增氧对水培棉花生长的影响研究

通过水培试验研究增氧对棉花生长的影响;试验设计3种增氧方式,分别为持续性增氧(Physical continuous oxygen,PCO)、间歇性增氧(Physical oxygen,PO),化学增氧(Chemical oxygen,CO),种棉花不增氧CK,不种棉花不增氧CK0;研究结果表明,不同增氧方式对营养液中溶解氧浓度都有不同程度的提高,表现为PCOPOCOCK;PCO处理对根体积、根系总吸收面积、根活性面积、根系生物量、株高、地上部生物量、氮和钾的吸收量的促进作用均达到显著水平,分别比CK增加了194.62%、261.89%、301.73%、57.15%、22.76%、38.03%、35.27%、84.78%;间歇性增氧PO处理对根系生物量、株高、地上部分生物量的促进作用显著,分别比CK高30.83%、15.65%、21.19%。通过以上结果表明,棉花对氧的需求敏感,不同增氧方式均能在一定程度上促进棉花生长,其中持续性增氧效果尤为突出,特别是对棉花生物量的积累,说明增氧可以提升棉花生长潜力。     

Genetics of rate limiting disease reaction to Alternaria solani in Tomato

A study was conducted to understand the genetics of rate limiting disease reaction to Alternaria solani in tomato. The results from χ² analysis and Castle Wright estimation revealed that resistance is an oligogenic character controlled by two to few genes. In general, the results for predominant gene effects reveal that both additive and non-additive effects are involved in the inheritance of early blight resistance. The results for predominant gene effects obtained for various crosses studied are discussed along with their implications for improvement of this trait.     

Reproductive stage tolerance to salinity and alkalinity stresses in rice genotypes

Salinity and alkalinity (sodicity) seriously threaten rice production in south Asia. Improving screening methodologies for identifying sources of tolerance is crucial for breeding salt tolerant rices. Rice genotypes of varying tolerance (tolerant, semi‐tolerant and sensitive) were screened in saline soil of electrical conductivity, ECe 4 and 8 dS/m and alkali soil of pH 9.5 and 9.8 in lysimeters. Vegetative growth events were less affected by both the stresses in comparison to reproductive stage. Grain yield was reduced by 26.7%, 45.7% and 50.3% at ECe 8 dS/m in three tolerance groups respectively. At pH 9.8 the reduction was 25.1%, 37.2% and 67.6% in the three groups respectively. Higher floret fertility contributed to higher seed set and grain yields in tolerant genotypes whereas higher spikelet sterility led to poor seed set and lower grain yields in sensitive genotypes. The 1000 grains weight was also significantly reduced at ECe 4 or pH 9.8. Screening at reproductive stage for morphological traits like floret fertility is thus more useful to identify rice genotypes tolerant to both salinity and alkalinity stress. Genotypic (G) and environmental (E) effects and GE interactions were highly significant for the growth attributes and grain yield. Based on analysis of variance, genotypes tolerant to salinity and alkalinity as well to both the stresses were identified.     

基于高光谱图像技术预测苹果大小

以新疆红富士苹果为研究对象,探讨应用高光谱图像技术和最小外接矩形法预测其大小的研究方法。提取苹果高光谱图像中可见红色区域受色度影响较小的713nm以及近红外区域793和852nm的3个波长图像,做双波段比运算处理。比较所得双波段比图像可知,852/713双波段比图像中背景和前景灰度对比度最大。对该图像做阈值分割以及形态闭运算去除果梗区域,使用8邻接边界跟踪法得到二值图像的轮廓坐标序列,采用最小外接矩形法求苹果的大小,与实测值建立回归方程。结果表明,基于高光谱图像技术采用波段比算法,结合最小外接矩形法,能够有效地检测苹果大小,预测值与实际值最大绝对误差为3.06mm,均方根误差为1.21mm。     

Evaluating eddy covariance cotton ET measurements in an advective environment with large weighing lysimeters

Eddy covariance (EC) systems are being used to assess the accuracy of remote sensing methods in mapping surface sensible and latent heat fluxes and evapotranspiration (ET) from local to regional scales, and in crop coefficient development. Therefore, the objective was to evaluate the accuracy of EC systems in measuring sensible heat (H) and latent heat (LE) fluxes. For this purpose, two EC systems were installed near large monolithic weighing lysimeters, on irrigated cotton fields in the Texas High Plains, during the months of June and July 2008. Sensible and latent heat fluxes were underestimated with an average error of about 30%. Most of the errors were from nocturnal measurements. Energy balance (EB) closure was 73.2–78.0% for daytime fluxes. Thus, daylight fluxes were adjusted for lack of EB closure using the Bowen ratio/preservation of energy principle, which improved the resulting EC heat flux agreement with lysimetric values. Further adjustments to EC-based ET included nighttime ET (composite) incorporation, and the use of ‘heat flux source area’ (footprint) functions to compensate ET when the footprint expanded beyond the crop field boundary. As a result, ET values remarkably matched lysimetric ET values, with a ‘mean bias error ± root mean square error’ of −0.03 ± 0.5 mm day⁻¹ (or −0.6 ± 10.2%).     

Mapping agricultural responses to water supply shocks in large irrigation systems, southern India

Irrigated agriculture experienced a water supply shock during a drought in southern India in 2002-2003. In this paper, hotspots of agricultural change were mapped and put in the context of hydrology and water management. Time series of MODIS imagery taken every eight days before (2001-2002) and during (2002-2003) the supply shock were combined with agricultural census data to document changes in cropping patterns in four large irrigation projects in the downstream sections of the Krishna and Godavari River basins (total command area 18,287 km²). The area cropped in rice in the four irrigated command areas decreased by 32% during the drought year, and rice production in the two districts that experienced the largest flow reductions fell below production levels of 1980. The irrigation project that showed the largest change in double cropped area (−90%) was upstream of the Krishna Delta. In the Krishna Delta, large areas changed from rice-rice to rice-gram double cropping. Historical water management contributed to the vulnerability of rice production to drought: the main reservoir in the system was drained to dead storage levels by the end of each growing season over 1968-2000, with little carryover storage. The land cover change maps suggested that the lower Krishna Basin has experienced a “hard landing” during basin closure, and revised management strategies that account for the new flow regime will be required to maintain agricultural production during droughts.     

世界主要农业发达地区农产品追溯体系发展现状

确保安全和提升品质是现阶段世界范围内农产品的两大主题。基于现代信息科技及物联网技术的农产品追溯机制主要涉及两方面功用,一方面通过将供应链的相关信息透明化,最大程度降低生产者和消费者之间的信息不对称;另一方面通过在农产品供应链上下游实现追踪和溯源两大功能,推进农产品安全责任制,迎合了人们对农产品安全和品质的需求,引起了世界范围内的广泛重视,纷纷予以推动和实施。该文从追溯法律与法规、标准与规范、推动与实施3个层面阐述了欧美、日韩及台湾等世界主要农业发达地区农产品追溯体系的推进和最新发展情况,在列举典型追溯系统实例的基础上对比分析并总结了各自发展的特点,指出综合与精简是农产品追溯体系的发展方向,最后从机构、立法、标准、实施、验证等多个角度对中国农产品追溯体系的进一步发展、推广与深化提出建议,以期真正发挥追溯体系效用、守护国人健康。     

Experimental Investigation and Artificial Neural Network-Based Modeling of Batch Reduction of Hexavalent Chromium by Immobilized Cells of Newly Isolated Strain of Chromium-Resistant Bacteria

The batch bioreduction of Cr(VI) by the cells of newly isolated chromium-resistant Acinetobacter sp. bacteria, immobilized on glass beads and Ca-alginate beads, was investigated. The rate of reduction and percentage reduction of Cr(VI) decrease with the increase in initial Cr(VI) concentration, indicating the inhibitory effect of Cr(VI). Efficiency of bioreduction can be improved by increasing the bioparticle loading or the initial biomass loading. Glass bioparticles have shown better performance as compared to Ca-alginate bioparticles in terms of batch Cr(VI) reduction achieved and the rate of reduction. Glass beads may be considered as better cell carrier particles for immobilization as compared to Ca-alginate beads. Around 90% reduction of 80 ppm Cr(VI) could be achieved after 24 h with initial biomass loading of 14.6 mg on glass beads. Artificial neural network-based models are developed for prediction of batch Cr(VI) bioreduction using the cells immobilized on glass and Ca-alginate beads.     

Analysis of two bentonites of enological interest before and after commercial activation by solid Na(2)CO(3)

Two natural calcium-rich bentonites used for the removal of wine proteins, originating from Greece and Turkey, were studied by X-ray diffraction, thermal analysis, and solid state NMR, before and after activation by solid Na(2)CO(3). Exchange of Ca(2+) by Na(+) mainly occurs for cations located at the edge of layers and only weakly for interlayer cations. This Na(2)CO(3) activation process leads to an increased efficiency in the adsorption process of bovine serum albumin (BSA) used as a model protein for both bentonites. A direct correlation is observed between the extent of Ca(2+)/Na(+) exchange, the strength of adsorption of BSA, and the extent of unfolding of BSA backbone.