Analysis of emergence stage facilitates the evaluation of chickpea (Cicer arietinum L.) genotypes for salinity tolerance imparted by mycorrhizal colonization

Salinity is an ever-increasing constraint limiting crop production in arid and semi-arid regions. Arbuscular mycorrhiza (AM) helps host plant to cope with detrimental effects of salinity. Experiments were aimed to examine the hypothesis that emergence is a better stage to determine salt tolerance of chickpea genotypes than germination and genotypic variability in their tolerance ability at emergence and subsequent vegetative growth is the manifestation of differential benefits imparted by mycorrhiza. Investigations were carried out at germination and emergence stage of genotypes (PBG 5, GPF 2, PBG 1, BG 1053, L 550) at 0, 40, 60, 80 mM NaCl. Significant genotypic variations in salt tolerance were observed at emergence rather than germination because of greater inhibitory effects on seedling emergence. Percent mycorrhizal colonization (MC) and its resulting impact on respiration rate (RR) and salt tolerance index (STI) at emergence indicated that PBG 5, with lowest RR, highest STI and mycorrhiza benefit percentage was the most tolerant whereas, L 550 the most sensitive genotype. Genotypic variability recorded at 30 days was consistent with that at emergence stage. Superior salt tolerance of PBG 5 than L 550 could be attributed to higher correlation between MC and physio-biochemical traits (RWC, chlorophyll a/b, proline accumulation, antioxidant activities). The study supported the hypothesis that both emergence stage and mycorrhizal effectiveness are important determinants of salt tolerance in chickpea genotypes. Evaluation of genotypes for relative adaptation to salinity should include estimation of their differential salt tolerance at different growth stages and symbiotic effectiveness of AM .