Characterising cowpea (Vigna unguiculata L. Walp) mini-core set for flowering responses to various photoperiod and temperature regimes

Flowering time in cowpea is majorly influenced by climatic factors like photoperiod and temperature. Identifying genotypes that flower consistently across seasons is crucial for fitting the crop into various established cropping systems, not only as primary and intercrop but also as fallow crop. In this regard, 172 genotypes including nine check cultivars constituting a mini core set were evaluated across six seasons, and comparison was made for differences in days to 50 percent flowering (DFF) and cumulative growing degree days (CGDD). Significant genotype by season interaction for these parameters unveiled differential responses of genotypes to distinct seasons, rendering the selection of stable flowering types imperative. Three approaches namely season stratification, random coefficient models (RCM) and rank of standard deviation (RSD) were employed to identify genotypes with consistent flowering time. Four different response groups were formed in first method, while two response groups viz., sensitive and insensitive were possible in the next two approaches. Three early flowering genotypes namely 524 (IC263015), 399 (EC738260), 41 (EC149457) and 102 (EC723684) were consistently selected by two methods, while first three genotypes were common to all the three approaches. These genotypes were thus identified as early maturing photo-thermo insensitive lines among the cowpea mini core collection.