Efficacité pollinisatrice de différents traitements sur 2 lignées de féverole de printemps (Vicia faba L var equina Steudel), à des niveaux d'autofertilité différents, avec utilisation de diverses espèces de Bombus Latr (Hymenoptera: Apidae)J. Le Guena, J. Mesquidab, J.S. Pierreb, G. Morina, J.N. Taseic and S. Carrec
a Station d'amélioration des plantes, BP 29, 35650 Le Rheu, France
b Laboratoire de zoologie, INRA, centre de recherches de Rennes, BP 29, 35650 Le Rheu, France
c INRA, centre de recherches de Poitou-Charentes, laboratoire de zoologie, 86600 Lusignan, France
Abstract - Efficiency of pollinating treatments on 2 lines of spring faba bean (Vicia faba L var equina Steudel) with different levels of self-fertility and using 3 species of Bombus (Hymenoptera: Apidae)
The objective was to compare the pollinating efficiency of Bombus lapidarius, B pascuorum and B hortorum with 3 types of treatments (hand tripping, self pollination and open pollination). This study was conducted under insect-proof cages 3 × 3 × 3 m on 2 faba bean lines, one with high self-fertility (D-27) and the other with low self-fertility (D-23). Another objective of the study was to further evaluate if self-fertility might increase the reliability of yield in faba bean. The cages with bumble bees contained 2 queens each, and the experimental design was a randomized complete block with 3 replications, 6 pollination treatments and 2 lines per treatment. Data were recorded on reproductive organs (flowers and pods) by node, on abortion rates, pod setting rates and seed yield components. Treatments did not affect flower production, the self-fertile line D-27 yielding ≈ 50% more flowers than the line D-23 with low self-fertility. But the abortion rates were significantly higher in the self-fertile line D-27 than in D-23. The self-fertile line was not affected by the various conditions of pollination. On the contrary, the line with low self-fertility was very susceptible to treatments and to the different species of bumble bees. Under self pollination, the low self-fertile line produced significantly less pods than with insects. On the contrary self-fertility enabled line D-27 to produce as many seeds under self-pollination as with bumble bees. Despite its higher abortion rate, the self-fertile line D-27 had a greater productivity than that of D-23 for practically all the treatments. We concluded that the non self-fertile line has a definite need of pollinating insects to significantly increase its pod setting and seed yield. The fact that the yield from the self-fertile line was completely independent of insect activity indicates that self fertility was an effective means of making faba bean yield more consistent and reliable, but this mechanism did not increase yield.
Key words: Vicia faba / Bombus / insect pollination / self-pollination / seed yield