How does phosphorus nutrition affect the growth and development of Cymbidium sinense?

1. Effects on the growth rate of leaf buds and leaves: 0.2 mM phosphorus has the greatest promoting effect on leaf bud growth; above this concentration, the leaf bud growth rate slows down. Within the phosphorus concentration range of 0 to 1.0 mM, the area of one-year-old leaves increases as the concentration rises. The plant's dry and fresh weight increase proportionally within the 0 to 1.0 mM range. 2. Effects on morphology and disease incidence: when phosphorus is deficient, plants are stunted, leaves are lusterless, and disease incidence is high. 3. Effects on flower bud formation and floweringflower: when phosphorus is deficient, flower bud formation is latest,flowerthe number is also small; within the 0 to 1.0 mM range, as phosphorus concentration rises, flower bud formation occurs earlier,flowerthe number of blooms is also greater. 4. Effects on photosynthetic and respiratory rates: within the 0 to 1.0 mM phosphorus range, the photosynthetic rate increases with rising phosphorus concentration. For the respiratory rates of leaves and pseudobulbs, the trend is consistent with that of the photosynthetic rate; phosphorus deficiency inhibits both photosynthesis and respiration. 5. Effects on protein and amino acid content: when phosphorus is deficient, the protein content of pseudobulbs and leaves is relatively low, while the amino acid content is very high; within the 0 to 1.0 mM phosphorus concentration range, as phosphorus level rises, protein content increases while amino acid content decreases. This may be caused by accelerated protein degradation or decreased synthesis due to phosphorus deficiency. When phosphorus is deficient, acid phosphatase activity increases greatly, and it can serve as a biochemical indicator of phosphorus deficiency in plants. 6. Effects on carbohydrate content: when phosphorus is deficient, the soluble carbohydrate content in roots and pseudobulbs is relatively high and decreases as phosphorus concentration rises; for leaves, the situation is the opposite. When phosphorus is deficient, the starch content in pseudobulbs and leaves is relatively high; as phosphorus concentration rises, the starch content in leaves and pseudobulbs decreases, which is clearly related to the obstruction of carbohydrate transport under phosphorus deficiency. (Ye Qingsheng, Pan Ruichi)