Effects Of Drip Irrigation Nitrogen On The Growth、Absorption Of ¹⁵N-urea、Utilization And Loss Of Apple Tree

Using the 15N-labeled tracer method in 2-year-old ‘Red Fuji’/Malus hupenensis apple saplings and 5-year-old yanfu 3/M26/Malus hupenensis apple studied the effect of three nitrogen levels and water levels in drip irrigation、four fertigation treatments according to timing of irrigation and fertilization and two different fertilizer placements,studied on the characteristics of absorption, utilization and loss of 15N-urea. The results showed that:1、Increasing of nitrogen fertilizer and water which could significantly increase apple plant shoot length、dry matter quantity and 15 N absorbed from15N-urea, W3N3 was highest, respectively was 21.42 cm,62.59 g, 14.06 mg, on the other hand, W1N1 was lowest, which was 21.40 cm,35.29 g and 3.55 mg. Increasing of nitrogen fertilizer and water which could significantly increase root activity 、arbitrary units and Ndff in organs of plants. The more water significantly increase higher utilization of 15 N.On the contrary, the more nitrogen fertilizer significantly reduce utilization of 15 N. The highest nitrogen efficiency was W3N3, which was 20.00%. But the W1N1 was 9.4%, which was lowest nitrogen efficiency.2、Four fertigation treatments were designed according to timing of irrigation and fertilization had no significant difference on apple leaf area and chlorophyll content. The treatment of W + N had significantly higher of the 15 N uptake, 15 N utilization efficiency than other treatment, which was 0.84 gand 18.45%,and had the lowest loss of 15 N,which was 39.33%. The treatment of N+W had significantly higher of the residues of 15N、15N residual rate、15N loss rate, which was 2.05g、44.62%、42.55%,but had lowest 15 N absorbed、15N-urea utilization rate,which was 0.58g、13.10%. W+N in the 0-60 cm soil layer of 15 N residual rate is highest, accounting for 68.29% of the total residue, but N+W was lowest, which was 54.14%,and N+W in the 60-100 cm soil layer of 15 N residual rate is lowest, accounting for 45.86% of the total residue. The treatment of W+N can significantly improve the apple on the 15 N uptake, improve the utilization rate of nitrogen fertilizer and reduce nitrogen leaching losses.3、The treatment of drop head set distance of tree trunks had higher chlorophyll content、total N of leaf and value of roots, trunk, fruit than the treatment of drop head set half the distance of the canopy, which was 54.03、31.72g、0.76、0.55、1.69、1.04g、22.57%、59.29%,but had a lower 15 N loss rate. The treatment of drop head set distance of tree trunks had highest nitrogen in the 20-40 cm(10.48%), soil residual rate is highest, accounting for 28.52% of the residual amount; the treatment of drop head set half the distance of the canopy had highest nitrogen in the 60-80 cm(8.39%), soil residual rate is highest, accounting for 22.31% of the residual amount. The treatment of drop head set half the distance of the canopy had more nitrogen fertilizer to the soil depth(60-100 cm). For planting dwarf apple drip fertigation recommended drop head set distance of tree trunks, trunk to improve fertilizer utilization ratio and reduce nitrogen leaching losses.