【作者】 代兴龙；

【导师】 贺明荣；

【作者基本信息】 山东农业大学 ， 作物栽培学与耕作学， 2014， 博士

【摘要】 试验于2010–2011和2011–2012生育季在山东省泰安市大汶口镇东武村试验田进行，试验采用大穗型冬小麦品种泰农18（T18）和多穗型品种山农15（S15）为供试材料，设置早播（10月1日）、传统播期（10月8日）和适当晚播（10月15日）三个播期处理，每播期分别设置四个种植密度（T18为135、270、405和540株m–2，S15为90、172.5、345和517.5株m–2），研究了种植密度和播期对冬小麦籽粒产量、氮素吸收和利用、茎秆抗倒性能的影响以及冬小麦籽粒产量和氮素利用率协同提高的群体构建途径。研究结果如下：种植密度显著影响冬小麦籽粒产量、氮素利用率、氮素吸收效率和氮素利用效率，播期对籽粒产量和氮素利用率无显著影响，但显著影响氮素吸收效率和氮素利用效率，种植密度和播期互作效应对籽粒产量、氮素利用率、氮素吸收效率和氮素利用效率的影响均未达显著水平。种植密度和播期显著影响冬小麦茎秆抗倒指数，且两者存在显著的互作效应。1种植密度对冬小麦籽粒产量和氮素利用率的影响提高种植密度显著降低了单株分蘖数和单株成穗数，但提高了群体分蘖数和叶面积指数。将T18和S15的种植密度分别由135提高至405株m–2和由90提高至172.5或345株m–2时均可显著提高单位面积穗数，虽然穗粒数和粒重略有降低，但其降低幅度远小于单位面积穗数增加幅度，从而提高冬小麦籽粒产量。提高种植密度显著提高了冬小麦成熟期干物质积累量，但收获指数略有降低，表明高密度处理干物质向籽粒的分配比例降低，提高种植密度主要是通过提高干物质生产能力提高了籽粒产量。提高种植密度虽然降低了单株次生根数和单株总根数，但群体次生根数和群体根总根数仍呈上升趋势。提高种植密度显著提高了冬小麦各土层中的根长密度，有利于植株养分吸收。利用稳定性同位素15N的标记试验表明，将T18和S15的种植密度分别由135提高至405株m–2和由90提高至172.5或345株m–2时可显著提高冬小麦对不同土层中氮素的吸收，且下层15N吸收增加量显著高于上层土壤，表明下层土壤中增加根长密度对氮素吸收的促进作用优于上层土壤。提高种植密度通过促进冬小麦对肥料氮和土壤氮的吸收，提高成熟期地上部氮素积累量，从而提高氮素吸收效率。高密度处理的单位面积籽粒氮素积累量相对于最低种植密度增加的比例显著低于地上部氮素积累量增加的比例，从而降低了氮素收获指数，表明高密度处理降低了氮素向籽粒的分配比例。增加种植密度显著提高了平均到单个籽粒的根条数和根长，提高了向单个籽粒的氮素供应能力，并且降低了籽粒粒重，从而提高了籽粒氮素含量。降低的氮素收获指数和提高的籽粒氮素含量共同降低了氮素利用效率，表明高密度处理利用所吸收的氮素进行籽粒生产的能力有所下降，提高种植密度提高了生产百公斤籽粒所需氮素。在本试验条件下，将T18和S15的种植密度分别由135提高至405株m–2和由90提高至172.5或345株m–2时氮素吸收效率提高的幅度显著高于氮素利用效率降低的幅度，从而提高了氮素利用率。氮素利用率与氮素吸收效率以及籽粒产量、氮素利用率、氮素吸收效率与地上部氮素积累量间均呈显著正相关关系，表明提高种植密度通过提高根长密度，促进冬小麦对肥料氮和土壤氮吸收，提高地上部氮素积累量实现了籽粒产量和氮素利用率的协同提高。2播期对冬小麦籽粒产量和氮素利用率的影响播期对冬小麦生长状况的影响在越冬期和拔节期较为显著，随着生育进程的推进，各播期间差异逐渐减小。虽然早播处理的单株分蘖数、群体大小、叶面积指数和干物质积累量在生育前期（越冬期和/或拔节期）与传统播期差异显著，但在孕穗期之后两播期的群体再无明显差异；晚播条件下积温较低，其单株分蘖数、群体大小、叶面积指数和干物质积累量在生育前期与传统播期差异较大，但随着生育期的推进，两播期之间的差异逐渐减小，并且从开花至成熟晚播处理的干物质积累量可维持与传统播期相当的水平。在本试验条件下，冬小麦的单位面积穗数、穗粒数和粒重在早播和传统播期间均无显著差异，所以两播期获得了相当水平的籽粒产量。适当晚播条件下，虽然单位面积穗数显著低于传统播期处理，但其穗粒数显著高于传统播期，两者可相互弥补从而维持冬小麦单位面积粒数，并且晚播条件下籽粒粒重与传统播期均无显著差异，所以晚播处理的籽粒产量仍可维持与传统播期相当的水平。收获指数在早播、传统播期和晚播处理间均无显著差异，表明播期并未影响冬小麦向籽粒分配干物质的能力。虽然早播在越冬期和拔节期的群体根条数、根长和地上部氮素积累量显著高于传统播期，但各指标从孕穗至成熟再无显著差异，所以氮素吸收效率在早播和传统播期间水平相当。晚播减少了全生育期单株次生根数、单株总根数和群体次生根数、群体总根数，降低了冬小麦各土层根长密度，降低了植株对土壤氮的吸收量，虽然肥料氮的吸收量并未受到显著影响（2010–2011），甚至略高于传统播期处理（2011–2012），但成熟期地上部氮素积累量显著低于传统播期处理，从而降低了冬小麦氮素吸收效率。氮素收获指数在早播、传统播期和晚播间无显著差异，表明播期并未影响氮素向籽粒分配的比例。籽粒氮素含量在早播和传统播期间亦无显著差异，所以氮素利用效率在早播和传统播期间水平相当，但晚播降低了籽粒氮素含量从而提高了氮素利用效率。表明晚播处理利用吸收的氮素进行籽粒生产的能力高于早播和传统播期处理，晚播条件下生产百公斤籽粒所需氮素显著下降。在本试验条件下，晚播与传统播期间氮素吸收效率降低的幅度和氮素利用效率提高的幅度可相互弥补，从而在晚播条件下维持与传统播期相当水平的氮素利用率。3种植密度和播期对冬小麦抗倒性能的影响在本试验条件下，冬小麦重心高度与植株株高、基部节间长呈显著正相关关系，茎秆基部节间机械强度与基部节间直径、壁厚、干重和充实度呈显著正相关关系，茎秆抗倒指数与茎秆株高、基部节间长、重心高度呈显著负相关关系，与基部节间直径、壁厚、干重、充实度和机械强度呈显著正相关关系。提高种植密度显著提高了冬小麦株高和基部节间长，从而导致灌浆中后期（T18）或灌浆后期（S15）茎秆重心高度上移；提高种植密度亦降低了基部节间直径、壁厚、干重和充实度，从而降低了茎秆机械强度；因此提高种植密度降低了冬小麦茎秆抗倒指数，增加了花后群体倒伏的风险。在早播和传统播期间冬小麦茎秆抗倒指数、重心高度和机械强度及各相关指标均无显著差异，但其抗倒能力均低于晚播处理。晚播可降低冬小麦株高、基部节间长，从而降低灌浆中后期茎秆重心高度，并可提高基部节间直径、壁厚、干重和充实度，提高茎秆机械强度，因此晚播可提高冬小麦茎秆抗倒指数，降低花后群体倒伏的风险。种植密度与播期对冬小麦茎秆抗倒性能影响的互作效应主要体现在早播高密度处理组合抗倒能力最低，而晚播低密度处理组合抗倒能力最高。而更重要的是，对于T18和S15获得最高籽粒产量和氮素利用率的405株m–2和172.5、345株m–2种植密度而言，其植株株高、基部节间长和重心高度可以达到甚至低于较低种植密度在早播或传统播期条件下的指标数值，基部节间直径、壁厚、干重、充实度和机械强度可以达到甚至高于较低种植密度在早播或传统播期条件下的指标数值，因此，获得最高籽粒产量和氮素利用率的种植密度在晚播条件下的抗倒能力可达到甚至高于较低的种植密度在早播和传统播期条件下的抗倒能力，即提高种植密度后降低的抗倒能力可通过晚播进行弥补，从而获得较高的抗倒能力，确保高产、稳产。综合分析种植密度和播期对冬小麦籽粒产量、氮素吸收和利用及群体抗倒能力的影响，表明晚播增密栽培技术可实现协同提高冬小麦籽粒产量和氮素利用率的群体构建。在本试验地区，T18以405株m–2、S15以172.5或345株m–2的种植密度结合10月15日的适当晚播是冬小麦高产、高效、稳产栽培的群体构建模式。更多还原

【Abstract】 The field experiments were carried out in2010–2011and2011–2012at the experimentalstation of Dongwu Village, in Dawenkou Town, Daiyue District, Tai’an, Shandong, P.R.China. Two widely planted cultivars, Tainong18(a cultivar with bigger ears and lowertillering capacity) and Shannong15(a cultivar with middle–sized ears and higher tilleringcapacity), were selected as the experimental materials (henceforth referred to as “T18” and“S15”, respectively). The winter wheat were sown on three dates (early sowing on1October,conventional sowing on8October and delayed sowing on15October) and plant densities of135,270,405and540plants m–2were designed for T18, and90,172.5,345and517.5plantsm–2were used for S15. The responses of grain yield, nitrogen (N) use efficiency (NUE), Nuptake efficiency (UPE), N utilization efficiency (UTE) and lodging resistance to plantdensity and sowing date were investigated. The main results are shown as follows:The effect of plant density was significant on the grain yield, NUE, UPE and UTE. Sowingdate had no effect on the grain yield and NUE but significantly affected UPE and UTE. Theinteraction of plant density and sowing date was not significant on the grain yield, NUE, UPEand UTE. The effects of plant density, sowing date and their interaction were significant onthe culm lodging resistance index.1. The grain yield and nitrogen use efficiency as affected by plan densityIncreasing plant density significantly decreased tillers per plant and spikes per plant butincreased total tillers per unit area and the leaf area index (LAI). Wheat yield componentsshowed compensatory relation in response to plant density changes. Increasing plant densityfrom135to405plants m–2for the cultivar T18or from90to172.5or345plants m–2for thecultivar S15significantly increased spikes per unit area but also decreased kernels per spikeand kernel weight. The increases of spikes per unit area for each cultivar were much higherthan the decreases of kernels per spike and kernel weight. Therefore, the grain yield was improved. The dry matter accumulation at maturity was significantly increased as the plantdensity was increased, while the harvest index was decreased. That indicated that higher plantdensity had a lower efficiency in dry matter partitioning to grain and increasing plant densityincreased grain yield mainly through increasing dry matter production.Although the nodal roots number and total roots number per plant significantly decreased,the total nodal roots number and total roots number per unit area trended to increase withplant density increasing. Significant synchronous increases in absorbed N from fertilizer (Nf)and soil (Ns) and significant root length density (RLD) and15N uptake increases at each soildepth were observed as the plant density increased from135to405plants m–2for the cultivarT18or from90to172.5or345plants m–2for the cultivar S15. Furthermore, the increasedRLD in deep soil had greater effects on N uptake than RLD increase in top soil. Increasingplant density enhanced N uptake of winter wheat and therefore increased above–ground Nuptake (AGN) and UPE.A relatively lower percentage of increase in N accumulation in grain than that in AGN withhigher plant density accounted for reduced N harvest index (NHI), indicating a lowerefficiency in N partitioning to grain with higher plant density and if higher N accumulation ingrain is required, much higher AGN is needed to ensure the N partitioning to grain. Increasingplant density significantly increased grain N concentration (GNC) mainly due to the increasein roots number per grain and root length per grain and reduction in kernel weight. Thereduced NHI and increased GNC together caused decreases in UTE with increased plantdensity. This indicated that higher plant density decreased the capacity of grain production perunit AGN and the required N for production of per unit yield was significantly increased withplant density increasing.The increase in UPE could compensate and exceed the reduction in UTE and a higher NUEwas achieved as the plant density increased from135to405plants m–2for the cultivar T18orfrom90to172.5or345plants m–2for the cultivar S15. Significantly positive correlationbetween NUE and UPE, and between grain yield, NUE, UPE and AGN indicated thatincreasing the plant density of winter wheat synchronously improved grain yield and NUEmainly through raising UPE due to the increased AGN as a result of increased RLD and asynchronous increase in Nfand Ns.2. The grain yield and nitrogen use efficiency as affected by sowing dateSignificant effect of sowing date on the winter wheat growth status was observed atwintering and jointing. With the advance of growing stages, the differences between sowingdates trended to decrease. Early sowing grew higher tillers per plant and per unit area, LAI and dry matter accumulation than conventional sowing at wintering and/or jointing, but nodifferences were observed after booting. Late sowing had lower accumulated temperature andtherefore significant lower tiller per plant and per unit area, LAI and dry matter accumulationwere observed compared to the conventional sowing. However, with the advance of growingstages, these differences were gradually reduced. Equivalent dry matter accumulation wasobserved between conventional and late sowing after anthsis.In present study, the grain yield at different sowing dates was equivalent for each cultivar.Early and conventional sowing showed equivalent grain yield mainly because of equivalentyield components. Compared with the early and conventional sowing, the maintenance ofgrain yield with late sowing was essential due to the maintenance of kernel weight andkernels per unit area owing to the trade–off relationship between the decrease in the spikes perunit area and the increase in the kernels per spike. Equal harvest indices were obtained duringthree sowing dates, indicating that sowing date did not affect the efficiency in dry matterpartitioning to grain.Equal NUE was observed among early, conventional and late sowing. Early sowingresulted in higher roots number and root length per unit area and AGN at wintering andjointing than that in conventional sowing. However, no significant differences in these indiceswere observed after booting. Therefore UPE was equivalent between early and conventionalsowing. The nodal roots number per plant and per unit area and the total roots number perplant and per unit area were significantly decreased with late sowing in the whole growingseason, and so was the RLD at each soil depth. Late sowing reduced the uptake of Nsbutshowed no significant effect on the uptake of Nf(2010–2011) or even increased it(2011–2012), although the AGN was significantly reduced. Late sowing decreased UPEowing to the reduced AGN.Equal NHIs were obtained among early, conventional and late sowing, suggesting thatsowing date did not affect efficiency of winter wheat in N partitioning to grain. EquivalentGNC between early and conventional sowing resulted in equivalent UTE, whereassignificantly lower GNC was observed with late sowing, and consequently resulted in higherUTE compared that with conventional sowing. These demonstrated that late sowing increasedthe capacity of grain production per unit AGN and the required N for production of per unityield was significantly decreased.In present study, the increment in the UTE offset the reduction in the UPE with late sowing,and consequently, and equivalent NUE was observed among early, conventional and latesowing. 3. The lodging resistance as affected by plant density and sowing dateIn present study, the culm height at the center of gravity (CHCG) was positively related tothe plant height and the length of base internode. The culm mechanical strength (CMS) ofbase internode was positively related to its diameter, wall thickness, dry weight and fillingdegree. The culm lodging resistance index (CLRI) was negatively related to the plant height,the length of base internode and CHCG, and positively related to the diameter, wall thickness,dry weight, filling degree and CMS of the base internode.Increasing plant density increased CHCG at mid and late filling (T18) or late filling (S15)through increasing plant height and the length of base internode, and also reduced the CMS ofthe base internode through decreasing its diameter, wall thickness, dry weight and fillingdegree. Consequently, increasing plant density significantly decreased the CLRI of winterwheat and increased the risk of lodging.Early and conventional sowing resulted in no significant differences in the CLRI, CHCGand CMS of winter wheat and relative indices associated with lodging resistance. Late sowingsignificantly increased lodging resistance and optimized the relative indices associated withlodging resistance. Compared with early and conventional sowing, late sowing significantlydecreased the CHCG through decreasing plant height and the length of base internode, andalso improved the CMS of the base internode through improving its diameter, wall thickness,dry weight and filling degree. Consequently, late sowing significantly improved the CLRI ofwinter wheat and reduced the risk of lodging.The effect of the interaction between plant density and sowing date existed in the highestlodging resistance under a combination of late sowing with the lowest plant density and thelowest lodging resistance under a combination of early or conventional sowing with thehighest plant density. Furthermore, the values of plant height, the length of base internode andthe CHCG of the highest yielding and NUE plant densities of405plants m–2for the cultivarT18and172.5or345plants m–2for the cultivar S15with late sowing could be optimized tothe equivalent or even lower levels which were observed with relatively lower plant density atearly or conventional sowing. The values of the diameter, wall thickness, dry weight, fillingdegree and CMS of the base internode and the CLRI of the highest yielding and NUE plantdensities could be optimized to the equivalent or even higher levels which were observed withrelatively lower plant density at early or conventional sowing. Namely, the reduction inlodging resistance through increasing plant density could be compensated through sowing latewhile maintaining equivalent grain yield and NUE.The comprehensive analysis about the effects of plant density and sowing date on the grain yield, N uptake and utilization and lodging resistance indicated that sowing late withhigh plant density could be used to regulate the community structure for synchronouslyimproving grain yield and NUE. In the target region, sowing on15October with relativelyhigh plant density (e.g. plant densities of405plants m–2for the cultivar T18and172.5or345plants m–2for the cultivar S15) represents a compromise for achieving high grain yield, highNUE and high lodging resistance in winter wheat production.更多还原