夏玉米群体光合速率特性及其与冠层结构、生态条件的关系

研究结果表明：高产夏玉米群体光合速率日变化呈单峰曲线。在水肥充足栽培条件下,光照强度是影响玉米群体光合速率的主导因素,最大自然光强下群体光合未测到光饱和点。群体光合速率随CO2浓度(50—900ppm范围)的增加而提高。土壤呼吸释放的CO2量占群体光合速率的11.68%。高产群体所形成的独特环境对单叶光合速率影响很大,群体生长下的单株,在8×104一9×104Lx光下的单叶光合速率为果穗叶高于下部和上部叶,品种、密度间差异不大;冠层自然状态下的单位叶面积光合速率上部叶却高于中、下部叶,高密度下,紧凑型品种高于平展型品种,低密度下则相反。     

冬小麦节水栽培群体“穗叶比”及其与产量和水分利用的关系

建立高光效低耗水的群体结构是小麦节水高产栽培的核心内容。为此,需要明确节水高产群体的适宜调控指标。以穗叶比(单位面积穗数与上三叶总面积之比,穗/m2)为指标,在不同品种、不同灌水和种植密度条件下研究了小麦群体穗叶比的变化,并分析了穗叶比与群体光合性能、水分利用的关系。结果表明,在相同密度下,随着灌水减少,孕穗、开花和灌浆期的穗叶比均相应增大;在限水灌溉下,随密度增加穗叶比也相应增加。不同品种的穗叶比也存在明显差异。在适宜叶面积基础上,随穗叶比增加,群体中非叶面积指数(NAI)增加,冠层内光照状况明显改善,群体光合效率提高;非叶器官贮藏物质转移率增加,收获指数提高。在一定范围内,随穗叶比增加产量明显增加,而耗水量显著减少,从而使水分利用效率得到提高。研究认为,群体穗/叶比是衡量小麦节水栽培库源关系是否协调的适宜指标。试验中小麦节水省肥高产栽培适宜的穗叶比值为230—270穗/m2。     

青海柴达木盆地气候生态资源特点和农业开发

柴达木盆地位于青海高原西北部,面积为2.5×10~5km~2,海拔3000m,周围山系海拔5400—6000m,较毗邻新疆塔里木盆地高2000m 左右,为我国海拔最高的内陆高原盆地。有可利用草场约6.67×10~6ha。耕地约6.0×10~4ha,作物主要为春小麦,分布于东南和东北部荒漠绿     

论吉林省中部玉米带的气候生态适应性

玉米是吉林省的主要作物之一,其产量占全省粮食总产量的60%以上,产值占全省农业总产值的1/3以上。吉林省中部地区13个县是玉米的主要产区,总耕地面积2.267×10~6ha,占全省的56%,1985年中部玉米面积1.0×10~6ha,占中部耕地面积的44%,占全省玉米面积     

竹叶眼子菜(POTAMOGETON MALAIANUS MIQ.)叶面积测定及与栽培密度的关系初探

通过人为控制种群密度的栽培实验 ,用叶特征度量估测单叶叶面积 ( AL)、用茎特征度量估测整株叶面积 ( AS) ,分析不同栽培密度对叶面积测定的影响。结果表明 :( 1 )叶长×叶宽 ( L× W)与单叶叶面积相关性最大 ;茎长×茎上叶片数 ( LS× NL)测定整株叶面积较为适宜。 ( 2 )随着栽培密度增大 ,叶片相对变长变窄 ,比叶面积则增加 ,平均整株叶面积相应减小。( 3)不同的栽培密度对叶片形状有明显影响 ,反映在不同密度处理条件下叶片的几何拟合图形不同。     

不同群体结构夏玉米灌浆期光合特征和产量变化

大田试验以夏玉米为试料,采用裂裂区试验设计,密度设计包含75000、90000\,105000株/hm² 3个密度作为主区,每个密度处理包括: ①等行距60 cm×单株留苗,②等行距60 cm×双株三角留苗,③宽窄行距(宽行70 cm + 窄行距50 cm)×单株留苗和 ④宽窄行距×双株三角留苗共12种方式进行处理,测定光合及叶绿素荧光参数。研究不同群体结构对夏玉米灌浆期群体光合特性的影响。结果表明,在吐丝期,随着种植密度的增加,群体光合速率提高;蜡熟期以90000株/hm²最高,种植方式上表现为宽窄行大于等行距种植,双株留苗种植方式大于单株种植方式,差异均达到显著水平;随着种植密度的提高,群体内3个层次叶片最大光能转换效率(Fv/Fm)、光化学猝灭系数(qP)逐渐降低,种植方式基本表现为宽窄行大于等行距,留苗方式表现为双株大于单株。试验条件下,以90000株/hm²,宽窄行,双株三角留苗产量最高。     

充分利用福建滨海沙滩植被资源发展种植业

福建滨海沙滩位于北纬23°37′—27°10′范围,面积约5.33×10~4ha,已植防护林近2.0×10~4ha,尚约有3.34×10~4ha 未开发利用,其中分布于闽江口以南岸段和岛屿约2.86×10~4ha,     

种植密度对川中丘区夏玉米冠层结构、干物质积累及产量的影响

通过设置4.50×104、5.25×104、6.00×104、6.75×104、7.50×104株·hm~(-2)(分别用T1、T2、T3、T4、T5表示)5个密度,研究种植密度对玉米冠层结构、干物质积累及产量的影响,为川中丘区夏玉米高产栽培提供理论依据和技术支撑。结果表明:随种植密度增加,玉米叶面积指数显著增加,茎粗、茎叶夹角和透光率显著降低;密度每增加1×104株·hm~(-2),茎粗分别降低1.4 mm(2015年)和1.3 mm(2016年),穗下、穗上第1叶夹角分别降低3.601°、1.440°,吐丝期和灌浆中期底层透光率分别降低3.73%和2.82%;玉米单株干物质积累随种植密度增加显著降低,T5较T1在成熟期分别降低37.13%(2015年)、25.95%(2016年);而群体干物质随种植密度呈增加趋势,2016年T5较T1在吐丝后7天、成熟期分别增加了26.72%、23.41%;玉米产量随种植密度呈先增后降的变化趋势,在密度为6.00×104株·hm~(-2)下产量最高;该密度下玉米群体和个体功能达到协同增益,玉米产量构成(有效穗数、穗粒数和千粒重)协调,是产量提高的主要原因。     

紧凑大穗型玉米品种陕单902群体源库性状与产量形成的研究

通过对紧凑大穗型玉米品种陕单902的研究发现,保证适宜种植密度,增加群体总粒数是陕单902高产的基础;建立合理的群全结构和干物质生产体系,提高吐丝至成熟期的干物质生产能力是陕单902高产的关键;协调群体库源关系,提高成粒率是陕单902高产的根本。采用合理密植（不超过60000株／hm^2),宽窄行和双株栽培,保证足量氮肥和适宜氮,磷,钾配比等主要配套技术可改善大穗型玉米品种陕单902的群体库源性状,提高产量潜和。     

池塘饲养鱼类优化结构及其增产原理 Ⅲ.池养草鱼适宜生长的食物结构及其需求量

在实验室以浮萍和苏丹草为青饲料,颗-1(蛋白质17％)和颗-2(蛋白质25％)为精饲料进行交叉梯度试验,用特定生长率、饲料总生长效率、蛋白质效率等作为评价指标,试验结果表明:草鱼种所需青饲料与颗-1、颗-2的适宜比例范围分别为20—50,1和15—30:1。根据上述试验结果,兼顾草鱼在不同季节的营养需求和控制池塘水质,调整各阶段青、精饲料的投喂量,于1987—1989年进行了池塘对比饲养试验,结果表明,青、精饲料的平均投喂量分别为11.25×10~4—12.00×10~4kg/ha和11.25×10~3—12.00×10~3kg/ha,试验池草鱼生长率、总体鱼增重量分别为常规池的1.4和1.5倍。     

Discontinuous expansion linked to sector formation in Pseudomonas aeruginosa colonies

Colonies of Pseudomonas aeruginosa exhibit sectors that were shown to be located at specific intervals within the colony. Maxima in the distribution of sectors were observed every 5 mm as measured from the center of the colony. These maxima correlated with changes in the expansion rates of colonies. The absolute average number of sectors per colony was higher for colonies grown at higher temperatures. These results increase our understanding of colony pattern formation. Received: 2 February 1999 / Accepted: 7 April 1999     

Effects of growth temperature and winter duration on leaf phenology of Erythronium japonicum,a forest spring geophyte

The effects of growth temperature and winter duration on the leaf phenology of Erythronium japonicum were examined in two experiments. Bulbs wintered in the field were cultivated at 10 and 20° C and the bulbs were cultivated at 15° C after chilling treatment at 3° C for 60 and 120 days and without chilling in winter. The plants cultivated at 20° C showed significantly earlier leaf emergence, a more rapid rate of leaf extension and shorter leaf longevity than those cultivated at 10° C. The decrease in the leaf longevity at 20° C resulted from the decreases in the durations of all of the developmental, mature, and senescent phases. The bulbs without chilling treatment did not sprout leaves and those with chilling treatment sprouted leaves. The increase in the length of chilling treatment from 60 to 120 days affected leaf phenology in same manner as the increase in the growth temperature from 10 to 20° C.     

Non-destructively predicting leaf area,leaf mass and specific leaf area based on a linear mixed-effect model for broadleaf species

Based on a linear mixed-effect model, we propose here a non-destructive, rapid and reliable way for estimating leaf area, leaf mass and specific leaf area (SLA) at leaf scale for broadleaf species. For the construction of the model, the product of leaf length by width (LW) was the optimum variable to predict the leaf area of five deciduous broadleaf species in northeast China. In contrast, for species with leaf thickness (T) lower than 0.10 mm, the surface metric of a leaf (e.g., LW or width) was more suitable for predicting leaf mass; and for species with leaf thickness larger than 0.10 mm, the volume metric of a leaf (e.g., the product of length, width and thickness together, LWT) was a better predictor. The linear mixed-effect model was reasonable and accurate in predicting the leaf area and leaf mass of leaves in different seasons and positions within the canopy. The mean MAE% (mean absolute error percent) values were 6.9% (with a scope of 4.1–13.0%) for leaf area and 13.8% (9.9–20.7%) for leaf mass for the five broadleaf species. Furthermore, these models can also be used to effectively estimate SLA at leaf scale, with a mean MAE% value of 11.9% (8.2–14.1%) for the five broadleaf species. We also propose that for the SLA estimation of the five broadleaf species examined, the optimum number of sample leaves necessary for good accuracy and reasonable error was 40–60. The use of the provided method would enable researchers or managers to rapidly and effectively detect the seasonal dynamic of leaf traits (e.g., leaf area, leaf mass or SLA) of the same sample leaves in the future.     

从水力结构的角度解释生长温度对烟草叶片形状和大小的影响（英文）

叶片形状和大小在不同的生长温度下变化非常大,但少有从水力结构的角度解释其变化原因的研究。本研究测定了生长于两个不同温度下(24℃/18℃昼/夜;32℃/26℃昼/夜)的烟草叶片的解剖结构,导水率,叶片长宽比和叶面积。生长在24℃/18℃下的烟草叶片与生长在32℃/18℃的叶片相比,更狭窄,并有更小的叶柄导管直径,更低的叶脉密度和导水率。然而,在不同的生长温度下,烟草叶面积并没有显著差异。叶片导水率与叶脉密度呈正相关,但与叶片长宽比呈负相关。结果表明在不同的生长温度下叶片解剖结构和叶片导水率可能对于改变叶宽比起着重要作用。     

不同温度对黑翅土白蚁初建群体的影响

黑翅土白蚁Odontotermes formosanus(Shiraki)是经济害虫之一,它常筑巢于水库和河堤的土质内危害堤坝,引起渗漏,甚至酿成塌堤垮坝,造成人民生命则产的严重损失。 外界环境温度对巢位深、巢体结构复杂、调节温湿度能力强的黑翅土白蚁成年巢群影响较小,但对入土筑巢位置浅、巢体结构简单的黑翅土白蚁初建巢群的生长、发育、繁殖、巢内白蚁个体数量变动等则影响较大。到目前止,国内外这方面的研究不多。本试验研究不同温度条件对黑翅土白蚁初建群体生长、发育、繁殖等方面的影响,这对深入了解其初建群体的生长发育规律及其初建巢群的控制方面有一定意义。     

南京地区落叶栎林主要木本植物的展叶动态研究

 植物的展叶过程是由自身遗传因子决定的,同时又受到多种生态因子的调节,反映了植物的生活史对策和群落物种多样性的维持机制。在2001和2002年的3～6月间,不定期记录了南京地区三个落叶栎(Quercus spp.)林中主要木本植物的展叶情况,包括被标记标准枝的叶数、叶的长度、宽度、叶面积、叶干重等参数。结果表明在所调查的落叶栎林中,林冠层物种的成熟叶面积和单位叶面积干重都显著大于林下层物种;最早展叶的物种为林下层物种,但林冠层展叶顺序与林下层无显著差异。叶面积越大、单位叶面积干重越小的物种展叶越晚;林冠层物种展叶较林下层快,物种成熟叶面积越大,展叶速率越大。最后对展叶顺序和展叶速度的生态学意义作了讨论。     

利用叶色特征监测小麦叶片的碳氮状况

研究了不同土壤水氮条件下小麦 (Triticumaestivum) 抽穗后叶片碳氮状况及其比例与叶片叶色 (SPAD值 ) 的关系。结果表明, 小麦中后期叶片氮含量和可溶性糖含量与顶部 3张叶片叶色 (SPAD值 ) 均呈显著的指数正相关, 其相关程度大小为L1>L2 >L3, 但与不同叶位叶色间的差值或比值相关并不显著 ;而叶片碳氮比与各叶位叶色相关不显著, 但与顶 1叶和顶 3叶的叶色差值呈极显著直线相关, 据此建立了基于叶色特征的叶片氮含量、可溶性糖含量和碳氮比监测模型, 检验结果显示, 顶 1叶叶色和顶 1叶与顶 3叶叶色的差值可用来有效地评估小麦叶片的碳、氮含量及碳氮比状况。     

Leaf dynamics and shoot phenology of eleven warm-temperate evergreen broad-leaved trees near their northern limit in central Japan

Dynamic features of shoot phenology including leaf emergence and leaf fall, and leaf life span for eleven evergreen broad-leaved tree species were investigated in a warm-temperate rain forest in Mount Kiyosumi, central Japan. All species had periodic leaf emergence or flushing pattern, and were classified into two types; single and multiple flush and only one species, Eurya japonica, represented the latter type and the rest had single flush in spring. The single flush type can further be subdivided into two groups according to their duration of shoot growth; short and long flush. Seasonal patterns of leaf fall were categorized into four; unimodal, bimodal, broad unimodal, and multimodal type though they were not fixed pattern. The leaf emergence and leaf fall patterns were correlated for the eleven species, and five phenological types were categorized. Four of them were the single flush types, i.e., short flush of leaf emergence with unimodal leaffall (SSU) type of Castanopsis sieboldii and Quercus salicina, short flush with bimodal leaf fall (SSB) type of Quercus acuta, Machilus thunbergii, Neolitsea sericea, and Cinnamomum japonicum, long flush with bimodal leaffall (SLB) type of Myrsine seguinii, and long flush with broad unimodal leaffall (SLR) type of Symplocos prunifolia, Cleyera japonica, and Illicium anisatum. The multiple flush type is only one species, Eurya japonica, and it had multimodal leaffall pattern (MM type). The phenological pattern varied in relation to leaf life span, leaf size, and tree habit. Leaf life span ranged from 1.1 to 5.8 yr. The short flush species or SSU and SSB types were all canopy or subcanopy trees, and the former had short and the latter had long leaf life spans. The long flush species were all microphyllous small trees, and SLB type had a relatively long leaf life span in understory, SLR type had a long leaf life span in understory or in open habitat and/or forest gap as a pioneer tree. MM type had a long leaf life span and colonizing species in open habitat but they can survive in understory as well. The phenological attributes of evergreen trees were well corresponded to the ecological guild of the tree in both forest structure and successional stage, and were also constrained by phylogenetic groups.