不同氮水平下功能叶片数量和位置对水稻产量性状的影响

Effects of the number and position of functional leaves on yield traits of rice under different nitrogen levels

【目的】功能叶片对水稻拔节期后的养分运转和积累起着举足轻重的作用。本文探讨了不同氮水平下,不同数量和位置的功能叶片对水稻产量构成的影响,为水稻生产提供更加科学、合理的指导。【方法】以在江苏省沿江及苏南地区适宜种植的早熟晚粳稻‘镇稻11号’为供试材料。田间试验主处理设置N0、90、180、270、360kg/hm^2 5个水平(即N0、N90、N180、N270、N360处理),副处理设置高栽培密度(32.5×10^4hill/hm^2,HD)和低密度(25.5×10^4hill/hm^2,LD)两个水平。于水稻开花齐穗期,每小区选择大小基本一致的单茎穗,挂上标签,分别修剪倒1叶(.T1)、倒2叶(.T2)、倒3叶(.T3)、倒1+2叶(.T1+2)、倒1+3叶(.T1+3)、倒2+3叶(.T2+3)、倒1+2+3叶(.T1+2+3)和不剪除(.T0,对照),组成8个叶位修剪处理。水稻成熟期选取具代表性的植株用于测定产量组成;同时记录各叶位修剪处理穗子的结实率及其强、弱势粒的千粒重。【结果】与N0相比,施氮能显著增加稻穗长度和穗梗数,各氮水平处理间穗长、穗梗数及单个稻穗重量无显著差异。低(N90)、中(N180)、高(N270)三个氮水平下从穗顶端至穗基部随梗位的增加,每梗粒数均呈先增加后下降的趋势,而氮水平对梗粒数没有显著影响。氮水平相同时,两栽培密度下叶片修剪的试验结果一致,均表现为:单独减去倒1、倒2、倒3叶时对单穗重无显著影响;同时减去上3叶中任意2片叶时,单穗重下降5.5%~10.3%;将上3片叶同时减去时单穗重下降24.6%;相同修剪处理下,单穗重的下降比例随氮水平的增加而增加,这表明了氮水平对穗部性状影响的稳定性。通过广义线性模型的分析表明,不同位叶剪处理下,解释单穗重下降比例的模型性能依次为结实率(SP)>SP和强势粒千粒重(S)组合模型>SP和弱势粒千粒重(I)组合模型>SP、S、I三者组合模型>I、S组合模型。【结论】氮水平通过影响稻穗长度、穗梗数、穗梗粒数、结实率和千粒重,进而影响单个穗重。花后稻穗功能叶片越少,单穗重下降越大;施氮水平越高,下降越严重。当功能叶片数量一定时,叶片位置不影响单穗重。花后功能叶依次通过影响结实率、结实率和强势粒千粒重、结实率和弱势粒千粒重、强势粒千粒重和弱势粒千粒重来影响稻穗的重量。

【Objectives】The functional leaves play key roles for the nutrient translocation from vegetative organs to spikes of rice. The paper studied the effects of different number and positions of functional leaves on the panicle characteristics under different nitrogen levels, so as to provide more scientific and reasonable guidance for the actual production of rice.【Methods】Taking early-maturing late japonicas ‘Zhendao 11’ as material, a field experiment was conducted in Jiangsu Province. Five nitrogen levels (N 0, 90, 180, 270, 360 kg/hm^2) were set up as the main treatments of N0, N90, N180, N270 and N360, and high and low transplanting densities of 32.5 × 10^4 and 25.5 × 10^4 hill/hm^2 as the secondary treatments (HD and LD). At heading stage of rice, panicles with the same size were selected and labeled in each plot. From the panicle downward, the leaves were pruned respectively as: the last 1st (-T), the last 2nd (-T2), the last 3rd (-T3), the last 1st+2nd (-T1+2), the last 1st+3rd (-T1+3), the last 2nd+3rd (-T2+3), the last three (-T1+2+3), and non-pruned (-T0, control), totally 8 pruning treatments. At maturity stage, representative plants were selected to measure the yield components. The seed setting percentage and the superior 1000-grains-weight and the inferior 1000-grains-weight were recorded in each panicles under each pruning treatments.【Results】Compared with N0, N application significantly increased the pantcle length and the number of per panicle, but not in panicle length, panicle branch number and weight per panicle among different nitrogen levels (N0, 90, 180, 270, 360 kg/hm2). Under N90, N180 and N270, with the increasing of the stalk position from the top to the base of panicle, the number of grains per branch increased first and then decreased. The results of leaf pruning under the two cultivation densities were similar, indicating the stability of the effect of N level on panicle traits. There was no significant effect on the weight of single spike when the last 1st, 2nd and 3rd leaves was pruned alone, while that was decreased by 5.5%-10.3% with any 2 or 3 leaves pruned together, and when the three leaves were all pruned, that was decreased by 24.6%. Under the same pruning treatment, the decline ratio of weight per panicle increased with the increase of nitrogen level. The analysis of the generalized linear model showed that under different leaf position pruning, the model performance to explain the falling ratio of weight per panicle is: seed setting percentage (SP)> SP, 1000-grain weight of superior spikelets (S) and 1000- grain weight of inferior spikelets (I), in which SP, S, I composite model > I, S composite model.【Conclusions】The nitrogen level affects the spike length, number of branches per panicle, number of grains per branch, seed setting percentage and 1000-grain weight, and then the weight of per panicle. Fewer functional leaves after anthesis leads to lower panicle weight, and the lower the higher the nitrogen level. When the number of functional leaves is constant, leaf position does not affect the single spike weight. The position of functional leaves after anthesis affect the single panicle weight of rice by influencing SP, SP and S, SP and I, I and S in turn.