Detached leaf test as a rapid stress appraisal in cowpea germplasm, Vigna unguiculata (L) Walp) for drought resistance

Abstract

A rapid stress appraisal method (a detached leaf test, DLT), was initiated under laboratory conditions in Italy to investigate the potential of the method for rapidly screening cowpea germplasm for drought tolerance. By the DLT, highly significant differences (p≤0.00001) were detected among the 100 accessions of the screened germplasm. Peak frequency of dehydration occurred at around 7% lost fresh weight (LFW, proportion of original fresh weight lost during a fixed incubation period) with an asymmetric empirical (frequency polygon) distribution with fewer accessions of greater than 19% dehydration occurring at the longer and highly skewed tail end. This pattern was indicative of the limited diversity in the advanced breeding lines that constituted the germplasm base. Pn 3-4552tvu and Pn 61-300ucr were rapidly and inexpensively identified as showing attributes of drought resistance and susceptible, respectively, by this method. It is concluded that the reported rapid stress appraisal strategies in cowpea germplasm might provide the empirical basis for identifying those traits likely to contribute to drought resistance in the breeding process.