Floral biology and breeding behavior in the bamboo Dendrocalamus strictus Nees.

Abstract

Floral biology and breeding behavior were studied in the bamboo Dendrocalamus strictus Nees. The inflorescence in this species is a large branching panicle. Fertile florets are intermixed with smaller sterile ones. There are six stamens. The ovary is stipitate and turbinate. The style is long and the stigma is bifid and plumose. Dendrocalamus strictus is typically dichogamous and protogynous. The gynoecium matures 3-4 days before the androecium, effectively preventing self pollination. Flower bloom, which took place over a period of 2 to 3 h, was dependent on air temperature and only occurred between 0600 and 1300 h. Dendrocalamus strictus is anemophilous. Flowers in the male phase were visited by insects. These insects completely neglected the flowers at the female phase. The insects fed on the pollen and were not pollen vectors. When wind was excluded by enclosing the inflorescences in bags there was no seed set, indicating that cross pollination by wind is necessary for fertilization and that parthenocarpy and apomixis are not occurring in this species. Pollen fertility was about 98% as indicated by staining fresh pollen at the time of anther dehiscence and pollen release with Alexander's stain (Alexander 1969). When placed on a modified Brewbaker-Kwak medium containing 1% glucose, the pollen grains germinated well, and the pollen tubes grew to 15-20 times the diameter of mature pollen grains. Although profound protogyny has its disadvantages in times of sporadic flowering, it can be useful in breeding programs because it eliminates the need for emasculation.

Breeding system and pollination of two closely related bamboo species

“…As in other grasses, wind pollination is common in bamboos (Janzen 1976; Nadgauda et al 1993). Insect visits to bamboo flowers have been recorded frequently although the effectiveness of insects as bamboo pollinators is controversial (Janzen 1976; Venkatesh 1984; Nadgauda et al 1993; Huang et al 2002).…”

Artificially induced protogyny: an advance in the controlled pollination ofEucalyptus

“…As with protandry, this temporal separation of male and female receptivity has most likely evolved to increase the likelihood of outcrossing. The advantages of protogyny in breeding programs of bamboo, a naturally protogynous species, have been discussed by Nadgauda et al ( 1993). Protogyny allows the emasculation process to be omitted, saving time and reducing costs.…”

Flowering and fruiting of Aulonemia aristulata: a gynomonoecious woody bamboo species from Atlantic Forest in Brazil

“…The overlap of the male and female phases inside the synflorescences and among florets of the same spikelet did not prevent geitonogamy and may explain the fruiting in bagged synflorescences. Pollen viability in Aulonemia aristulata was high, as reported for Ochlandra travancorica (Kennard 1955), a tropical bamboo species, but was lower than that reported for two Asian species Sinarundinaria fangiana (97%) (Taylor & Quin 1988) and Dendrocalamus strictus (98%) (Nadgauda et al 1993). The fruiting on pistilate florets can be related to the positions of the synflorescences.…”

“…Protandrous florets (the androecium matures earlier than the gynoecium) are rare in bamboos (Ramanayake & Weerawardene 2003). The presence of seed set in enclosed synflorescences and embryo development in a few fruits indicates that apomixis is also possible in bamboo species (Nadgauda et al 1993, Ramanayake & Weerawardene 2003.…”