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Subject: Plant Physiology × Author: Dharamvir × End date: 2018 × Start date: 2016 × Type: Thesis ×
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    ThesisItemOpen Access
    Physiological and biochemical responses of chickpea (Cicer arietinum L.) under salinity
    (CCSHAU, 2016) Dharamvir; Neeraj Kumar
    The present investigation was carried out with two chickpea genotypes viz. HC-3 and CSG- 8962 differing in their salt sensitivity, to study the high salinity induced changes in morphological, physiological, biochemical, reproductive behavior, protein profile, yield and its attributing character in the screen house conditions. Sampling was done at 50-60 and 80-90 days after sowing (DAS). The water potential (Ψw) of leaves, osmotic potential (Ψs) of leaves and roots decreased in both the genotypes under different salinity levels i.e. 2.0, 4.0 and 6.0 dS m-1. HC-3 showed more negative values Ψw of leaves i.e. from -0.47 to -0.54 MPa as compared to -0.45 to -0.51 MPa in CSG-8962, respectively with increasing salinity level from control to 6.0 dS m-1 at 50-60 DAS. Likewise, the Ψs of leaves decreased from -0.75 to -1.32 MPa in HC-3 and -0.62 MPa to -1.18 MPa in CSG-8962. A similar trend of change in the Ψw of leaves, Ψs of leaves and roots was observed at 80-90 DAS. With increase in salinity levels, RWC (%) of leaves and roots also declined in both the genotypes. RWC (%) was higher in HC-3 than CSG-8962 at 50-60 DAS. Dry weight (g plant-1) decreased with increase in salinity, decrease being less in HC-3 in shoots, roots and nodules than CSG-8962. The proline content of leaves increased significantly from 0.573 to 0.904 and 0.565 to 0.782 mg g-1 dry weight with increasing level of salinity from control to 6.0 dS m-1 at 50-60 DAS. Likewise, the total soluble carbohydrate (TSC) content of leaves also increased from 17.5 to 24.5 and 16.60 to 20.3 mg g-1 dry weight in HC-3 and CSG-8962, respectively. A marked increase in hydrogen peroxide (H2O2), lipid peroxidation (MDA content) and relative stress injury (RSI %) was noticed in leaves and roots which was much higher in CSG-8962 than HC-3 at 50-60 DAS. A similar trend was observed at 80-90 DAS. Salinity levels increased the Cl- concentration in leaves by 93.3 % in HC-3 and 120.1 % in CSG-8962, and SO4 - concentration in leaves by 11.1 % in HC-3 and 19.7 % in CSG-8962 respectively, at 6.0 dS m- 1 salinity levels as compared to their respective controls. The genotype HC-3 had overall lower accumulation of Cl- and SO4 2- than the CSG-8962. More negative values of Ψw of leaves, Ψs of leaves and roots and better accumulation of osmotically active solutes, i.e. proline, TSC of HC-3, helped in maintaining the higher RWC % of these organs than noticed in CSG-8962. The specific activities of ROS scavenging enzymes such as SOD, CAT, POX, APX, GPX, GR and GST increased in leaves of both the chickpea genotypes, upon increasing levels of salinity from control to 6.0 dS m-1 at 50-60 DAS. The increase was more in HC-3 as compared to CSG-8962. Despite the increase in the activity of these enzymes, AsA content decreased 42.3 % and 36.1 % in the leaves of CSG-8962 and HC-3, respectively. Higher activities of antioxidant enzymes, lower accumulation H2O2, MDA and AsA content in HC-3 than in CSG-8962 indicated that these enzymes play a key role in removal of ROS better in HC-3 than CSG-8962, thus minimizing the cellular damage caused by ROS under salinity levels. Pollen viability (%), in vitro pollen germination and tube length were also adversely affected with increasing salinity; the effect being most pronounced in CSG-8962. SDS-PAGE revealed more deletion than addition of polypeptide bands in CSG-8962 than HC-3 with increasing levels of salinity in leaves and roots at both the stages. The yield parameters like number of branches plant-1, number of pods plant-1, number of seeds plant-1, 100 seed weight and seed yield plant-1 decreased more in CSG- 8962 than HC-3 with increasing salinity levels. Hence, the mechanism of salt tolerance was better in HC-3 than in CSG-8962 as found from physiological, biochemical, reproductive behavior, protein profile, yield and its attributing traits studied.