Genotype by environment studies demonstrate the critical role of phenology in adaptation of chickpea (Cicer arietinum L.) to high and low yielding environments of India

In order to investigate specific and general adaptation of chickpea in India, a wide range of sub-continental, Australian and Mediterranean genotypes were grown across seven sites characterizing the major chickpea growing areas over 3 years, and extensive data on plant stand, early vigour, phenology, productivity and yield components collected. High and low yielding sites were clearly separated by a range of physical and biological characters, low yield being associated with low latitude and pre-season rainfall, high temperature, early phenology, short crop duration, low biomass and fecundity. Genotype by environment interactions for yield were highly significant (P < 0.001), and accounted for more variance than that attributed to genotypes alone. Ward's hierarchical clustering indicated that the genotypes could be separated into discrete groups, comprising material specifically adapted to the north (Clusters 2 and 3) or south (Cluster 5), widely or consistently poorly adapted germplasm (Clusters 1 and 4, respectively).Cluster 5, comprising germplasm from southern and central India, was characterized by early phenology, confirming the role of drought escape in southern India. With increasing latitude Cluster 5 genotypes remained early, but had the capacity to delay maturity considerably, resulting in average, and occasionally above average yields. However, compared to well-adapted material in the north, Cluster 5 biomass was low, and the time interval between flowering and podding up to 50 days, representing repeated cycles of flowering and subsequent abortion. Clusters 2 and 3, dominated by northern Indian genotypes, were characterized by later phenology, and were able to delay the onset of flowering significantly more than the remaining germplasm at late flowering northern sites. In Cluster 3, the second highest yielding group overall, this increased both source and sink potential at productive northern sites. Cluster 2 was uniformly later than Cluster 3, and lower yielding at most sites. Cluster 1 was characterized by intermediate flowering and relatively early, responsive maturity, a phenological compromise responsible for wide adaptation, by providing sufficient drought escape in the south, and enough biomass in the north to produce above average yields in these contrasting environments. ICCV 10 from the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), and 2 Indian Agricultural Research Institute (IARI) lines, BG 391 and BG 1006, were the most consistently high yielding, ranking in the top 10 at 10 and 8 sites, respectively. Cluster 4, comprising largely Australian cultivars, was characterized by late, unresponsive phenology and the lowest yield at each site.