Research on the flowering biological characteristics of different clones of Bambusa emeiensis

A systematic study was conducted on the flowering biological characteristics of Bambusa emeiensis L. C. Chia & H. L. Fung to clarify the flowering rhythm of bamboo species under artificial cultivation conditions, so as to provide a scientific basis for the effective implementation of cross-breeding of Bambusa emeiensis.

Two clonal lines of Bambusa emeiensis, DTW and JJS, transplanted in Hangzhou were used as research materials. The forest appearance and flowering phenology of the two clones were observed via field investigation. The morphological structure of floral organs was observed and recorded by dissecting spikelets. Pollen viability was detected using the iodine-potassium iodide (I₂ - KI) staining method and in vitro germination assay, while stigma receptivity was examined with the benzidine-hydrogen peroxide method. The breeding characteristics of the two clones were analyzed by estimating the pollen-ovule ratio (P/O).

1) The two clones of B. emeiensis L. C. Chia & H. L. Fung exhibited identical flowering periods, with full bloom from mid-May to early August, and a few florets continued to open for another two weeks thereafter; 2) The spikelets of the DTW clone are purple - brown overall, while those of the JJS clone are purple-brown with a slight green tint. The anthers of the DTW clone are 5.48±0.55 mm long and yellowish-brown, while those of the JJS clone are 4.51±0.32 mm long and bright red; 3) The pollen viability and germination rate of both the DTW and JJS clones reach their peaks when the anthers are completely exposed. The optimal pollen viability is achieved in May and July, with the proportions of strong pollen viability being 75.2% and 79.2% respectively. The optimal germination rates are achieved in June and July, with the proportions of good germination being 4.3% and 4.9% respectively; 4) Both clones exhibited the strongest stigma receptivity during anther dehiscence; 5) Under artificial pollination, the seed-setting rate reached 4.00% for DTW and 2.67% for JJS, while no seed-setting was observed under natural pollination conditions in either their original habitats or transplanted habitats.

The flowering characteristics of the two clones of B. emeiensis L. C. Chia & H. L. Fung are different, and their flowering is not synchronized under the same environmental conditions. The DTW clone is suitable for pollination in June, while the JJS clone is suitable for pollination in July, but both clones possess a certain degree of fertility. Although the overall fertility of the two clones is relatively low, they can still serve as breeding materials.