养分元素在荔枝叶片-枝条-果实间的转移能力

采集了华南荔枝主产区不同产地的11个优新品种荔枝果穗，测试了叶片、枝条及果实不同部位（果柄、果蒂、果皮、种柄、果肉及种子）大中微量元素养分含量，比较不同养分元素在荔枝叶片、枝条和果实的累积及转移特性。结果表明，多数养分元素如N、Ca、Mg、Fe和Mn在叶片中含量最高，而P和K则在叶片中含量最低，在果柄最高，部分元素如Zn、B和Mo在种柄含量最高，在果肉最低。根据养分从叶片向不同部位的移动性，Mo从源（叶片）到库（果实）的转移能力最强，表现出优先向繁殖器官转移累积的特点；K、P、Zn、Cu和B的移动能力也较强，Ca、Mg、Fe和N则较差，而Mn的移动性最差。如对养分从叶片至种子的逐级转移能力进行比较，则K、Cu、P、B在不同部位的逐级移动能力强；Mo、Mg、Zn和N整体移动性也较强，但同时均存在从果皮或种柄向果肉移动的运输障碍；Fe和Mn逐级移动能力中等，但也存在从种柄或果皮至果肉移动性差的共性问题；Ca的逐级移动能力均较差，尤其难以从果皮及种柄运输至果肉。综合而言，Ca、Mn、Mg、Mo、Zn营养从果皮或种柄到果肉的移动性低，尤其是Ca和Mn极难从果皮或种柄移动到果肉，可能成为荔枝果实发育的营养限制因子。

Mobility of Nutrient Elements Via Leaf-Twig-Fruit in Litchi

In this study, 11 new litchi cultivar samples were collected from different producing areas in South China, and the nutrient contents of macro-, secondary and micro-elements in leaf, twig and various parts of fruit including fruit stem, fruit base, peel, seed stalk, pulp and seed from the fruit cluster were tested. We compare the accumulation and transfer characteristics of different nutrient elements in litchi leaf, twig and fruit. The results show that most of the nutrient elements such as N, Ca, Mg, Fe and Mn, was in the highest levels in the leaf, while P and K had the lowest contents in leaf and the highest contents in fruit stalk. Some elements like Zn, B and Mo were in the peak in seed stalk, and in the bottom values in the pulp. According to the mobility of nutrients from leaf to other tissues, Mo was the most easily transported from source (leaf) to sink (fruit), with a transfer preference to the reproductive organs. Generally, the migration of K, P, Zn, Cu and B among tissues was strong as well, while Ca, Mg, Fe and N were poor in transferability, and Mn was the element with the lowest mobility. If the transfer capability of nutrients via leaf-twig-fruit was compared, the delivery of K, Cu, P and B through various tissues was facile, and Mo, Mg, Zn and N were easily migrated in most of the tissue, with the exception of delivery obstacle from peel or seed stalk to pulp, respectively. Fe and Mn were moderately mobile, however, the poor transferability from seed stalk or peel to pulp was found as well. Ca was poor in mobility among tissues, especially from the peel or seed stalk to the pulp. In summary, the migration of Ca, Mn, Mg, Mo and Zn, in particular Ca and Mn from the peel or seed stalk to the pulp is poor. The transport obstacle of these nutrient elements might be nutritional limiting factors for litchi fruit development.