摘要：

为了明确增密对玉米源库关系的影响特点,选用郑单958和金秋119为试验材料,设置4.5万,6.0万,7.5万,9.0万,12.0万株/hm² 5个不同的种植密度,探讨不同品种玉米花期植株形态、冠层光合特性、粒库建成对增密的响应特征及变化关系。结果显示:增加种植密度,株高、穗位高、穗位系数显著增加;基部第Ⅲ节间直径、消光系数(k)、单株叶面积、穗位叶面积等显著降低;穗位叶净光合速率、穗位叶光合能力和穗粒数变化趋势同上;增密对不同品种玉米的影响总体表现一致。种植密度从4.5万株/hm²增加到12万株/hm²,郑单958和金秋119穗位叶面积分别降低20.63%和12.30%,穗位叶光合能力降低33.76%和33.31%,穗粒数降低21.55%和36.07%。进一步建立了穗位叶光合能力、穗粒数与种植密度的线性关系,从线性关系可以看出,种植密度每增加1×10⁴株/hm²,郑单958穗位叶光合能力降低0.076 μmol/s、穗粒数降低13.03粒,金秋119穗位叶光合能力降低0.088 μmol/s、穗粒数降低27.93粒;从线性斜率看出,相对于郑单958,金秋119叶源与粒库对增密较为敏感,且2个品种的差异主要表现在粒库建成上;此外,此线性模型可应用于增密对玉米冠层光合特性与粒库建成的模拟预测上,为玉米适度增密丰产提供参考。综上,增源扩库是夏玉米增密增产的关键。

关键词: 玉米, 种植密度, 光合特性, 粒数, 源库关系

Abstract:

In order to clarify the characteristics of the effect of increasing plant density on the source-sink relationship of maize,ZD958 and JQ119 were chosen as the experimental materials,and five different planting densities (45 000,60 000,75 000,90 000 and 120 000 plants/ha) were set to explore the response characteristics and changes of plant morphology,leaf canopy photosynthetic characteristics and establishment of grain sink of different hybrids at anthesis of maize to increase plant density. The results showed that with the increase of plant density,plant height,ear height and ear coefficient increased significantly. The basal intersegmental diameter Ⅲ,the extinction coefficient (k),the leaf area per plant and the ear leaf area of maize were significantly decreased,and the net photosynthetic rate of ear leaf,photosynthetic capacity of ear leaf and kernel number per ear were the same as above. The effects of increasing of plant density on different maize hybrids were generally consistent. When plant density was increased from 45 000 to 120 000 plants/ha,the ear leaf area decreased by 20.63% and 12.30%,the photosynthetic capacity of ear leaf decreased by 33.76% and 33.31%,and the kernel number per ear decreased by 21.55% and 36.07%for ZD958 and JQ119,respectively.The linear relationship between photosynthetic capacity of ear leaf,kernel number per ear and plant density was further established. The linear relationship showed that for every 1×10⁴ plants/ha increase in plant density,the photosynthetic capacity of ear leaf of ZD958 decreases by 0.076 μmol/s and the kernel number per ear by 13.03,while the photosynthetic capacity of ear leaf of JQ119 decreases by 0.088 μmol/s and the kernel number per ear by 27.93.From the linear slope,compared with ZD958,JQ119's leaf source and grain sink were more sensitive to increasing plant density,and the difference between the two hybrids was mainly manifested in the establishment of grain sink. In addition,this linear model can be applied to the simulation and prediction of maize canopy photosynthetic characteristics and grain sink establishment by increasing plant density,which can provide reference for moderately increased plant density for high yield of maize.In summary,enhancing the source and expanding the sink is the key to increasing yield in summer maize under increasing plant density.

Key words: Zea mays L., Planting density, Photosynthetic characteristics, Grain number, Source-sink relationship