Studies On The Reproductive Biology Of Dendrocalamus Latiflorus And Dendrocalamus Farinosus

The two bamboos? reproductive process, such as floral structure, flowering process, stigma receptivity, pollen viability and germination, gametophyte development and pollen tube growth, were studied, in order to expound its seed-setting characteristics thus to facilitate its crossbreeding. Results are as follows :(1) Their florets were consist of lemma, glumelle, stamen and pistil. Florets on the spiklet were development from the base to top, but matured from the top to base in turn. The two bamboos were protogynous. Normally, all the anthers were outcropped from the hull, but only parts of stigmas on the top of spikelet wound outcropped, while the rest wound not and counld not be fertilized and fruiting.(2) Their stigma have a 6 days stigma receptivity period, and has pollen receptivity from the first day when it outcropped. Embryo sac development belongs to polygonum type. Their embryo sac were matured when the stigma outcropped and consist of egg apparatus, polar nuclei and antipodal cells. Therefore, their low maturing rate have nothing to do with pistil.(3) Fresh pollen germination rate counld reach to 50.6% and 46.5%, respectively. Under natural condition, pollen life were 36 h and 24 h, respectively. And in-vitro preservation of pollen were difficult. Gametophyte development were out of sync in the same anther, this led to 3-cell pollen and 2-cell pollen both exist when pollination. When discussing the affect to seed-setting, we should take into account whether the 2-cells pollen counld fertilize successfully, although half of pollen germination well.(4) Based on the P/O and OCI value, the breeding system of two bamboos were given priority to outcrossing. However, bamboos are a group of plants with asexual reproduction, flowering plants at the same period maybe clones with the same genetic background, so the pollination among different individuals maybe an incrossing. The pollen tube growth process experiment showed that lots of pollen tube stopped growing midway because of callose, although many pollen were germinated. This may be the main reason that led to low seed-setting rate.(5) Fresh pollen were easy deactivation, and in-vitro preservation were difficult. Stigma has pollen receptivity from the first day when it outcropped. Thus, in crossbreeding experiment, if they were used as male parent, pollination should be conducted on the day that the pollen poured out from the anther; if they were used as female parent, pollination should be conducted from the day that the stigma outcropped from the hull.