Impact of drought and regulated deficit irrigation on attractiveness of Diplotaxis tenuifolia (Brassicaceae) to bees and hoverflies

Abstract: Wild rocket, Diplotaxis tenuifolia (Brassicaceae), is one of the three commercially cultivated rocket species, which demand and production has recently increased in Mediterranean countries. Besides its use as a crop, it has been recommended as a beneficial insectary plant in habitat management of agro-ecosystems due to its long flowering duration and its attractiveness to pollinators (bees and hoverflies) in Central Spain. The main objective of this study was to assess the effect of different regimes of drought, moderate deficit irrigation (MDI) and severe deficit irrigation (SDI) on attractiveness of D. tenuifolia to pollinators. The results showed that in late spring-summer conditions, potted D. tenuifolia can cope with drought of 4 days without having any consequences on neither number of flowers or attractiveness of D. tenuifolia to pollinators. However, a drought period of 8 days or longer, reduced the number of flowers and their attractiveness to pollinators. Additionally, the study showed that regulated deficit irrigation (RDI) can improve the water use efficiency without affecting the floral development and attractiveness of D. tenuifolia to bees and hoverflies.