Agronomic performances of three vetch species growing under different drought levels

Abstract

The current challenge of agriculture is to get the best yields while overcoming frequent water deficit conditions. The objective of this study was to compare performances of three vetch species (Vicia narbonensis L., V. sativa L., and V. villosa Roth) subjected to water stress. Plants were sown in pots under rainout shelter and submitted to four water regimes: control (100% field capacity [FC]), 80%, 60%, and 40% FC through 3 yr experiment. Results showed that V. narbonensis had the smallest declines in all the studied variables in response to water restriction but the highest water use efficiency (WUE) and stress tolerance index (STI) in both control and water-treated plants. This indicates the greater tolerance of this species to water constraint and its better water use. Vicia villosa was characterized by drastic declines in leaf area and DM yield (75% and 64%, respectively). It had also the smallest WUE and STI suggesting its low adaptation to water stress. Vicia sativa showed severe reductions in seed yield and yield components; accordingly, it was the most sensitive species in terms of seed yield. The three species implied avoidance strategies to cope with water stress. The different levels of drought tolerance explain the species ecological distribution in Tunisia.