不同水氮处理对玉米-大豆间作群体内作物光能截获、竞争和利用的影响

通过田间试验研究了不同水氮处理对玉米-大豆间作群体的光能截获、竞争与利用的影响。试验设置充分供水和水分亏缺两种水分处理以及施氮(亩施纯氮7.5 kg)和不施氮两种氮肥处理。结果表明,在生育中后期,同一氮肥处理条件下,充分供水处理间作作物的光能截获率显著高于水分亏缺处理;相同水分条件下,施氮处理间作大豆的光能截获率略高于不施氮处理,但未达到显著水平,而施氮处理间作玉米的光能截获率则显著高于不施氮处理。从播后第64天到成熟,同一氮肥处理条件下,充分供水提高了间作玉米的光能竞争比,但却降低了间作大豆的光能竞争比。从播后第73天到成熟,相同水分条件下,施氮处理间作玉米的光能竞争比显著高于不施氮处理,而大豆的光能竞争比在两个氮肥处理间则没有显著差异。充分供水条件下,施氮处理间作玉米的光能利用效率(LUE)为3.87 g/MJ,略高于不施氮处理(3.81 g/MJ);水分亏缺条件下,施氮处理间作玉米的LUE(3.86 g/MJ)比不施氮处理(3.72 g/MJ)高3.6%。充分供水条件下,施氮处理间作大豆的LUE(1.62 g/MJ)比不施氮处理(1.57 g/MJ)高3.2%;水分亏缺条件下,施氮处理间作大豆的LUE为1.55 g/MJ,与不施氮处理(1.54 g/MJ)基本相同,表明与氮肥处理相比,水分状况对大豆LUE的影响更为明显。     

栽培模式对冬小麦光能利用和产量的影响

以‘泰农18’小麦为材料,于2012—2013年进行大田试验,设置当地农民习惯栽培模式(FP)、超高产栽培模式(SH)和高产高效栽培模式(HH)3个处理,研究了不同栽培模式对小麦光能截获量、光能利用效率、干物质积累量、收获指数、籽粒产量和肥料偏生产力的影响.结果表明: SH模式小麦全生育期的光能截获量、光能利用效率、干物质积累量和籽粒产量显著高于FP模式.相对于FP模式,虽然HH模式的小麦全生育期光能截获量较低,但其光能利用效率、干物质积累量及收获指数均显著提高,从而使其籽粒产量显著提高.相对于SH模式,虽然HH模式的籽粒产量在高、低肥力水平下分别降低3.8%和2.8%,而氮、磷、钾肥的偏生产力在两肥力水平下分别提高26.4%、68.5%、92.6%.在本试验条件下,综合考虑籽粒产量和养分利用效率,以“降肥、增密、延播”为技术特点的高产高效栽培模式为推荐的优化栽培模式.     

秸秆覆盖和灌溉对冬小麦农田光能利用率的影响

研究了秸秆覆盖和灌溉对冬小麦农田光能利用率的影响.结果表明,秸秆覆盖降低了冬小麦的基本苗、分蘖数及生育前期的叶面积指数,但到生育后期,覆盖处理的叶面积指数反而升高.覆盖和灌溉降低了光合有效辐射（PAR）的底层透射率和冠层反射率,使PAR总截获率升高.覆盖和灌溉主要增加了40～60 cm高度的PAR截获率.覆盖处理籽粒光能利用率降低,茎叶光能利用率和总光能利用率升高.     

限根对不同品种油桃幼树光截获能力和一些生理特性的影响

以一、二年生油桃早红宝石、沪油004、沪油018为试验材料,分析了设施栽培中限根对幼树树冠光截获能力、叶片可溶性蛋白含量变化以及叶片干重变化的影响。结果表明:(1)限根能改良冠层内叶片的水平分布、叶倾角,降低光在冠层内的损失,提高叶片光截获能力,有利于提高果树群体光能利用率。(2)限根对不同品种油桃幼树叶片中可溶性蛋白含量变化和叶片相对含水量、比叶重的影响明显不同。(3)编织袋限根处理比竹筐限根能更有效地改善幼树冠层光截获能力,提高光能利用率。早红宝石、沪油004采用编织袋限根栽培对果树生长发育比较有利;沪油018是个高光效品种,以竹筐限根较为适宜。     

株行距配置对齐穗期粳稻冠层结构及产量的影响

以辽宁稻区3种穗型粳稻及杂交稻为试材,研究了不同株行距配置对齐穗期粳稻光截获能力、群体内部光分布特征和光转化效率以及产量构成的调控作用.结果表明：与光能截获密切相关的叶面积指数随着密度减小而先降低后升高.一天之内消光系数(K)的变化同样表现为先降低后升高,而不同株行距配置间K值随着种植密度的增加而增大.产量与各冠层消光系数、上部3叶叶倾角呈正相关.在光能利用率方面,产量与剑叶气孔导度、胞间CO₂浓度、蒸腾速率均呈正相关.在高密度(15 cm×25 cm)和低密度(20 cm×30 cm和20 cm×35 cm)株行距配置下,水稻分别可以提高光截获能力和光转化效率,却分别受到倒伏和单位面积穗数的限制而无法获得高产稳产.株行距为15 cm×30 cm和 20 cm×25 cm配置下,可以确保足够穗数,优化冠层结构并降低倒伏风险,为高产优质提供保障.     

鸢尾(Iris L.)叶片取向与其光合特性及光抑制的关系

通过气体交换、叶绿素荧光、反射光谱等方法,研究了鸢尾叶片取向对植株光合特性及光抑制的影响.自然状态下,鸢尾的叶片不同取向影响植株对光能的截获;叶片净光合速率Pn与光合有效辐射PAR呈极显著相关;东西取向叶片的Pn要大于南北取向.南北取向的植株中叶片叶绿素(Chl a和Chl b),类胡萝卜素(Car)含量略高于东西取向.日进程中,各取向的叶片在一天中均没有发生明显的光抑制.相对于东西取向的植株,南北取向植株发生了明显的倾斜;在两种取向的植株中,叶片东侧和南侧的光化学反射指数(PRI)下调幅度较大;PRI的变化量(△PRI)大小依次为:东侧>南侧>西侧>北侧.鸢尾植株取向改变了叶片倾斜角度,两者共同导致光能截获减小;同时,叶片光能利用效率下调和叶黄素循环增强,这可能是不同取向植株均未发生严重光抑制的原因.     

氮肥运筹对小麦产量、氮素利用效率和光能利用率的影响

连续2年在西南冬麦区的重庆、仁寿、广汉、西昌4个地点,开展3种施氮水平(每公顷纯氮0、120、180 kg,简写为N₀、N₁₂₀、N₁₈₀)和3种氮肥分配模式(N_A:底肥100%;N_B:底肥70%+苗肥30%;N_C:底肥60%+拔节肥40%)的田间试验,监测小麦花后冠层叶片SPAD值、群体光合速率(CAP)、光能利用等生理参数和籽粒产量,计算氮素利用效率、光能利用率等.结果表明: 随施氮水平增加,小麦上三叶SPAD值、CAP、光合有效辐射(PAR)截获率和产量均呈增加趋势,而氮肥农学利用效率、生产效率、吸收效率和利用效率呈降低趋势.氮肥后移的增效作用因施氮水平而异,SPAD于N₁₈₀增效明显,而CAP于N₁₂₀增效明显,不同氮肥管理模式的光能利用率因地点而异.氮肥后移能明显提高小麦氮肥农学效率、生产效率、吸收效率和氮素表观回收率,但氮肥利用效率则略有减少.氮肥后移效果N_C总体优于N_B处理.不同地点比较,广汉的SPAD值、CAP、PAR截获率、氮肥利用参数较高,其产量也相应最高;西昌的产量、SPAD值及氮素利用效率较高,但其光能利用率和CAP较低;重庆和仁寿的SPAD值、光能利用率及氮素利用效率均较低,其产量也最低.小麦生物产量与各地点的籽粒产量、CAP、SPAD值和PAR累积截获量均呈显著或极显著的正相关关系.表明不同生态区域增施氮肥都能促进小麦增产,氮肥后移可进一步优化产量结构、改善氮肥和光能利用效率,但存在年份和地点差异,各地需要制定有针对性的氮肥管理模式.     

冠层结构对梨叶片光合特性及果实品质的影响

冠层结构是影响果树生长发育及丰产优质的重要因素。该研究以20年生‘玉露香’梨大冠分层树形为对照(CK),以冠层整形修剪后的3、4和5个主枝的开心树形为处理(分别记为OCC_(3b)、OCC_(4b)和OCC_(5b)),测定了冠层截获的光合有效辐射、叶片的气体交换、叶绿素荧光和果实品质特性,探讨不同冠层结构内光环境的变化对梨树叶片光合特性及果实品质的影响,探讨果树的光合调控和结实规律,为西北黄土高原产区果树的标准化整形修剪提供理论依据。结果表明:(1)OCC_(3b)、OCC_(4b)和OCC_(5b)的冠层不同方位和不同时刻截获的光合有效辐射(PAR)均高于CK。与CK和OCC_(5b)相比,OCC_(3b)和OCC_(4b)叶片光响应的最大净光合速率(P_(nmax))和羧化效率(CE)显著提高。(2)在强光胁迫下,开心树形叶片光呼吸速率(P_r)占总光合速率(P_g)的比例(P_r/P_g)和非光化学淬灭(NPQ)中可恢复组分r(qE)提高,同时不可恢复组分r(qI)降低。(3)OCC_(3b)和OCC_(4b)比OCC_(5b)和CK的单果重、果面红晕面积、果皮花青苷含量、可溶性固形物含量和可溶性总糖含量均显著提高,而可滴定酸含量显著降低。(4)PAR与果面着色面积和果皮花青苷含量呈极显著正相关关系,P_(nmax)与单果重呈极显著正相关关系,而PAR和P_(nmax)均与可滴定酸呈极显著负相关关系。研究发现,OCC_(3b)和OCC_(4b)的梨树冠层内可截获更多的光能,叶片光合能力更强,遭遇强光胁迫时能够通过更高效的热耗散和光呼吸进行自我保护,而且开心形树冠结构还能显著提升果实品质。     

关于日本扁柏人工林光能利用效率的研究 (Ⅱ)群落生产结构对光能分配与利用效率的影响

本文以日本扁柏人工林为研究对象,通过对间伐林分和不间伐林分的生产结构、光能分布、光合速率、枝叶生长等季节变化的观测,进而计算了光能利用效率的季节变化。通过比较研究,证明了生产结构影响光能利用效率,而密度影响群落生产结构。合理的生产结构可以使光能在群落内合理分配、各层叶的光合潜力充分发挥、提高群落的光能利用效率。为了标定林分生产结构的合理性,本文提出了相对光合时间数和相对光能利用率的概念及数学公式。绘制了生产结构与功能图。对合理的生产结构与合理密度的关系进行了论述。     

冬小麦高产高效群体的年际间稳产性能

以冬小麦品种‘泰农18’为试验材料,设置传统农民管理习惯的农户模式(T₁)、不计肥水和人工等投入以获得高产的高产模式(T₂)和优化种植密度、播期、肥水管理运筹的高产高效模式(T₃)3种种植模式,于2012年10月—2016年7月连续4个小麦生育季,研究了不同种植模式小麦主茎与分蘖成穗特性、不同年份的光合有效辐射截获、利用、光合产物分配等光能利用特性和产量差异,结合年际间的光、温、水等生态因子分布差异,分析了高产高效群体的稳产性能.结果表明: 冬小麦不同生育时期内的光、温、降雨等生态因子的总量和各生育时期分布存在较大变异.T₁、T₂、T₃模式主茎穗的比例分别为38.9%、58.7%、66.9%,表明T₁、T₂、T₃模式在群体结构构建上分别是以分蘖穗为主、主茎穗和分蘖穗并重、主茎穗为主.T₂模式的生物量和产量最高,T₁最低,T₃模式自孕穗期之后,尤其是在开花14 d后仍能维持较高的叶面积指数、光能截获率和截获量、群体光合速率,并具有较高的干物质分配能力,使其在干物质积累相对偏低的情况下仍可获得高产.T₃模式花后的叶面积指数、光能截获率和截获量以及光合速率等的年际间极差、标准差、变异系数均小于T₁和T₂模式,由此也保证了T₃模式生物产量的稳定.相关分析表明,以主茎成穗为主的T₃种植模式能够有效应对年际间气候变化并实现稳产,关键是具有年际间稳定的生物产量.     

间伐改形对陇东旱塬密闭苹果园树体冠层结构和发育后期叶片质量的影响

为研究间伐改形对红富士成龄乔化密植果园树体冠层特征、生育后期叶片生理特性、养分积累分配规律、光合生产力和土壤水分时空分布动态的影响,以18年生‘红富士’苹果密闭园为试材,对苹果树单株结构参数、枝量、枝类组成、覆盖率、叶片光合速率等参数进行测定.结果表明: 密闭果园叶片光合作用受非气孔因素限制,导致PSII最大光化学效率、PSII光合潜能、光合性能指数下降了1.2%、11.5%、13.9%.间伐改形后,叶面积指数、树冠覆盖率有所降低,使得冠层直射光透过系数增加了79.0%,树形结构有所改善.苹果园总枝数降低到约1100400条·hm^-2,单株枝量增加了5.0%,短枝比例提高至73.0%.由于冠层光照条件的改善,叶面积、比叶质量、百叶重、叶绿素含量有不同程度的提高.叶片光合速率的提高促进了光合产物的积累,淀粉、蛋白质含量为密闭果园的143.5%、107.8%.叶片的发育质量与其所处的光照辐射环境有着密切联系,密闭果园经间伐、改形后,果园群体结构和冠层光照得以改善,促进了叶片生长发育,提高了叶片光合效能,降低了果园土壤水分的无效消耗,是陇东旱塬苹果产区密闭果园适宜的调整、优化方案.     

Simple equations to estimate light interception by isolated trees from canopy structure features: assessment with three-dimensional digitized apple trees

* Simple models of light interception are useful to identify the key structural parameters involved in light capture. We developed such models for isolated trees and tested them with virtual experiments. Light interception was decomposed into the projection of the crown envelope and the crown porosity. The latter was related to tree structure parameters. * Virtual experiments were conducted with three-dimensional (3-D) digitized apple trees grown in Lebanon and Switzerland, with different cultivars and training. The digitized trees allowed actual values of canopy structure (total leaf area, crown volume, foliage inclination angle, variance of leaf area density) and light interception properties (projected leaf area, silhouette to total area ratio, porosity, dispersion parameters) to be computed, and relationships between structure and interception variables to be derived. * The projected envelope area was related to crown volume with a power function of exponent 2/3. Crown porosity was a negative exponential function of mean optical density, that is, the ratio between total leaf area and the projected envelope area. The leaf dispersion parameter was a negative linear function of the relative variance of leaf area density in the crown volume. * The resulting models were expressed as two single equations. After calibration, model outputs were very close to values computed from the 3-D digitized databases.     

土丘陵沟壑区苹果树冠截留规律

以陕北黄土丘陵沟壑区的盛果期山地苹果为研究对象,2008-2010年连续3年监测其树冠外大气降水、树冠穿透降水和树干径流,分析不同降水因子对树冠截留能力的影响.结果表明： 研究区苹果树干径流率为0.8%,树冠截留率为8.9%,且株间的截留量高于行间,距树干越近,截留量越高.苹果树冠在雨季截留量较大而截留率较低,旱季截留量较小但截留率较高.苹果树冠截留量随降水量、降水强度、降水历时、降水间隔的增大而增加,为幂函数或对数函数关系;截留率随降水量、降水强度、降水历时的延长而降低,随降水间隔的延长而增加,呈幂函数关系.不同降水因素中,降水量对苹果树冠截留能力的影响最大.     

Interception of Diffuse and Direct-beam Radiation by a Hedgerow Apple Orchard

A model for the interception of diffuse and direct-beam radiationby parallel rows of trees has been used to simulate the radiationtransmission profiles for row transects in a hedgerow appleorchard. The simulated profiles are in close agreement withexperimentally measured radiation transmission profiles foran apple orchard. The model has been used to predict average daily and seasonalvariations in the proportions and amounts of the incident radiationabsorbed by the orchard. The effects of row orientation androw spacing on the absorption of radiation by the orchard havealso been examined.     

Light interception in apple trees influenced by canopy architecture manipulation

Improvement of light penetration within tree canopies has been a constant objective of fruit tree architecture manipulation through the setting up of training systems. Recently, centrifugal training, i.e. the removal of fruiting shoots in the tree centre and on the underside of branches, has been proposed to improve fruit size and colour as well as return-bloom as compared to conventional solaxe-trained trees with equivalent crop loads. The present study was conducted to quantify the benefits of centrifugal training on light interception by the fruiting shoots via computer-assisted three-dimensional representations of foliage geometry. Data were collected on six 5-year-old apple trees cv.Galaxy, trained either with solaxe or centrifugal training systems, using an electromagnetic 3D digitiser. The 3D distribution of the foliage in the tree canopy was recreated by combining both the spatial locations of shoots (as measured from 3D digitising) and foliage reconstruction. Light interception efficiency properties of the trees were characterised by silhouette to total area ratio (STAR) values computed from images of the 3D mock-ups. Compared to the solaxe system, centrifugal training significantly improved the STAR of the whole tree by 20%. It also increased both leaf area and STAR of the fruiting shoots by approximately 15%, regardless of their position in the canopy. In this paper, we discuss the role of this enhanced light interception by the canopy in increasing the autonomy of the fruiting shoot, i.e. improved fruit size and colour, and return-bloom.     

Simulated insect defoliation on soybean: influence of row width

An ongoing change in soybean production gaining popularity in the United States is a reduction in row spacing. Plant canopy closure is quicker and leaf area index is greater, thus yield is usually higher. Because yield response to insect defoliation is primarily a function of how defoliation causes changes in light interception, the possibility exists that the insect-injury-yield-loss relationship might differ among row widths. Soybean was grown in four states using similar methodologies. Insect defoliation was simulated by picking leaflets based on an insect defoliation model. Plant growth measurements were taken immediately following the end of defoliation. Numerous independent variables were measured or calculated, including percentage light interception, leaf area index, percentage defoliation, and leaf area per plot. Analyses of covariance were conducted on the resultant data to determine whether insect-injury-yield-loss relationships interact with row width. A significant interaction would indicate that the impact of the variables on yield was dependent on the row width, whereas a nonsignificant interaction would suggest that the relationship between the variables and yield is similar at all row widths. Few significant interactions were obtained, indicating that the impact of the variables on yield is similar across row widths. Because of the lack of significant interactions, the insect-injury-yield-loss relationships previously developed should be usable across varying row widths. Thus, treatment decisions based on light interception and leaf area indices, both considered more appropriated measures of insect injury, should be applicable for all row spacings.     

A generic method of pesticide dose expression: Application to broadcast spraying of apple trees

The recommended dose for many pesticides is expressed as a constant mass or volume per unit ground area covered by the crop. This method of dose expression is well suited to boom spraying where a reasonably uniform horizontal distribution of deposit can be achieved with a well‐adjusted sprayer. However, in many practical situations (e.g. broadcast spraying of apple trees or other row structures where the spray application is made from within the canopy) the horizontal deposit distribution is strongly influenced by the crop area density and other crop structural parameters. This paper describes a generic method of pesticide dose expression to investigate these effects. The method incorporates a model of the spray volume deposition process. The model assumes that the pesticide deposit is proportional to the tank‐mix concentration of pesticide. The model also assumes that spray volume deposit is proportional to the applied spray volume per unit row length and is inversely proportional to a crop length scaling function L (i.e. a parameter with the units of length that is expressed as a generic function of different crop parameters). The useful working range of this model is bounded by the condition for high spray volume where target losses become significant due to saturation and the condition for very low volume where evaporative transport losses become significant. Within this framework, four different models are formulated using first‐order approximations for the length‐scale as functions of the following crop parameters: tree row spacing, tree row height, tree area density and tree row volume to ground area ratio. Published measurements of crop structure and spray volume deposit on apple trees are compared with the output from these models. Light detection and range (LIDAR) measurements of apple orchards are presented and used in conjunction with the different models to predict pesticide use associated with different methods of dose expression. The results demonstrate the relative potential for varying the pesticide application rate according to the different crop parameters. The results enable the identification of reference orchards that could be used to establish worst‐case pesticide application rates for registration purposes. The results also enable the identification of other orchards and growth stages where pesticide application rate might be reduced by up to a factor of five and give the same pesticide deposit as the reference structure.     

Row structure and foliage geometry as determinants of the interception of light rays in a sorghum row canopy

Abstract. The interception of light rays by the canopy of a widely spaced sorghum row crop was assessed from a series of hemispherical photographs taken on five occasions during its vegetative growth. Analysis of the photographs shows that most of the temporal and spatial variation in the canopy's interception could be accounted for by treating the row as an array of solid parallel walls with rectangular cross sections. Within the space occupied by rows, the effect of the distribution of foliage elements on interception could be assessed by the porosity of a single row. The north-south asymmetry observed in the distribution of ray interception indicates that this sorghum canopy, grown under unirrigated, arid summer conditions, adopted a light-avoiding growth pattern.     

Odor-baited trap trees: a novel management tool for plum curculio (Coleoptera: Curculionidae)

The plum curculio, Conotrachelus nenuphar (Herbst) (Coleoptera: Curculionidae), one of the most important pests of apple (Malus spp.) in eastern and central North America, historically has been managed in New England apple orchards by three full block insecticide applications. Efforts to reduce insecticide inputs against plum curculio include perimeter row sprays, particularly after petal fall, to control immigrating adults. The odor-baited trap tree approach represents a new reduced input strategy for managing plum curculio based on the application of insecticides to a few perimeter-row trap trees rather than the entire perimeter row or full orchard block. Here, we compared the efficacy of a trap tree approach with perimeter row treatments to manage populations after petal fall in commercial apple orchards in 2005 and 2006. Injury was significantly greater in trap trees compared with unbaited perimeter row treated trees in both years of the study. In 2005, heavy rains prevented growers from applying insecticide applications at regular intervals resulting in high injury in nearly all blocks regardless of type of management strategy. In 2006, both the trap-tree and perimeter-row treatments prevented penetration by immigrating populations and resulted in economically acceptable levels of injury. The trap tree management strategy resulted in a reduction of approximately 70% total trees being treated with insecticide compared with perimeter row sprays and 93% compared with standard full block sprays.     

Light Interception by an Isolated Plant A Simple Model

A simple model for light interception by an isolated plant isproposed. The model assumes that the leaves are uniformly distributedover a region of space bounded by an ellipsoid and a plane,and that light traversing this region is attenuated accordingto Beer's law. It is shown how the model can be extended toexamine a closed row of plants, or a closed array of plants.Simulated light profiles have been calculated for single plantswith different shapes, and an isolated row of plants, underuniform and standard overcast skies.