Characterization of Lablab purpureus Regarding Drought Tolerance,Trypsin Inhibitor Activity and Cyanogenic Potential for Selection in Breeding Programmes

Climate change is responsible for the decrease in rainfall in many regions. One consequence is a reduction in arable land for traditional crops. Therefore, we are looking for drought‐tolerant crops from many regions to replace sensitive crops currently in use. Lablab purpureus (L.) Sweet, which is grown mainly in Africa and South Asia, is considered to be drought tolerant. The species L. purpureus is a member of the Fabaceae family and has multiple functions, for example as food or forage. In this study, L. purpureus genotypes were compared to find the best genotypes adapted to the new climate conditions and with the highest benefits as food and fodder. The drought tolerance of four L. purpureus genotypes was examined. Classical growth parameters, infrared thermography and stomatal conductance were measured after induction of drought stress to monitor the impact of drought on plant growth and development. Significant differences among the genotypes were found in the tested growth stage. The ranking of the most drought‐tolerant genotype was method dependent. To find potentially usable genotypes, the trypsin inhibitor activity was determined and an analysis of the cyanogenic potential (HCNp) was performed. Both trypsin inhibitor activity and HCNp showed significant differences among the genotypes without showing a correlation to each other. In summary, we recommend as selection criteria of the best genotypes for future breeding programmes: (i) a combination of at least two, better three, independent methods for the determination of drought effects on L. purpureus and (ii) the chemical analysis of compounds which are important for the nutritional value.