首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 135 毫秒
1.
采用FACE(Free Air Carbon-dioxide Enrichment)技术,研究了不同N、P施肥水平下,水稻分蘖期、拔节期、抽穗期和成熟期根、茎、穗生长,C/N比、N、P含量及N、P吸收对大气CO2浓度升高的响应,结果表明,高CO2促进水稻茎、穗和根的生长,增加分蘖期叶干重,对拔节期、抽穗期的成熟期叶干重没有显著增加,降低茎、叶N含量;增加抽穗期穗N含量;降低成熟期穗N含量;对分蘖期根N含量影响不显著,而降低拔节期,抽穗期和成熟期根N含量,增加拔节期、抽穗期和成熟期叶P含量,对茎、穗、根P含量影响不显著,水稻各组织C含量变化不显著,C/N比增加,显著增加水稻地上部分P吸收;增加N吸收,但没有统计显著性,N、P施用对水稻各组织生物量没有显著影响,高N(HN)比低N(LN)增加组织中N含量,而不同P肥水平间未表现出明显差异,高N条件下高CO2增加水稻成熟期地下部分/地上部分比,文中还讨论了高CO2对N、P含量及地下部分/地上部分比的影响机制。  相似文献   

2.
采用盆栽试验,研究了Cd胁迫下施N对台湾桤木植株的干物质及N、P、K、Cd积累和分配的影响。结果表明:不施N条件下,Cd胁迫显著降低了台湾桤木根、茎和叶干物质积累量以及各器官N、P、K的积累量,在一定程度上降低了根和叶的N、K含量,但对根和叶的P含量均无显著影响;台湾桤木通过增加N、P、K和干物质在根中的分配比例,降低N、P、K在叶中的分配比例,以及提高N利用率(NUEN)和K利用率(NUEK)来更好地适应Cd胁迫环境;台湾桤木Cd的富集部位主要为根部,转移系数在0.06~0.22,而Cd的添加均降低了台湾桤木Cd转移系数和富集系数;30 mg·kg-1Cd胁迫下,施N在一定程度上提高了台湾桤木根、茎和叶干物质以及N、K含量和积累量,缓解了Cd胁迫所引起的对N、K吸收的限制,但对P含量和积累量无显著影响;施N提高了干物质在台湾桤木根中的分配比例和根冠比,而低N(0.4 g·kg-1)促进作用更明显;施N提高了Cd在台湾桤木茎、叶中的积累量和分配比例,而降低了其在根中的积累量和分配比例,提高了Cd转移系数(TF)和茎叶生物富集系数(BCF),显著降低了根BCF。说明施N有利于提高台湾桤木对Cd胁迫环境的适应能力。  相似文献   

3.
查美琴  成向荣  虞木奎  韩有志  汪成  江斌 《生态学报》2021,41(21):8556-8567
了解林木功能性状在不同培育模式下的变异和关联,对揭示林木生态适应性及其生态功能具有重要意义。选取了亚热带地区两种常见人工林树种杉木、大叶榉幼苗为研究对象,设置4种不同栽培模式的盆栽试验:单一杉木(4C),单一大叶榉(4Z)和杉木、大榉树3种混栽模式(1C3Z、2C2Z、3C1Z),研究不同混交比例对其叶、茎、根功能性状的影响。结果表明:(1)杉木总叶面积、叶干物质含量、净光合速率、蒸腾速率和气孔导度在混栽模式下显著减小,而比叶面积显著增大;根长和比根长在不同处理间无显著差异;叶、茎、根生物量和单株总生物量在混栽模式下显著低于4C处理,不同混栽模式之间差异不显著。(2)大叶榉单叶面积在3C1Z处理下最高,总叶面积随大叶榉在树种组成中所占比例的降低而逐渐增大,比叶面积在不同处理间无显著差异,叶干物质含量、净光合速率、蒸腾速率和气孔导度均在2C2Z处理下最大,而瞬时水分利用效率在2C2Z处理下最小;根长在3C1Z处理下显著增大,比根长在不同处理间无显著差异;叶、茎、根生物量和单株总生物量随大叶榉在树种组成中所占比例的降低而逐渐增大。综合来看,杉木和大叶榉混合处理中杉木种间竞争大于种内竞争,而大叶榉相反;随杉木在混栽处理中比例减少,其主要通过增加比叶面积,提高净光合速率,减少茎生物量积累来适应种间竞争关系;而大叶榉随其在混栽处理中比例的减少,显著增加叶面积和根长来提高资源利用率,减少地下资源分配,提高地上茎生物量积累。因此,树种混交比例将显著影响林木功能性状及其生物量积累,选择适宜混交比例对混交林可持续经营具有重要意义。  相似文献   

4.
营养元素含量及化学计量比可反映植物器官营养元素的分配及互作关系,亦可反映其营养利用效率及生长环境的养分限制状况。以青桐(Firmiana platanifolia)幼苗为材料,分析4种不同光强(全光照,50%、75%和95%遮荫)对青桐幼苗生长,C、N、P、K含量及其化学计量特征的影响。结果表明:遮荫对青桐幼苗的生长性状、生物量、元素含量和积累量及化学计量比均有显著影响(P<0.05)。苗高和比叶面积随遮荫强度增加而升高,而地径和粗壮度随遮荫强度增加而减小。总生物量在75%遮荫下最大,在95%遮荫下最小。在各遮荫处理下,叶片C、N、P、K含量均大于根和茎,且N含量顺序为叶>根>茎,K含量顺序为叶>茎>根。C、P、K积累量随遮荫强度增大而增加,在75%遮荫下达到最大值,而在95%遮荫下达到最小值。青桐幼苗C∶N和C∶P呈现出相同的变化趋势,随遮荫强度变大先增加后减小,均在50%遮荫下达最大值。青桐各器官N∶P远低于14,即青桐幼苗在不同遮荫条件下的生长严重受N限制。这些结果说明,遮荫可调节青桐幼苗在不同光环境中的养分积累与分配,进而影响生物量。因此,青桐苗期培育宜选75%遮荫,有助于苗高、比叶面积、生物量、养分含量和积累量的增加,而过度遮荫可抑制幼苗生长发育。  相似文献   

5.
CO2与养分交互作用对番茄幼苗根生长的影响   总被引:1,自引:0,他引:1  
在营养液栽培条件下,以番茄(合作906)为研究材料,设计不同的CO2及养分浓度处理,采用定期取样的方法研究番茄定植后根重齄的动态变化及CO2与不同养分供应强度的交互作用对根中碳氮含量与碳氮比的影响。结果表明:番茄苗期根干物质在生长前期积累速率较慢,中后期积累速率较快,在育苗后期CO2对根干物质积累的影响大于前期,根干重对CO2的响应随营养液离子浓度的改变而变化,表明对天番茄幼苗根的生长发育,CO2施肥结合高养分浓度的营养液,才能达到最佳效果。定量分析番茄根干鲜重与生长时间的关系,结果表明:生长条件的改变,会改变番茄根系的生长,对于根鲜重.在较高的CO2条件下,1/2山崎番茄营养液与1/4山崎番茄营养液里生长的根系鲜重在拟合方程中以幂函数拟合得到的相关系数最大,其余处理以二次曲线方程拟合得到的相关系数最大;对于根干重,在较高的CO2条件下,1/2山崎番茄营养液里生长的根系干重在所拟合的方程中以幂函数拟合的相关系数最大,其余的处理以二次曲线方程拟合的相关系数最大。CO2降低了在1/2山崎番茄营养液中生长的根系中的N含量,升高其它营养液处理中的根的N含量,降低了在1/2、1/4山崎番茄营养液中生长的番茄根系中C的百分含量,增加在1/8、1/16山崎番茄营养液中生长的番茄根系中C的百分含量,增加所有营养液浓度条件下的C、N总量,降低根系中的C/N比,在同一CO2条件下C/N比随营养液浓度的降低而升高。  相似文献   

6.
油松幼苗对干旱胁迫的生理生态响应   总被引:8,自引:2,他引:6  
在适宜水分(田间持水量为80%)、轻度干旱(60%)、中度干旱(40%)和重度干旱(20%)4种土壤水分条件下研究了油松的生理生态特征,结果显示; 油松各器官(根、茎、叶)的干物质积累量、干物质积累总量、相对生长率、株高和基径均表现为适宜水分>轻度干旱>中度干旱>重度干旱,而根冠比大小顺序与其相反.气体交换参数(净光合速率、气孔导度、蒸腾速率) 随干旱程度的加剧显著下降,并且净光合速率的下降主要受气孔因素限制.油松的瞬时水分利用效率和长期水分利用效率(稳定碳同位素含量,δ13C)表现适宜水分<轻度干旱<中度干旱<重度干旱,而且中度和重度干旱显著提高油松的水分利用效率.另外,单位干重叶片氮元素含量(N%)随胁迫增加呈下降趋势,而单位干重碳元素含量(C%)却与之相反,从而导致碳氮比随胁迫增加而增加,并且我们的结果显示光合速率与氮含量存在显著正相关. 结果表明,油松可以通过调节自身生长特征、生物量分配模式和叶片营养元素的含量及提高水分利用效率而增强应对干旱胁迫的能力.  相似文献   

7.
盐碱土区植物可利用营养匮乏是植物生物量限制的主要因素之一,藜科(Chenopodiaceae)植物是盐碱环境中的最大类群,其整体营养策略对盐碱地育种和农业开发具有重要意义。本研究以呼伦贝尔4种典型盐碱地藜科植物碱蓬(Suaeda glauca)、尖头叶藜(Chenopodium acuminatum)、刺沙蓬(Salsola tragus)、雾冰藜(Bassia dasyphylla)为研究对象,通过分析不同器官C、N、P生态化学计量特征,试图揭示藜科植物C、N、P计量特征共性及其与土壤因子之间的耦合关系。结果显示:①藜科植物茎、叶N/P>16,根N/P<14;各器官C、N含量显著相关,且根C含量>茎C含量>叶C含量,N含量表现为叶N含量>茎N含量>根N含量,表明N元素从根、茎到叶之间具有良好的转移效率。②相对于C元素和N元素,各器官内P元素含量具有最大变异系数,叶P、茎P含量与叶N、根N含量显著正相关,根P含量与叶N、根N含量显著负相关,表明N、P元素在叶和根中具有较强的协调关系。③RDA排序表明土壤P是影响植物叶片化学计量的主要因素,土壤K是茎化学计量变异的主要因素,土壤N是根化学计量变异的主要因素。本研究发现藜科植物通过叶N、叶P积累和N、P协调降低土壤N、P限制的影响,对于盐碱土营养管理具有重要意义。  相似文献   

8.
目的:研究遮荫对掌叶半夏生长、药材产量和光合生理指标的影响,分析适宜掌叶半夏药材高产的遮荫度,探寻其产量差异形成的光合生理机制。方法:采用遮荫网遮荫,共设置了5种光强处理,透光率分别为全光对照CK(100%)、T1(75%)、T2(65%)、T3(50%)、T4(25%),测定各遮荫处理下掌叶半夏的株高、单株叶片数、单株叶面积、单片叶面积、药材产量、叶绿素含量、光合日进程和叶绿素荧光参数。结果:(1)遮荫可显著(P〈0.01)提高掌叶半夏的株高、单株叶面积和叶绿素含量;(2)光合日进程曲线测定结果表明,除T4处理外其他处理均发生光合"午休"现象,日平均光合速率(Pn)以T1处理最高,绝对光能利用率(Eu)以T3处理最高;(3)叶绿素荧光参数测定结果表明,CK的Fv/Fm最低,发生的原因可能与PSⅡ反应中心的光化学伤害有关;(4)药材产量以T2处理最高,较CK增产56.34%。结论:掌叶半夏更适宜在遮荫条件下栽培,透光率在65%时有利于掌叶半夏药材高产,其产量差异的形成可能与日均光合速率的不均衡有关。  相似文献   

9.
采用FACE(Free Air Carbon-dioxide Enrichment)技术,研究了不同N、P施肥水平下,水稻分蘖期、拔节期、抽穗期和成熟期根、茎、叶、穗生长,C/N比,N、P含量及N、P吸收对大气CO2浓度升高的响应.结果表明,高CO2促进水稻茎、穗和根的生长.增加分蘖期叶干重,对拔节期、抽穗期和成熟期叶干重没有显著增加.降低茎、叶N含量;增加抽穗期穗N含量,降低成熟期穗N含量;对分蘖期根N含量影响不显著,而降低拔节期、抽穗期和成熟期根N含量.增加拔节期、抽穗期和成熟期叶P含量,对茎、穗、根P含量影响不显著.水稻各组织C含量变化不显著.C/N比增加.显著增加水稻地上部分P吸收;增加N吸收,但没有统计显著性.N、P施用对水稻各组织生物量没有显著影响.高N(HN)比低N(LN)增加组织中N含量,而不同P肥水平间未表现出明显差异.高N条件下高CO2增加水稻成熟期地下部分/地上部分比.文中还讨论了高CO2对N、P含量及地下部分/地上部分比的影响机制.  相似文献   

10.
设置适宜水分、轻度、中度和重度干旱胁迫处理(即80%、65%、50%和35%田间持水量),研究干旱胁迫对榆树幼苗不同器官C、N、P化学计量的影响.结果表明:与适宜水分处理相比,干旱胁迫导致C含量在叶、茎、粗根和细根中增加,N含量在叶、茎和粗根中增加,P含量在叶、茎和粗根中下降,在细根中增加,C:N在叶和茎中下降,C:P及N:P在叶、茎和粗根中增加,在细根中下降.各器官间C含量呈显著正相关,而各器官间N与P相关性均不显著.土壤含水量与各器官C含量,叶N含量,细根P含量及C:N,叶、茎和粗根C:P及N:P呈显著负相关,而与细根N含量,叶、茎和粗根P含量,细根C:P及N:P呈显著正相关.因此,干旱胁迫影响榆树幼苗对N、P的吸收及向上运输,幼苗生长主要受N限制;随着干旱胁迫的加剧,叶、茎和粗根生长受P限制作用增强.  相似文献   

11.
为了研究不同生育时期遮光对马铃薯光合特性和产量的影响,明确马铃薯不同生育时期对弱光的耐受性,对2个马铃薯品种(‘冀张薯12号'和‘冀张薯8号')进行了4个生育时期(苗期、苗期至现蕾期、现蕾期至开花初期、开花初期至收获期)和3个遮光度(不遮光对照、20%遮光率和50%遮光率)的处理试验。结果表明: 与不遮光处理相比,20%遮光率下,2个品种马铃薯苗期SPAD值显著降低,苗期至现蕾期、现蕾期至开花初期SPAD值无显著变化,开花初期遮光15 d可使SPAD值呈一定程度增加;50%遮光率下,2个品种马铃薯SPAD值变化趋势与前者相同,除开花初期增幅加大外,其他生育时期变化幅度接近。各时期遮光对马铃薯叶片气孔导度(gs)影响不大,除50%遮光率下‘冀张薯8号'叶片gs在开花初期较对照显著降低43.9%外,其他处理的gs与对照均无显著差异。遮光后叶片胞间CO2浓度(Ci)呈增加趋势,苗期、苗期至现蕾期50%遮光可使Ci显著增加,其余各时期的Ci无显著变化。4个时期遮光处理的叶片净光合速率(Pn)均降低,2个品种马铃薯叶片Pn在50%遮光处理下的降幅均大于20%遮光处理,‘冀张薯12号'除在苗期遮光处理的叶片Pn降幅大于‘冀张薯8号'外,其余时期的降幅均小于‘冀张薯8号'。4个时期遮光使马铃薯产量均降低,且50%遮光处理降幅大于20%遮光处理。‘冀张薯12号'在苗期不耐弱光,其余时期的耐弱光能力优于‘冀张薯8号'。综合分析表明,耐弱光能力强的品种遮光处理后,叶片Pngs降幅小、Ci增幅小,产量降幅也小。  相似文献   

12.
不同生育期遮光对水稻生长发育和产量形成的影响   总被引:64,自引:12,他引:52  
研究了不同生育期遮光45%(水稻生长的前期、中1期、中2期、后期)对水稻形态发育、光合产物积累、稻株养分含量、产量构成等的影响,并重点研究了植株对N、P、K养分的吸收规律.结果表明,各期遮光后均使干物质积累速率降低,植株N、P、K养分吸收量减少,对产量有不同程度的影响,但植株体内N、P、K养分含量上升.前期遮光主要使分蘖数急剧下降,有效穗数减少,叶面积系数下降,产量下降11.56%,但株高增加;中1期遮光后对水稻生长影响不大,产量仅降低5.46%;中2期遮光主要使每穗粒数和千粒重下降,对产量影响较大,降低幅度达30.80%;后期遮光主要影响结实粒和千粒重,其产量最低,降低55.40%.文中还对弱光照条件下的生育期安排和施肥决策提出了建议  相似文献   

13.
弱光胁迫对不同基因型玉米生长发育和产量的影响   总被引:59,自引:5,他引:54  
以不同基因型玉米为材料,在玉米生长发育的3个主要阶段(苗期、穗期、粒期)进行分期遮光试验,研究不同时期弱光胁迫对不同基因型玉米生长发育和产量的影响。结果表明,遮光延缓了玉米叶片的出生速度,使叶片变薄;遮光可以延缓叶片的衰老,但遮光解除后则加速叶片的衰老;遮光造成植株高度增加,但恢复正常光照后,其株高却逐渐低于对照;遮光使干物质积累下降,抽雄吐丝日期推迟,尤其是吐丝日期推迟更多,并使产量降低,但不同基因型玉米不同遮光处理下降程度不同。试验的4个品种中,掖单2 2和豫玉2号受遮光影响较小,而掖单36 38和丹玉13受影响较大,即不同基因型玉米对弱光胁迫的敏感性不同  相似文献   

14.
Cherry (Prunus avium L.) saplings were grown under natural sunlight (controls) or moderate shading (up to 30%, depending on the incident light intensity and the hour of the day). Reduced light intensity increased the dry mass of each of the plant components studied. Consequently, the total dry mass of shaded plants was significantly greater than that of controls at the end of the growing season. However, the diurnal trend in the level of photosynthesis (per unit of leaf area) of shaded plants was similar to the controls in August, but lower in September. As the growing season proceeded, reduced photosynthetic rates, thinner mesophyll and larger specific leaf area in the shaded plants indicated that leaf development had adapted to shaded conditions throughout the growing season. It is suggested that increased growth of shaded plants was caused by a higher initial relative growth rate and a greater whole-plant photosynthesis. Shading consistently reduced transpiration over the season, therefore improving water use efficiency of shaded leaves. Our results suggest that a moderate reduction in light intensity can be a useful method for improving growth and saving water in hot and dry environments.  相似文献   

15.
针对江汉平原小麦生长季阴雨天气持续时间长、光照辐射少而形成的弱光环境,本试验以江汉平原大面积推广品种‘郑麦9023’和‘扬麦23’为材料,研究了孕穗期遮光处理(S1)和开花期遮光处理(S2)对两品种小麦产量的影响及其生理基础,并设置遮光前喷施6-BA处理(S1+6-BA、S2+6-BA),探究喷施6-BA对弱光胁迫的缓解作用.结果表明:孕穗期与开花期遮去自然光强的45%均显著降低了各处理籽粒产量,且开花期遮光处理籽粒产量下降幅度大于孕穗期遮光处理,遮光处理开花后14~21 d籽粒干物质积累量显著下降导致的粒重降低是造成籽粒产量下降的主要原因;两时期遮光均降低了成熟期干物质积累量,改变了营养器官干物质分配比例,使籽粒产量更多地依赖于开花前营养器官贮藏同化物,从而导致遮光处理籽粒产量下降.开花期遮光前喷施6-BA处理的籽粒产量显著大于开花期遮光处理,主要是由于喷施6-BA能够延缓遮光处理下旗叶的衰老进程,其灌浆速率和粒重亦显著大于遮光处理,同时提高了开花期遮光处理植株在成熟期的干物质积累量,且S2+6-BA花后同化物的转运量及对籽粒的贡献量较S2增大,最终提高了遮光处理的籽粒产量.总之,开花期遮光对小麦籽粒产量的影响大于孕穗期,开花期遮光前喷施外源6-BA对遮光造成的不利影响有一定的缓解效应,降低了开花期遮光造成的产量损失.  相似文献   

16.
遮阴对夏玉米干物质积累及养分吸收的影响   总被引:2,自引:0,他引:2  
以振杰2号(ZJ2)、登海605(DH605)和郑单958(ZD958)为试验材料,在大田条件下设置花粒期遮阴(S1)、穗期遮阴(S2)、全生育期遮阴(S3)3个遮阴处理,以自然光照条件为对照(CK),研究了遮阴对夏玉米干物质积累和氮、磷、钾吸收的影响.结果表明: 遮阴后夏玉米籽粒产量和单株干物质积累量显著降低,降低程度与遮阴时期有关,表现为S3>S1>S2,其中S1、S2和S3籽粒产量平均降低61.6%、25.3%和92.8%,说明花粒期遮阴较花前遮阴对夏玉米干物质积累和籽粒产量影响更大,不同品种的变化趋势相同.夏玉米植株花前养分吸收量表现为钾>氮>磷,植株吸收总量表现为氮>钾>磷.遮阴后植株氮和磷积累量显著减少,由于遮阴后干物质较对照降低程度大于对氮、磷吸收的降低程度,各处理氮、磷相对含量有所升高;遮阴后各处理植株钾吸收量较对照显著降低,但S2处理的钾吸收降低程度大于干物质积累降低程度,钾相对含量降低,即花前遮阴对玉米钾吸收的影响大于氮和磷.  相似文献   

17.
The plant growth regulator PGR-IV has been reported to improve the growth, boll retention, and yield of cotton (Gossypium hirsutum L.) under optimum growing conditions. However, little is known about the response of cotton to PGR-IV under low light stress. A 3-year field study was conducted to determine if applying PGR-IV before an 8-day period of shade (63% light reduction) benefitted the growth and yield of shaded cotton. Shading during early squaring did not affect yield. Shading after the first flower stage significantly increased leaf chlorophyll concentration and fruit abscission and decreased the leaf photosynthetic rate, nonstructural carbohydrate concentrations, and lint yield. Foliar application of PGR-IV at 292 mL ha−1 at early squaring and first flower did not improve the leaf photosynthetic rate of shaded cotton. However, shaded plants receiving PGR-IV had higher nonstructural carbohydrate concentrations in the floral buds and significantly lower fruit abscission than the shaded plants without PGR-IV. Applying PGR-IV to the foliage before shading resulted in a numeric increase (6–18%) in lint yield compared with shaded plants without PGR-IV. The decreased fruit abscission from the application of PGR-IV was associated with improved assimilate translocation. The yield enhancement from foliar application of PGR-IV was attributed to increased fruit retention. However, the average boll weight of shaded plants with PGR-IV tended to be lower than that of shaded plants without PGR-IV. Lint percentage was not affected by PGR-IV. Foliar application of PGR-IV appears beneficial for increasing the fruit retention of shaded cotton. Received June 12, 1997; accepted January 19, 1998  相似文献   

18.
Shading is assumed to reduce allocation to plant phenolics and to defense in general. We here report the results of experimental shading of individual branches or whole canopies in mountain birch on foliar chemistry and on the growth and consumption of a geometrid, Epirritaautumnata. Branch‐wide shading tended to have at least as strong effects on both leaf chemistry and herbivore performance as canopy‐wide shading, indicating local responses of the host to shading. Responses to shading varied among the key leaf traits. Leaf water content was higher and toughness lower in shaded than in non‐shaded leaves. Leaf sugars were lower and protein‐bound and free amino acids higher in shaded than in control leaves. Sucrose and galactose were at high levels in unshaded branches adjacent to shaded ones, suggesting that partial shading enhanced translocation of sugars within canopies. Total phenolics and soluble proanthocyanidins were low in both shading treatments. Of the other phenolic groups, concentrations of gallotannins and cell‐wall‐bound proanthocyanidins did not differ between shaded and non‐shaded leaves. Epirrita larvae grew better in both types of shading treatments compared to either unshaded control trees or to unshaded branches in the branch‐shading trees. By far the most important correlate of larval growth was the amount of water consumed with leaf mass (r=0.94). When variance in water intake was standardized (also largely eliminating parallel variation in proteins), fructose and glucose still had significant positive correlations and proanthocyanidins negative with larval growth on control but not on shade leaves. Concentrations of several phenolic compounds correlated negatively with intake of dry matter and especially water, and different phenolics were important in shaded (gallotannins) and in control (flavonoids) leaves. Our findings strongly suggest that the effects of putatively defensive leaf traits on insect consumption and growth interact with nutritive leaf traits, particularly with water.  相似文献   

19.
In order to reduce heat energy consumption in greenhouse cucumber production, (transparent) screens may be used also during the day, particularly in the early growth phase when high temperatures are required to achieve rapid leaf area development. However, energy savings must be optimised against light reduction‐induced yield loss. For this reason, two experiments were conducted to quantify the effect on photosynthesis and growth of screening cucumber plants during their early growth phase, and on yield in the following generative phase. Screening with different light transmission coefficients was simulated using shading nets. Shading the plants during the first 5 weeks under Central European winter conditions reduced the leaf area by 0.40% per 1% reduction in photosynthetic active radiation (PAR). Moreover, potential leaf net photosynthesis decreased by 0.46% per 1% PAR reduction. A major impact was that the leaf dry matter content, leaf starch content and leaf sugar content of shaded plants diminished significantly. In the course of the following 2 weeks under full light, the leaf photosynthesis of the plants previously shaded recovered fully and the leaf area index rose to 3.3 m2 m?2, considered sufficient for optimal crop photosynthesis. The yield from plants previously shaded diminished slightly as early as from the first harvest week on. These yield losses increased further over the next few weeks, measuring approximately 0.8 kg m?2 per 1 mol m?2 day?1 PAR reduction in the early growth phase. The effect of PAR on plant growth was proportional when relating the PAR integral over the entire experimental period to the total yield and to the total dry matter production, respectively.  相似文献   

20.
Plants of barley were grown under controlled conditions andthe first or second leaves covered with tubular shades thusreducing the light intensity at the leaf surface to low levels.Expansion of the shaded leaves was not prevented, but appearanceof the next leaf but one and all subsequent leaves on the mainstemwas delayed by up to 3 days. Primordia of the first four leaveswere present in the dry grain. Shade treatment delayed slightlythe initiation of the eighth and subsequent leaves and transitionto the double ridge stage at the mainstem apex. Shading the first leaf caused a temporary reduction in the rateof dry-matter increase of plants, but after 14 days the ratewas similar to that of control plants. Smaller effects werefound when the second leaf was shaded. Dry-matter productionfollowed two logarithmic phases in the period prior to awn emergence,and rates for the whole plant and for plant parts were similarfor control and shaded plants. Thus, apart from the initialperturbation, shading had no effect on growth in terms of rateof dry-weight gain. Shade treatment did not affect weight per grain or numbers ofgrain per ear, but over-all yield of grain was significantlyreduced since shading delayed the appearance of tillers andalso reduced the number of tillers bearing grain. The effectof shade was especially marked on tillers originating on primarytillers. Similar qualitative effects on tiller development werefound in an experiment on wheat.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号