Effects Of Guofengling And Two Plant Growth Regulators On Yield And Quality Of Shatian Pomelo

Experiments were conducted by using Shatian Pomelo adult trees as the materials for two years. Three concentrations of "Guofengling", which was prepared by Guangxi University and contained ethephon, lanthanum-rich rare earth and macro and micro nutrients for plants, were sprayed on crown foliage at the early growth stage of fruit (April-May) in 2003. The results showed that "Guofengling" could increase the fruits and their weight, yet pericarp thickness and seeds were added, and soluble sugar and vitamin in the fruits were increased and the acidity was decreased in some extend. Moreover, the treatment also enhanced the net photosynthetic rate (Pn), transpiration rate (Tr), stomatal conductance (Cs) and intercellular CO2 concentration (Ci) in the leaves. Therefore, "Guofengling" could increase the yield, and improve the quality and the characteristics of respiratory exchange when it is used in Shatian Pomelo at suitable time and at appropriate rate.In 2004, three plant growth regulators ,that is ,Guofengling, 2,4-D and gibberellin were sprayed on leaf surface at the second physiological prematuredropping stage, and Guofengling again at the fruit enlargement stage of Shatian pomelo. The characters related to the yield and quality were investigated, and the results were as follows:1. Foliar spray of Guofengling at the second physiological premature dropping stage enlarged the fruits and increased fruit yield and kept the fruits from physiological premature dropping in a certain degree.2. Foliar spray of gibberellin might promote the enlargement of the fruits, but the concentration was very important and it should be paid high attention to. The gibberellin treatment produced the most fruits and the highest fruit yield among the three plant growth regulators.3. Foliar spray of Guofengling at late growth stage could improve the fruit quality of Shatian pomelo.4. The treatment with the mixture of Guofengling and 2,4-D resulted in more fruits and higher fruit yield and less seeds in the fruits, and improved the fruit quality.5. The yield and quality could be improved by applying appropriate plant growth regulators at the relevant growth stages based on the physiological functions of the regulators.