【作者】 刘志新；

【导师】 曹敏建；

【作者基本信息】 沈阳农业大学 ， 作物栽培学与耕作学， 2009， 博士

【摘要】 玉米是一个高产、稳产的作物。但是,随着育种水平和生产水平的不断提高,个体与群体的矛盾越来越突出,单靠挖掘单株生产力而达到大幅度提高玉米产量已十分困难。选育和推广耐密植玉米品种,依靠群体产量来增加单产是进一步提高玉米生产水平的必然趋势。关于玉米的密植育种和生产还有很多不确定因素。比如加大种植密度后,密度对不同耐密性品种有哪些影响?哪些性状可以做为玉米耐密性鉴定指标?玉米的耐密性是如何遗传的?密植品种对肥力水平、种植方式、种植密度等的要求如何?等等。论文设置不同试验对上述问题进行研究,以期通过栽培试验为密植育种提供选择依据,同时也为大面积生产提供指导;反过来,通过栽培试验提出的问题使育种更有针对性,进而提高玉米育种效率,选育出更优秀的密植品种服务生产。本试验主要研究结果如下:1、种植密度对产量影响很大,适当增加密度可以显著提高玉米产量。种植密度对各种性状的影响最终反映到对产量的影响。密度对产量构成三要素的影响在不同耐密性品种间方向是相同的,但影响程度有所不同。即随着密度的增加三个品种单位面积穗数显著增加;穗粒数、千粒重则呈减小趋势,不同品种减小幅度不同。高产的形成过程实际上是三要素之间相互协调的过程。2、密度对不同耐密性品种农艺性状的影响是相当复杂的。其中,株高、穗位高和穗行数的差异主要来自于品种,密度对其影响较小,在研究密度效应时此三个性状可以不做重点考查;穗长、穗粗、行粒数的差异虽然来自于品种要多一些,但密度的效应加大,在研究密度效应时该三个性状应适当加以考查;倒伏率、空秆率、ASI、秃尖长受密度影响最大,在研究密度效应时应重点加以考查并可以做为品种耐密性的鉴定指标。3、不同品种的单株叶面积和LAI都随生育时期呈单峰曲线变化,但不同品种的变化趋势不同。密植品种辽单565在抽雄-蜡熟期以后叶片不早衰、维持了较长时间较大的叶面积、光合势和净同化率,这有利于植株籽粒建成和灌浆。中间型品种辽单527和稀植品种丹玉39都是在抽雄以后就迅速下降,单株叶面积较大值维持时间较短;LAI随着密度的增加而增大,以拨节期-抽丝期增长速率最快,抽雄期以后开始下降。耐密品种对不同密度有较好的自身调节能力,生育后期在高密度下光合性能好是产量较高的原因之一;而稀植品种增加密度后光合态势不尽合理,导致产量下降。4、耐密型品种在一定的密度范围内干物质积累量随密度增加而增加,稀植品种密度增加到一定程度干物质积累不再增加甚至减少。密植品种辽单565干物质生产率的峰值出现在抽雄-乳熟期;而稀植品种丹玉39峰值则相对提前,出现在大喇叭口-抽雄期。这一差异导致稀植品种由于前期徒长、经济系数下降而减产;相反密植品种由于干物质的运输与贮藏相对协调而高产。5、在密植育种中,很多性状在高低两种种植密度下的遗传特性存在较大差异。如果在低密度下进行选择,选出的“耐密”试材具有较大的假象。或者说,当密度提高到一定程度,这些材料就不再具有耐密性,进而更难选育出耐密植品种。因此,耐密材料的选择应具有一定的密度压力,且不同性状要侧重于不同世代进行选择。总体来说,株高、穗位、空秆率、千粒重和小区产量可以在早代选择而ASI、倒伏、穗长、穗粗、穗行数、行粒数、秃尖长要在晚代选择。6、通过对辽宁省上个世纪八十年代以来选育及引入的一些主要品种的耐密性进行评价认为,辽宁省的品种耐密性呈增加之势。通过密植品种的选育和推广将使我省玉米生产水平再上一个新的台阶。在新品种的选育中,加大试验材料的种植密度可以提高耐密材料的选育效率。本试验筛选出的自交系7029、7038等耐密性较好,将在密植育种中发挥重要作用。7、不同肥力条件需要的品种和适宜的种植密度不同。在中、上等肥力地块,无论哪种密度都以耐密型品种产量最高,稀植品种产量最低。在肥力较差地块,品种之间产量差异不显著。因此,生产上选择品种时,当肥力条件较好时应选择耐密或较耐密型品种,以获得高产;当肥力较差时,不宜盲目引种密植品种,而是要边引进边试验,为品种寻找一个合适密度;辽宁省是我国优势玉米产区、土地肥沃,绝大部分地区都应适当增加种植密度。种植模式对产量影响较大。本试验产量最好的模式是缩距增密,其次是大垅双行,偏窄行模式居中,常规种植和二比空种植产量都不高。对于较耐密植的品种辽单565和辽单527采用大垅双行、缩距增密模式有利于品种产量潜力的发挥。生产中,应该根据品种的基因型特性选择合适的种植模式并配置合适的密度才能保证产量的提高。更多还原

【Abstract】 Maize was a high and stable yield crop. However, contradiction between individual and population became more and more serious with breeding and production level developed, it was very hard to increase maize yield by exploiting individual productivity alone. Developing and extension of density-tolerant maize variety,depending population yield on increasing unit yield was an inevitable trend in increasing unit yield further.There were many uncertain factors to high density maize breeding and production. For example, request of soil fertility level, cropping pattern and planting density of high density variety, effect of planting density on different genotype variety when planting density enhanced, which traits could used to evaluate maize density tolerance? How maize density tolerance inheritance? etc. This paper designed different trials to answer the questions above. Hope to providing selective reference for high density maize breeding and guiding for production by cultivation experiment. Conversely, it would also promote maize breeding more pertinent, efficient and breed more excellent high density variety service for production by posing problems. The main results showed as follows:1. Effects of planting density on yield ie very big, yield may be increased obviously if planting density be increased suitably. Effects of planting density on characteristics finally reflects to the influence to yield and the directon of them on three factors of yield component is same,only different in level. Ear number in unit area of three varieties increased obviously along with density while grain number per ear and 1000-grain weight decreased and the degree was different in varieties. The high production forming process is intercoordination process among three factors of yield component.2.Effects of planting density on agronomic traits of different varietys were very complicated. Variation of plant height, ear insertion and ear rows were derived from varietys, planting density had little effect on them, so that 3 indices should not be considered deeply. Though the variation of ear length, ear diameter and kernels per row were derived from varietys, the 3 indices changed with the planting density increased, so that 3 indices should be considered properly. Effects of planting density on lodging rate, bare plant rate and anthesis silking interval (ASI) and bare top length were relatively strong, so that indices should be paid more attention and could be considered to be the appraising indices of density-tolerant variety.3. Different variety single leaf area and LAI assume the unimodal curve changed along with the birth time, but the different variety changing tendency was different. Leaf of LiaoDan 565 with no premature senescence after tasseling stage, duration of larger leaf area, LAD and NAR of LiaoDan 565 was relatively long, it was beneficial to maize kernel formation and filling. While Leaf of middle type variety LiaoDan 527 and thin density variety DanYu 39 would drop rapidly after tasseling stage, duration of larger leaf area was short. LAI increased along with the density increase. The increasing rate of LAI was bigest at jointing stage and droped at tasseling stage. Autoregulation ability of density-tolerant maize variety to different planting density was better than that of other varietys. Higher photosynthesis at high density treatment at late growth stage was one of reason of high yield. But photosynthesis potential of thin density variety was unreasonable with planting density increased, which leaded to the decrease of yield.4. Dry matter accumulation of density-tolerant variety increased with planting density enhanced in a certain range. That of thin density variety increased at the beginning, then decreased with planting density increased. The peak of dry matter production rate of density-tolerant variety LiaoDan 565 appeared at tasseling-milk stage, thin density variety DanYu 39 appeared from Tuba mouth stage to tasseling stages, which earlier than density-tolerant variety. That variation leaded to plant growing so fast at early growth stage, HI relatively low and yield decrease finally. Conversely, transportation and storage of dry matter of high density variety were relatively coordinate, which resulted in yield increase finally.5. There had big difference in genetic characteristic of many traits at high and low planting densities. If breeding selection was carried out at low planting density, the selected varietys often showed false appearance, or say, these materials would have no high density tolerance when planting density increased to a certain degree, those materials would even harder to breed density-tolerant variety. Therefore, the selection of density-tolerant variety should be carried out under a certain density pressure and different traits should be selected at different generation. Plant height, ear insertion , bare plant rate, 1000-kernel weight and plot yield should be selected at early generation, ASI, lodging rate, ear length, ear diameter, ear rows, kernels per row and bare top length should be selected at late generation.6.High density tolerance of maize varietys in LiaoNing province appeared increasing trend by evaluation of many typical high density tolerance varietys, which selected and introduced in the 1980s. The maize production level of LiaoNing province would go to a new step further by breeding and extension of density-tolerant varietys. The breeding efficiency of density-tolerant variety would be promoted by increasing planting density. Inbred lines 7029 and 7038 etc screened in this trial had better high density tolerance, which would play an important role in high density breeding.7. Different soil fertility condition needed different variety and suitable planting density. Density-tolerant variety obtained high yield when soil fertility level was better regardless of the density while thin density variety did low. Therefore, if the soil fertility condition was good we should choose density-tolerant variety to obtain high production. When the fertility was bad, we should not introduce density-tolerant variety blindly, thin density tolerant variety had good yield on the contrary. The soil fertility condition is good in LiaoNing province, so the planting density should be increased suitably in most areas.Cropping pattern had a great effect on yield. Conclusively, pattern of shorten row spacing and increase planting density obtained the highest yield, pattern of double lines at one width ridge ranked second, pattern of width and narrow row ranked between them, patterns of traditional and 2:0 planting obtained the lowest yield. Double lines at one width ridge and shorten row spacing and increase planting density patterns were beneficial to yield potential booming of LiaoDan 565 and LiaoDan 527. For increasing maize yield, suitable planting pattern and density should be established according to different genotype characteristics of varietys.更多还原