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不挂果荔枝(Litchi chihens-is Sonn.,CV BengaⅠ)叶片中 N、K、Zn 的浓度一般随叶龄(2—25周)的增大而下降,而 Ca、Mg、Na、Cl、Fe、Mn、B则升高,N 和 Cu 的浓度随施肥水平而变,测定单项养分,依特定的养分可采取嫩叶或老叶,但同时测定多种养分,则取新梢的老熟叶片,或前一次梢的第一、二张叶片较为合适:荔枝低产通常可以归因子养分的不足(Menzel 和 Simpson,1987)。尽管叶片分析已广泛应用于研究果树的营养问题(Shear 和 Faust,1980),但对于荔枝叶片制定的标准只是根据有限的试验(Menz-el 和 Slmpson,1987)。要使叶片分析可靠地用于诊断营养状况,几种因素必须考虑,即叶龄、叶位、品种、气候、季节、病虫害和时间等(Robson,1981)。生理年龄可能是影响植物矿质养分的最重要因素(Bates,1971)。作物负荷、土壤类型、气候或栽培措施基本上不会改变养分浓度与叶龄之间的关系,但施肥水平却可能使树体营养纵向位移,以叶片反映树体营养状况的灵敏性还受到生理叶龄的影响(Guardiola,1974)。对于柑桔类,当叶龄为3—4月时,叶片含氮量与产量之间具有最好的相关性。本文研究了与生理叶龄(从出叶开始)有关的荔枝养分的变化,以及建立标准采样程序的重要资料。
The concentrations of N, K, Zn in leaves of Litchi chihens-is Sonn. (CV Benga I) generally decreased with leaf age (2-25 weeks), but Ca, Mg, Na, Cl, Fe, Mn and B increased, while the concentration of N and Cu varied with the fertilization level. Individual nutrients could be measured and young leaves or old leaves could be taken according to specific nutrients. However, , Or the first and second leaves of the previous shoot are more suitable: low yield of litchi can often be attributed to nutrient deficiencies (Menzel and Simpson, 1987). Although leaf analysis has been widely used to study the nutritional problems of fruit trees (Shear and Faust, 1980), the standard set for litchi leaves is based on a limited number of trials (Menz-el and Slmpson, 1987). Several factors must be taken into account for reliable leaf profiling to diagnose nutritional status: leaf age, leaf position, variety, climate, season, pest and disease (Robson, 1981). Physiological age may be the most important factor affecting plant mineral nutrients (Bates, 1971). Crop load, soil type, climate or cultivation practices do not change the relationship between nutrient concentration and leaf age, but the level of fertilization may make the longitudinal shift of tree nutrition, the sensitivity of leaves to reflect the nutritional status of the tree is also affected by physiology Effect of Leaf Age (Guardiola, 1974). For citrus, the best correlation was found between leaf nitrogen content and yield when leaf age was from March to April. In this paper, the changes of nutrients in litchi associated with physiological leaf age (from leaf outset) and important data for establishing standard sampling procedures were studied.