80.48) and pollen load (29.66) in HC 5 compared with ICCV 92944 (91.27 and 31.09), respectively. High temperature significantly reduced the plant height, number of branches per plant, days to maturity, duration of reproductive phase, number of pods per plant and 100 seed weight under LS condition. The reduction was also observed in biological yield, seed yield and yield components under LS compared to that of NS. Based on mean performance of chickpea genotypes for yield and its components, the genotype ICCV 92944 was found to have high values than HC 5. Genotype ICCV 92944 also showed low value of HIS, high value of HI and YS.
In genotype HC 5, high temperature caused disappearance of some specific proteins in leaves, i.e. bands of MW 35.48, 28.84, 23.44, 19.95, 11.59 and 8.51 kDa, but new bands of MW 102.33, 56.26, 33.48, 12.48, and 6.92 were appeared. Similarly in genotype ICCV 92944, protein bands with MW 81.28, 73.29, 67.25, 63.10, and 5.62 kDa were disappeared and newly formed protein bands with MW 151.36, 93.05, 91.20, 63.09, 30.48, 13.18, 8.12, 7.28 and 5.01 kDa were appeared with increasing period of DAE. Increase/decrease in the intensities of certain bands observed in both genotypes. Based on above physiological, biochemical, antioxidant defense system, reproductive behavior and protein profile studies and yield characters, it is concluded that genotype ICCV 92944 showed better performance under high temperature than HC 5 and in future these traits can be used in crop improvement programme.
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Keywords
Planting, Genotypes, Chickpeas, Biological phenomena, Tolerance, Enzymes, Irrigation, Developmental stages, Yields, Proteins