水稻品种氮肥群体最高生产力及其增长规律

在提出氮肥群体最高生产力概念的前提下, 以长江中下游地区有代表性的50个早熟晚粳品种(系)为供试材料, 比较研究品种间氮肥群体最高生产力的差异及其与产量构成因素、株型和氮肥农学利用率的关系。结果表明: (1)在基础地力产量为6 t hm^-2的沙壤土上, 50个早熟晚粳品种氮肥群体最高生产力对应的施氮量主要集中在225~300 kg hm^-2, 各品种的氮肥群体最高生产力因种而异, 变动在7.42~11.02 t hm^-2, 差异显著。(2)氮肥群体最高生产力与群体颖花量呈显著正相关(r = 0.865), 生产力处于顶层与高层水平品种的颖花量极显著高于中层、低层品种, 而颖花量的增加主要体现在每穗粒数的极显著增加。(3)氮肥群体最高生产力随高效叶面积与单穗重增加而增长, 顶层和高层水平品种的基本株型性状均显著优于中层和低层水平品种, 主要表现为株高105~110 cm, 基部节间粗0.65 cm左右, 高效叶面积大(高效LAI大于5), 穗型较大。(4)品种间理论氮肥群体最高生产力随对应施氮量增加而增长, 但相同对应施氮量下, 品种生产力亦有一定差异。(5)筛选出6个氮肥群体最高生产力(≥10.5 t hm^-2)与氮肥农学利用率均较高且协调统一的品种。

The Highest Population Productivity of Nitrogen Fertilization and Its Variation Rules in Rice Cultivars

Based on the concept of the highest population productivity of N fertilization, we carried out a field experiments with 50 early-maturing late japonica rice varieties which were the representativein the region of Yangtze River, using seven nitrogen applying levels (0, 150, 187.5, 225, 262.5, 300, 337.5 kg ha^-1), to investigate the difference of the most population productivity of N fertilization in varieties. Its relationships with yield components, plant-type characteristics and nitrogen agronomic efficiency were also analyzed. The main results were as follows. (1)With the basic yield capacity of sandy loam being 6 t ha^-1, optimum N levels of 50 tested varieties which were corresponding to their highest population yield converged in the range of 225–300 kg ha^-1, while the highest grain yield showed significant differences, varying from 7.42 to 11.02 t ha^-1.(2) There was significantly positive correlation between the highest productivity of N fertilization and the total spikelet number, with the correlation coefficient of 0.865. The top- and high-level yielding varieties had extremely significantly larger amount of population spikelets than the middle- and low-level yielding varieties, and this superiority of total spikelets was mainly due to the extremely remarkable increase of spikelets per panicle. (3) The highest productivity of N fertilizer rose as the high-efficiency leaf area and the weight per panicle increased. Compared with middle- and low-level yielding cultivars, top- and high-level yielding cultivars performed superior plant type characteristics: the plant height ranged from 105–110 cm, the width of basal internodes was circa 0.65 cm, the high-efficiency leaf area index was higher than 5, and panicles were big. (4) Generally speaking, the theoretical highest population productivity of N fertilization increased with the increasing of corresponding applied N amount. But within each group of similar optimum N level, various rice cultivars produced significantly different grain yields. (5) Taking into consideration of the production capacity and the nitrogen agronomic efficiency of all 50 rice varieties, six varieties with high yield and high efficiency were selected and recommended.