不同产量水平下小麦倒伏与茎秆力学特性的关系

为探讨晋中晚熟冬麦区高产与倒伏的矛盾，研究小麦基部茎节形态结构与抗倒力学的关系，该文采用SAN-CMT6104微机控制电子万能材料测试仪，对大田不同产量水平及倒伏程度下的小麦基部第2茎节进行了弯折力、惯性矩、弹性模量、抗弯刚度和弯曲强度等生物力学指标的测定。结果表明：不同产量水平随基本苗的过量增加，拔节期最高分蘖峰值的增加，群体倒伏时间提早，面积加大。虽然成穗数差异不大，但穗粒数降低，特别是千粒质量明显降低，产量递减。表明受该地区自然条件与种植制度的制约，合理的基本苗（450万/hm2左右），通过返青后适期适量的水肥调控，保持稳健的最高分蘖数是关系高产不倒的两个重要的群体临界指标。研究明确了倒伏与基部第2茎节形态结构、株高、节间距与力学指标弯折力、惯性矩、弹性模量、抗弯刚度、弯曲强度都呈负相关。而茎秆干质量、茎秆外径、壁厚与弯折力、惯性矩、弹性模量、抗弯刚度、弯曲强度都呈正相关。说明随着基本苗的过量增加与拔节最高茎蘖数的增加，基部茎秆力学负荷降低，就会发生倒伏。研究筛选出与茎节抗倒、群体质量、植株形态结构以及产量结构关系密切的两个力学指标，即“弯曲强度”与“弹性模量”，可作为抗倒育种或株型育种以及高产群体架构设计的参考指标。

Relationship between lodging and mechanical characteristics of winter wheat stem under different yield levels

Understanding the relationship between the structure of the base node and mechanics of lodging resistance would be helpful to solve the contradiction of high-yield and lodging. In order to identify the relationship between the yield and lodging, the biomechanical properties (such as kink force of inertia, cross sectional moment of inertia, young modulus bending rigidity and bending strength) of basal second internodes and morphological traits were measured with the SANS-CMT6104 multifunctional testing machine controlled by computer, in 21 wheat fields, which have different yield levels in late-maturing winter wheat area in Jinzhong, Shanxi Province. The results showed that under the different production levels, with the excessive increase of the basic seeding number and the peak number of tiller in jointing stage, the lodging rate of groups was greater, lodging time was earlier, the grain number per spike and the weight of 1 000 grain were reduced significantly in particularly, the yield was decreased. Moreover, it showed that wheat production in the area was constrained by natural conditions and plant system. The reasonable basic seeding amount and the highest number of the tiller after re-green stage determined by the appropriate irrigation and fertilizer regulation were two important critical values of wheat groups with relations to high-yield and no lodging. The relationship between lodging and the morphology of base second internodes was defined. All the biomechanical indictors were negatively related to the indexes of wheat stem such as plant height and spacing bending section, while positively to dry weight, diameter and wall thickness of stem. With the excess increase of basic seeding amount, the number of highest tiller in joint stage was increased, and mechanics load of basal stem was decreased, which led to lodging. Two biomechanical properties including bending strength and elasticity modulus, which were close to lodging resistance of internodes, quality of population, morphosis of plant and yield structure, were screened out, and were regarded as reference indexes for lodging resistance or plant type breeding and high yielding population framework designed.