Biologia reprodutiva da "catingueira" (Caesalpinia pyramidalis Tul., Leguminosae-Caesalpinioideae), uma espécie endêmica da Caatinga

Abstract

-(Reproductive biology of catingueira (Caesalpinia pyramidalis Tul., Leguminosae-Caesalpinioideae), an endemic species of Caatinga). The Leguminosae comprises 293 species in the Caatinga, and only eight were studied for pollination and, or breeding system. We analysed the floral biology, pollinators and breeding system of Caesalpinia pyramidalis Tul. The pollen tube growth was observed eight, 24 and 48 hours after hand pollinations. There were 5.7 ± 0.9 ovules/flower, 66.9 ± 47.8 flowers and 2.1 ± 1.2 fruits per inflorescence and 2.88 ± 1.44 seeds/fruit. Nectar production was about 1.0 µL during the first day of anthesis, 0.5 µL in the second day, and there was no production in the third day. C. pyramidalis is self-incompatible but self-pollen tubes grew down to the embryo sac. Species of Xylocopa and Centris are important pollinators of C. pyramidalis. During the visits, the bees promote mostly geitonogamy which favours the loss of fruits, and generates a low fruit/flower ratio (0.03). However, high seed/ovule ratio (0.50) shows highest investment in seeds by cross-pollination, reducing the effects of geitonogamy.Key words -Caatinga, Centris, late-acting self-incompatibility, preemergent reproductive success, Xylocopa RESUMO -(Biologia reprodutiva da "catingueira" (Caesalpinia pyramidalis Tul., Leguminosae-Caesalpinioideae), uma espécie endêmica da Caatinga). Leguminosae está representada na Caatinga por 293 espécies, das quais oito foram estudadas quanto à polinização e/ou sistema reprodutivo. Foram analisados a biologia floral, os polinizadores e o sistema reprodutivo de Caesalpinia pyramidalis Tul. Houve produção de 5,7 ± 0,9 óvulos/flor, 66,9 ± 47,8 flores e 2,1 ± 1,2 frutos por inflorescência e 2,88 ± 1,44 sementes/fruto. O volume de néctar foi cerca de 1,0 µL durante o primeiro dia da flor, 0,5 µL no segundo dia, não havendo produção no terceiro dia. C. pyramidalis é auto-incompatível, com tubos polínicos oriundos de autopolinização manual crescendo até o saco embrionário. Espécies de Xylocopa e Centris constituem importantes polinizadores de C. pyramidalis. Durante as visitas, as abelhas promovem principalmente geitonogamia, a qual favorece a perda de frutos e leva à baixa razão fruto/flor (0,03). Entretanto, a razão semente/óvulo relativamente elevada (0,50), demonstra maior investimento em sementes provenientes de polinizações cruzadas, reduzindo os efeitos da geitonogamia.Palavras-chave -auto-incompatibilidade de ação tardia, Caatinga, Centris, sucesso reprodutivo pré-emergente, Xylocopa

Reproductive biology of woody species in Caatinga, a dry forest of northeastern Brazil

“…Species of the genera Caesalpinia and Senna (Leguminosae-Caesalpinioideae) and Sideroxylon (Sapotaceae) studied here show LSI mechanisms, with pollen tubes from manual self-pollination growing to the micropyle of the ovule (for details to C. pyramidalis see Leite and Machado, 2009). LSI has been reported for many families (Seavey and Bawa,1986), but S. obtusifolium, from this study, represents the first report of this kind of mechanism for Sapotaceae.…”

Research Article Genetic diversity in a Poincianella pyramidalis (Tul.) L.P. Queiroz population assessed by RAPD molecular markers.

“…Its main pollinators are bees (genera Xylocopa and Centris), occasionally butterflies, and uncommonly birds of the species Coereba flaveola. This bird, just as the species Xylocopa and Centris, likely has a long flight distance, dislocating across individuals with greater frequency and promoting gene flow via pollen (Leite and Machado, 2009).…”

Does successful ovule development depend on its position within the pod? Examples from Neotropical Fabaceae

“…The low fruit : flower and seed : ovule ratios in P. pyramidalis have been attributed to resource limitation and selective abortion (Leite & Machado ). This species has late acting self‐incompatibility (Borges et al .…”

“…) and is endemic to the Caatinga vegetation (Maia ). This species seems to show pollen limitation, since there are high rates of pods developing without seeds (Leite & Machado ) and hand cross‐pollination increases reproductive success compared to natural fruit set (Borges et al . ); pollination is performed mainly by large bees, such as Xylocopa and Centris (Borges et al .…”