What conditions are needed for lychee flower bud differentiation?
The fruiting mother branches of lychee are robust, the maturation period is suitable, and the tree vigor is moderate, making it easy to control winter shoots, accumulate nutrients, and favor flower bud differentiation. The more organic nutrients accumulated, the better the flower bud differentiation. If the tree vigor is excessively strong and vegetative growth is vigorous, it is unfavorable for flower bud differentiation, and flower-bearing leaves are easily produced, causing reduced yield or crop failure; or...
The fruiting mother branches of lychee are robust, the maturation period is suitable, and the tree vigor is moderate, making it easy to control winter shoots, accumulate nutrients, and favor flower bud differentiation. The more organic nutrients accumulated, the better the flower bud differentiation. If the tree vigor is excessively strong and vegetative growth is vigorous, it is unfavorable for flower bud differentiation, and flower-bearing leaves are easily produced, causing reduced yield or crop failure; or excessively long flower panicles are produced, consuming too many nutrients, with a low proportion of female flowers and many male flowers, also causing reduced yield.
If the fruiting mother branches mature too late, the accumulation of organic nutrients and carbohydrates is low, and the concentration is low, which is unfavorable for flower bud differentiation; if the fruiting mother branches mature too early, the period of controlling winter shoots is too long. Although nutrients are accumulated, which favors flower bud differentiation, winter shoots are also easily produced, consuming nutrients and disrupting flower bud differentiation. If the fruiting mother branches grow too weakly, vegetative growth is poor, and accumulated nutrients are insufficient, this is likewise unfavorable for flower bud differentiation. The basic speculative condition for flower bud differentiation is that vegetative growth slows or stops.
When transitioning from vegetative growth to reproductive growth, the nutritional status within the tree and the types and proportions of endogenous hormones must undergo obvious changes to meet the needs of reproductive growth. The process of flower bud differentiation requires a large amount of cytokinins to promote flower bud differentiation. Low winter temperatures and a long cold period inhibit vegetative growth, promote reproductive growth, and result in good flower bud differentiation quality. Different varieties have different low-temperature requirements; for example, Sanyuehong and Feizixiao can undergo flower bud differentiation regardless of whether temperatures are on the high or low side. During the flower bud differentiation period, the longer the low-temperature period, the better the flower bud differentiation. Baila and Heiye require low temperatures of 8-15°C, while Feizixiao and Baitangying require temperatures below 20°C. The last autumn shoots of lychee should emerge from early September to mid-October; early-maturing varieties should emerge early, and late-maturing varieties should emerge late. For trees with excessively weak vigor, an appropriate amount of fertilizer should be applied as a supplement, along with spraying 2-3 times of compound-type nucleotides, to enhance photosynthesis and cultivate robust fruiting mother branches; if the tree vigor is excessively strong, no further fertilizer is needed.
At the same time, spray acaricides twice to protect the fruiting mother branches. For example, use the acaricide Ben Shuang De at 2000 times dilution or Guomanhong at 2000 times dilution, mixed with the insecticide Kaifeng at 2000 times dilution or Shachongwang at 2000 times dilution, or Saibokai at 2000 times dilution. After the fruiting mother branches mature, spray 1-2 times of compound-type cytokinins to increase the cytokinin content of the fruiting mother branches and promote flower bud differentiation.