Abstract:

Objective: This study aims to reveal the characteristics of germination and growth of lateral buds on rhizome, explore the effect of rhizome carbon on the growth of lateral buds, and provide a reference for promoting germination of lateral buds and increasing the yield of bamboo forests. Method: One-year-old rhizomes of Indocalamus decorus with basically same rhizome diameter were used as the material. The rhizome segments with a mother culm (M) or without mother culm (N) were selected, and three different lengths of rhizome segments (L1, 3 cm; L2, 6 cm; L3, 9 cm) were retained by cuting off the rest part. The position of lateral bud germination and the growth of each treatment were investigated, the number, ground diameter and height of the young culms were measured, and the photosynthetic pigments and non-structural carbohydrate content were measured and analyzed. Result: 1) there was no significant difference in the germination ratio and growth of lateral buds over different parts of the rhizome in ML1 treatment, while lateral buds were sprouted out much more at both segment ends than those in its middle part in other treatments. It was showed that more lateral buds sprouted apically or basally, and the bias characteristics became more dramatic with the increase of the rhizome segment length. 2) Compared with the treatment without a mother culm, the ground diameter and height of young culms with a mother culm treatment were significantly increased with the same rhizome segment length, but there was no obvious difference in the number of young culms in general between the two treatments. As the increase of the rhizome segment length, the number of young culms increased in the treatment without mother culms, while the number of young culms in the treatment with a mother culm showed little difference. There was no significant difference in the ground diameter and height of young culms whether the rhizome segment had a mother culm or not. 3) The content of photosynthetic pigments and NSC in the leaves of young culm in the treatment with a mother culm were significantly higher than those in the treatment without mother culm. However, the content and proportion of NSC components in different rhizome lengths were different. At the same time, the soluble sugar content in young bamboo leaves with ML1 treatments showed no significant change compared with that in young bamboo leaves with ML2 and ML3 treatments, but the content of starch and NSC was significantly higher. The change of photosynthetic pigment content was opposite. The results indicated that the shorter rhizome segment with a mother culm had excessive carbohydrate accumulation and photosynthesis was inhibited by feedback. Effects of rhizome with mother culm or not on the diameter, height, photosynthetic pigment and NSC of young bamboo were significantly higher than those of the length of the rhizome segment. Conclusion: Carbon has an obvious restrictive effect on the germination of lateral buds on rhizome, which is an important factor causing the positional bias of the lateral bud germination. The continuous increase of carbon supply could gradually eliminate this biased germination characteristics, and the rhizome segment carbon gives priority to ensuring the quantity of young bamboo, and then the quality. Increasing the carbon storage capacity of rhizome segment is an important way to improve the lateral bud germination rate.

Key words: Indocalamus decorus, rhizome segment, lateral bud directional sprouting, NSC, carbonlimitation