Niveles de fructificación en "Crataegus monogyna" Jacq., "Prunus mahaleb" L. y "Prunus spinosa" L. ("Rosaceae")

GUITIAN, J., J. M. SANCHEZ & P. GUITIAN (1992). Fruit/flower ratio in Crataegus monogyna Jacq., Prunus mahaleb L. and Prunus spinosa L. Anales Jard. Bot. Madrid50(2): 239-245 (in Spanish). We determined fruit/flower ratio in populations of Crataegus monogyna, Prunus mahaleb and Prunus spinosa (Rosaceae) in the northwest Iberian Peninsula. All three species showed low ratios (< 0.3) as a result of fecundity reductions which were both intrinsic and extrinsic in origin. Leveis of flower and fruit loss varied between individuais and between species, and were independent of the length of the phenological periods. In Crataegus monogyna and Prunus spinosa the most important reductions occurred at the beginning of fruit development, whilst in Prunus mahaleb they were recorded during the flowering period. In all three species, the intrinsic mechanism which regulate fruit/flower ratio act at all stages of the reproductive cycle, although with different intensity.