Standardization of a screening technique for salinity tolerance in groundnut (Arachis hypogaea L.) and pigeonpea (Cajanus cajan L.)

Salinity affects plant growth, development and yield in approximately 100 M ha of arable land worldwide. Besides, various management options available the introduction of salinity tolerant varieties in such areas could partly ease the increasing global food demand. Here, six groundnut (ICG (FDRS) 10, ICGS 44, ICGS 76, ICGV 86031, JL 24, and TAG 24) and pigeonpea (ICPL 88039, ICPL 88034, ICPL 87119, ICPL 96058,ICP 7035 and ICPL 366) genotypes were screened by conducting two experiments in soli treated with five different NaCl (mM) concentrations (0, 50, 100, 125, 150) and (0,50, 75, 100, 150) respectively for groundnut and pigeonpea, under controlled conditions. Salt concentrations of 100–125 mM were found to be critical to screen groundnut genotypes whereas 75 mM NaCl appeared most suited treatment for plgeonpea. There was a positive and significant correlation between the SPAD Chlorophyll Meter Reading (SCMR) under salinity and the ratio of biomass under salinity to that of control, our proxy for salinity tolerance, though this relation was better in plgeonpea. The sodium concentration in shoot was well correlated with the ratio of biomass in plgeonpea but not in groundnut. Finally, the nodule dry weight was positively and significantly related to the ratio of blomas in both the crops. Our results show a suitable protocol to screen salinity tolerant germplasm of groundnut and pigeonpea and propose few traits, SCMR, shoot Na accumulation, and nodulation, that could be used to understand better the mechanisms of tolerance, and/or possibly to screen for salinity tolerance.