Effect of Phosphorus on Cluster Bud Growth in Proliferating Seedlings of Acacia melanoxylon

Abstract:

To understand the effect of phosphorus on the induction and growth of cluster buds in the proliferating seedlings of Acacia melanoxylon, the tissue-cultured seedlings of clone SR17 as materials was inoculated proliferation medium containing 0.9, 1.2, 1.6, 2.0, 2.4, and 2.7 mmol/L KH₂PO₄, respectively, and the growth and development indexes of cluster buds were investigated after for 1 and 2 cycles of subgeneration, respectively. The results showed that 2.0–2.7 mmol/L KH₂PO₄ promoted the rapid growth of height, number of cluster bud and base callus of proliferating seedlings, among which 2.4 mmol/L KH₂PO₄ had the best effect, and the accumulation of biomass and chlorophyll content was higher. With the enhance of phosphorus content in the medium, phosphorus and potassium contents in the cluster buds significantly increased, while nitrogen content had no significant change. Pearson correlation analysis revealed that the phosphorus level had significantly positive correlation with height, number, base callus, fresh weight, dry weight, tissue water content, and contents of total chlorophyll, chlorophyll a, chlorophyll b, phosphorus, potassium of bud in 1 and 2 cycles of subgeneration. Therefore, phosphorus plays an essential regulatory role in the growth and development of cluster buds of A. melanoxylon.