Nutrient Management for Litchi in Guangdong

This 3-year study, initiated in 2009, aimed to investigate the effect of different ratios of K to N on litchi yield and quality in Guangdong province. There were five K: N ratios employed ranging from 0.6 to 1.2 based on the fixed N rate of 500 kg N/ha and P rate of 150 kg P₂O₅/ha. Appropriate amounts of Ca, Mg, Zn, B, and Mo fertilizers were added to each treatment as identified by soil test and previous studies. The popular litchi cultivar, Feizhixiao, was selected for the field experiment. All nutrients were applied four times in the odd years: after harvest, before blossom, at young fruit setting and fruit expansion, and two times in the even year: after harvest and between young fruit setting and fruit expansion. The results obtained from this experiment along with other related studies will be used to develop the best nutrient management for litchi in southern China.

Results showed that the K: N ratio at 1:1 generally favored all the growth parameters of litchi such as phonological index, enzyme activity, plant hormones, fruit yield, and quality. The parameters tended to gradually become unfavorable as the K: N ratio deviated from 1:1. The contents of hydrogen peroxidase and starch in leaf, indoleacetic acid (IAA) in male flower, and fruit yield were the highest in the treatment of K: N ratio at 1:1. Further, the fluorescent index of chlorophyll was moderate in late April and the highest in late November. The percent of flowering trees and flowering branches at blossom, contents of Abscisic Acid (ABA) and zeatin (ZT) in male flower as well as ZT in female flower were at moderate levels while ABA contents in female flower were the lowest. Amino acids that are believed to govern fruit palatability consisting of delicacy, sweetness, and fragrance (mainly from aromatic amino acids) were relatively richer than the other treatments. The remaining parameters appeared to be similar in all treatments. Since economic benefit is usually closely correlated to yield and input cost, this treatment resulted in the highest net income of USD 9,040 in 2010 and USD 10,849 in 2011. This study demonstrates that optimal fertilization is crucial and effective in improving litchi yield and farmer income. Guangdong-BFDP-09