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REPRODUCTIVE BIOLOGY OF PETAL COLOR VARIANTS IN WILD POPULATIONS OF RAPHANUS SATIVUS: II. FACTORS LIMITING SEED PRODUCTION
Author(s) -
Stanton Maureen L.
Publication year - 1987
Publication title -
american journal of botany
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.218
H-Index - 151
eISSN - 1537-2197
pISSN - 0002-9122
DOI - 10.1002/j.1537-2197.1987.tb08596.x
Subject(s) - biology , raphanus , pollinator , petal , pollen , pollination , ovule , botany , fecundity , reproductive success , horticulture , population , demography , sociology
Wild radish (Raphanus sativus) populations in California contain several conspicuously different petal color morphs. Pollinators are known to discriminate among color variants, and this study was done to determine whether such discrimination influences seed and fruit production. Seed set potential, as determined by total flower production and the number of ovules per flower, did not vary among color morphs. Total fruit set was high in these populations, ranging from 60% to 80%, and did not vary significantly among common petal colors in any site. The number of seeds per fruit did vary among color morphs, but the pattern was different in 1983 and 1984 and did not correspond to concurrent patterns of pollinator visitation. Hand pollination studies showed that pollen limitation is not a major factor influencing seed production; in 1984, addition of pollen to flowers failed to enhance fruit or seed set, while in 1983, addition of pollen slightly increased the number of seeds per fruit. Additional experiments demonstrated that all petal color morphs were mostly self‐incompatible. Resource limitation appeared to be a major force regulating seed production. Despite consistently high pollinator visitation rates, flower production rate, fruit set, and seeds per fruit all declined markedly through the five wk flowering season. Pollinator discrimination among colors is likely to have its greatest impact on paternity success rather than maternal fecundity.