咸阳市建国60年来耕地利用因素与粮食生产相关分析

首先从粮食产量计算模型中解析出耕地利用4因素,即耕地利用广度、耕地利用程度、耕地利用结构以及耕地利用集约度,进而采用相关分析法求得各阶段耕地利用4因素与粮食产量的相关系数,并参考其偏相关系数,研究建国60年来耕地利用这4方面对粮食生产影响的时序变化,结果表明:(1)不断加强的耕地利用集约度始终是第一位的贡献因素,但其影响趋势缓慢减弱;(2)耕地利用广度对粮食产量的影响趋势减弱,二者互动效应不明显,然而,在耕地面积大幅度减少和农业生产技术快速发展的情况下,耕地面积对粮食生产的约束力增强;(3)耕地利用程度与粮食生产的相关性增强趋势凸显,从而,加大耕地利用程度成为推动粮食生产的有效新动力。(4)耕地利用结构变化对粮食产量的贡献减弱,然而其对粮食生产的制约性渐强。     

Effects of Gradual Water Deficit Stress on Phenological and Morphological Traits in Chickpea （Cicer arietinum L.）

The aims of this study were to investigate the effect of gradual water deficit stress on some phonological and morphological traits and grain yield of desi and kabuli chickpea cultivars. This study was carried out in 2007 and 2008, to evaluate responses of three chickpea cultivars （Hashem and Arman from kabuli and Pirooz from desi type） under well watering （I1： 70mm evaporation from class A pan）, gradual water deficit （12 and 13： 70→90→ 110→130 and 70→100→130mm evaporation from class A pan, respectively） and severe water stress （14： 130mm evaporation from class A pan）. Result showed that days to flowering and plant height were decreased, as water limitation increased. This reduction was significant under gradual water stress （I2 and I3） and Severe water deficit （I4）, compared with control （I1）. There were no significant differences in grain filling period and grain yield among I~, I2 and I3 irrigation treatments. No significant differences in days to physiologic maturity and number of sub branches were recorded among irrigation treatments. Interactions of year×cultivar for days to physiologic maturity, grain filling period and grain yield （P≤0.01） and for days to flowering and plant height （P≤0.05） were significant. The superiority of Arman in producing comparatively greater grain yield could be attributed to higher grain filling period of this cultivar in both years.     

Influence of long-term nitrogen fertilization on micronutrient density in grain of winter wheat (Triticum aestivum L.)

A long-term (1999–2007) field experiment was conducted to investigate the effects of three nitrogen (N) fertilization rates (0, 130, and 300 kg N/ha) on micronutrient density in wheat grain and its milling fractions. At maturity, grains were harvested and fractionated into flour, shorts, and bran for micronutrient and N analysis. N fertilization increased iron (Fe), zinc (Zn), and copper (Cu) density in wheat grain compared to the control. Increase of N application rate from 130 to 300 kg N/ha, however, did not further increase the three micronutrient densities in grain. Micronutrient concentrations were usually highest in the bran and lowest in the flour. High N application increased Zn and Cu densities in all three milling fractions and increased Fe concentration in shorts and bran but not in flour. N application did not affect the manganese (Mn) concentration in grain. N fertilization changed the proportions of Fe and Cu in flour and bran but did not affect the distribution of Zn. Because N fertilization increased micronutrient accumulation in wheat grain, proper management of N fertilization has the potential to enhance the nutritional quality of this important food.     

Contamination of internationally traded wheat by herbicide‐resistant Lolium rigidum

As herbicide‐resistant weeds have spread in the agricultural fields of grain‐exporting countries, their seeds could be introduced into other countries as contaminants in imported grain. The spread of resistance genes through seed and pollen can cause significant economic loss. In order to assess the extent of the problem, we investigated the contamination by herbicide‐resistant annual ryegrass (Lolium rigidum) of wheat imported from Western Australia into Japan. Annual ryegrass seeds were recovered from wheat shipments and seed bioassays were conducted to identify resistance to the herbicides that are commonly used in Australia: diclofop‐methyl, sethoxydim, chlorsulfuron, and glyphosate. Nearly 4500 ryegrass seeds were detected in 20 kg of wheat that was imported in both 2006 and 2007. About 35% and 15% of the seeds were resistant to diclofop‐methyl, 5% and 6% were resistant to sethoxydim, and 56% and 60% were resistant to chlorsulfuron in 2006 and 2007, respectively. None was resistant to glyphosate in either year. As the contamination of crops by herbicide‐resistant weeds is probably a common phenomenon, the monitoring of incoming grain shipments is necessary to stem the further spread of herbicide‐resistant weeds into importing countries.     

种植密度和施肥水平对油菜茎叶可溶性糖和游离氨基酸及籽粒产量的影响

以湘杂油763为材料,测定不同施肥量(以N、P<,2>O<,5>、K<,2>O、B计,处理A:240、120、210、1.2kg/hm<'2>;处理B:180、90、157.5、0.9kg/hm<'2>;处理C:120、60、105、0.6kg/hm<'2>;处理D:60、30、52.5、0.3kg/hm<'2>;E:...     

基于农户模型的粮食补贴政策绩效模拟研究

基于粮食主产区安徽省塘溪村的农户调查数据,采用数学规划方法,构建农户模型,并根据调查地区的现实状况,设置补贴强度、农资要素价格、农产品价格以及土地经营规模变化等情景条件,模拟研究粮食补贴政策在不同情景条件下对农户粮食生产和家庭收入的影响。结果显示,粮食补贴政策的增产增收效应与农产品价格变化呈现出正比关系,但与要素价格变化呈现反比关系,且粮食生产成本提高的负面影响明显超过粮食补贴政策的激励效应;扩大土地经营规模,有助于发挥粮食补贴政策对农户粮食增产和家庭增收的乘数效应。建议提高粮食补贴标准,进一步推进农村土地流转,促进粮食规模化生产经营;规范农业生产资料市场,逐步建立粮食补贴与农产品价格、尤其是生产要素价格的联动机制。     

国际粮食市场价格风险评估研究

为探讨国际粮食市场价格风险管理,本研究构建了国际粮食市场价格风险评估的基本模型,建立国际粮食市场价格波动序列,拟合国际粮食市场价格波动概率分布和计算国际粮食市场的风险价值（VaR）。通过对国际大米、玉米、小麦和大豆市场价格风险的实证分析,结果表明：正态分布并不是国际粮食市场价格波动的最优概率分布模型,国际粮食市场价格波动表现为服从Lognormal、Log-logistic和Burr分布;就整体而言,国际粮食市场价格风险较为严重,上涨的风险要大于下跌的风险;就具体品种而言,国际大米的市场价格风险最大,其上涨和下跌的VaR分别达到69.23%和34.31%,远高于玉米、小麦和大豆。     

气候变化对喀什市粮食产量的影响

利用1971—2007年气象资料及相关统计数据,以喀什市为研究区域,运用主成分分析法,定量分析气候变化对粮食产量的影响。研究表明:粮食产量变化波动中上升;气候生产潜力偏低,自然因素在粮食增产中的影响比重越来越高;降水稀少、蒸发旺盛成为限制作物增产的主要因素。     

玫瑰与粮食蔬菜间作种植研究

玫瑰与蔬菜、粮食间作田间试验研究表明,玫瑰花与粮食蔬菜间作经济效益是单植玫瑰的1.5~6.0倍,从地力、空间和时间3个方面分析了间作成功的机理;筛选出的7种优良模式,可在不同的条件下推广应用于生产。     

基于模拟实验的淀粉粒形态变化及其农业考古学意义——以小麦为例

[目的]为了迅速准确的对中国各农业遗址中的淀粉粒残留物进行鉴定,需要进行现代植物淀粉粒形态变化研究和模拟实验分析不同试剂和实验处理方法对淀粉粒形态的影响。[方法]研究现代小麦成熟过程中淀粉粒形态变化,完成了对成熟小麦的一系列模拟试验,如：研磨、超声波处理、盐酸和双氧水处理、干燥处理。[结果]成熟过程中小麦淀粉粒经历了由小到大的变化,最后稳定在由大、小两组淀粉粒组成;研钵研磨会使小麦淀粉粒粒径增大;较长时间的超声波处理使得小麦淀粉粒粒径增大;浓度为10%的盐酸和浓度为6%双氧水对小麦淀粉粒的影响很小;低温干燥处理不会使小麦淀粉粒出现糊化。[结论]该研究结论可有效地指导考古遗址古代样品淀粉粒分析实验流程以及处理参数的选择,提高了淀粉粒分析的效率和结果的可靠性。同时也为中国的农业起源和作物传播的研究提供了基础实验资料。