COMPARATIVE STUDY OF THE EFFECT OF ABSENCE OF ENTOMOPHILOUS POLLINATION ON THE PRODUCTIVITY OF RAPESEED AND FABA BEAN
Several crops receive benefits from the presence of pollinating insects and therefore a decline or disappearance of these could compromise agricultural production, essentially that of cross-pollinated and partially cross-pollinated crops. A comparative study of the effect of the absence of entomophilous pollination on some parameters of rapeseed and faba bean, two partially cross-pollinated crops, was performed through a field experiment carried out on plots placed under insect-proof cage to simulate the absence of pollinating bees (self-pollination) and other plots placed outside the cage to ensure the presence of bees (open-pollination). Field trial was conducted in 2013/14 at the experimental station of Douyet of INRA-Morocco according to a completely randomized blocks design, with two replications. Effect of the absence of entomophilous pollination was evaluated on morphological, phenological and agronomic parameters, such as plant height, flowering duration, number of fruits per plant, number of seeds per fruit and seed yield. In rapeseed, absence of entomophilous pollination reduced drastically the number of fruits per plant by 15.54% and seed yield per plant by 33.45%, while in faba bean, these parameters were reduced, respectively, by 28.20% and 20.83%. Also, under bee’s absence conditions, average number of rapeseed seeds per silique decreased by 20.92%. However, for faba bean, no significant difference was observed between bees absence and bees presence for this parameter, with an average seeds number per pod of 2.94 and 2.74, respectively. In absence of pollinating bees, seed yield of rapeseed was more affected than that of faba bean. Thus, in particular environments with decline of bees, it would be wiser to integrate faba bean rather than rapeseed in the traditional cereal-based cropping system. Protection of pollinating bee populations is a necessity, not only for the maintenance of plant and animal biodiversity, but also for preserving the economic activities related to agriculture and beekeeping.