转基因作物安全研究进展及南繁转基因生物安全管理对策

本文从生物多样性、生态系统和人畜安全三方面概述了转基因作物生物安全研究进展,并介绍了全世界转基因生物安全评价原则与方法和我国转基因作物安全管理法规.表明转基因作物存在潜在的生物安全风险,全世界正在积极构建转基因生物安全管理体系.通过对我国南繁转基因环境安全问题和情况进行分析,认为南繁地区有成为染缸的潜在威胁.为保护南繁...     

Cropping systems and crop residue management in the Trans-Gangetic Plains: Issues and challenges for conservation agriculture from village surveys

Conservation agriculture practices are being advocated to help sustain crop productivity gains and secure environmental sustainability in the Trans-Gangetic Plains, India’s Green Revolution heartland. The paper illustrates the use of village surveys as a quasi-quantitative system analysis tool to derive implications for agricultural research and development. Drawing from village surveys in 170 communities, the paper assesses current crop residue management practices in Punjab and Haryana’s rice-wheat, basmati-wheat and non-rice-wheat cropping systems. The prevalence of wheat as the winter crop implies an intensive collection, trading and use of wheat straw as basal feed for dairy livestock; which contrasts with the diverse crop residue management of the monsoon crops. The increased use of combine harvesters has spurred the rapid advent of mechanical wheat straw reapers whereas the bulk of combine harvested rice straw is burned in situ. Present crop residue management practices are largely incompatible with year-round mulch retention despite significant biomass production. The research and development community faces the challenge of evening out straw use and management over seasons to ensure at least partial residue retention if its calls for conservation agriculture in this important sub-region are to succeed. The paper also reiterates the worrying decline of groundwater tables associated with the rice-wheat system.     

Changes in evapotranspiration over irrigated winter wheat and maize in North China Plain over three decades

Evapotranspiration (ET) is an important component of the water cycle at field, regional and global scales. This study used measured data from a 30-year irrigation experiment (1979-2009) in the North China Plain (NCP) on winter wheat (Triticum aestivum L.) and summer maize (Zea mays L.) to analyze the impacts of climatic factors and crop yield on ET. The results showed that grass reference evapotranspiration (ET_o, calculated by FAO Penmen-Monteith method) was relatively constant from 1979 to 2009. However, the actual seasonal ET of winter wheat and maize under well-watered condition gradually increased from the 1980s to the 2000s. The mean seasonal ET was 401.4 mm, 417.3 mm and 458.6 mm for winter wheat, and 375.7 mm, 381.1 mm and 396.2 mm for maize in 1980s, 1990s and 2000s, respectively. The crop coefficient (K_c) was not constant and changed with the yield of the crops. The seasonal average K_c of winter wheat was 0.75 in the 1980s, 0.81 in the 1990s and 0.85 in the 2000s, and the corresponding average grain yield (GY) was 4790 kg ha⁻¹, 5501 kg ha⁻¹ and 6685 kg ha⁻¹. The average K_c of maize was 0.88 in the 1980s, 0.88 in the 1990s and 0.94 in the 2000s, with a GY of 5054 kg ha⁻¹, 7041 kg ha⁻¹ and 7874 kg ha⁻¹, respectively, for the three decades. The increase in ET was not in proportion to the increase in GY, resulting improved water use efficiency (WUE). The increase in ET was possibly related to the increase in leaf stomatal conductance with renewing in cultivars. The less increase in water use with more increase in grain production could be partly attributed to the significant increase in harvest index. The results showed that with new cultivars and improved management practices it was possible to further increase grain production without much increase in water use.     

水稻生产中的农田生态问题与可持续发展对策

从农田生态系统整体出发,分析水稻生产中的农田生态问题,并重点就水资源短缺、旱涝灾害日趋频繁,生物多样性减少、病虫暴发频率上升,化肥农药利用率低、化学品污染严重等问题,提出了建生态化农田、设生态化布局、行生态化栽培等水稻可持续生产对策。     

棉田高效种植施肥模式研究

用微区试验方法,研究了不同施肥模式对棉花+辣椒—包菜三熟种植模式的作物产量及土壤肥力的影响。结果表明:在总施肥量基本一致的条件下,根据作物的生长发育规律分期施肥比一次性作为基肥施入能获得更高产量,同时可提高土壤肥力。     

利用品种混合控制小麦病害的研究进展

作物多样性在病害防治上的应用包括多系混合、品种混合和物种混合,其中品种混合策略备受重视。对于小麦,品种混合与它的组分净种时的表现相比至少有两方面的优势,即增加籽粒产量的稳定性和减少病害的危害．特别是对减轻锈病和白粉病的危害更为明显。但是,由于病害防治而获得的产量收益比较小．一般平均只有4％-5％。对于小种专化的病原物,小麦混合群体中复杂小种(能侵染两个或两个以上混合组分)的相对频率高于简单小种的情况并不少见,因此有必要实行小组分数目品种混合系统的多样化、增加组分之间的抗性差异或增加混合组分数目。影响品种混合防病效应的因素是今后需要大力研究的问题。     

丘陵半干旱区作物需水规律的研究进展

对目前国内外丘陵半干旱区作物需水量的主要理论和方法,包括水量平衡法、蒸渗仪法、波文比-能量平衡法、经验公式法和遥感方法进行了总结,探讨了其使用中存在的问题,预测了作物需水量在测定和估算研究方面的发展趋势。     

WeibuⅡ作物损失模型的差分法拟合

Pennypacker(1980)、Madden(1981)等学者将韦布尔(Weibull)曲线y(x)=1-exp{-((x-a)/b)~c}(x>a,b>0,c>0)用以描述植病进展和植病导致产量损失的非线性回归关系,其生物学意义和适应性引起人们注意。但是如何利用一组实验数据来拟合该模型,一直没有一个简便易行的方法。为了解决这个问题,本文研究了Weibull模型的差分法拟合技术。     

Comparison of Statistical Models for Regional Crop Trial Analysis

Based on the review and comparison of main statistical analysis models for estimating varietyenvironment cell means in regional crop trials, a new statistical model, LR-PCA composite model was proposed, and the predictive precision of these models were compared by cross validation of an example data. Results showed that the order of model precision was LR-PCA model ＞ AMMI model ＞ PCA model ＞ Treatment Means (TM) model ＞ Linear Regression (LR) model ＞ Additive Main Effects ANOVA model. The precision gain factor of LR-PCA model was 1.55, increasing by 8.4% compared with AMMI.     

模糊环境下的农业生产计划模型

庄稼规划问题常被认为是一个线性优化问题。但在许多实际情况中,由于未来天气因素的影响,农产品的利润系数一般是不确定的值。因此,带有常系数的线性优化模型不能准确地描述决策环境。基于可信性理论,提出一个庄稼规划模糊模型,并给出一个数值例子以表明模型的合理性和有效性。