White Lupin (lupinus Albus) Variation for Adaptation to Severe Drought Stress

This study aimed to reduce the gap of knowledge on white lupin drought tolerance variation, by assessing the grain yield of 21 landraces from major historical cropping regions, one variety and two breeding lines in a large phenotyping platform that imposed controlled severely stressed or moisture-favourable conditions after an initial stage of favourable growth. Drought stress reduced grain yield by 79%. Genetic correlation coefficients indicated moderate consistency of genotype responses across conditions for grain yield (r(g) = 0.76), fairly high consistency for straw yield (r(g) = 0.85) and harvest index (r(g) = 0.91), and high consistency for flowering time (r(g) = 0.99). However, low genetic correlation for yield (r(g) = 0.31) occurred among a subset of genotypes with early phenology. Specific adaptation to either condition implied significant (p = 0.05) genotype x condition interaction of crossover type between well-performing genotypes. Early flowering was an important stress escape mechanism, but intrinsic drought tolerance could be inferred from responses of a few genotypes. Various landraces out-yielded the improved germplasm under stressed or favourable conditions.