不同株行距配置对夏大豆群体结构及光截获的影响

以田间试验(2006—2007年)为基础,分析了地上部干物质、叶面积指数(LAI)、光合有效辐射(PAR)、光能利用率和植株形态指标变化特征,夏大豆‘鲁豆4号’(Glycine maxcv.Ludou 4)在同一密度(3.09×105株/hm2)下设5种株行距配置方式,即行距×株距分别为18 cm×18 cm(A)、27 cm×12 cm(B)、36 cm×9 cm(C)、45 cm×7.2 cm(D)、54 cm×6 cm(E)。结果表明,大豆在生育期间干物质变化因株行距不同而产生差异,2006和2007生长季的各处理干物质分别在播种后第70天和90天达到最高,播种后第80天和100天时,A处理比E处理分别高21.6%和34.0%;不同层次干物质积累重心随行距加大有上移趋势。各处理LAI随行距扩大、株距减少有下降趋势,其中,A和B处理LAI表现较稳定,LAI相对较高且时间较长。光能利用率随行距加大有降低趋势,A和B处理显著高于E处理(P0.05)。夏大豆在不同株行距配置下,株粒数、百粒重与产量相关系数分别为0.941*和0.926*(2006年),0.995*和0.892*(2007年),随行距变小PAR透射率降低、截获率和光能利用率上升而产量增加,A和B处理产量显著高于E处理(P0.05)。说明夏大豆在雨养农业条件下,植株相对均匀分布可改善群体结构和增强光截获,进而提高群体光能利用率和产量。     

冬小麦种植模式对水分利用效率的影响

在同一种植密度下,设3种种植模式,包括25 cm等行距平作、"20+40"大小行平作和"20+40"沟播。研究了冬小麦沟播和平作种植对产量及水分利用效率的影响。结果表明,"20+40"沟播产量显著高于平作;叶片相对含水量(RWC)、水势(Ψw)和叶片水平水分利用效率随生育进程的推进呈整体下降趋势,其中,沟播处理RWC、Ψw和叶片水平水分利用效率的平均值均显著高于等行距和"20+40"平作处理;另外,"20+40"沟播还能明显提高冬小麦田土壤贮水量,减少总耗水量,从而提高水分利用效率。灌水增加了冬小麦产量和叶片相对含水量等各水分指标,降低了水分利用效率,减小了各种植模式间差异。"20+40"沟播在灌水135 mm条件下既保障产量又较等行距节水25%。由此表明,冬小麦"20+40"沟播可改善叶片水分状况,提高水分利用效率,增加作物产量。     

小麦苗期水分利用效率及其相关性状的QTL分析

以小麦DH群体(旱选10号×鲁麦14)为研究材料,采用复合区间作图法,对小麦幼苗在水分胁迫及非胁迫条件下的水分利用效率(WUE)及其相关性状的QTL进行定位,并对比分析QTL的加性效应.两种水分条件下共检测到14个具显著加性效应的QTL,分布在2A、3A、4A、5A、6A、7A、1B、3B、3D染色体上,可解释表型变异的范围在6.36%～19.73%.其中,非胁迫(对照)条件下检测到10个QTL,包括2个单株WUE的QTL,5个地上部WUE的QTL,1个根系WUE的QTL及2个总耗水量的QTL;水分胁迫条件下上述性状各检测到1个QTL.对于同一性状没有检测到在两种水分条件下均位于同一标记区间的QTL,表明不同水分环境条件下同一性状的QTL表达模式是不同的.论文也讨论了可能用于标记辅助选择的QTL及其分子标记.     

底墒和种植方式对夏大豆光合特性及产量的影响

选择华北地区冬小麦-夏大豆一年两熟制度,冬小麦设置90 mm、135 mm、180 mm3种灌水量。冬小麦收获后,播种夏大豆,夏大豆设置30 cm等行距、“20 40” cm大小行、“20 40” cm垄作3种种植方式。研究了底墒和种植方式对夏大豆光合特性及产量的影响。结果表明,冬小麦灌溉能够明显影响夏大豆播种时的土壤蓄水量（底墒）。随冬小麦灌水量的增加,夏大豆播种时底墒改善,180 mm和135 mm较90 mm处理明显提高了夏大豆净光合速率、蒸腾速率、气孔导度、细胞间隙CO2浓度、叶绿素含量指数、Fo、Fv及ΦPSⅡ,增产效果显著。180 mm较135 mm处理增产效果不显著,且水分利用效率显著降低。夏大豆种植方式也能明显影响其净光合速率、蒸腾速率、气孔导度、细胞间隙CO2浓度、叶绿素含量指数、Fo、Fm、ΦPSⅡ、Fv/Fm、产量及水分利用效率,具体表现为：“20 40” cm垄作> 30 cm等行距>“20 40” cm大小行。综合评价,冬小麦135 mm灌水量条件下,夏大豆采用“20 40” cm垄作是生产上可行的栽培模式。     

冬小麦生长季不同灌溉模式对冬小麦-夏玉米产量与水分利用的影响

在华北平原黑龙港流域对冬小麦实行3种灌溉模式,研究了不同灌溉模式对冬小麦-夏玉米产量、耗水特性和水分利用效率的影响.结果表明:浇底墒水+拔节水处理(W2,75 mm+90 mm)和浇底墒水+拔节水+灌浆水处理(W3,75 mm+90 mm+60 mm)周年总产量均显著高于只浇底墒水处理(W1,75 mm),增幅分别为8.7%和12.5%.冬小麦全生育期对土壤水的消耗随灌溉量的增加而减少,夏玉米季总耗水量随冬小麦季灌溉量的增加而增加.W2处理冬小麦水分利用效率(WUE)比W3处理高11.1%,而其夏玉米水分利用效率(WUE)与W3处理差异不显著.W2和W1处理的周年水分利用效率(WUET)分别为21.28和21.60 kg.mm-1.hm-2,比W3处理分别高7.8%和9.4%.综合周年产量、耗水量和水分利用效率,W2是较好的节水丰产灌溉模式.     

樟科幼树水分生理特征的种间差异和相关性分析

为了阐明樟科(Lauraceae)幼树的水分生理特征,比较了同质园中自然生长的5年生刨花楠(Machilus pauhoi)、香樟(Cinnamomum camphora)和闽楠(Phoebe bournei)幼树在生长季节叶片的水分生理特征和地径(D)、株高(H)的差异。结果表明,香樟的相对含水量(RWC)、叶片水势(Ψ)、枝条木质部比导率(Ks)都显著高于闽楠和刨花楠(P0.05),而枝条木质部导水损失率(PLC)则显著低于闽楠和刨花楠(P0.05),说明香樟具有更高的保水能力、水分传输效率,并对水分缺失具有更高的抵抗力。3物种幼树均会因枝条空穴化的加强而降低枝条水分的运输效率。刨花楠幼树通过提高水分利用效率以应对导水效率的降低,香樟幼树叶片具有较高的含水量,气孔保持膨胀,可实现较高的蒸腾速率,闽楠幼树通过提高水分运输的效率和安全性以维持叶片相对含水量。     

夏玉米苗期有限水分胁迫拔节期复水的补偿效应

以作物调亏灌溉原理为基础 ,对夏玉米苗期水分胁迫拔节期复水进行了试验研究。结果表明 ,复水增加了夏玉米叶片气孔导度和光合速率 ,提高叶片水平上的水分利用效率(WUE)。复水 2天后 ,叶片气孔导度和光合速率即恢复到对照水平 ,部分时段 ,特别在下午 ,复水处理表现出高于对照的“反冲”现象。复水使苗期受旱的夏玉米株高、叶面积、地上 (下 )部分干物重和根系生长发育都恢复到或接近充分供水的植株生长水平。使其产量及构成因子与对照接近 ,水分利用效率显著地提高了 2 4 7%。这为玉米中后期的水分管理 ,提高玉米水分利用效率 ,提供了一定的理论依据 ;也提供了一种便于广大农民掌握的简单易行的灌溉方式     

中国东部南北样带森林优势植物叶片的水分利用效率和氮素利用效率

通过测定中国东部南北样带主要森林生态系统中10种优势植物(兴安落叶松、蒙古栎、水曲柳、紫椴、色木槭、红松、杉木、木荷、马尾松、锥栗)叶片的碳氮含量(Cmass、Nmass)、同位素丰度(δ13C、δ15N)以及光合响应曲线,分析了不同优势植物叶片的水分利用效率和氮素利用效率之间的差异及其相互关系.结果表明： 不同生活型植物叶片的Nmass和δ15N差异显著,表现为阔叶植物>针叶植物,落叶植物>常绿植物;最大光合速率(Pn max)表现为针叶植物>阔叶植物,落叶植物>常绿植物;植物叶片的瞬时水分利用效率(WUEi)和长期水分利用效率(WUE)均表现为阔叶植物>针叶植物,常绿植物>落叶植物;植物叶片的瞬时氮素利用效率(NUEi)和长期氮素利用效率(NUE)则表现出相反的规律,且常绿植物和落叶植物叶片的NUE差异显著;WUEi和WUE之间相关性不显著,而NUEi和NUE之间呈显著正相关.植物叶片的水分利用效率与氮素利用效率显著负相关.两种资源利用效率均受植物生活型的影响,并且存在一定的制约关系.     

HgCl2胁迫对小麦幼苗水分利用效率和叶绿素含量的影响

水通道蛋白(aquaporin,AQP)是植物体内水分吸收和运输的通道.以小麦品种石4185的幼苗为材料,在正常供水供养条件下,采用不同浓度的AQP抑制剂HgCl2对其根部进行胁迫处理,研究植株水分利用效率等性状的变化,以明确水通道蛋白与水分利用效率(WUE)的关系.结果表明:(1)小麦水通道蛋白在受到HgCl2抑制后,其幼苗的单株生物量和单株WUE(生物学产量干重/耗水量)显著低于对照处理,并且随着HgCl2浓度的增加呈逐渐下降趋势.(2)处理后植株24 h5、d和14 d的单株耗水量均显著低于对照组.(3)HgCl2胁迫处理后5 min内小麦叶片叶绿素含量持续下降,处理24 h的含量均远低于初始值,并且随胁迫时间延长处理叶片逐渐变黄.研究发现,HgCl2在抑制小麦幼苗水通道蛋白的同时,也对其光合作用相关酶和蛋白质体在短时间内产生一定影响,从而阻碍幼苗正常生长.     

杂交马褂木叶片发育过程中资源利用效率的变化格局

对一年生杂交马褂木( Liriodendron chinense Sarg.× L. tulipifera L.)叶片展开过程中光能转换效率、水分利用效率和光合碳同化的变化规律及栽植密度对中下部叶片资源利用效率的影响进行了研究,结果表明(1) 叶片展开过程中,净光合速率(Pn)、气孔导度(Gs)、蒸腾速率(E)、气孔限制值(Ls)、总光合速率(Pm)、净光合比率(Pn/Pm)、PSⅡ的原初光能转化效率(Fv/Fm)和PSⅡ的光量子产率(φPSⅡ) 、羧化效率(CE) 和水分利用效率(WUE)显著上升,而胞间CO2浓度(Ci)和呼吸速率(R)显著下降;(2) 叶片展开过程中,光合碳同化"暗系统"的完善远远慢于能量转换的"光系统";(3) 叶片展开过程中,影响净光合速率增长的主导因素不是气孔导度,而是"暗系统"完善程度, "光系统"的影响远小于"暗系统"的影响; (4) 郁闭的高密度群体中,中下部叶片的Pn、Gs、E、Ls、Pm、Fv/Fm、φPSⅡ、CE和WUE显著低于上部完全展开叶,Ci显著高于上部完全展开叶,Pn/Pm和上部完全展开叶没有显著差异,而未郁闭的低密度群体中,中下部叶片的上述所有参数与上部完全展开叶无显著差异;(5) 导致高密度群体叶片Pn大幅度下降的主导因素是CE的大幅下降,而不是"光系统"和气孔导度;(6) 密度过大加速了中下部叶片光合功能的下降.     

Water relations of six sclerophylls growing near Trieste (Northeastern Italy): has sclerophylly a univocal functional significance?

Abstract

The annual time course of the water relations of six sclerophylls has been studied with the aim of: a) defining strategies adopted for withstanding summer water stress and b) to check whether their common sclerophyllous habitus could represent a case of convergent evolution devoted to a univocal functional role. In particular, Phillyrea latifolia L. showed to behave like a drought tolerant as indicated by deep summer drop in leaf water potential (Ψ₁) to near the full turgor loss point (Ψ_lp) and in leaf relative water content (RWC) as caused by xylem cavitation. Prunus laurocerasus L. and Laurus nobilis L. showed to be drought avoiding water spenders in that their Ψ₁ dropped in summer causing prompt recovery in RWC. This was made possible by low cavitation in their twigs. Ilex aquifolium L. was a typical drought avoiding water saver in that both Ψ₁ and RWC remained at very high levels throughout the year. Quercus ilex L. behaved like a drought avoiding water spender which switched to drought tolerance in the warmest period of the year. This was explained by its high vulnerability to cavitation. The extreme heterogeneity of the six species studied suggested that sclerophylly cannot be interpreted as an anatomical feature leading to a specific and unifying functional role, at least as regards drought resistance.     

Vulnerability to xylem cavitation and the distribution of Sonoran Desert vegetation

We studied 15 riparian and upland Sonoran desert species to evaluate how the limitation of xylem pressure (Ψ(x)) by cavitation corresponded with plant distribution along a moisture gradient. Riparian species were obligate riparian trees (Fraxinus velutina, Populus fremontii, and Salix gooddingii), native shrubs (Baccharis spp.), and an exotic shrub (Tamarix ramosissima). Upland species were evergreen (Juniperus monosperma, Larrea tridentata), drought-deciduous (Ambrosia dumosa, Encelia farinosa, Fouquieria splendens, Cercidium microphyllum), and winter-deciduous (Acacia spp., Prosopis velutina) trees and shrubs. For each species, we measured the "vulnerability curve" of stem xylem, which shows the decrease in hydraulic conductance from cavitation as a function of Ψ(x) and the Ψ(crit) representing the pressure at complete loss of transport. We also measured minimum in situ Ψ(x)(Ψ(xmin)) during the summer drought. Species in desert upland sites were uniformly less vulnerable to cavitation and exhibited lower Ψ(xmin) than riparian species. Values of Ψ(crit) were correlated with minimum Ψ(x). Safety margins (Ψ(xmin)-Ψ(crit)) tended to increase with decreasing Ψ(xmin) and were small enough that the relatively vulnerable riparian species could not have conducted water at the Ψ(x) experienced in upland habitats (-4 to -10 MPa). Maintenance of positive safety margins in riparian and upland habitats was associated with minimal to no increase in stem cavitation during the summer drought. The absence of less vulnerable species from the riparian zone may have resulted in part from a weak but significant trade-off between decreasing vulnerability to cavitation and conducting efficiency. These data suggest that cavitation vulnerability limits plant distribution by defining maximum drought tolerance across habitats and influencing competitive ability of drought tolerant species in mesic habitats.     

The partitioning of water uptake between growth forms in a Neotropical savanna: do herbs exploit a third water source niche?

In addition to trees and grasses, the savannas of central Brazil are characterised by a diverse herbaceous dicot flora. Here we tested whether the coexistence of a highly diversified assemblage of species resulted in stratification or strong overlap in the use of soil water resources. We measured oxygen and hydrogen isotope ratios of stem water from herbs, grasses and trees growing side by side, as well as the isotopic composition of water in soil profile, groundwater and rainfall, and predawn (Ψ_pd) and midday (Ψ_md) leaf water potentials. We used a stable isotope mixing model to estimate vertical partitioning of soil water by the three growth forms. Grasses relied on shallow soil water (5–50 cm) and were strongly anisohydric. Ψ_pd and Ψ_md decreased significantly from the wet to the dry season. Trees extracted water from deeper regions of the soil profile (60–120 cm) and were isohydric. Ψ_pd and Ψ_md did not change from the wet to the dry season. Herbs overlapped with grasses in patterns of water extraction in the dry season (between 10 and 40 cm), but they took up water at soil depths intermediate (70–100 cm) to those of trees and grasses during the wet season. They showed seasonal changes in Ψ_pd but not in Ψ_md. We conclude that vertical partitioning of soil water may have contributed to coexistence of these three growth forms and resulted in a more complex pattern of soil water extraction than the two‐compartment model of soil water uptake currently used to explain the structure and function of tropical savanna ecosystems.     

不同栽培措施下火炬松穗条产量的变化

以1年生火炬松Pinus taeda实生苗为材料,进行3因素(截干高度、施肥配方、种植密度)3水平L9(34)正交试验,分析不同栽培措施对穗条产量的影响。结果表明,春季促进穗条产量增加的优化组合为截干高度15 cm,施用农家肥,种植行间距50 cm×80 cm;夏季优化组合为施用农家肥+复合肥,截干高度15 cm,种植行间距为50 cm×80 cm;秋季优化组合为施用农家肥+复合肥,种植行间距50 cm×80 cm,截干高度为12 cm;冬季优化组合为施用农家肥,截干高度15 cm,种植行间距40 cm×50 cm;提高单株穗条年产量的优化组合为施用农家肥+复合肥,截干高度15 cm,种植行间距40 cm×50 cm。因此,在火炬松生长不同时期,选用不同的栽培措施有助于提高穗条产量。     

灌水量与密度互作对冬小麦籽粒产量和水分利用效率的影响

为明确协同提高冬小麦产量和水分利用效率的适宜灌水量和种植密度,选用大穗型品种‘泰农18’(T18)和中穗型品种‘山农22’(S22)为试验材料,设置4个灌溉水平(不灌水、每次灌水45、60、75 mm)和4个种植密度,其中泰农18选用135×10⁴、270×10⁴、405×10⁴、540×10⁴ 株·hm^-2,山农22选用90×10⁴、180×10⁴、270×10⁴、360×10⁴株·hm^-2,研究了籽粒产量、麦田耗水特性和水分利用效率对灌水量和密度互作效应的响应。结果表明: 籽粒产量、总耗水量、土壤贮水消耗量和水分利用效率均受到灌溉水平、种植密度及两者互作效应的显著影响。每次灌水量为45 mm,泰农18种植密度为405×10⁴株·hm^-2、山农22种植密度为270×10⁴株·hm^-2时,两品种籽粒产量均达到最高,拔节后棵间蒸发量占阶段农田总耗水量的比例最小,1 m以下土壤水消耗比例、水分利用效率高。种植密度与灌溉量合理组合,有利于降低水分无效损耗,提高水分利用效率。     

甘肃旱作大豆全膜双垄种植的土壤水热及产量效应

以晋豆23为材料,在甘肃省农业科学院镇原试验站进行田间试验,研究了全膜双垄沟播(FMRFC)、覆膜沟播(FMFC)、覆膜条播(FMSC)和露地条播(NMSC,CK)4个处理的水热及产量效应.结果表明: 在大豆生育期降水量为246.3 mm(干旱年)和407 mm(丰水年)两种年型下,各覆盖处理0～20 cm土层平均地温在24 h内呈“S”型变化,并随生育进程波动振幅缩小.各覆盖处理使大豆苗期(VE～V3)至鼓粒期(R6)0～20 cm土层平均土壤温度显著提高0.5～2.5 ℃,并使全生育期平均地温提高1.3～1.6 ℃.各覆盖处理分别加速了大豆植株对0～120 cm土层土壤水分的消耗,但使0～200 cm土层的平均含水量和贮水量分别提高了1.2%～1.4%和62.7～70.3 mm.与CK相比,FMRFC和FMFC在旱年增温增湿作用显著,改善了大豆株高、分枝数、单株荚数和百粒重等经济性状,使水分利用效率分别提高47.7%～56.3%和33.3%～35.4%,产量分别提高27.7%～51.1%和10.2%～25.2%,是旱作大豆优选的抗寒抗旱覆盖种植方式.     

行距配置对晚熟冬麦区群体结构与光合性能的影响

合理的行距配置可以调节群体冠层结构的光合作用。山西太谷冬小麦产量徘徊不前,为了研究晚熟冬麦区不同行距配置对不同穗型冬小麦光合性能与群体结构的影响,在大田条件下选用两种不同穗型品种,在播量一致的前提下,分别采用10 cm和20 cm两种行距配置,研究冬小麦群体结构、光能利用和产量结构的差异。研究结果表明:全生育期总LAI值表现为B2高于B1,10 cm行距配置改变了叶片的垂直分布,尤其对多穗型小麦品种冠层(60-80 cm)叶面积的提高最为明显。在小麦植株中、上部分45-90 cm处,两种行距配置LI%均表现为B2配置大于B1配置,在株高60-75 cm处,两种行距配置LI%差异最为明显,B2配置较B1配置LI%提高达30%以上。花后旗叶PN和孕穗期至蜡熟期群体NPR均表现为10 cm行距配置高于20 cm行距配置。四个处理的总干物质重、绿叶、茎和穗的干物质重均表现为B2B1行距配置。两个小麦品种的B2处理(10 cm行距配置)的产量和生物产量均极显著高于B1处理(20 cm行距配置);但经济系数则呈现B2处理(10 cm行距配置)均小于相应小麦品种的B1处理。行距配置对不同小麦品种的影响不大。表明10 cm行距配置适用于北方晚熟冬麦区。     

Effects of elevated CO2, drought and temperature on the water relations and gas exchange of groundnut (Arachis hypogaea) stands grown in controlled environment glasshouses

Stands of groundnut (Arachis hypogaea L. cv. Kadiri‐3) were grown in controlled environment glasshouses at mean atmospheric CO₂ concentrations of 375 or 700 μmol mol^?1 and daily mean air temperatures of 28 or 32°C on irrigated or drying soil profiles. Leaf water (Ψ_l) and solute potential (Ψ_s), relative water content (RWC), stomatal conductance (g_l) and net photosynthesis (P_n) were measured at midday for the youngest mature leaf throughout the growing season. Elevated CO₂ and temperature had no detectable effect on the water relations of irrigated plants, but higher values of RWC, Ψ_l and Ψ_s were maintained for longer under elevated CO₂ during progressive drought. Turgor potential (Ψ_p) reached zero when Ψ_l declined to ?1.6 to ?1.8 MPa in all treatments; turgor was lost sooner when droughted plants were grown under ambient CO₂. A 4°C increase in mean air temperature had no effect on Ψ_s in droughted plants, but elicited a small increase in Ψ_l; midday g_l values were lower under elevated than under ambient CO₂, and Ψ_l and g_l declined below ?1.5 MPa and 0.25 cm s^?1, respectively, as the soil dried. Despite the low g_l values recorded for droughted plants late in the season, P_n was maintained under elevated CO₂, but declined to zero 3 weeks before final harvest under ambient CO₂. Concurrent reductions in g_l and increases in water use efficiency under elevated CO₂ prolonged photosynthetic activity during drought and increased pod yields relative to plants grown under ambient CO₂. The implications of future increases in atmospheric CO₂ for the productivity of indeterminate C₃ crops grown in rainfed subsistence agricultural systems in the semi‐arid tropics are discussed.