The effect of hot dry wind on the pod set of faba bean (Vicia faba) cv. Fiord: a preliminary wind tunnel study

Abstract

Wind tunnel studies have been used to simulate hot dry wind events that occur in Mediterranean climates and to investigate their possible impact on field crop production. This study investigates the effects of wind speed, duration, flower development stage and soil moisture on flower abortion and pod set in faba bean (Vicia faba L.) using a wind tunnel. At an air temperature of 30°C and relative humidity of 15–25%, rates of flower abortion increased with wind speed across a range of 2 to 12 m/s with the proportion of flowers setting a healthy pod following treatment declining for all stages of flower development tested. At 12.5 m/s, flower abortion reached close to the maximum observed, with a 35% reduction in pod set below that observed in the control plants at flower development stages up to and including anthesis. As the flowers develop, they become less sensitive to the hot windy conditions with abortion rates declining gradually from early developmental stages and showing a sharp decline in sensitivity after anthesis. Once the pod has set and extended beyond the withered petals, it is not vulnerable to extreme wind conditions and has a high chance of continuing to develop if moisture is available. Lower soil moisture levels and increased duration inconsistently increased the rate of flower abortion. When soil moisture is not limiting, hot dry wind will significantly contribute to flower abortion and may reduce crop yield. This level of flower abortion does not necessarily translate directly to yield reduction as pods that have already set on proximal nodes have a low vulnerability to adverse conditions and may remain unaffected by a severe wind event, while flowers at an early stage of development on distal nodes are vulnerable and may be affected leading to flower loss. If plant development is interrupted due to ending of the growing season, the more distal flowers may not have an opportunity to reach a harvestable stage and the impact of the wind event will not be expressed in the final yield. Net yield reduction therefore depends on seasonal conditions and the timing of the event. These results infer that the risk and extent of yield reduction in faba beans following severe climate events during the flowering phase could be minimised by creating sheltered zones of reduced wind speed with planted windbreaks.