Canola genotypes differ in potassium efficiency during vegetative growth

There is no knowledge about the differential capacity of canola genotypes to take up potassium (K) and produce dry matter under conditions of low soil K availability. Hence, 84 canola genotypes were screened for K efficiency in the glasshouse. Plants were grown in sealed pots containing K-responsive, sandy soil without or with K added. Twelve genotypes were selected for advanced screening in the glasshouse in a different K-responsive soil. Genotypes with a mean K efficiency ratio (the ratio of shoot dry weight at deficient and adequate K supply) greater than one standard error above or below the median genotype value were classified as K-efficient or K-inefficient, respectively. There were significant differences between genotypes in the K efficiency ratio in both screening experiments, indicating that genotypes responded differently to K availability. In the initial screening experiment, 19 genotypes were rated as K-efficient and nine genotypes rated as K-inefficient based on the K efficiency ratio. In the advanced screening experiment with 12 genotypes, three genotypes were rated as K-efficient and two as K-inefficient. Genotypes Wesbarker and Rainbow were K-efficient and Genkai K-inefficient in both experiments. Correlation of the K efficiency ratio with (i) shoot K content in the initial and advanced screening and (ii) shoot K concentration in the advanced screening, indicates that the observed differences in K efficiency were due to genotypic differences in both the uptake and the utilization of K. K-efficient genotypes have a potential to improve canola yields on soils with low K availability.     

中国各地区“以工补农”的经济结构特征 分析与政策建议

当前中国总体上已进入工业化中期阶段,但由于地区发展不平衡,各地区不可能都进入工业化中期阶段,统一的“以工补农”政策模式和措施在各个地区也不一定都适用。作者采用美国经济学家钱纳里与赛尔昆设计的标准模型,构建了当前全国及各地区“以工补农”的经济结构特征评价指标,对中国各地区当前的经济结构特征作了初步的分析,得出了在中国总体上跨入工业化中期阶段的事实中,有8个省与中国总体进入工业化中期阶段的判断一致;仍有17个省、区、市尚未进入“以工补农”政策转折期;有6个省市明显超越全国平均水平,已基本进入大规模反哺期的结论,并提出了相应的政策建议。     

中国森林碳汇的区域差异及动态演进分析

基于1988—2013年全国森林资源清查数据,采用改进的森林蓄积量法估算了中国大陆31个省(市、区)的森林碳汇量,并以单位面积森林碳汇量为指标,借助Dagum基尼系数和Markov链方法系统分析了中国森林碳汇的区域差异及其动态演进趋势。结果表明:1)中国森林碳汇在省域间存在较大差距,由南方林区向西南、东北林区递增变化;2)Dagum基尼系数及其分解结果显示,中国森林碳汇的地区差异呈波动下降趋势。从四大林区来看,南方、北方和东北地区内差距与全国一致,基本呈下降趋势。而西南地区内差距呈现先上升后下降趋势。地区间差距是造成中国森林碳汇区域差异的首要原因,并且地区间净差距和超变密度差距对全国总体差异的贡献率呈此消彼长的"∞"型变化。3)Markov链分析发现,不同水平的森林碳汇地区间跨区流动的可能性较低。但从动态演进来看,中国森林碳汇呈上升态势,预期较低水平的省份将逐步减少,整体会向着高水平趋势发展。     

基于相位差的时域反射仪测定土壤含水量的标定和田间验证

为了检验具有我国自主知识产权的基于相位差检测原理的时域反射仪(TDR)测定土壤水分的性能,利用室内土柱试验,获得了该仪器测定土壤含水量的标定曲线,分析了影响因素,并在田间对标定曲线进行了实际验证。结果表明,容重对仪器测定土壤含水量的影响不显著;土壤质地对校正结果有明显影响,供试的砂质土类,壤质黏土类和黏土类分别可以使用一个特定标定公式,R2均大于0.98,估计标准误差均小于0.020cm3/cm3;该仪器用于田间测定含水量的均方根误差小于0.035cm3/cm3。因此,经过室内标定后,将新型时域反射仪用于测定田间土壤含水量是可靠的。     

不同海拔环境中甘蓝型油菜RIL主要性状的差异分析

为研究海拔高度对甘蓝型油菜RIL群体主要性状的影响,运用方差分析、相关及通径分析方法,比较了在两种不同海拔环境条件下,两个甘蓝型油菜重组自交系（RIL）群体的种子千粒重、含油量、蛋白质含量、皮壳率以及黄籽度等5个主要性状的差异.结果表明：①5个性状都呈连续变异,表现多基因控制的数量性状特点,其中千粒重、含油量和蛋白质含量的频率分布符合正态分布;②高海拔环境的含油量要显著高于低海拔环境,低海拔的蛋白质含量要显著高于高海拔地区,含油量与蛋白质含量呈极显著的负相关;③高海拔环境中的含油量＋蛋白质含量显著地高于低海拔地区;④海拔环境对黄籽度的影响不显著;⑤海拔环境对皮壳率和千粒重的影响可能与群体基因型有关.     

Canopy temperature on clear and cloudy days can be used to estimate varietal differences in stomatal conductance in rice

Leaf photosynthetic potential, a major determinant of yield potential in rice, is mostly explained by stomatal conductance (g_s) as well as leaf N content (Rubisco protein content). Therefore, the rapid and precise evaluation of g_s as well as leaf N content would be a valuable addition to rice breeding programs aimed at improved yield potential. We established a simple method based on infrared thermography to estimate varietal differences in g_s. Seven rice varieties were cultivated in two-row plots in 2007, and canopy temperatures in three varieties, including a control variety, Koshihikari, were simultaneously measured to determine canopy temperature difference (CTd) between Koshihikari and the other varieties on clear days. The varieties Takanari, Habataki, and TUAT1-5-6a displayed significantly (P < 0.05) lower leaf temperature and higher g_s and leaf photosynthetic rate (P_n) than Koshihikari. CTd was closely correlated with g_s and P_n. These results indicate that CTd may be useful as a relative index to estimate varietal differences in g_s. A significant CTd was still observed even under cloudy conditions in 2008. Takanari and TUAT1-5-6a had lower leaf temperature than Koshihikari on cloudy days as well as on clear days. Subsequent investigation of photosynthetic light response curves revealed that Takanari and TUAT1-5-6a had higher g_s and P_n than Koshihikari under lower irradiance. These results suggest that infrared thermography may be a simple method of evaluating varietal differences in g_s through CTd, and that it may be practicable even under cloudy conditions.     

不同供水条件下冬小麦冠气温差、叶片水势和水分亏缺指数的变化及其相互关系

为了给以作物高效灌溉制度提供理论依据,对不同供水条件下冬小麦冠层温度进行了多年田间观测,模拟了以土壤水分条件为主导的冠气温差、叶水势、水分亏缺指数等的变化规律及其对影响因素的响应。结果表明,冬小麦各生育阶段不同供水处理冠层温度(T c)受土壤水分影响明显,处理间冠气温差(ΔT)差异极显著。叶水势(LW P)与ΔT、作物水分胁迫指数(CW S I)相关显著。LW P=-1.8M Pa,CW S I=0.40是指示冬小麦发生水分胁迫的关键性指标。综合各指标,为了达到节水目的,使ΔT维持在0~-4℃,可获得冬小麦产量最优值,此时冬小麦灌溉量下限应使土壤相对含水量达到58.7%。     

不同生育时期冬小麦叶片相对含水量高光谱监测

为实现冬小麦不同生育时期叶片水分含量的快速监测,以冬小麦冠层高光谱数据和红外热成像数据为基础,计算得到5种光谱参数,通过对不同生育时期叶片相对含水量与光谱参数拟合状况进行分析和筛选,分别构建了基于光谱参数的叶片相对含水量反演模型,并对模型进行检验。结果表明,不同生育时期叶片相对含水量与比值指数（RVI）、归一化差值植被指数（NDVI）、比值/归一化植被指数（R/ND）、优化土壤调整植被指数（OSAVI）、冠气温差（TDc-a）均呈极显著相关（P＜0.01）;拔节期、抽穗期、开花期、灌浆前期和灌浆后期叶片相对含水量分别与NDVI、OSAVI、R/ND、TDc-a和TDc-a拟合效果较好,决定系数分别为0.842、0.884、0.831、0.864和0.945;预测模型的均方根误差分别为0.019、0.016、0.027、0.032和0.024,相对误差分别为2.16%、1.80%、3.30%、3.81%和3.53%。因此,在拔节期、抽穗期、开花期、灌浆前期和灌浆后期,可以分别利用NDVI、OSAVI、R/ND、TDc-a和TDc-a估测冬小麦叶片相对含水量。     

不同地理种源南酸枣苗期生长性状差异分析

对来自9个省(区)的36个南酸枣种源在江西省林业科学院苗圃地进行了育苗试验。结果表明：两次调查结果均显示,36个南酸枣种源的树高和地径均存在极显著差异。来自福建南靖、福建南平、江西高安和湖南地区南酸枣的平均树高与地径均高于群体平均值,生长表现较好,可进行进一步的选优研究。     

笼养孟加拉虎雌雄白昼行为的差异

2005年12月～2006年8月,采用瞬时扫描取样法和全事件取样法,对云南野生动物园内5只孟加拉虎行为进行了初步观察。结果表明,在观察期内,笼养孟加拉虎白昼行为时间分配上两性存在一定差异,即雌性的睡眠和卧息多于雄性的睡眠和卧息;雌性的走动和其它行为少于雄性的走动和其它行为。在活动节律上,两性有极大的相似性,只是雌虎在下午的卧息高峰值比雄虎晚约1h。