供氮水平对矮化苹果15N-尿素吸收、利用、损失及产量和品质的影响

以7年生烟富3/M26/平邑甜茶为试材,采用¹⁵N同位素示踪技术,研究不同供氮水平[低氮(100 kg N·hm^-2,N₁₀₀)、中氮(200 kg N·hm^-2,N₂₀₀)和高氮(300 kg N·hm^-2,N₃₀₀)]对烟富3/M26/平邑甜茶¹⁵N-尿素吸收、利用、损失及产量和品质的影响.结果表明: 不同供氮水平植株的生长状况及氮素吸收、利用和损失特性差异显著.N₂₀₀处理植株叶绿素含量(SPAD)、光合速率(P_n)、叶片全氮含量和生物量显著高于N₁₀₀和N₃₀₀处理,植株根冠比也显著增加.不同供氮水平下植株各器官对氮的吸收能力(Ndff值)存在显著差异,各测定时期果实(花)、叶片、一年生枝、多年生枝和中心干的Ndff值均为N₁₀₀>N₂₀₀＞N₃₀₀;而根的Ndff值在盛花期和春梢缓长期为N₁₀₀ >N₂₀₀＞N₃₀₀,在秋梢生长期、果实膨大期和果实成熟期为N₂₀₀ >N₁₀₀＞N₃₀₀.在果实成熟期,N₂₀₀处理¹⁵N肥料利用率为23.6%,显著高于N₁₀₀(16.3%)和N₃₀₀处理(14.4%),而¹⁵N损失率为56.4%,显著低于N₁₀₀(60.6%)和N₃₀₀处理(66.1%).不同供氮水平植株的平均单果质量、单株产量、可溶性固形物、硬度、可溶性糖、可滴定酸、糖酸比均存在显著差异,且均以N₂₀₀处理最高,其次是N₃₀₀处理,N₁₀₀处理最低.

Effects of different nitrogen application rates on 15N-urea absorption,utilization, loss and fruit yield and quality of dwarf apple

Seven-year-old ‘Yanfu3’/M₂₆/M. hupehensis Rehd. seedlings and ¹⁵N trace technique were used to explore the characteristics of ¹⁵N-urea absorption, utilization, loss and fruit yield and quality under different nitrogen application rates (N₁₀₀, N₂₀₀ and N₃₀₀). The main results were as follows: the plant growth, ¹⁵N absorption, utilization and loss differed significantly under different treatments. The plant leaf chlorophyll content (SPAD value), photosynthetic rate (P_n), total N content of leaves and the biomass, as well as the root-shoot ratio of N₂₀₀ treatment were obviously higher than the N₁₀₀ and N₃₀₀ treatments. Significant differences were observed in the ¹⁵N derived from fertilizer (Ndff value) of different organs under different nitrogen application rates. The Ndff of fruits (flowers), leaves, one-year-old branch, and perennial branches in each measurement period was N₁₀₀ >N₂₀₀＞N₃₀₀, while that of the roots at full-bloom and spring shoot growing slowly stage was N₁₀₀ >N₂₀₀＞N₃₀₀, and in a trend of N₂₀₀ >N₁₀₀＞N₃₀₀ at autumn shoot growing stage, fruit rapid-swel-ling stage and fruit maturity stage. At fruit maturity stage, plant ¹⁵N nitrogen utilization ratio of N₂₀₀ treatment was 23.6%, which was obviously higher than the N₁₀₀ (16.3%) and N₃₀₀ (14.4%) treatments, with the ¹⁵N loss rate of 56.4%, obviously lower than the N₁₀₀ (60.6%) and N₃₀₀ (66.1%) treatments. There were significant differences among the treatments in fruit mass, yield per plant, soluble solid, fruit firmness, soluble sugar, titratable acids and sugar-acid ratio of different nitrogen rates, and the N₂₀₀ treatment showed the best performance, followed by the N₃₀₀ treatment, and then the N₁₀₀ treatment.