P. Sathish

Variability in Drought Stress Induced Responses of Groundnut (Arachis hypogaea L.) Genotypes

Drought stress is one of the important abiotic stresses which can limit the crop growth and yield by altering various physiological and biochemical processes. Groundnut (Arachis hypogaea L.) is an important oil seed cash crop and can be affected by dry spells during critical pheno-phases. A field trial was conducted with six genotypes- JL-24, ICGV 91114, Narayani, Abhaya, Dharani and Greeshma in order to identify genotypic variability in physiological and biochemical changes that are triggered during drought stress. Drought stress imposition at flowering stage reduced Anet, gs, Tr and WUE. Reduction of Anet ranged from 60% (Abhaya) to 77% (ICGV 91114) whereas the reduction in Tr was lower. The genotypes Dharani and Abhaya with higher Anet and better intrinsic WUE at leaf level during stress period along with highest membrane stability index (MSI), higher accumulation of proline, FAA and total soluble proteins with better yield potentials proved to be tolerant to drought stress. The results indicated that response of groundnut genotypes to drought stress differed significantly and genotypes Dharani and Abhaya are likely to be tolerant to drought stress.

Impact of Elevated CO2 on Growth and Physiological Parameters of Groundnut (Arachis hypogaea L.) Genotypes

Impact of Elevated CO2 on Growth and Physiological Parameters of Groundnut (Arachis hypogaea L.) Genotypes Five groundnut (Arachis hypogaea L.) genotypes- JL-24, ICGV 91114, Narayani, Abhaya, Dharani were evaluated at elevated (550 ppm) CO2 in OTCs during 2013 kharif to assess the variability in growth, biomass and physiological parameters. Elevated CO2 enhanced biomass and physiological parameters of all the selected groundnut genotypes, however the magnitude of response varied. Total biomass of genotypes was improved by 19% at 550 ppm and maximum response (34%) was recorded in ICGV 91114 and Narayani. The genotype ICGV 91114 recorded significant improvement of leaf and root biomass, total biomass and specific leaf weight with elevated CO2. Genotype Dharani recorded maximum root length, shoot length and leaf area at flowering stage and JL-24 at pegging stage. At elevated CO2, higher biomass was allocated to stem in JL-24, to roots in ICGV 91114, and no influence in Dharani as compared to other genotypes revealing its differential influence on biomass allocation. Increased Anet at enhanced CO2 was recorded in all the genotypes and it ranged from 18% (Abhaya) to 36% (Narayani), and the less efficient genotype at ambient condition recorded highest response and vice versa. The response of gs to elevated CO2 varied, whereas reduced Tr was recorded in all genotypes. At 550 ppm, groundnut genotypes showed 44% improvement in leaf level intrinsic WUE and maximum advantage (62%) was registered by Dharani. It is evident that the magnitude of groundnut crop response to elevated CO2 is cultivar, growth stage and component specific.

In vitro screening of Vigna mungo genotypes for PEG induced moisture deficit stress

Two black gram (Vigna mungo L. Hepper) genotypes LBG20 and PU19 were selected to study the impact of PEG induced drought stress on seed germination, metabolite concentration and activities of antioxidant enzymes. Stress caused considerable decrease in germination and fresh weight of seedlings of both the genotypes. It led to increase in protein concentration, contents of starch and total soluble sugars while decrease was observed in the activities of antioxidant enzymes, contents of free amino acids, reducing sugar and total phenols. SDS-PAGE analysis indicated accumulation of some proteins with the germination under stress conditions. LBG20 which showed increase in soluble sugars, starch, proteins and higher activities of antioxidant enzymes was observed to be relatively more tolerant to drought stress over PU19.