不同密度下棉花群体光辐射空间分布及生物量和纤维品质的变化

【目的】研究不同密度群体棉花生育期、光合有效辐射(PAR)分布、叶面积指数(LAI)和干物质累积特征值的差异。【方法】供试品种为转Bt(Bacillus thuringiensis)基因杂交种中棉所75(CCRI 75)和常规品种鲁棉研28(SCRC 28),2012和2013年密度处理为1.5万、5.1万和8.7万株·hm~(-2)。【结果】不同密度群体在棉花不同生育期PAR存在显著差异,且冠层光透射率随密度增加而减少,不同种植密度的棉花群体冠层株型结构各不相同,不同群体棉花茎叶的空间分布决定PAR的分布;LAI随生育进程呈现出开口向下的抛物线,不同的密度群体LAI均在播种后60 d左右开始快速增加,100 d或110 d后LAI开始急速下降;随密度增加最大生物量累计值减少,且营养器官占单株总干物质的比例增加,而生殖器官所占比例下降;密度显著影响马克隆值大小,高密度下马克隆值最大。【结论】本研究为棉花田间管理、合理密植提供理论依据。     

基于空间统计学的棉花冠层光合有效辐射空间格局分析方法

 运用空间统计学的模拟方法,以不同密度棉花群体为研究对象,对其冠层内光合有效辐射（PAR）的空间分布予以研究。通过拟合PAR透射率的半方差函数模型和绘制等值线图来反映不同密度群体冠层内PAR透射率的空间格局。利用克里格空间内插法和Simpson3/8法计算出盛蕾期棉花群体平均PAR透射率,分析其与LAI的回归关系,并对克里格插值法进行交叉验证。结果表明,冠层PAR存在强烈的空间自相关性,变异函数的最佳理论模型为高斯模型,决定系数均在0.9以上。各密度冠层PAR透射率具有相似的空间格局,但其变异程度有随密度增加而上升的趋势。群体平均PAR透射率与叶面积指数（LAI）呈指数回归关系,与前人研究结果一致。应用空间计学研究PAR空间分布格局,将有助于对PAR 进行精确定位和定量化地估算,为作物科学配置和作物冠层结构调控提供理论依据。     

土壤水分对冬小麦生长后期光能利用及水分利用效率的影响

通过控制不同土壤水分条件形成不同的小麦（Triticum aestivum L.）群体结构,测定了抽穗到成熟期间小麦冠层光合有效辐射（PAR）截获及垂直分布、干物质积累和产量。研究表明,不同处理小麦冠层对PAR的截获量差异较小（小于15.7%）,但冠层上部（60~80 cm）的PAR截获量和生长后期PAR转化效率差异明显（100.7%和63.7%）,与产量和光能利用效率变化一致,可见土壤水分是通过改变小麦群体内PAR垂直分布及PAR转化效率对作物产量和光能利用效率产生影响。抽穗到成熟期间维持小麦冠层上部PAR截获率在50%左右是实现高产的重要保证。随着土壤水分改善,冬小麦光能利用率和产量持续增加,但水分利用效率却先于二者提前降低,说明改善水分利用效率是提高华北地区农业气候资源利用效率的关键。在底墒充足的条件下,分别在拔节和挑旗期灌水60 mm可获得较高的光能和水分利用效率及经济产量     

棉花冠层光合有效辐射空间分布插值方法

获取冠层光合有效辐射PAR(Photosynthetically active radiation)信息对于作物估产、长势监测以及优化种植有重要意义。运用地统计学空间网格法原理测定了鲁棉研28号的棉花冠层PAR值,综合应用等值线图、残差和交叉验证比较分析了12种插值方法,发现克里金插值法最优;进一步利用克里金插值法分析了冀958、中棉所60、零式果枝品系L0三个品种PAR透射光的空间分布特征,等值线图显示PAR透射光空间分布与株型对光的影响一致,即验证了克里金插值法为模拟研究棉花冠层PAR值的最佳方法。     

棉花群体冠层PAR与农艺性状及产量的关联性研究

本文研究了陆地棉品种徐州553三种密度群体冠层PAR的分布规律、PAR与农艺性状及产量的关联性。结果表明:(1)棉田冠层PAR随密度增加而递减;冠层PAR值的高低随生育期变化的顺序是初花期>盛花期>吐絮期>盛铃期。(2)棉田封行后,冠层PAR的垂直分布符合Y=axe~(bx)曲线变化规律。(3)PAR对结果系数、NAR、果枝与主茎夹角、单株果枝数、单铃重和成铃率的直接效应为较大正值,对主茎节距、第一果枝高度、总果节数为较大负值。(4)PAR与皮棉产量(Y)的关系可由Y=a十bx+cx~2拟合,且曲线拟合的理论值与实际值差异小于1％。这些结果丰富了棉花光能利用的理论研究,也为合理密植、改善棉田光能分布以增加产量提供了理论依据。     

垄作行间非等量播种技术对小麦群体及冠层的影响

为明确垄作行间非等量播种技术对小麦群体及冠层性状的影响,研究了垄上不同密度的垄作模式对小麦群体的冠层结构和光辐射的影响。结果表明,T5处理(垄上边行比内行播量增加30%)的群体结构最为合理,冠层光截获较多,光能利用率最高,产量也最高。     

种植密度对不同生育期玉米品种光温资源利用率和产量的影响

探究不同生育期玉米光温利用、物质生产和产量形成对密度的响应,以期为陕北灌区春玉米密植高产高效栽培提供理论依据。试验于2019—2020年以东单60 (中晚熟)和大丰30 (中早熟)为试验材料,设置45,000 (D1)、60,000(D2)、75,000 (D3)和90,000 (D4)株hm^-2 4个种植密度,测定了叶面积指数、冠层光分布、物质生产与转运、光温利用和产量及其构成等指标。结果表明,大丰30和东单60分别在90,000株hm^-2和75,000株hm^-2密度下达到最高产量18,787.5kghm^-2和16,953.0kghm^-2,较低密度分别提高了37.7%和41.4%,且高产下大丰30籽粒含水率较东单60低11.5%。随着种植密度的增加,群体叶面积指数明显提高,上部冠层光能截获率显著增大,而中部冠层光能截获率显著下降且东单60降低幅度高于大丰30,下部冠层光能截获率无显著差异。对于光能辐射利用而言,大丰30花前截获的光合有效辐射和光能利用率较东单60分别高7.9%...     

整枝方式和冠层高度对棉铃时空分布及产量的影响

【目的】结合整枝方式和冠层高度这两种措施,塑造良好的群体冠层结构,实现棉花增产增效。【方法】在2016—2017年以冀棉958为试验材料,采用裂区设计,在保定清苑研究不同整枝方式(去、留叶枝)和冠层高度(高矮相间冠层、矮冠层和高冠层)对棉铃时空分布、产量及产量构成因素的影响。【结果】整枝方式和冠层高度对棉铃的时空分布具有显著影响。在时间分布上,留叶枝处理相比去叶枝处理能够显著增加"三桃"(伏前桃、伏桃和秋桃)数量;高矮相间冠层与高冠层相比伏前桃数增多,但秋桃数显著减少。在空间分布上,留叶枝使果枝结铃数下降,但果枝棉铃分布较去叶枝群体更均匀,去叶枝群体下部果枝棉铃分布较多,留叶枝群体则集中在中部果枝;不同冠层结构处理的内围铃数均多于外围铃数。整枝方式和冠层高度对棉花产量形成具有显著的互作效应,以去叶枝、高矮相间群体籽棉产量最高,但其皮棉产量和留叶枝、高矮相间群体相比,并没有显著差异。【结论】塑造留叶枝、高矮相间冠层能够促使棉株中部多结铃,增加伏桃数及其比例,提高单位面积铃数,有利于形成产量,还可节省人力和物力,节约成本,因此可作为黄河流域棉区实现棉花高产高效的一项重要简化栽培措施。     

不同行距配置方式对夏玉米冠层结构和群体抗性的影响

为探究行距配置方式对冠层微气象因子及群体抗逆性的影响,明确夏玉米适宜的行距配置方式,在方城和辉县设置大田试验,以3个不同株高类型的玉米杂交种为材料(中秆品种郑单958、高秆品种先玉335和矮秆品种512-4),设置2个种植密度(60 000株 hm^-2和75 000株 hm^-2),研究了5种行距配置方式(50 cm、60 cm、70 cm、80 cm等行距和80 cm+40 cm宽窄行)下冠层结构和群体抗逆性的变化。结果表明,不同株高类型杂交种在相同密度下,随行距扩大,株型变得松散,穗部叶片叶向值减小,并偏离种植行,向种植行垂直方向发展,冠层温湿度降低,群体抗逆性增强,但冠层光照截获率降低,产量也随之减少。对比发现,不同品种和密度下,60 cm等行距能够较好地协调冠层微气象因子与玉米产量的关系,叶片分布适宜,冠层温湿度和光能分布合理,显著提高了中下部的光能截获率,病虫害和倒伏的发生率较低,获得最高产量的频率最高,且适宜机械化田间作业,建议作为适宜黄淮海地区推广的种植方式。     

小麦生长后期群体光截获量及其分布与产量的关系

在高产条件下,通过设计群体数量大小和植株分布不同的小麦群体类型,测定了小麦生长后期群体光合有效辐射(PAR)截获量及其分布、小麦产量和干物质生产量,研究表明:群体分布状况明显影响群体的光截获量.均匀分布群体比大小行种植的不均匀群体具有较高的光截获率.种植密度对均匀分布群体的光截获量影响较小;随着密度增加,不均匀     

Spatial and Temporal Distributions of Soil Available Phosphorus in Wheat-Cotton Double-Cropping Systems

[Objective] Here, the spatial and temporal distributions of soil available phosphorus (AP) were investigated during cotton growth stages in wheat-cotton double-cropping systems in northern Henan, China. [Method] Using the spatial grid sampling and geo-statistical analysis methods, we analyzed the spatial and temporal distributions of soil AP in a cotton monoculture, wheat-cotton 3-1 intercropping system (3-1) and wheat-cotton 6-2 intercropping system (6-2) during the wheat and cotton co-growth stage and the key growth stages of cotton only. [Result] The AP contents were significantly influenced by the cropping systems on different dates. In the co-growth stage, the AP content in the cotton monoculture was higher than that in 3-1, at 20.98% on May 12 and 24.26% on June 7. After wheat was harvested (July 3 and August 4), there were no significant differences among the three cropping systems, and in the boll-opening stage of cotton, the order of the AP contents were as follows: cotton monoculture＞6-2＞3-1. In the vertical direction, the AP contents decreased as the soil depth increased, while in the horizontal direction, the AP distribution was influenced significantly by the cropping system. Based on the semivariance, there were strong spatial dependencies in the vertical direction in all three cropping systems. [Conclusion] Wheat-cotton double-cropping systems changed the distribution of soil AP, but had no influence on the spatial heterogeneity of the soil AP in the vertical direction. Geo-statistics provide a more intuitive method and guide to study the soil nutrients of the wheat–cotton and other double-cropping systems.     

不同氮素水平下双季稻株型与冠层内光截获特征研究

本文旨在阐明双季稻株型与冠层内光合有效辐射截获的时空分布特征。选用4个不同株型早、晚稻品种,设置4个不同施氮水平,系统观测其植株形态和冠层内光合有效辐射截获率(IPAR)的时空分布状况。结果表明,施氮水平对早、晚稻株高、穗长、叶长和叶基角均有显著影响,均表现为随施氮水平的增加而增大;早、晚稻孕穗期的分层叶面积指数(LAI)和向上累积LAI大于抽穗后12 d,分层LAI呈冠层中部大于上部和下部的分布特征,最大分层LAI出现在0.58相对高度处;冠层上中部分层LAI和向上累积LAI随施氮水平的增加而增大;向上累积LAI随相对高度呈S型曲线分布,可用Logistic方程定量描述(R~2 0.99);早、晚稻孕穗期的冠层IPAR大于抽穗后12 d,且随施氮水平的增加而增大,其日变化表现为正午较小,早晚较大;株型紧凑的早、晚稻品种,冠层IPAR低;冠层IPAR与向下累积LAI之间的关系可用方程IPAR=a (1-e~(-b×LAI))定量描述(R~2 0.88);冠层内IPAR的三维空间分布表现为冠层上中部水平面上IPAR较低,光斑变化大,冠层下部水平面上IPAR较高,光斑变化较平缓,同一冠层高度水平面上的IPAR呈不均匀分布。研究结果可为双季稻高产栽培及理想株型的优化设计提供支撑。     

麦棉两熟双高产条件下麦棉复合根系生长的时空动态分布

在麦棉两熟双高产条件下,以单作棉和单作麦为对照,利用根钻与DT-SCAN扫描相结合的方法研究麦棉复合根系群体生长的时空动态分布,结果表明,套作棉和单作棉的根长和根长密度、根表面积以及根系平均直径均随生育进程呈单峰曲线,套作棉40 cm以下各土层根系根长和根长密度、根表面积的衰退速率在盛花期后明显低于单作棉,根系     

退耕雷竹春季林冠截留特性研究

为了研究退耕雷竹林冠截留特性,于2012年春季对不同林分密度的退耕雷竹林进行水文观测。结果表明：2个林分密度的雷竹林外降雨与林内降雨、树干径流均具有极显著的开口向上的抛物线函数关系,与林冠截留具有开口向下的抛物线函数关系。分布均匀和郁闭度高(0.96)的1号样地（(15000±750)株/hm2）林冠截留率平均为51.19%,雷竹分布和郁闭度(0.85)较低的2号样地（(22500±750)株/hm2）平均为38.04%。2块样地林冠截留率的巨大差异,意味着退耕雷竹林冠截留具有很大的可塑性和改造潜力,可通过调整退耕雷竹林的结构、密度等经营措施来提高其生态水文效益,从而达到水土保持高效经营的最终目标。     

麦棉套种对棉行太阳辐射和温度的影响

对３－２式麦棉套种预留棉行的小气候效应进行研究在明，小麦对预留棉行有根强的遮荫作用；致使齐穗期预留棉行中央的光合有效辐射较冠层减少３０％，太阳总辐射削减１９％；小麦黄熟前，预留棉行内风速较一熟棉田小，午后气温也较一熟棉田低；共生前期麦套露地棉田地温较一熟棉田低，小麦黄熟后较一熟棉田高，而麦套地膜棉田的地温一直较一熟棉田高。降低小麦株高，留足预留棉行，麦套棉地膜覆盖。加强小麦生育后期的水分管理，都有利于减轻麦棉套种的不利和小气候的影响。     

Effects of Pruning Methods and Canopy Patterns on the Temporal-Spatial Distribution of Cotton Bolls and Yield

[Objective] The purpose of this study was to shape the good canopy structure and achieve efficiency production of cotton. [Method] With Jimian 958 as test material, a split-plot field experiment was conducted over two years (2016—2017) to determine the effect of different pruning methods (removal and retention of vegetative branches) and canopy height treatments (high and low staggered canopy, low canopy and high canopy) on the temporal-spatial distribution of cotton bolls, yield and yield components in Baoding. [Result] Pruning method and canopy pattern had significant effects on the temporal-spatial distribution of cotton bolls. Regarding temporal distribution, retention of vegetative branch treatment (P₂) significantly increased the number of total bolls (pre-summer, summer and autumn bolls) compared with removal of vegetative branch treatment (P₁). Staggered canopy (C₁) increased the number of pre-summer bolls but resulted in relatively fewer autumn bolls to that of the high canopy (C₃) pattern. Spatial distribution of bolls varied by pruning method, with P₂ treatment producing a greater number of fruit bolls concentrated in the middle part of the plant. P₁ treatment produced a greater number of fruit bolls concentrated in the lower canopy. The combined effects of pruning methods and canopy pattern on seed cotton yield were significant, with the largest yield observed in P₁C₁ (vegetative branch removal×staggered canopy). The P₁C₁ group did not make significant difference in lint yield to the P₂C₁ (vegetative branch retention×staggered canopy) group. [Conclusion] The P₂C₁ canopy structure can produce a greater number of fruit bolls concentrated in the middle part of the cotton, enhance the number and proportion of summer bolls, increase the number of bolls per unit area, and produce higher yields while reducing labour usage, material resources and costs. This simplified cultivation measure offers an important opportunity to efficiently achieve high yields of cotton in the Yellow River Region.     

Density responses and spatial distribution of cotton yield and yield components in jujube (Zizyphus jujube)/cotton (Gossypium hirsutum) agroforestry

Trees are the dominant species in agroforestry systems, profoundly affecting the performance of understory crops. Proximity to trees is a key factor in crop performance, but rather little information is available on the spatial distribution of yield and yield components of crop species under the influence of trees in agroforestry systems. Also, little information is available on how crop density may be exploited to optimize the yield in such systems. Here we studied the performance of cotton in jujube/cotton agroforestry. Field experiments were conducted in 2012 and 2013 in Hetian, Xinjiang, China. Cotton was grown at a row distance of 60 cm in three densities, 13.5, 18.0 and 22.5 plants m⁻² in six m wide paths between tree lines in a jujube plantation. Plant density affected both cotton aboveground dry matter and yield significantly. The highest yield was attained at the intermediate density of 18.0 plants m⁻² (20.0 plants m⁻² corresponding in sole cotton), lower than the optimal density in sole cotton (25.0 plants m⁻²). Yield at the lower density was constrained by the low number of bolls per m² as a direct consequence of the low density, whereas at the high plant density yield was constrained by a lower allocation of assimilates to cotton seed and lint, as a consequence of intraspecific and interspecific competitions. There were strong gradients in yield and yield components in relation to the distance from the tree rows. Leaf area and total dry matter of cotton in rows close to the tree lines were reduced, especially in the rows next to the trees. Moreover, biomass allocation to cotton fruits was reduced in these rows. Competitive influences from the trees on cotton performance extended two rows deep in a six-year old jujube stand, and even three rows deep in a seven-year old stand. Shading effects on cotton yield were compensated by increasing plant density as a result of greater boll numbers per unit ground area. Data from this study help guide the design of optimal plant density of cotton in jujube plantations and give insight in the spatial distribution and dynamics of competitive effects in agroforestry systems in general.