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

Abstract

【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/hm2 (HF), 324 kg/hm2 (MF) and 162 kg/hm2 (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 0.74 g/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/hm2 of nitrogen fertilization is optimal for yield and fruit quality of the golden pear in the studied area.

Keywords

• water-nitrogen coupling
• golden pear
• spring shoot total nitrogen
• leaf total nitrogen
• fruit total nitrogen
• related analyze