Biologia floral e polinização artificial de pinhão-manso no norte de Minas Gerais

Abstract

Resumo -O objetivo deste trabalho foi avaliar alguns aspectos da biologia floral e do sistema reprodutivo de Jatropha curcas, em Janaúba, MG. Foram registrados: o número de flores femininas e masculinas; o intervalo de abertura das flores femininas; e a formação de frutos por apomixia, autofecundação, geitonogamia e xenogamia. A proporção de flores masculinas para femininas foi de 20:1. O intervalo de abertura das flores femininas variou de um a sete dias, conforme o número delas na inflorescência. No teste de apomixia, houve formação de frutos em apenas 5% das flores avaliadas. A percentagem de frutificação variou de 79 a 88% na autofecundação manual, na geitonogamia e na xenogamia. Na autofecundação sem a polinização manual a frutificação foi de 20%, e os frutos formados foram significativamente menores, com número inferior de sementes por fruto e menor índice de velocidade de emergência. As sementes foram semelhantes às formadas por polinização natural. É possível a realização de cruzamentos controlados em pinhão-manso, e não há autoincompatibilidade nesta espécie.Termos para indexação: Jatropha curcas, autofecundação, geitonogamia, polinização natural, xenogamia. Floral biology and artificial polinization in physic nut in the north of Minas Gerais state, BrazilAbstract -The aim of this work was to evaluate some aspects of the floral biology and of the reproductive system of Jatropha curcas, in Janaúba county, MG, Brazil. The number of female and male flowers, the interval between the opening of female flowers, and the formation of fruits by apomixis, self-pollination, geitonogamy and by xenogamy were registered. The ratio of male to female flowers was 20:1. The interval of opening of female flowers was of one to seven days, depending on the number of female flowers in the inflorescence. On the apomixy test, the formation of fruits occurred in only 5% of the evaluated flowers. The fruit set was between 79 and 88% through the manual self-pollination, and through the geitonogamy, and the xenogamy. In the self-pollination treatment, without the hand-pollination, the fruit set was of 20%, and the fruits formed were significantly smaller, with a lesser number of seeds per fruit and lower rate of emergence. The seeds were similar to the ones formed by natural pollination. Artificial cross-pollination is possible on physic nuts, and there is no self-incompatibility within this species.Index terms: Jatropha curcas, self-pollination, geitonogamy, natural pollination, xenogamy. IntroduçãoOs procedimentos adotados na execução dos trabalhos de melhoramento genético de espécies perenes frutíferas arbóreas dependem, fundamentalmente, do seu modo de reprodução, do conhecimento da biologia floral, inclusive a morfologia floral, do tipo de reprodução e dos aspectos relativos à polinização e à fertilização. São importantes, também, as consequências das alterações induzidas artificialmente no modo de reprodução, nos cruzamentos dirigidos e nas autofecundações. Além disso, o fruto e as sementes são economicamente as partes mais ...

Floral biology and characterization of seed germination in physic nut (Jatropha curcas L.)

“…This was also observed by Saturnino et al (2005) and Juhász et al (2009), but not by other authors, who reported the opposite, i.e. that the male flowers opened before the female ones (Raju and Ezradanam, 2002;Chang-Wei et al, 2007;Dnissa and Paramathma, 2007).…”

“…Several studies of J. curcas floral biology have been done over the last few years (Abdelgadir et al, 2008;Juhász et al, 2009;Paiva Neto et al, 2010). The variations found in flowering patterns can be attributed to species genetic variability and to the effects of environmental factors, principally photoperiod and temperature.…”

Genetic diversity analysis of Croton antisyphiliticus Mart. using AFLP molecular markers

“…This is because its seed has a structure called a caruncula, which is capable of attracting these insects (Leal et al, 2007). Although Croton studies have demonstrated that pollen is primarily dispersed by wind and secondarily by insects (especially bees) (Dominguez and Bullock, 1989;Juhász et al, 2009), the present study provides evidence that C. antisyphiliticus has low N m . This result is probably due to the difficulty associated with pollen and seed dispersal, since the localization of the collected individuals was restricted to small bands of vegetation along roads and permanent protection areas.…”

Reproductive biology of the biofuel plantJatropha curcasin its center of origin

“…For example, Raju & Ezradanam (2002) reported in India that an inflorescence could produce 1–5 female flowers and 25–93 male flowers, with a ratio of male flowers to female flowers of 1:29. Also, Pinto et al (2009) found 4–12 female flowers and 87–222 male flowers (relation: 1:20). This variable is not preserved and the differences depend on the genetic material, geographic region, climate, nutrition, time, and cultural practices, among other factors, which makes it a highly variable feature (Bhattacharya, Datta & Kumar, 2005; Chang-Wei et al, 2007a; Pinto et al, 2009).…”

“…Also, Pinto et al (2009) found 4–12 female flowers and 87–222 male flowers (relation: 1:20). This variable is not preserved and the differences depend on the genetic material, geographic region, climate, nutrition, time, and cultural practices, among other factors, which makes it a highly variable feature (Bhattacharya, Datta & Kumar, 2005; Chang-Wei et al, 2007a; Pinto et al, 2009). Pollen production per anther and per flower was higher than that reported in other studies, such as Bhattacharya, Datta & Kumar (2005), who found that each flower produced 1617 pollen grains, with a ratio of pollen:ovule (P:O) of 539:1.…”