Effect of N supply on the developments of N in leaves and new _branches in “Fuji” apple | N肥用量对红富士苹果叶片和新生枝条中N营养动态的影响

Chinese. 研究不同N肥用量对黄土高原地区红富士苹果叶片和新生枝条中N营养动态的影响，以期为果树营养诊断提供理论依据。试验共设6个处理，分别为CK（不施N, 对照）、N1（施纯N 0.3 kg/株）、N2（施纯N 0.6 kg/株）、N3（施纯N 1.2 kg/株）、N4（施纯N 2.4 kg/株）和N5（施纯N 4.8 kg/株），每处理设3次重复，随机排列，自04-29至收获前每隔30 d采集1次叶片和新生枝条样本，测定其N含量。施用N肥使红富士苹果叶片和新生枝条中的N含量都明显增加，分别较CK 平均增加2.6～6.2和1.0～3.1 g/kg。5－8月，N肥用量与苹果叶片和新生枝条中的N含量之间均呈显著或极显著的相关关系，相关系数分别高达0.814 2～0.948 0和0.908 3～0.981 2。苹果树N素供应丰缺诊断可以以5－8月苹果叶片和新生枝条中N含量为依据，而其中叶片以8月、新生枝条以6－8月为最佳采样时期。

English. The objective of this study was to explore the effect of different N supplies on the developments of N in leaves and new branches in “Fuji” orchard in the Loess Plateau to supply theoretical basis for nutrient diagnosis of apple tree. The experiment contained six treatments: CK (the control treatment with no nitrogen fertilizer), N1 (0.3 kg/tree), N2 (0.6 kg/tree), N3 (1.2 kg/tree), N4 (2.4 kg/tree) and N5 (4.8 kg/tree). Each treatment had three repeats, random arrangement, sampling the leaves and new branches every thirty days from late April to early harvest. And then the N content in leaves and new branches was measured. Results showed that the content of N in apple leaves and new branches, with the application of nitrogen obviously increased, from 2.6 to 6.2 g/kg, 1.0 to 3.1 g/kg respectively compared to CK (the control treatment); From May to August, the rates of N and the N content in apple leaves and new branches were fitted by a polynomial (P0.05 or P0.01), the correlation coefficients reached 0.814 2-0.948 0 and 0.908 3-0.981 2 respectively. From May to August, N content of leaves and new branches can be used as the basis to diagnose the supply of N nutrient in apple trees, while August for leaves and June to August for the new branches are the best sampling period.