黄金梨树氮素营养状况对不同水氮用量的响应

Change in Nitrogen Content in Golden Pear Trees in Response to Irrigation and Nitrogen Fertilization

【目的】探究黄金梨树氮吸收对水氮耦合的响应规律。【方法】设定灌水下限和施氮量2个因素,每个因素设定3个水平,即灌水下限:高水(HW:75%Fc)、中水(MW:65%Fc)和低水(LW:55%Fc)(Fc:田间持水率(体积含水率));施氮量:高氮(HF:486 kg/hm^(2))、中氮(MF:324 kg/hm^(2))、低氮(LF:162 kg/hm^(2)),正交设定9个试验处理,对照处理为园区常规管理(CK)。测定了果实膨大期和成熟期梨树春梢、叶片和果实全氮量。【结果】果实膨大期,中水中肥(MWMF)处理梨树春梢和叶片全氮量最高,较CK分别提高了26.20%和8.66%;灌水下限对春梢全氮量影响差异不显著,施氮量和耦合作用对春梢全氮量提高差异显著;灌水下限、施氮量及耦合作用对叶片全氮量提升差异不显著。成熟期时,中水中肥(MWMF)处理梨树春梢全氮量最高为0.74g/kg,高水中肥(HWMF)处理春梢全氮量最低,为0.54 g/kg;高水中肥(HWMF)处理梨树叶片全氮量最高为1.83 g/kg,高水低肥(HWLF)处理全氮量最低为1.70 g/kg;水氮耦合方案下果实全氮量较CK显著提高,其中,低水高肥(LWHF)处理果实全氮量最高,为0.82 g/kg,较CK提高了52.70%;灌水下限和水氮耦合作用对春梢全氮量的影响差异不显著,施氮量对春梢全氮量影响差异显著;灌水下限、施氮量和耦合作用对叶片全氮量差异不显著;灌水下限、施氮量和耦合作用对果实全氮量影响差异显著。2个时期梨树春梢和叶片全氮量均有:叶片>春梢。梨树春梢、叶片和果实等3个器官全氮量相关性不显著,春梢全氮量与果实全氮量呈弱正相关,叶片全氮量与春梢和果实全氮量呈弱负相关。【结论】不同时期3个器官对水氮耦合处理响应规律不一,适宜的水氮耦合处理能促进各器官对氮的吸收,各器官全氮量相关性不显著。考虑梨树生长与生产和采收后生长分化,推荐灌水下限为65%Fc,施氮量为300~350 kg/hm^(2)。

【Background and objective】Gold pear is a main fruit in northern China and its production relies on irrigation and fertilization. The purpose of this paper is to study the effects of different combinations of irrigation and nitrogen-fertilization on nitrogen uptake by roots and its translocation in the trees.【Method】The experiment was conducted in an orchard;it consisted of three irrigation treatments by keeping the lowest soil water content controlled for irrigation at 75(HW), 65(MW)and 55%(LW)of the field capacity, respectively, and three nitrogen treatments by applying 486 kg/hm^(2)(HF), 324 kg/hm^(2)(MF)and 162 kg/hm^(2)(LF), respectively. Standard irrigation and fertilization used by local farmers was taken as the control(CK). In each treatment, we measured nitrogen content in different parts of the tree at different growth stages.【Result】At fruit-expansion stage, the total nitrogen content in spring shoots and leaves were the highest in MW+MF, increasing by 26.20% and 8.66% respectively,compared to CK;the total nitrogen content differed significantly in spring shoots but not in leaves between the treatments. At maturity stage, the total nitrogen content in spring shoots was the highest in MW+MF, reaching 0.74g/kg, and least in HW +MF, dropping to 0.54 g/kg. The total nitrogen content in the leaves in HW+MF was the highest, reaching 1.83 g/kg, and least in HW+LF being 1.70 g/kg. The nitrogen content in fruits in LW+HF was the highest, reaching 0.82 g/kg, a 52.70% increase compared to CK. The treatments did not result in considerable changes in total nitrogen contents in spring shoots and leaves, but significantly changed the total nitrogen contents in shoots and fruits. Correlation analysis did not find correlation between total nitrogen contents in spring shoots,leaves and fruits. The total nitrogen content in spring shoots and fruit were positively but insignificantly correlated,while total nitrogen content in leaves was negatively but insufficiently correlated with the total nitrogen content in spring shoots and fruits.【Conclusion】For all treatments we compared, keeping the lowest soil water controlled for irrigation at 65% of the field capacity combined with 300~350 kg/hm^(2) of nitrogen fertilization is optimal for yield and fruit quality of the golden pear in the studied area.