Consistent Variation Across Soil Types in Salinity Resistance of a Diverse Range of Chickpea (Cicer arietinum L.) Genotypes

Chickpea is considered sensitive to salinity, but the salinity resistance of chickpea germplasm has rarely been explored. This study aimed to (i) determine whether there is consistent genetic variation for salinity resistance in the chickpea minicore and reference collections; (ii) determine whether the range of salinity resistance is similar across two of the key soil types on which chickpea is grown; (iii) assess the strength of the relationship between the yield under saline conditions and that under non-saline conditions; and (iv) test whether salinity resistance is related to differences in seed set under saline conditions across soils and seasons. The seed yield of 265 chickpea genotypes in 2005-2006 and 294 cultivated genotypes of the reference set in 2007-2008 were measured. This included 211 accessions of the minicore collection of chickpea germplasm from the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT). The experiments were conducted in a partly controlled environment using a Vertisol soil in 2005-2006 and an Alfisol soil in 2007-2008, with or without 80 mm sodium chloride (NaCl) added prior to planting. In a separate experiment in 2006-2007, 108 genotypes (common across 2005-2006 and 2007-2008 evaluations) were grown under saline (80 mm NaCl) and non-saline conditions in a Vertisol and an Alfisol soil. In 2005-2006 in the Vertisol and 2007-2008 in the Alfisol, salinity delayed flowering and maturity, and reduced both shoot biomass and seed yield at maturity. There was a large variation in seed yield among the genotypes in the saline pots, and a small genotype by environment interaction for grain yield in both soil types. The non-saline control yields explained only 12-15 % of the variation of the saline yields indicating that evaluation for salinity resistance needs to be conducted under saline conditions. The reduction in yield in the saline soil compared with the non-saline soil was more severe in the Alfisol than in the Vertisol, but rank order was similar in both soil types with a few exceptions. Yield reductions due to salinity were closely associated with fewer pods and seeds per pot (61-91 %) and to lesser extent from less plant biomass (12-27 %), but not seed size. Groups of consistently salinity resistant genotypes and the ones specifically resistant in Vertisols were identified for use as donor sources for crossing with existing chickpea cultivars.