施氮量对不同株型小麦品种叶型垂直分布特征的影响

在大田生产条件下，以紧凑型高秆品种宁麦9号和矮秆品种矮抗58、中间型品种扬麦12、松散型品种淮麦17为材料，测定并分析了3个施氮水平下不同生育时期的小麦冠层叶型特征，以及开花期小麦叶长和叶宽、单叶面积、茎叶夹角、分层叶面积指数和群体透光率的垂直分布特征。结果表明，小麦叶型特征存在显著的基因型差异，而施氮量的调控作用因叶型性状和生育时期不同而各异。叶片定形后，从植株基部向上，4个小麦品种不同叶位叶片单叶面积呈“升－降－升－降”的变化趋势，而茎叶夹角呈递减趋势。其最大分层叶面积指数所在的相对冠层高度为0.60。从冠层基部向上，群体透光率逐渐增加，符合二次多项式曲线。施氮提高了单叶面积，其中扬麦12和淮麦17的增加幅度较大。施氮提高了各叶位茎叶夹角，且对宁麦9号、淮麦17和扬麦12冠层下部茎叶夹角的调控作用大于冠层上部，而对矮抗58正好相反。施氮提高了各株型小麦品种的分层叶面积指数，降低了群体透光率，但过量施氮条件下，宁麦9号和矮抗58透光率的下降幅度小于扬麦12和淮麦17。各株型小麦品种群体透光率随累积叶面积指数的增加而递减。籽粒产量为N150 (150 kg hm^-2) > N225 (225 kg hm^-2) > N75 (75 kg hm^-2)。施氮显著提高了小麦品种穗数和收获指数，但对千粒重的影响不显著。穗粒数以高氮处理最高，低氮处理其次。籽粒产量、千粒重、穗数、穗粒数和收获指数在4个株型品种间差异显著，籽粒产量为矮抗58 > 宁麦9号 > 扬麦12 > 淮麦17，穗数和穗粒数是造成籽粒产量差异的主要原因。

Effect of Nitrogen Rate on Vertical Distribution Characteristics of Leaf-Type in Wheat with Different Plant Types

The objective of this study was to elucidate the vertical distribution characteristics of leaf using wheat (Triticum aestivum L.) cultivars in compact-high, compact-short, intermediate, and loose plant types with three nitrogen rates in two growing seasons. The leaf-type characteristics at the stages of stem elongation, flowering and grain-filling, and the vertical distribution characteristics of leaf and light within canopy at flowering were measured. Significant differences were observed among genotypes for leaf-type characteristics, and the regulating effects of nitrogen rate varied with leaf-type traits and growth stages. Single leaf area changed in a double-peak curve from canopy base to top. A gradually decreasing tendency with increasing canopy height was found in angle between stem and leaf (ABSL). The maximum leaf area index was located at 0.60 relative canopy height. Light transmission rate increased from the base to top of canopy, and presented a good fitness to quadratic polynomial curve. Single leaf area increased with increasing nitrogen rate, with greater increments in Yangmai 12 and Huaimai 17 than in Ningmai 9 and Aikang 58. The ABSL enhanced with the increasing nitrogen rate. The nitrogen regulation effects on ABSL of Ningmai 9, Huaimai 17, and Yangmai 12 were stronger at canopy base than at canopy top, but Aikang 58 showed a reverse pattern. With the increase of nitrogen rate, leaf area index accumulation at different relative canopy heights increased, while light transmission decreased. The smaller decline of light transmission in Ningmai 9 and Aikang 58 was observed than those in Yangmai 12 and Huaimai 17 when more nitrogen was applicated. The transmittance rate decreased in an exponential pattern with increasing leaf area index accumulation. The grain yield ranked in the order of treatments supplied 150 (N150), 225 (N225) and 75 (N75) kg ha-1. Nitrogen fertilization increased remarkably spike number and harvest index, excluding 1000-grain weight. The grain number per spike was the highest in the N225 treatment, follwded by the N75 treatment. Four wheat cultivars with different plant types differed markedly in grain yield, spike number, grain number per spike, and harvest index. The grain yields were ranked as Aikang 58 > Ningmai 9 > Yangmai 12 > Huaimai 17. These results may provide a technical basis for optimizing nitrogen application to wheat cultivars with different plant types.