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1.
为探究小麦叶面积指数(LAI)的空间分布及与不同光质透光率间的关系,通过三年田间试验,设置不同品种、氮肥水平和灌水次数,测定分析了小麦拔节期至灌浆后期冠层不同空间层次的透射光及叶面积指数(LAI),并对不同光质透光率与LAI间进行回归分析。结果表明,小麦LAI随生育时期的推进呈单峰动态变化,最高值出现在抽穗-开花期,且随灌水和施氮水平的增加而增大;光合有效辐射(PAR)透光率随生育时期呈先降后升趋势,且随灌水和施氮水平的增加而减小。LAI与PAR透光率均存在时空异质性,叶面积的垂直分布直接影响冠层内光分布。水氮处理对植株上层LAI影响较小,而对下层影响较大;40 cm处透光率递变明显,低水高氮以及高水低氮处理对透光率递减的影响较大。不同光质透光率均随冠层高度的下降均出现不同程度消减,透光率与向下累积LAI间均呈显著指数相关,相关性由强到弱依次为红边、蓝光、光合有效辐射(PAR)、绿光、近红外和红光。经回归分析,红边和蓝光透光率与LAI的定量关系表现较好,拟合性均优于PAR,尤其是红边透光率(R2=0.749),因此可以利用红边透光率建立模型,以监测小麦冠层LAI。 相似文献
2.
An experiment was carried out in which simulated swards of ryegrass (cv. S23) were grown in boxes. In the first instance the swards were cut at weekly intervals to maintain five levels of leaf area index (LAI) from LAI 1 to 4–5 in simulation of continuous grazing. Measurements were made of growth, senescence and net growth rate and of net canopy photosynthesis at constant irradiance. The results showed that the swards adapted to the defoliation regimes mainly by changes in tiller population density and pseudostem length. When the swards had equilibrated to the cutting regime growth rate increased with LAI but, since tiller density and the partitioning of growth between herbage harvested and that lost by sensecence also changed with LAI, net growth rate was constant over the LAI range 2–4·5. Maximum weight of herbage harvested was obtained between LAI 2 and 3.
After 10 weeks of weekly cutting all the swards were cut back to LAI 1 and allowed to regrow. Growth rate showed almost no response to the previous culling treatments. The relationship of net canopy photosynthesis to LAI was linear for the frequently defoliated swards and curvilinear for regrowing swards. The reasons for this difference were examined. 相似文献
After 10 weeks of weekly cutting all the swards were cut back to LAI 1 and allowed to regrow. Growth rate showed almost no response to the previous culling treatments. The relationship of net canopy photosynthesis to LAI was linear for the frequently defoliated swards and curvilinear for regrowing swards. The reasons for this difference were examined. 相似文献
3.
杂种稻的光合适应性及光合生产力研究 总被引：12，自引：1，他引：12
用不同光强生态型水稻品种Lemont和七桂早，利用化学杂交剂配制得杂种稻Le／七。对Le／七及其亲本在人工气候箱中高、低光强条件下处理30 d，每10 d作一次光合测定及生长分析。量子产量和单叶净光合速率的测定结果表明：Le／七对高、低光强的适应范围比双亲有所扩大，尤其是在高光强下量子产量相对降低值Le／七比七桂早明显为低。处理期间杂种Le／七比七桂早明显为低。处理期间杂种Le／七的光合生产力(以作物生长率CGR表示)和生物学产量增加值在高、低光强条件下均明显超过了其父本广东当地优良品种七桂早，其CGR和生物学产量高的主要原因是其叶面积指数(LAI)、净同化率(NAR)由于杂种优势比七桂早明显为高。 相似文献
4.
Two growth experiments were carried out in January-March 1978 in which simulated swards of perennial ryegrass were (1) heated by soil warming cables to give soil surface temperatures of approx. 7·5-9·C above ambient temperature, (2) shaded with netting to reduce light levels by approx. 50%, or (3) both heated and shaded.
Heating alone increased leaf appearance, death, extension, lamina size, leaf area index (LAI), tillering (month 1)and whole plant weight (month 2) and reduced stubble water-soluble carbohydrates and specific leaf weight (SLW).
Shading alone increased leaf extension, lamina size and LAI but to a lesser extent than did heating. Shading decreased SLW, leaf death rate, tillering (month 2), stubble carbohydrates and whole plant weight, but not herbage weight.
The effects of heating plus shading were similar to those of heating alone, except that the increases in leaf size, extension and LAI were even greater, and shoot bases and roots had low or negative growth rates.
In general the heating treatments caused a rapid turnover of leaf material, but net herbage growth was relatively insensitive. It is concluded that (1) temperature rather than light was limiting whole plant growth, especially from mid-February to mid-March and (2) mild, dull weather in winter is likely to induce tiller death associated with reduced investment in carbohydrate reserves. 相似文献
Heating alone increased leaf appearance, death, extension, lamina size, leaf area index (LAI), tillering (month 1)and whole plant weight (month 2) and reduced stubble water-soluble carbohydrates and specific leaf weight (SLW).
Shading alone increased leaf extension, lamina size and LAI but to a lesser extent than did heating. Shading decreased SLW, leaf death rate, tillering (month 2), stubble carbohydrates and whole plant weight, but not herbage weight.
The effects of heating plus shading were similar to those of heating alone, except that the increases in leaf size, extension and LAI were even greater, and shoot bases and roots had low or negative growth rates.
In general the heating treatments caused a rapid turnover of leaf material, but net herbage growth was relatively insensitive. It is concluded that (1) temperature rather than light was limiting whole plant growth, especially from mid-February to mid-March and (2) mild, dull weather in winter is likely to induce tiller death associated with reduced investment in carbohydrate reserves. 相似文献
5.
The relationship between net canopy photosynthesis (Pnc) measured at 400 J m−2 s-1 and leaf area index (LAI) was determined on ryegrass-dominant swards over a range of her bage masses in five grazing experiments. In three experiments the swards were continuously stocked either by sheep or by cattle to maintain a number of herbage heights and hence LAI values. In two experiments the swards were intermittently grazed with 21 -d regrowth intervals. On the continuously stocked swards measurements were made over nine periods each of 7 to 21 d in length. On the intermittently grazed swards measurements were made over six periods while the herbage was being grazed down from a high to a low LAI and over three periods during the regrowth phase.
On all the swards where measurements were made while grazing was in progress, the relation of Pnc to LAI was linear. The photosynthetic rate was greater on the continuously grazed than on the intermittently grazed swards up to LAI 35 and in two experiments to LAI 5. The relationship of Pnc to LAI of swards in the regrowth phase was predominantly curvilinear and such that over much of the LAI range they had a greater photosynthetic potential than the same swards being grazed down from high to low mass. Daily rates of CO2 uptake and growth in the field were calculated for one continuously stocked experiment. Both were linearly related to LAI in the range LAI 2–4·5. The agronomic implications of the results are discussed. 相似文献
On all the swards where measurements were made while grazing was in progress, the relation of Pnc to LAI was linear. The photosynthetic rate was greater on the continuously grazed than on the intermittently grazed swards up to LAI 35 and in two experiments to LAI 5. The relationship of Pnc to LAI of swards in the regrowth phase was predominantly curvilinear and such that over much of the LAI range they had a greater photosynthetic potential than the same swards being grazed down from high to low mass. Daily rates of CO
6.
《Plant Production Science》2013,16(2):209-217
AbstractThe growth and seed yields of 2 Japanese and 3 Chinese cultivars of soybeans cultivated in 2002-2005 using a drip irrigation system in the arid area of Xinjiang, China, were analyzed with respect to growth parameters and air temperature. Seed yield was very high in 2002, 2003 and 2004, but relatively low in 2005. The variation among years in seed yield clearly depended on pod number. The mean leaf area index (LAI) and crop growth rate (CGR) in 2005 was lower than those in the other 3 years. CGR showed significant positive correlations with mean LAI at the early growing stages, and with net assimilation rate (NAR) at the later growing stages. The increasing rate of pod number (IRP) was positively correlated with the mean LAI and CGR at the pod setting period, suggesting that an adequate supply of photosynthates would be required for pod setting. It was concluded that excellent growth in the years with high yields was supported by the large LAI before the pod setting periods and by high NAR and vigorous pod growth at the latter half of the growing season. 相似文献
7.
Leaf area index (LAI) is one of the major determinants of crop photosynthesis. The objectives of this study were to clarify the relationship between LAI development and crop growth in diverse rice genotypes grown under widely different climate conditions and to develop a model explaining genotypic and environmental variation in LAI dynamics based on environmental and plant factors. Cross-locational experiments were conducted with nine different rice genotypes at eight locations in Asia covering a wide climate range under irrigated conditions with sufficient nitrogen application. The LAI observed at the heading stage ranged from 0.85 to 8.77 among the genotypes grown at the eight locations. A fairly stable allometric relationship was observed between LAI development and above-ground biomass growth during the period from transplanting to 2 weeks before heading over all the genotypes, sites and years (r = 0.91). The allometric relationship was, however, under the influence of leaf nitrogen content per unit leaf area (LNC, g m−2 leaf) and air temperature. On the basis of these results, we modeled the LAI development as a function of relative crop growth rate (RGR), LNC and air temperature. The rate of LAI decrease associated with leaf senescence was also described as a function of LNC. 相似文献
8.
超高产条件下玉米产量及冠层结构 总被引：1，自引：0，他引：1
2011~2012年,选用郑单958为供试材料,以传统栽培模式为对照(CK),研究超高产栽培条件下春玉米的冠层结构。结果表明,超高产条件下春玉米产量及有效穗数均显著高于对照;玉米在超高产栽培条件下,其群体叶面积指数(LAI)均高于传统栽培模式(CK),且LAI最大值的持续天数比CK长。棒三叶及棒三叶以上叶增加幅度明显,与CK均达到显著水平;超高产栽培条件下玉米叶倾角明显小于CK,叶向值增大,群体受光态势较好。叶片光合速率(Pn)均随生育时期的推移而不断降低,在全生育期超高产栽培条件均高于CK,并且在大喇叭口期差异显著;整个生育时期超高产栽培条件的光合势均高于CK。超高产栽培LAI持续天数长,叶倾角小,叶向值大,进而改善玉米群体受光态势,提高叶片光合能力,具有高光效的冠层结构。 相似文献
9.
Tillering and leaf area index in grasses in the vegetative phase 总被引：3，自引：0，他引：3
The relationship between tillering of a vegetative grass stand and Leaf Area Index (LAI) has been studied during sward establishment of perennial ryegrass and Italian ryegrass with different seedling densities and nitrogen fertilizer rates and on established swards of tall fescue during winter and early spring after different dates of last cut in autumn.
The different experiments on different species led to the conclusion that in every instance the tillering rate slows down as soon as the LAI reaches a value of 3 and terminates rapidly at higher LAI, which corresponds with the almost complete extinction of light at the level of the tiller buds. The results confirm the direct role of light on morphogenesis previously demonstrated by several authors. The existence of such a limit of LAI helps to explain some contradictory effects of temperature or nitrogen on tillering. 相似文献
The different experiments on different species led to the conclusion that in every instance the tillering rate slows down as soon as the LAI reaches a value of 3 and terminates rapidly at higher LAI, which corresponds with the almost complete extinction of light at the level of the tiller buds. The results confirm the direct role of light on morphogenesis previously demonstrated by several authors. The existence of such a limit of LAI helps to explain some contradictory effects of temperature or nitrogen on tillering. 相似文献
10.
Because an outgrowth of auxiliary bud in plant is regulated by light quality detected by phytochrome, branching differences in various environment or cultivars in soybean would be the results of the responses to light environment. Therefore, we analyzed differences in the number of branches of two determinate soybean cultivars, ‘Hatsusayaka’ and ‘Sachiyutaka’, between low and high planting densities in relation to light quality within the canopy. We compared changes in the ratio of red to far red (R:FR) irradiance at the ground level over time and with canopy height with those in the fraction of intercepted photosynthetically active radiation (FIPAR) and leaf area index (LAI). Regardless of time or distance from the top of the canopy, the changes in R:FR were sigmoidal, and were symmetrical with those of FIPAR and LAI. The effects of density and cultivar on FIPAR, LAI, and R:FR could be modeled with a logistic function. The number of branches was greater at low density than at high density, and in Hatsusayaka than in Sachiyutaka. However, there were no notable differences in the dynamics of R:FR between planting densities or between cultivars. Close relationships between parameters of the dynamics of the changes in R:FR and of those in FIPAR and LAI suggest that FIPAR and LAI are major factors that regulate R:FR, regardless of time or canopy depth. We found no evidence of a causal relationship between the dynamics of R:FR within the canopy over time or with canopy depth and number of branches of either cultivar. 相似文献
11.
Ting-ting Xie Pei-xi Su Li-zhe An Li-shan Shan Zi-juan Zhou Zhong-ping Chai 《Plant Production Science》2016,19(1):165-172
Cotton produces more biomass and economic yield when cluster planting pattern (three plants per hole) than in a traditional planting pattern (one plant per hole), even at similar plant densities, indicating that individual plant growth is promoted by cluster planting. The causal factors for this improved growth induced by cluster planting pattern, the light interception, canopy microclimate and photosynthetic rate of cotton were investigated in an arid region of China. The results indicated that the leaf area index and light interception were higher in cluster planting, and significantly different from those in traditional planting during the middle and late growth stages. Cotton canopy humidity at different growth stages was increased but canopy temperatures were reduced by cluster planting. In the later growth stage of cluster planting, the leaf chlorophyll content was higher and the leaf net photosynthetic rate and canopy photosynthetic rate were significantly increased in comparing with traditional planting pattern. We concluded that differences in canopy light interception and photosynthetic rate were the primary factors responsible for increased biomass production and economic yield in cluster planting compared with the traditional planting of cotton. 相似文献
12.
Net photosynthesis per unit area of ground surface was determined at saturating light energy levels in Dactylis glonwrata swards over a wide range of leaf area indices (LAI). The relationship between net photosynthesis and LAI was influenced by the particular defoliation regime to which the sward was subjected. In most instances net photosynthesis and LAI were linearly related, with defoliation regime influencing both the slope and intercept of the regression. However, a defoliation regime which left leaves below 3 inches (7.5 cm) resulted in a curvilinear relation. The net photosynthesis-LAI relationships were compared with the DM production of the swards on which they were obtained. Differences in these relationships did not entirely explain the differences in sward yield. The significance of these findings is discussed with reference to the theories of light interception and pasture growth. 相似文献
13.
Much of the yield variation in soybean (Glycine max L. Merrill) crops is related to changes in pod and seed number. Pod number is the result of pod initiation and pod abscission while seed number is the result of potential seed per pod and seed abortion. However, the physiological regulation of these processes is not well understood. A field experiment was conducted to investigate the role of post-flowering changes in source size and canopy structure on pod initiation, pod abscission and seed abortion in soybean. Two soybean genotypes: DM48 and A7409 (maturity groups IV and VII, respectively) were used. Leaflet removal treatments (L) consisted of removing none (L0), one (L1) or two (L2) lateral leaflets of every developed trifoliate leaf present. Leaflet removals were applied twice: the first at full bloom and the second shortly after the beginning seed stage. Crop growth rate (CGR), leaf area index (LAI), light interception (LI), and relative leaf growth rate, were determined during the periods in which numerical components are established. For the period between the first and the second leaflet removal, CGR remained unchanged among L treatments in both genotypes because LAI reductions were compensated through an increase in the net assimilation rate of the remaining leaves. The first leaflet removal increased the relative leaf growth rate and the number of pods initiated (PI) and these increases were inversely related to the remaining LAI in both genotypes. Moreover, the inverse relationship between LAI and PI was sustained at LAI below and above critical (i.e., LAI for 95% LI) and was not related to CGR or LI. The number of pod abscised also increased with the level of leaflet removal during the first and main abscission period in both genotypes and the percentage of pod abscission was directly related to the seed growth rate per unit leaf area during the abscission period. Seed abortion was inversely related to LAI after the second leaflet removal. Only the highest level of leaflet removals (i.e., L2) was able to reduce seed size in both genotypes. Whereas pod abscission, seed abortion and seed size could be related to indicators of canopy assimilatory capability pod initiation was not, suggesting that other physiological mechanism/s operate in the regulation of pod initiation. In addition, our results suggest that early (i.e., at flowering) canopy closure may negatively impact pod initiation in soybean. To the best of our knowledge, this study is the first to document that the number of initiated pods is inversely related to LAI in soybean canopies. 相似文献
14.
大豆“两垄一沟”栽培法冠层中光分布特点的研究 总被引：2，自引：0，他引：2
本文于大豆鼓粒期（Ｒ５）晴天条件下,对“两垄一沟“栽培法冠层内叶面积指数,光照强度,干物质积累的垂直分布特点进行了研究。结果表明,该栽培法整个冠层叶面积指数大。从冠层内空间分布看,叶面积指数最大值出现的植株部位高度比７０ｃｍ大垄和５０ｃｍ窄行科播低,中部的光照强度高。但冠层内消光系数小。说明“两垄一沟”栽培法改善了冠层中的光照条件,提高了光能的截获率,积累了更多的干物质。 相似文献
15.
不同密度春玉米叶面积系数动态特征及其对产量的影响 总被引：15，自引：5，他引：15
研究了两个品种吉单209(JD209)、郑单958(ZD958)不同密度群体各生育期LAI动态变化特征,并分析了主要动态特征参数与产量及产量构成的关系,探讨春玉米高密度高产群体叶面积系数(Leafarea index,LAI)动态变化特征对产量的效应。结果表明:各密度群体LAI动态变化呈单峰曲线趋势,随密度增加峰值增大,相同密度下ZD958群体LAI大于JD209,表现较强的耐密性。两个品种高产的适宜密度范围是6万～9万株/hm2,群体的最大LAI在5～7;各生育期的群体LAI与密度呈显著线性正相关,其中抽雄吐丝期LAI对密度的增长率最大,分别为0.583和0.679;灌浆期群体LAI对产量的影响最大,表明此时期是产量形成的关键期。大喇叭口期LAI对穗数、穗粒数影响最大。密度是通过调控群体的LAI和穗数来影响产量构成和最终产量。 相似文献
16.
不同时期干旱和干旱程度对夏玉米生长发育及耗水特性的影响 总被引：6，自引：3，他引：3
通过防雨棚下测坑试验,研究不同生育期干旱,设轻度干旱和重度干旱对夏玉米生长状况、耗水规律、产量以及水分利用效率的影响。结果表明,不同生育期干旱均会抑制植株株高和叶面积指数增长,受旱越重,株高和叶面积指数越小。适宜水分处理的植株株高与叶面积长势优于其他处理;与适宜水分处理相比,随着干旱时期的后移,产量呈先降后升的趋势,其中,苗期轻度干旱的处理减产最少,为9.88%,抽雄期重度干旱穗粒数最少,为349.98粒,减产最多,达32.67%;夏玉米拔节期重度干旱处理的耗水量最低,为258.09 mm,任何生育阶段受旱,其日耗水量随着干旱程度的加重而降低。对各处理产量和耗水量进行分析,两者呈良好的二次曲线关系,拔节期轻度干旱处理的水分利用效率(WUE)最高,为2.202 kg/m3,其次是苗期重度干旱的处理,后期干旱处理由于减产幅度超过节水的幅度,WUE降低。通过对各处理的产量和WUE综合分析,确定了夏玉米节水高产的灌溉控制指标。 相似文献
17.
优质丰产杂交籼稻品种机直播产量构成及其群体质量研究 总被引：6，自引：2，他引：4
【目的】本研究旨在明确适宜平原(崇州)与丘陵(三台)稻区机直播优质杂交籼稻高产品种群体质量的共性特征,构建规范化的机直播优质杂交籼稻高产品种的鉴选方法和评价标准,以及为杂交籼稻机械化直播配套技术的融合提供理论及实践依据。【方法】两生态区以29个品种为试材,采用人工模拟精量穴直播(以下简称机直播),研究机直播对平原与丘陵稻区不同产量水平的优质杂交籼稻群体质量特征及产量的影响,并探讨机直播优质杂交籼稻群体质量特征与产量间的关系。【结果】依据两生态区各品种的平均籽粒产量聚类分析,将两生态区供试品种分为高产、中产、低产3种类型。其中,三台高产类型品种占17.24%,中产、低产类型品种占82.76%;崇州高产类型品种占10.34%,中产、低产类型品种占89.66%。与中产、低产类型品种相比,两生态区高产类型品种的共性特征为分蘖能力强、有效穗数多、结实率高,拔节期后叶面积指数(LAI)大,干物质累积量高;结实期顶3叶叶长、叶位、叶张角、株高及其顶部截获光能优势明显。相关分析表明,机直播条件下,除群体透光率、顶3叶叶张角、分蘖盛期LAI及干物质累积量外,各群体质量指标与籽粒产量均呈显著或极显著正相关(r =0.37*~0.90**),尤其是齐穗期高效LAI率、成熟期干物质累积量及其收获指数与产量的相关性。【结论】机直播条件下,高产类型品种能够获得较高的有效穗数和每穗实粒数,并协同提高结实率,实现生育后期群体干物质的高增长,从而获得较高产量。 相似文献
18.
19.
Photosynthetic potential of ryegrass pastures when released from continuous stocking management 总被引：1，自引：0，他引：1
The relationship between the rate of canopy gross photosynthesis and LAI was investigated for ryegrass swards released from grazing after a period of continuous stocking to maintain the pasture at LAI 2–3. The regrowing swards were allowed to increase to about LAI 5 over a period of about 2 weeks while the rate of photosynthesis was measured and compared with that for continuously stocked swards maintained at LAI values between 2 and 6. Gross photosynthesis was found to increase more rapidly than LAI on the regrowing swards than on the steady-state control pastures. However, this response appeared to be influenced by seasonal factors. The potential increase in net COi uptake was estimated to range from 0 to 22%. The response was attributed to an increasing proportion of young photosynthetically-efficient leaves near the top of the canopy, modified by seasonal changes in the rate of tillering. The agronomic implications of the results are iscussed. 相似文献
20.
The effect of defoliation interval on growth patterns of contrasting perennial ryegrass (Lolium perenne)–white clover (Trifolium repens) mixtures was studied. The dynamics of increase in leaf area, light interception and dry-matter (DM) production were measured within successive regrowth periods. No N fertilizer was applied. During 1995 six mixtures were cut eight (F1) or six times (F2) at a stubble height of 5 cm. The stubble composition was stable throughout the growing season: after harvest about 50 g DM m?2 (with a white clover proportion of 0·52) was present with a leaf area index (LAI) of 0·5 (0·38 white clover). The percentage of intercepted radiation after cutting was 20–30% and increased during 3 weeks to about 95%. The relative growth rate of leaf area and DM was higher for white clover than for perennial ryegrass, with the proportion of clover in the LAI and DM increasing during each regrowth period. Mixtures with large-leaved white clover cv. Alice had a lower initial clover content after harvest, but a more rapid increase in clover LAI and DM than mixtures with the smaller leaved cvs Gwenda or Retor. Alice had the highest total and clover LAI and DM at harvest. Cutting frequency affected the change in white clover–perennial ryegrass ratio during regrowth. This was significantly higher in mixtures with Alice than in mixtures with Gwenda, but only under less frequent cutting (F2). In spring there was a mean white clover proportion of about 0·55 in the LAI and 0·45 in the total harvested DM. In summer the white clover proportion in the LAI and DM increased to 0·70–0·75. There was a decline during autumn, especially in F2 and in the mixtures with the small-leaved white clover cv. Gwenda and the medium-leaved cv. Retor. In contrast, grass DM and LAI declined from spring to summer. The decline in clover LAI in autumn was similar in Alice and Gwenda at frequent cutting (F1), but stronger in Gwenda in F2. Retor had the lowest clover specific leaf area (SLA). The SLA values of Alice and Gwenda were similar, SLA being similar between cutting treatments. No differences were found for leaf weight ratio (LWR) among the three white clover cultivars or between the grass cultivars, and LWR was not affected by cutting treatment. Defoliation interval had limited effects on the growth pattern and leaf characteristics of perennial ryegrass–white clover mixtures. 相似文献