玉米冠层光分布对茎秆抗倒伏性能的影响

发布时间：2018-04-06 07:48

本文选题：玉米　切入点：冠层结构　出处：《石河子大学》2016年博士论文

【摘要】：增加种植密度是提高玉米产量的重要措施之一,但是种植密度增加后玉米茎秆机械强度降低,倒伏现象严重。倒伏不仅降低了玉米产量和品质,同时也增加了机械收获难度。玉米高密度种植时具有较大的叶面积指数,导致营养生长至灌浆早期冠层中下部叶片的相互遮荫和光合有效辐射大幅下降。叶片在遮荫或者弱光条件下的光合能力下降,使转运到茎秆中的碳水化合物降低。由此推测,密植条件下玉米冠层内部光照强度下降可能是引起基部节间强度降低、倒伏增加的重要因素。基于上述推论,本文设置不同种植密度、整体遮荫和局部剪叶等试验处理改变玉米冠层的光照环境,通过对不同光环境下玉米植株形态、基部节间外部形态及内部碳水化合物组分、解剖结构、机械强度和倒伏率等进行系统研究,探讨冠层光环境对玉米节间发育的影响机制;明确玉米节间碳水化合物变化与解剖结构及机械强度的相互关系;揭示玉米冠层光分布与茎秆机械强度形成及抗倒伏能力的关系。研究结果可为玉米密植高产稳产栽培及耐密抗倒品种选育提供理论依据。主要研究内容和结果如下:1 种植密度对玉米节间发育的影响玉米节间发育过程中先进行快速增粗和伸长,接着节间干物质快速积累、茎壁的结构性化学组分合成,最后是茎秆强度形成。其中基部节间穿刺强度(RPS)快速形成期大约在拔节后14 d至25 d。随着种植密度增加,玉米基部节间形态快速建成的起始时间和终止时间均有所提前。在高密度条件下,玉米基部节间快速伸长速率提高,使节间变长;而节间快速增粗、干物质积累持续期缩短,导致节间变细,节间单位长度干重(DWUL)降低,茎秆抗倒伏强度有所下降。2 密植条件下玉米冠层内部光照强度对茎秆抗倒伏能力的影响增加种植密度降低玉米冠层内部的光照强度,玉米基部节间单位长度干重和穿刺强度有所降低,倒伏率增加。与自然光照下相比较,对玉米冠层进行30%和60%遮荫后,基部节间单位长度干重分别降低40%和50%;穿刺强度分别降低40%和50%;倒伏率增加10%和20%。由此可知,玉米冠层光照强度是影响节间强度形成和倒伏发生的重要因素。3 遮荫和剪叶处理对玉米茎秆强度和倒伏的影响整体遮荫处理后,明显增加了玉米株高和穗位高,但植株重心高度有所降低。遮荫后玉米基部节间长度增加、直径变小;穿刺强度降低,倒伏率增加。进一步分析节间碳水化合物可知:遮荫处理后显著降低基部节间单位长度干重、水溶性碳水化合物(WSC)、纤维素、木质素和半纤维素的含量,且对WSC含量的影响程度最大。由此说明,遮荫后由于玉米节间WSC含量降低,使节间结构性碳水化合物含量显著降低,倒伏率增加。在玉米抽雄期局部剪去棒三叶以上全部或1/2叶片(RAE或RAE/2)后,基部第3节间单位长度结构性碳水化合物含量显著增加,穿刺强度分别提高5.4-11.6%和7.7-8.2%,倒伏率分别下降4.9-7.8%和4.2-4.6%。抽雄前剪去玉米棒三叶以下3片叶(RBE),基部第3节间单位长度结构性碳水化合物含量显著降低,穿刺强度降低9.1-17.4%,倒伏率增加7.0-11.2%。抽雄前剪去玉米冠层底部3片叶(RB),第3节结构性碳水化合物含量、穿刺强度和倒伏率无显著变化。由此表明,玉米棒三叶以下3片叶是基部节间碳水化合物积累和机械强度形成的关键叶层。4 玉米节间碳水化合物、解剖结构与茎秆机械强度的关系茎秆RPS形成主要在节间定长后,节间DWUL中后期积累为RPS形成提供物质来源。高密度条件下玉米基部节间纤维素和木质素积累的起始和终止时间均提前;节间纤维素和木质素快速积累速率下降,使节间外皮组织发育受阻;节间RPS形成速率下降,最终导致RPS显著降低。因此,生产中应在拔节期通过农艺和化学调控等措施,控制玉米节间伸长速率,缩短节长,增加单位长度干重;使茎秆纤维素和木质素积累速率加快,茎秆强度提高,从而降低田间倒伏率。5 改善玉米冠层光分布对茎秆抗倒伏能力的影响玉米穗位至穗下1/2叶层功能对基部节间干物质积累和机械强度形成有至关重要的作用,提高玉米穗位层光照强度以及穗位至穗下1/2层光截获量可显著提高基部节间单位长度干重、结构性碳水化合物含量和穿刺强度,显著减少田间倒伏率。因此,高密条件下选用植株上部叶片较小、直立的玉米高产品种,有利于冠层下部透光,提高基部节间的机械强度和抗倒伏能力,为实现玉米大面积密植高产栽培技术提供必要的保障。
[Abstract]:The increase of planting density is one of the important measures to improve the yield of maize, but the planting density increased after the mechanical strength of the corn stalk decreased, serious lodging. Lodging not only reduces the yield and quality of maize, but also increase the difficulty of mechanical harvesting corn. High planting density has larger leaf area index, resulting in mutual shading from vegetative growth to early grain filling in the lower leaf and canopy photosynthetic active radiation decline. Leaves in the shade or in low light conditions decreased photosynthetic ability, make the transfer to the carbohydrate in stem decreased. Thus, dense planting conditions of corn canopy light intensity decrease may be caused by the decrease of basal internode strength, an important factor in the increase of lodging this paper set up. Based on the above corollary, different planting density, the shade and leaf cutting treatments change the local maize canopy light environment, through the Under different light environment of maize plant morphology, internode morphology and internal carbohydrate components, anatomical structure, systematic study of the mechanical strength and lodging rate, to explore the canopy light environment on the influence mechanism of maize internode development; maize internode carbohydrate change clear relationship between anatomical structure and mechanical strength; reveal the relationship of maize canopy light distribution and lodging resistance and culm mechanical strength. The research results can provide theoretical basis for maize planting high yield cultivation and breeding density tolerant varieties. But the main research contents and results are as follows: 1. The effect of planting density on Maize internode development of corn in the first internode development of rapid thickening and elongation of internode, then dry the rapid accumulation of material, structural chemistry of stem wall synthesis, finally is formed. The stem strength of basal internodes puncture strength (RPS) - fast A period of about 14 d to 25 D. after jointing stage with the increase of planting density, the starting time of maize internode morphology built quickly and termination time were advanced. In the case of high density, maize internode elongation rate increased rapidly, the internode length and internode; rapid thickening, dry matter accumulation duration in shorter, thinner internode, dry weight per unit length (DWUL) decreased, lodging strength decreased.2 under the high planting density of maize canopy light intensity on the internal lodging resistance of stem the increase of planting density reduced maize canopy internal light intensity, maize internode dry weight per unit length and puncture strength reduced lodging rate increased. Compared with natural light, 30% shading and 60% shading of maize canopy, basal internode dry weight per unit length were decreased by 40% and 50% respectively; puncture strength decreased by 40% and 50%; the lodging rate An increase of 10% and 20%. the corn canopy light intensity is an important factor influencing the occurrence of.3 shading and lodging internode strength formation and leaf cutting effect on corn stalk strength and lodging overall after shading treatment, significantly increased the maize plant height and ear height, but the plant height of the center of gravity is reduced. After shading of corn internode length increased, the diameter becomes smaller; puncture strength decreased, lodging rate increased. Further analysis indicated that shading internode carbohydrate decreased significantly after basal internode dry weight per unit length, water soluble carbohydrate (WSC), cellulose, lignin and hemicellulose content, and the degree of influence of the WSC content. The maximum that shade due to reduced WSC content in maize internode, the internode structural carbohydrate content decreased significantly, lodging rate increased. In maize tasseling stage to local shear rod or 1/ all of the above three 2 leaves (RAE or RAE/2), the third internode length of structural carbohydrate content increased significantly, puncture strength were increased by 5.4-11.6% and 7.7-8.2%, 4.9-7.8% and 4.2-4.6%. respectively decreased lodging rate before tasseling to cut Corn Cob following the 3 leaf clover (RBE), the third internode length of structural carbohydrate content was significantly reduced. Puncture strength decreased 9.1-17.4%, increased 7.0-11.2%. lodging rate before tasseling to cut corn canopy at the bottom of the 3 leaf (RB), the third section structural carbohydrate content, puncture strength and lodging rate had no significant change. The key that Corn Cob leaves 3 leaf clover following primary internode carbohydrate accumulation and the mechanical strength of the layer.4 Maize internode carbohydrate, anatomical structure and culm mechanical strength RPS formed mainly in the relationship between culm internode length, internode DWUL accumulation in late offering for RPS Quality source. The initial time of high density maize under basal internode of cellulose and lignin accumulation and early termination; internodes of cellulose and lignin accumulation rate decreased, which hindered the development of internode cortical tissue; internode RPS formation rate decreased, resulting in significant reduction of RPS. Therefore, the production should be in the jointing stage by agronomic chemical regulation and control measures of maize internode elongation rate, shorten the length, increase the dry weight per unit length; the stalk cellulose and lignin accumulation rate, stem strength increased, thereby reducing the field lodging rate.5 to improve the effects of light distribution in maize canopy lodging of corn ear to ear leaf layer under 1/2 the function of basal internode dry matter accumulation and mechanical strength formation plays a crucial role in Improving Maize Ear layer of light intensity and light interception of ear to ear of 1/2 can significantly improve the base layer Dry weight per unit length, structural carbohydrate content and puncture strength, significantly reduced the rate of lodging in the field. Therefore, under the condition of the plant density of upper leaves are smaller, High-yield Maize Varieties with erect, conducive to lower canopy light, increase the mechanical strength of the basal internode and lodging resistance, to provide the necessary protection of maize high yield dense planting technology.

【学位授予单位】：石河子大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：S513

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