杂交棉标杂A1和石杂2号超高产冠层特性及其与群体光合生产的关系

在田间自然条件下, 以标杂A₁、石杂2号为材料, 研究了超高产(3 500 kg hm^-2以上)杂交棉冠层的叶面积配置、叶倾角和光分布等冠层特性的变化及与群体光合生产的关系。结果表明, 超高产条件下杂交棉叶面积指数高且持续期长, 群体叶面积配置与光分布较均匀, 花铃期冠层中部有较好的透光性, 吐絮期底部漏光损失较小, 整个冠层仍保持较高的光吸收率。超高产杂交棉不仅群体光合速率峰值高, 而且高值持续时间长, 生育后期非叶器官仍维持较高的光合能力, 特别是茎的光合贡献率为常规高产棉花的1.6~4.9倍, 这是杂交棉在生育后期能保证群体光合优势的一个重要原因。超高产杂交棉的棉铃干物质空间分布与叶分布、光分布和冠层光合分布的比例吻合程度较高, 保证了光能的有效利用, 促进同化物及时向棉铃转运, 有利于挖掘杂交棉品种的增产潜力。     

成熟期苹果树冠层器官异源图像配准

为精确构建果树冠层彩色三维空间结构,以成熟期苹果树冠层为研究对象,将PMD摄像机及彩色摄像机相结合获取冠层器官异源图像,开展异源信息配准技术研究。将SIFT算法应用于异源图像特征点提取研究中,并应用目标函数优化RANSAC算法完成同名点提纯以保证特征点匹配的有效性,避免了异源图像尺度变化及果园自然光照的影响;在分析异源图像成像效果基础上,确定了应用双线性映射模型求解异源图像空间映射关系,有效克服了应用仿射变换模型求解异源图像空间映射关系的不精确性。果园不同自然环境下的配准实验表明:提出的混合算法适用于苹果树冠层器官异源图像的配准,晴天顺光环境下的正确配准率为88.2%,晴天逆光环境下的正确配准率为84.2%,阴天环境下的正确配准率为72.7%。     

Water balance, transpiration and canopy conductance in two beech stands

Measurements of sap flow, vapour fluxes, throughfall and soil water content were conducted for 19 months in a young beech stand growing at low elevation, in the Hesse forest. This experiment is part of the Euroflux network, covering 15 representative European forests. Study of the radial variation of sap flow within tree trunks, showed a general pattern of sap flux density in relation to the depth below cambium. Among-tree variation of sap flow was also assessed, in order to determine the contribution of the different crown classes to the total stand transpiration. Stand sap flow and vapour flux, measured with eddy covariance technique, were well correlated, for half hourly as well for daily values, the ratios of the fluxes for both averaging periods being 0.77. A strong canopy coupling to the atmosphere was found, omega factor ranging between 0.05 and 0.20 relative to the windspeed. Canopy conductance variation was related to a range of environmental variables: global radiation, vapour pressure deficit, air temperature and soil water deficit. In addition to the effect of radiation and of vapour pressure deficit often found in various other tree species, here beech exhibited a strong reduction in canopy conductance when air temperature decreased below 17°C. The model of transpiration was calibrated using data measured in the Hesse forest and applied to another beech stand under mountainous conditions in the Vosges mountains (east France). Measured and modelled stand transpiration were in good agreement.     

磷营养胁迫对冬小麦冠层光谱的影响

因为磷素重要的营养作用,其胁迫的存在影响冬小麦的正常生长。借助地面遥感仪器获取冬小麦在磷营养胁迫下的多个生育期里的冠层光谱数据并对其影响特征进行了分析。利用因子分析方法提取主因子与含有丰富信息的光谱变量,并结合极显著水平(0.01)的均值比较与检验过程考察了冬小麦冠层光谱,确定了对磷营养胁迫敏感的光谱波段:760nm,810nm和870nm与950nm,并在此基础上结合冬小麦对磷素的吸收利用特征选定了运用冠层光谱敏感波段反射率探测和区分磷营养胁迫的关键生育期:拔节期。结果同时表明,对冬小麦磷营养胁迫而言,近红外区间(760nm~1100nm)光谱反射特征的区分能力要强于可见光区。本文同时指出了研究与发展利用遥感技术进行营养胁迫监测的方法和着重点。     

不同熟期大豆R4-R5期冠层某些生理生态性状与产量的关系

 应用冠层分析仪和光合测定系统，分析不同熟期、不同产量类型的大豆R4-R5期冠层结构特征、光合生理、冠层内微生态环境。结果表明，不论熟期早晚，高产大豆群体的共同特征在于LAI较高，叶片在各个方向上的分布均匀；上下冠层叶片的光合速率差异小，全冠层的光合速率相对较高，从而使全冠层有较高的光合生产力。结果增加了植株荚、粒数及粒重，特别是增加了中上部的荚、粒数。不同熟期间的高产群体冠层特征的差异在于早熟大豆的LAI相对较低，截获的光能多少对于产量形成有着更重要的意义，高产群体叶倾角小，叶片平展，有利于截获更多光能；而晚熟大豆冠层郁蔽，LAI大，高产冠层各层次叶倾角大则有利于太阳辐射透射到冠层内部，增加群体内部受光量，利于产量形成。     

杂种小麦碳同化特性及籽粒产量性状的研究

 在春季小麦返青后的各生育期中，供试化杀型（CHA）杂种麦优4号和T型三系杂种麦优1号与亲本和对照相比，在群体光合速率（CAP）、群体叶源量（CLSC）和叶面积指数（LAI）上都表现明显杂种优势，这些优势随生育进程呈逐渐增强趋势。杂种小麦在返青后各生育期的群体干物重（PDW）均优于亲本。CLSC与PDW呈极显著正相关表明，CLSC可作为反映群体物质生产力大小的可靠指标。供试杂种在籽粒产量上的优势亦较明显，其平均优势（AH）大于超标优势（SH）。麦优4号、麦优1号的穗数、粒数、粒重三产量构成因素的AH均为正值，SH在麦优4号中表现为单位面积穗数和千粒重为正值，穗粒数为负值；在麦优1号中则单位面积穗数和穗粒数为正值，千粒重为负值。麦优4号的籽粒产量优于麦优1号。杂种小麦在CAP、CLSC上的明显优势是其获得PDW优势及籽粒产量优势的重要生理基础。本文还就杂种光合优势和光合作用与产量的关系进行了讨论。     

Vertical and leaf-age-related variations of nonstructural carbohydrates in two alpine timberline species, southeastern Tibetan Plateau

Spatial pattern of nonstructural carbohydrates (NSC) was analyzed in two alpine timberline species (Abies georgei and Juniperus saltuaria) growing at the timberline in Sergyemla Mountain, southeastern Tibetan Plateau. We aimed to examine the effect of canopy height and leaf age on balance between carbon uptake and consumption of timberline tree species in extremely environmental condition. The results showed that no significantly vertical variation in sugars, starch or NSC (soluble sugars plus starch) in A. georgei was found for any aged needles. Also, there were no significant differences among vertical gradients in both current and last-year leaves for J. saltuaria. However, different-aged needles/leaves showed significant differences in NSC concentrations in both A. georgei and J. saltuaria. For A. georgei, needle mean NSC across vertical canopies showed a significant increase from current-year to 2-year needles (P < 0.05), followed by a gradual decrease from 2- to 5-year needles (P < 0.05), whereas for J. saltuaria, last-year leaves had significant higher NSC except sugars compared with current-year leaves across canopies (P < 0.01). The observed trends of NSC along vertical canopy heights and leaf ages suggested that, in extreme environmental condition, not only light-induced carbon acquisition in photosynthesis but also carbohydrate export from leaves should be taken into account to explain the spatial pattern of NSC.     

Effect of nitrogen addition on DOC leaching and chemical exchanges on canopy leaves in Guangdong Province,China

The impact of nitrogen(N)deposition on dissolved organic carbon(DOC)fractions in throughfall is not well understood.We performed a laboratory experiment and compared DOC leaching from canopy leaves after dipping leaves in pure water(control)and NH4NO3 solution(N-treatment)for 18 h.Net changes of DOC,NH4^+,NO3^-,SO4^2-,K^+,Mg^2+,Ca^2+and H^+contents after dipping leaves were determined by comparing solutions with and without leaves.We recorded no differences of DOC leaching between control and N-treatment,implying that N deposition had minor impacts on canopy DOC production.This confirmed that previous experiments testing the effects of N addition on DOC dynamics without considering the effects of the canopy reaction successfully described the real situation.We also confirmed the previously-reported canopy exchange process in spite of a high background N deposition at our study site.N-treatment significantly increased base cation leaching,especially K^+,and the increase was positively correlated with foliar NH4?retention.Net leaching of H^+and SO4^2-was not affected by the N-treatment.     

用岭估计研究以RS和GIS为基础的森林郁闭度估测

本文根据最小二乘估计（LS）及岭估计（R）原理，利用平均残差平方和准则，从样地对应的RS和GIS信息中，用计算机仿真方法筛选出影响郁闭度估测的主要信息。在分析LS估计存在缺陷的基础上，提出采用岭估计建立郁闭度估测方程。实例分析表明，当在影响郁闭度估测的变量间存在复共线性时，岭估计比LS估计具有较高的预报精度，可以满足生产的需要。     

小黑麦群体冠层结构及产量构成差异分析

为了解不同类型小黑麦冠层结构及产量构成差异,以加工型品种东农8809、饲用型品种东农5305和粮饲兼用型品种东农96026为材料,采用随机区组设计,探讨了三种类型小黑麦主要生育阶段的平均叶倾角、天空散射辐射透过率、太阳直射辐射透过率、消光系数和叶面积指数的特点。结果表明,加工型品种东农8809的消光系数小,生育后期叶倾角过大,出现漏光现象,这种不合理的冠层结构造成太阳辐射的浪费,使籽粒产量形成受到限制;饲用型品种东农5303的平均叶倾角在营养生长阶段最大,孕穗期降低,营养生长阶段较合理的冠层结构成为其较高叶面积指数形成的基础;粮饲兼用型品种东农96026的平均叶倾角、天空散射辐射透过率和直接辐射透过率均小,消光系数大,冠层结构合理,对光的截获能力强,籽粒产量最高。