不同施氮水平下不同氮利用效率小黑麦植株氮素积累分配特性

采用土培盆栽试验,以小黑麦氮高效利用品种‘Clxt82’、‘PI429186’和氮低效利用品种‘Clxt74’为材料,研究0(不施氮)、0.033 g(N)·kg-1(低氮)和0.066 g(N)·kg-1(正常氮)3个不同施氮水平下,各生长时期氮素在器官间和器官内不同功能性氮素分配的特性。结果表明:氮高效利用品种在氮素不足的条件下优势更明显,抽穗期高效利用品种和低效利用品种间生物量的差异随施氮量的增加而减小,在不施氮、低氮和正常供氮时‘Clxt82’、‘PI429186’地上部生物量分别为‘Clxt74’的1.55倍、1.19倍、1.06倍和1.79倍、1.35倍、1.30倍。不同生育时期,小黑麦氮积累量均随施氮量的增加而显著增加,低氮和正常供氮处理,在分蘖期、拔节期氮高效利用品种氮积累量均显著高于低效利用品种,而在抽穗期差异则不大。随施氮量的增加,氮素在叶片和穗部的分配比例减小,在茎的分配比例增大;分蘖期和拔节期,氮高效利用品种茎中氮素分配比例小于低效利用品种,叶片氮素分配比例则大于低效利用品种。抽穗期氮高效利用品种穗部氮素分配比例大于低效品种,而叶部则相反。各生育时期各器官不同形态氮素含量总体上随施氮量的增加而增加。不施氮和低氮处理,拔节期氮高效品种‘Clxt82’、‘PI429186’叶片营养性氮含量是低效品种‘Clxt74’的1.31倍、1.76倍和1.12倍、1.35倍,而结构性氮含量则是低效品种的86.12%、64.01%和80.82%、71.51%;抽穗期氮高效品种‘Clxt82’、‘PI429186’叶片营养性氮含量是低效品种‘Clxt74’的1.01倍、1.11倍和1.04倍、1.13倍,结构性氮含量为低效品种‘Clxt74’的74.99%、63.08%和75.78%、62.84%;各时期品种间功能性氮素含量差异不大。低氮条件下氮高效利用品种通过降低结构性氮素含量、增加营养性氮素含量来满足氮素的利用和体内循环。

Accumulation and distribution of nitrogen in triticale varieties with different nitrogen utilization efficiencies under different nitrogen application levels

Nitrogen (N) is a critical factor influencing yield and quality of triticale. To analyze the effects of N accumulation and distribution on N use efficiency (NUE) at different growth stages (tillering, jointing and heading) of triticale, a pot experiment with three N fertilization rates [0 (zero-N), 0.033 g(N)·kg^-1 (low-N) and 0.066 g(N)·kg^-1 (normal-N)] and three triticale varieties [two high NUE ('Clxt82', 'PI429186') and one low NUE ('Clxt74')] was carried out. The distribution of N in plant organs, and contents of different N forms were analyzed at various growth stages. The results showed that high NUE triticale varieties were advantages in low N conditions. The differences in biomass between high and low NUE varieties gradually decreased with increasing N fertilization rates at heading stage. Above-ground biomass of 'Clxt82' was respectively 1.55 times, 1.19 times and 1.06 times that of 'Clxt74' under zero-N, low-N and normal-N treatments. Similarly, above-ground biomass of 'PI429186' was respectively 1.79 times, 1.35 times and 1.30 times that of 'Clxt74' under zero-N, low-N and normal-N treatments. N accumulation increased significantly with increasing N fertilization rates at different growth stages. Under low-N and normal-N treatments, N accumulation in both high NUE varieties was significantly higher than that in low NUE variety at tillering and jointing stages. However, no significant difference was noted between the varieties at heading stage. Allocation ratio of N in plant leaves and ears decreased with increasing N fertilization rates and the reverse was the case for plant stems. At tillering and jointing stages, N allocation ratios of stems of high NUE varieties were less than that of low NUE variety, and for leaves it was reverse. At heading stage, N allocation ratio of ears of high NUE varieties was higher than in low NUE varieties and the reverse was the case for leaves. Contents of different forms of N increased with increasing N fertilization rates at various growth stages. At jointing stage, assimilable N (AN) contents in 'Clxt82' and 'PI429186' leaves were respectively 1.31 times and 1.76 times that in 'Clxt74' under zero-N treatment, and 1.12 times and 1.35 times under low-N treatment. Then structural N (SN) contents were respectively 86.12% and 64.01%, and 80.82% and 71.51% that of 'Clxt74'. At heading stage, AN content in 'Clxt82' and 'PI429186' leaves were respectively 1.01 times and 1.11 times that of 'Clxt74' under zero-N treatment, and 1.04 times and 1.13 times under low-N treatment. Also SN content were respectively 74.99% and 63.08%, and 75.78% and 62.84% that of 'Clxt74'. However, functional N (FN) content was not significantly different for the varieties at various growth stages. High NUE varieties maintained N utilization and N cycle by reducing SN content and increasing AN content.