Drought stress tolerance in vetch plants (<i>Vicia</i> sp.): agronomic evidence and physiological signatures

Abstract This study aimed to investigate vetch genotypes’ responses to moderate and severe drought stress and identify stress tolerance markers in arid conditions. Ten vetch genotypes ( Vicia dassycarpa Ten., V. pannonica Crantz., V. michauxii Spereng., V. sativa -Ardebil, V. sativa -Dashtyar, V. sativa -Fereydonshahr, V. sativa -Mashhad, V. sativa -Semirom, V. sativa -Shahrekord and V. villosa Roth.) were cultivated under three water-deficit conditions: control, moderate and severe drought stress. These conditions represented maximum allowable depletion levels of 30, 50 and 85% of soil available water, applied after the six-leaf stage in the 2019–20 and 2020–21 growing seasons. The findings highlight the vetch's response to drought stress is influenced by stress severity and genotype. The result indicated a wide range of genetic diversity in agro-physiological traits among the studied vicia germplasm. Vicia dassycarpa Ten. shows highest straw yield and shorter days to flowering and maturity. Vicia michauxii Spreng. demonstrates high grain yield and advantageous traits like increased water content, photochemical efficiency of photosystem II, chlorophyll b , carotenoids and membrane stability index. It has lower soluble carbohydrate, DPPH (2,2-diphenyl-1-picrylhydrazyl) and proline content. Additionally, V. michauxii Spreng. exhibits superior agronomic traits such as more seeds per pod, per plant and higher 1000 seeds weight, serving as reliable markers for drought tolerance. The results emphasize V. dassycarpa Ten. for fodder and V. michauxii Spreng. for grain production in water-limited regions. Further research on gene expression related to drought tolerance traits should enhance our understanding of vetch.