Nutritional survey of lychee on the coast area of the Gulf of Mexico, Mexico.

摘要

To know the nutritional status and to propose an appropriate management of lychee orchards (Litchi chinensis Sonn) in the coast area of the Gulf of Mexico, a nutritional survey was carried out in 32 representative lychee orchards, using 64 leaf samples and 67 soil samples. In the leaf samples, N was analyzed using semimicroKjeldahl method, and P, K, Ca, Mg, Fe, Zn and Cu by digestion with nitric and percloric acid, and quantified by atomic absorption. In the soil samples the following determinations were performed: texture, pH, N with semicroKjeldahl method, and P with Bray-1 method; K, Ca, Mg with ammonium acetate; Fe, Zn and Cu with EDTA. Foliar analysis showed that levels of N, P, K, Ca, Mg and Cu are low, compared to the set thresholds, in 68.7, 35.8, 14.9, 35.8, 49.3 and 73.1% of samples respectively. The K, Fe and Zn were the most frequently within the appropriate intervals in a 59.7, 77.6 and 70.1% of samples respectively. It was found significant correlation between the content of Zn and Ca in the leaf tissue and the availability of such elements in the soil (r_Zn=0.3275, r_Ca=0.6916). P, Ca and Zn correlated with pH (H2O: soil, 2:1) of the soil (r_P=0.3477, r_Ca=0.6479, r_Zn=0.3672). In the leaves, the nitrogen level was often low (68.7%) of samples, P and K were more frequently within the appropriate levels (64.2 and 85.1%) of samples and Cu was low in a 73.1% of the samples. The N, K, Mg and Cu of the leaves correlated with the levels in the soil. In Mexico, the lychee fruit production is declining because of changing climatic conditions. In 2008, some orchards will produce no fruit. As a conclusion, there were nutritional deficiencies in N, K, Ca, Mg, Zn and Cu in most of the lychee orchards.