新疆石河子棉区高密条件下冠层结构和光分布特征

对新疆石河子5个棉花主栽品种全生育期的干物质积累、生长参数、产量和盛铃期的冠层结构、光渗透能力和光分布等进行了测量分析。结果表明,作物生长速率、铃生长率以及子棉产量等均与总受光量呈正相关关系,净同化率则与单位叶面积受光量呈正相关关系,说明受光量是决定干物质生产和产量的重要因素;单位叶面积受光量即光的渗透能力与单位土地面积总受光量呈正相关关系、而与LAI呈负相关关系,说明冠层结构也是影响冠层受光量的主要因素;总受光量与LAI呈显著的正相关关系,说明LAI最大值并未达到最适宜水平。新疆地区棉花高产棉田的主要特征可以总结为叶数少、叶片大、冠层结构为椭圆形。由于叶面积指数尚未达到最适宜水平,增加种植密度可能是提高产量的一个途径。     

淮河流域麦田湍流通量输送特征分析

利用淮河流域寿县国家气候观象台2007年11月至2008年5月的湍流通量观测资料,分析了该区域麦田湍流通量输送特征,结果表明：小麦各生育期净辐射通量、显热通量和潜热通量都存在明显的日变化;净辐射日变化最大值出现在成熟期;显热通量在中午温度最高时达到最大值,夜间显热通量多为负值;潜热通量峰值出现时间比净辐射通量峰值延迟1h左右;自拔节期开始,麦田潜热通量日平均值都大于50.0 ;三叶期和分蘖期,土壤热通量日平均值都为负值,其它时期为正值;H/Rn和LE/Rn均有明显的季节变化,且变化方向相反。     

亚热带稻田能量平衡闭合状况分析

通过采用线性回归,能量平衡比率和相对残差频率分布3种统计方法对涡度相关法通量观测的稻田能量平衡闭合状况进行了评价,并分析了能量平衡闭合程度的季节变化趋势。结果表明,在稻田生态系统中存在能量不闭合现象,年能量平衡比率为0.87,年平均不闭合程度为13%;能量平衡比率在5—8月份平均为0.85,能量不闭合程度较高;1—4月份和9—12月份平均为0.92,不闭合程度较低。在假定常规的有效能量测定正确的前提下,可以认为涡度相关测定的湍流通量可能被低估了     

参考作物蒸发蒸腾量计算简化方法

基于国家“863”节水农业重大专项子课题示范现场的气象资料，对参考作物蒸发蒸腾量及其影响因素进行了相关性分析。选取净辐射和空气饱和差建立了参考作物蒸发蒸腾量的简化计算公式，并引入风速函数进行修正。研究结果表明：参考作物蒸发蒸腾量与净辐射相关系数最大，然后依次是空气饱和差、日照时数和温度；且与净辐射和空气饱和差呈直线关系，与日照时数和温度呈指数关系，而与相对湿度呈负相关关系；考虑风速修正后的简化公式与标准方法（FAO56 Penman-Monteith）的计算结果有较高的一致性。     

设施滴灌条件下甜瓜茎流变化及其对环境因子的响应

设施甜瓜栽培已成为中国一个具有较大增长空间的重要产业。采用合理的灌溉方式和决策来提高甜瓜产量与品质显得尤为重要。为探明设施滴灌条件下甜瓜植株茎流速率变化规律及其影响因素,有效诊断植株水分指标,为制定灌溉策略提供理论依据,采用基于茎热平衡法的Dymaxax包裹式茎流计、小型自动气象站和TRIME-IPH土壤剖面水分测量仪等对温室内覆膜滴灌条件下甜瓜植株茎流速率变化及其周围环境影响因子进行长时间连续定点监测。研究结果表明：温室内甜瓜的茎流速率日变化曲线基本呈双峰曲线,多云及阴天甜瓜白天液流启动推迟,峰值减小15%~47%;晴天条件下温室内太阳辐射(Rs)、空气相对温度(Rh)滞后于茎流速率,阴天及多云条件下,辐射与茎流速率基本同步达到峰值,相对湿度在晴天中午辐射较高区间内的小幅提高会对茎流速率产生一定的拉低效应;温室内太阳辐射是甜瓜茎流变化的主要驱动因素,并建立了以太阳辐射(Rs)和空气相对湿度(Rh)为主要因子反映甜瓜茎流速率(F)变化的多元线性回归模型(F=26.204+0.0890Rs-0.2540Rh,R2=0.831,P<0.001),可对甜瓜蒸腾变化进行预测。     

Carbon assimilation,leaf area dynamics,and grain yield in contemporary earlier- and later-senescing maize hybrids

Maize breeding during the past 50 years has been associated with a delay of leaf senescence, but it is not clear whether this trait is likewise associated with higher grain yield in modern hybrids. Post-silking growth, leaf area dynamics, photosynthetic parameters and yield were compared in modern maize hybrids differing in canopy senescence rate. In the first two experiments, four hybrids were grown in the field at Balcarce, Argentina (37°45′ S, 58°18 W). In spite of differences in chlorophyll retention and photosynthesis of the ear leaf, post-silking growth and grain yield were very similar in all four hybrids while kernel N concentration was lower in the later-senescing hybrids. In a third experiment, a later-senescing (NK870) and an earlier-senescing (DK682) hybrid were grown to analyze the potential photosynthetic contribution of delayed leaf senescence. Leaf area and chlorophyll content were larger in NK870, especially at the lower canopy level (0.75 m above the ground). However, hybrids did not differ for canopy light interception. Because photosynthetic photon flux density below 1 m above the ground was less than 10% of incident radiation and photosynthesis quantum yield did not change during senescence, the potential photosynthetic output of lower leaves below 1 m was very low. Lower leaves of NK870 had N concentrations higher than those needed to sustain photosynthesis at the light conditions below 1 m. Therefore, we show that delayed senescence does not necessarily improve post-silking C accumulation because: (i) canopy light interception is not reduced by senescence except at very late stages of grain filling; (ii) contrasting hybrids show more pronounced senescence differences at canopy levels receiving less than 10% of incident radiation; (iii) delayed senescing hybrids present lower kernel N concentrations while extra N is retained in leaves exposed to a light limiting micro-environment. Delayed senescence at lower canopy levels may be unproductive, at least under non-stressing conditions.     

氮素对哈尼梯田水稻冠层温、光生态因子及稻瘟病的影响

为了研究氮素对云南哈尼梯田水稻冠层昼温、光合有效辐射截获率及稻瘟病的影响,探索水稻冠层光合有效辐射截获率与稻瘟病发生的相关性,构建合理健康的群体冠层结构。以当地种植的常规水稻品种‘月亮谷’为试验材料,采取单因素随机区组设计,共6个处理,包括5个不同施氮处理和1个传统施肥对照处理。研究结果表明,高施氮水平下(125.0 kg/hm²)齐穗期的冠层昼温最低,冠层光合有效辐射最大截获率最大。中等施氮(75.0 kg/hm²)和高施氮水平下穗颈瘟的病情指数最高,中等施氮水平下的发病率最高,为51.0%。穗颈瘟发病率和病情指数均和冠层光合有效辐射最大截获率存在正相关性 (r=0.6696^*和r=0.7130^**),发病率与1级病穗百分比呈正相关性(r=0.7511^**),而和2级至5级病穗百分比的关系不大,病情指数分别与5级、1级病穗百分比呈正相关性(r=0.6324^**、r=0.4936^*),而和2级至4级病穗百分比关系不大。     

棉花冠层不同尺度光能空间分布特征研究

【目的】棉花冠层光能空间分布是光能利用率高低的直接影响因素之一。为科学量化光能在棉花冠层的空间分布,本研究旨在分析冠层内光合有效辐射(Photosynthetically active radiation,PAR)各分量的空间变化特征。【方法】用空间统计学方法分析了冠层不同空间点、线、面位置PAR的分布特征。【结果】盛花期棉花行间冠层PAR截获率整体变化呈"V"形,即棉行间PAR截获率低于棉行附近位置;高密度的群体冠层中下部PAR截获率纵向变化速率较缓,同时在距地面60 cm处PAR截获率横向变化幅度也较小;不同冠层区域的PAR截获率与密度呈正相关关系,且随播种后时间均呈现先增后减的变化趋势。【结论】适当增大种植密度可以提高群体PAR截获率。运用空间统计学原理精确定位定量分析冠层内PAR的分布,对合理配置棉花种植模式、研究群体株型结构、培育高光效品种具有指导意义。     

A dynamic model of potential growth of olive (Olea europaea L.) orchards

A model of potential olive oil production is presented, based on a three-dimensional model of canopy photosynthesis and respiration and dynamic distribution of assimilates among organs. The model is used to analyse the effects of planting density (high and super-high density orchards with 408 and 1667 trees ha⁻¹, respectively) and climate change (ΔT of 4 °C and CO₂ concentration of 740 ppm) on olive oil production. To evaluate its predictive power, the simulations were tested with published measurements of leaf area, growth and yield for a high density olive orchard cv. ‘Arbequina’ in Cordoba, Spain. The model slightly overestimated (less than 7%) the different measurements reported in the experiment. For all simulations, the maximum yields obtained were in agreement with literature. Simulations showed that climate change had a very small effect on yields due to compensation of the negative and positive effects of temperature and CO₂ on photosynthesis and respiration. However, high temperatures led to some sterile years due to lack of vernalization. The model predicts that super-high density olive orchards achieve higher potential yields than high-density systems and that maximum yields are reached on the third year of the orchard. The advantage of a higher density is a higher interception of solar radiation, especially during the first years of the orchard. In all the simulations, the model predicted a small decrease of the radiation use efficiency for oil production with the age of the orchard as well as an important inter-annual variability (range of 0.11–0.19 g (MJ PAR)⁻¹), indicating that the use of a constant radiation use efficiency may not be adequate to predict oil production.     

功能结构模型在黄瓜栽培密度最优化设计中的应用

本研究选择秋冬季日光温室黄瓜为研究对象,利用参数化方法构建了不同株距和行距处理的虚拟冠层结构模型,并在与光分布模型和光合模型相结合的基础上,模拟分析了株行距改变对冠层叶片分布、光截获以及光合速率的影响。模拟结果显示,株行距的增加,促进了冠层对光的透性,对方位角朝向北部和行内的叶片的光截获有明显促进作用,也使得叶片在北部和行内的分布频率显著增加。从单株平均光截获来看,改变株距和行距分别使单株光截获量提高了34.78%和23.18%。通过将光截获模拟结果与光合模型相结合,得到了冬季栽培的最优株行距,即45.70 cm(株距)及43.22cm(行距)。与传统的40×40 cm株行距栽培方式相比,最优株行距略有增加。本研究结果为功能结构模型在实际生产中的应用以及作物栽培株行距最优化设计提供定量化的决策依据。     

Deficit irrigation maintains maize yield through improved soil water extraction and stable canopy radiation interception

Deficit irrigation (DI) is an effective way to save irrigation water while maintaining sustainable yield in irrigated crops. However, limited information is available related to canopy structure and solar radiation use under DI condition. In this study, our objective was to assess maize hybrids for leaf development, photosynthetically active radiation (PAR) interception and water use under DI condition. Field experiments were conducted in 2016 and 2017 in four maize hybrids at well-watered (I₁₀₀, referring to 100% evapotranspiration [ET] requirement) and DI (I₇₅, referring to 75% ET requirement) water regimes. Compared to I₁₀₀, I₇₅ did not reduce maize biomass and grain yield. Although DI reduced the leaf appearance rates (1.5% in 2016 and 7.6% in 2017) and resulted in greater variations in leaf area index (LAI) among hybrids, the amount of PAR interception was not affected during the growing season. DI significantly reduced the seasonal ET in both years (19.8% in 2016 and 26.6% in 2017). All the hybrids extracted more soil water (29 mm in 2016 and 27 mm in 2017) at I₇₅ than at I₁₀₀. Maize plants at I₇₅ had greater water use efficiency (WUE) (1.68 kg m⁻³) than those at I₁₀₀ (1.41 kg m⁻³). However, DI did not affect radiation use efficiency (RUE). In conclusion, DI at I₇₅ maintained grain yield through improved soil water extraction and WUE but stable canopy radiation interception and RUE.     

Influence of Varying Humidity and Temperature Upon the Adsorption of Radon

On the basis of theoretical analysis, this article describes the experiment of the absorption of Radon 222 Rn and Thoron 220 Rn in air on active charcoal under condition of varying humidity and temperature. The result of experiment shows that, under the condition of lower humidity, the absorption of 222 Rn reduce as the temperature raises. Since the half life of 220 Rn is short, the influence of the temperature is small. But as the relative humidity raises, the absorption of 222 Rn and 220 Rn reduces significantly.     

A model for simulating the height of rice plants

A reliable approach for modelling rice plant height would allow the simulation of processes with a significant impact on yields, e.g., lodging, floodwater effect on leaves temperature, crop–weeds competition for radiation interception. In this paper we present a new model for the simulation of rice plant height based on the integral of the percentage of biomass partitioned to stems. The model was compared with four alternative approaches using data collected during eight experiments carried out in Russia, Japan and US between 1991 and 2000, proving to be the most accurate in reproducing plant height during the whole crop cycle. RRMSE ranged between 8.02% and 20.87%, modelling efficiency was always close to one and the absolute value of coefficient of residual mass never exceeded 0.16. It resulted also the most robust and the less complex (according to the Akaike's Information Criterion) among those compared. The model presents a lower level of empiricism with respect to the other approaches found in the literature, deriving plant height from the allocation of biomass to stems, which are the plant organs most involved in determining canopy height. This model represents a suitable base for further developments aiming at including the effect of management practices (e.g., fluctuating water depth) and environmental factors (e.g., crop–weeds competition for radiation interception). Moreover, the low input requirements favour its inclusion in operational cropping systems models.     

Shade Effects on Phaseolus vulgaris L. Intercropped with Zea mays L. under Well-Watered Conditions

Field experiments were carried out under unstressed conditions of soil water during two summer crop growing seasons (1998–99 and 1999–2000 seasons) in a South African semi‐arid region (Bloemfontein, Free State, South Africa). The aim of this study was to investigate shade effects on beans intercropped with maize in terms of plant mass and radiation use. The experimental treatments were two cropping systems (no shading/sole cropping and shading/intercropping) and two row orientations (north–south and east–west). At the top of bean canopies shaded by maize, incident radiation was reduced by up to 90 %. Shading reduced total dry matter of beans by 67 % at the end of the growing season, resulting in yield losses. The dry matter partitioning into leaf and stem (the ratios of leaf and stem to total biomass) was about 50 % higher in intercropping than sole cropping. In contrast, intercropped beans had 40 % lower dry matter partitioning into pod (the ratio of pod to total biomass). Fraction of radiation intercepted by sole‐cropped beans steeply increased until canopy closure (0.9) and then slowly decreased, while fraction of radiation intercepted by intercropped beans remained constant between 0.0 and 0.2 throughout the growing seasons. However, intercropped beans had 77 % higher radiation use efficiency (RUE) than sole‐cropped beans. In contrast, for maize, no effect of intercropping (shading) was found on growth, partitioning, yield, radiation interception or RUE. Consequently, lower bean yield losses can be attained in association with late shading rather than early shading. This can be controlled by growing crops with different temporal and spatial treatments. As regards row treatment, no effect of row direction was found on growth, partitioning, yield, radiation interception or RUE.     

Effects of climate on different potato genotypes 1. Radiation interception, total and tuber dry matter production

In 11 field trials in Rwanda, Tunisia and The Netherlands, the total dry matter production and tuber dry matter production of eight potato cultivars were analysed in terms of radiation interception and radiation use efficiency. The variation in length of the growing season was the most important factor explaining the differences in both total and tuber dry matter production among cultivars and sites. Radiation interception was the most important factor because the radiation-use efficiency was negatively correlated with radiation intensity and the variation in harvest index was of minor importance. Variation in length of the growing season among sites was related to daylength and temperature, in that shorter days at emergence and higher temperatures throughout the season resulted in a shorter growth cycle. The extent of these effects differed among cultivars, and it was concluded that climatic effects on tuber dry matter production could be attributed to the effects of temperature and daylength on the length of the growth cycle.     

退耕雷竹春季林冠截留特性研究

为了研究退耕雷竹林冠截留特性,于2012年春季对不同林分密度的退耕雷竹林进行水文观测。结果表明：2个林分密度的雷竹林外降雨与林内降雨、树干径流均具有极显著的开口向上的抛物线函数关系,与林冠截留具有开口向下的抛物线函数关系。分布均匀和郁闭度高(0.96)的1号样地（(15000±750)株/hm2）林冠截留率平均为51.19%,雷竹分布和郁闭度(0.85)较低的2号样地（(22500±750)株/hm2）平均为38.04%。2块样地林冠截留率的巨大差异,意味着退耕雷竹林冠截留具有很大的可塑性和改造潜力,可通过调整退耕雷竹林的结构、密度等经营措施来提高其生态水文效益,从而达到水土保持高效经营的最终目标。     

Nitrogen‐, water‐ and radiation‐use efficiencies affected by sugarcane breeding in Argentina

This study aimed to identify whether and how sugarcane (Saccharum spp.) breeding in Argentina modified nitrogen‐use efficiency (NUE), water‐use efficiency (WUE) and radiation‐use efficiency (RUE). Thirteen varieties were grown in two consecutive seasons. Trends in different traits were estimated by fitting the data to linear or bilinear regression models. There was a linear increase in NUE and WUE with the year of release throughout the 70‐year span, whereas water use was not modified by sugarcane breeding. There was a positive and strong (r > 0.90; P < 0.01) association between NUE and WUE and between sugar yield and NUE or WUE. Although RUE was not modified by sugarcane breeding, the amount of radiation intercepted by the crop increased with the year of release. Modern varieties had a higher maximum interception and needed fewer days to reach maximum interception than old varieties. This study suggests that applying ecophysiological knowledge would be instrumental in sugarcane breeding programmes in order to develop varieties with high resource‐use efficiency and capable to adapt to global climate change.     

玉米农田生态系统水碳通量日变化特征研究

农田生态系统作为陆地生态系统的重要组成部分,研究其CO2通量和水汽通量的变化特征对于探讨整个陆地生态系统的碳、水循环具有重要的意义。笔者采用涡度相关系统测定了晴天条件下夏玉米农田生态系统抽穗期的水碳通量,分析其日变化特征。研究结果表明：（1）农田生态系统CO2通量随着光合有效辐射的增强而增大,用米氏方程拟合达到极显著水平,最大潜在碳通量为3.63398 mg/(m2· s);（2）CO2通量上午和下午没有明显的差异,不存在气孔抑制现象;（3）水汽通量随着光合有效辐射的增强而增大,但下午的水汽通量显著大于上午,其原因在于下午的饱和水汽压差远远大于上午,造成下午的蒸腾和蒸发更大;（4）冠层导度随时间的推移基本呈减小的趋势,到11:00 左右基本保持恒定,到14:00左右随着光合有效辐射越来越弱,冠层导度逐渐减小,造成这一结果的原因可能是露水蒸发引起上午冠层导度被高估。     

Diurnal and Seasonal Light Transmission to Cowpea in Sorghum–Cowpea Intercrops in Mali

Tall cereal–short legume intercropping is ubiquitous in the semiarid tropics of West Africa, yet little is known regarding the dynamics of light interception in these systems. A field study was conducted in Cinzana, Mali, to characterize light transmission to cowpea in sorghum [Sorghum bicolor (L.) Moench]–cowpea [Vigna unguiculata (L.) Walp] intercropping systems. Different sorghum–cowpea planting configurations were used to examine photosynthetically active radiation (PAR) incident on the cowpea. The 4‐m tall sorghum cultivar CSM 219E intercepted > 60 % of incoming PAR from 2 m height to harvest (50 days). Consequently, total seasonal PAR received by intercropped cowpea was 60–66 % that of the unshaded monocrop. Thirty‐minute averages of PAR transmitted around solar noon had poor agreement (R²=0.53) with fractional daily light interception and overestimated seasonal PAR received by cowpea by 17 % in the north–south row orientation used. Thirty‐minute averages at 1100 h (R²=0.93) and 1430 h (R²=0.91) had the closest correlation to diurnal average PAR incident on cowpea. This study indicates that tall guineense sorghum captures significant amounts of light at low leaf area index (LAI) (< 2.0). Row orientation, time of measurement, plant height and LAI should be considered in calculating light interception in these intercropping systems.     

Radiation interception and radiation use efficiency of potato affected by different N fertigation and irrigation regimes

Three years of field experiments were carried out to explore the response of potato dry matter production, accumulated intercepted photosynthetic active radiation (Aipar) and radiation use efficiency (RUE) to five N levels providing 0, 60, 100, 140 and 180 kg N ha⁻¹ and three drip irrigation strategies, which were full, deficit and none irrigation. Results showed that, irrespective of years, dry matter production and Aipar were increased by prolonged N fertigation, even though N fertigation was carried out from middle to late growing season. The highest total and tuber dry matter and accumulated radiation interception in all three years were obtained when potatoes were provided with 180 kg N ha⁻¹. RUE on the other hand was not affected by N regime. Thus, increases in total dry matter production with increasing N levels were essentially caused by higher Aipar. The strongest response to N fertilization occurred when most N was applied early in the growing season and the latest N fertilization should be applied no later than 41–50 days after emergence. Deficit irrigation, which received ca.70% of irrigation applied to full irrigation, did not reduce radiation interception and radiation use efficiency.