共查询到18条相似文献，搜索用时 218 毫秒
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此前,我曾在本刊发表过两篇介绍Kip Cullers创造大豆高产纪录的短文,有读者询问美国大豆高产竞赛的情况。我一直对美国的高产竞赛感兴趣,1997年在美期间,拿到一本1996年版的"衣阿华州玉米大豆种田能手竞赛手册",近来又搜集了 相似文献
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美国转基因玉米的生产概况和发展趋势 总被引：1，自引：1，他引：1
美国是世界上最大的玉米生产国, 种植面积、总产和单产均居世界首位。转基因玉米自1996年引入生产以来,使玉米生产上了一个新台阶。当前推广利用的转基因玉米品种基本上是抗虫和抗除草剂两种类型。抗虫是由在玉米体内表达Bacillus Thuringiensis(Bt)毒素结晶蛋白(cry蛋白)基因所致,除草剂的抗性(Herbicide tolerance, HT)是由外源的或改良的EPSPS基因在玉米体内表达来实现。转基因玉米的种植面积每年都稳步上升,转基因玉米的也由单一的Bt或HT转变为多基因多性状的叠加,将抗玉米螟和抗Rootworm结合,使玉米的地上部和地下部都得到了有效的保护,再加之抗除草剂基因的叠加,使得转基因品种在生产上更具竞争力。转基因玉米的抗虫和抗除草剂等优良性状带来了巨大的经济和环境效益, 并被越来越多的大众所接受。转基因玉米在短短10年间的应用和发展,还不能回答转基因作物对人类和环境的长期影响等问题。因此,对转基因作物的管理和利用仍不能掉以轻心,不能因对生物技术的热情而对人类和环境造成无意的不可挽回的破坏。 相似文献
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《Field Crops Research》2005,91(2-3):329-336
Southwestern corn borer (Diatraea grandiosella Dyar) is a major pest of corn (Zea mays L.) in the southern United States. In addition to the direct yield losses caused by southwestern corn borer, larval feeding on developing ears provides a site for fungi to enter the ear. Aspergillus flavus Link: Fries infection and the subsequent accumulation of aflatoxin in corn grain are major limitations to profitable corn production in the southern United States. This investigation was conducted to determine the effectiveness of transgenic corn hybrids expressing the δ-endotoxin insecticidal (CryIAb) proteins isolated from Bacillus thuringiensis (Bt) in reducing southwestern corn borer damage and aflatoxin accumulation. Ear damage and aflatoxin accumulation were compared among 10 pairs of conventional nonBt and transgenic Bt corn hybrids following infestation with southwestern corn borer and inoculation with A. flavus using kernel-wounding and nonwounding techniques. Both nonBt and Bt hybrids exhibited high levels of aflatoxin accumulation when inoculated with a kernel-wounding technique. When inoculated with a non-wounding technique and infested with southwestern corn borer, aflatoxin accumulation was significantly higher in nonBt than Bt hybrids. Aflatoxin accumulation was also significantly higher for nonBt hybrids inoculated with A. flavus and infested with southwestern corn borer than for hybrids that were only inoculated with A. flavus. Southwestern corn borer larval establishment was significantly higher on nonBt hybrids than on Bt hybrids. Larval survival was extremely low on the Bt hybrids. The results of this investigation indicate that these Bt hybrids should be effective in reducing aflatoxin contamination in areas where high southwestern corn borer infestations occur. The reduced levels of aflatoxin accumulation associated with Bt hybrids are likely a consequence of reduced insect damage rather than resistance to A. flavus infection or aflatoxin accumulation per se. 相似文献
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Brown stink bugs, Euschistus servus, are an important early-season pest of field corn in the southeastern United States. Feeding in the early stages of corn development can lead to a number of growth deformities and deficiencies and, ultimately, a reduction in yield. An observational and two experimentally manipulated trials were conducted in 2017 and 2018 to 1) determine optimal timing for assessing brown stink bug damage, 2) assess the level of damage from which yield compensation can occur, and 3) examine the relationship between brown stink bug density and early-season damage and yield. Fields were identified with infestations of brown stink bugs and a damage rating system for early stages of corn was established. Varying rates of brown stink bug densities were introduced using field cages and damage was assessed throughout the season. The density and duration of stink bug infestations were critical factors for damage potential, with each day of active feeding per plant resulting in a loss of ~14 kg/ha in yield. The level of damage in early stages of corn was categorized into easily identifiable groups, with only the most severe damage leading to a reduction in yield. Moderate and minimal feeding damage did not result in yield loss. This study emphasizes the need for early and frequent scouting of corn to determine the risk of damage and yield loss from brown stink bugs. Results from this study can be used to help develop management programs for brown stink bugs in the early vegetative stages of field corn. 相似文献
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高产优质甜玉米新品种筛选 总被引：4，自引：0，他引：4
试验以33个甜玉米新品种为材料,进行两年区域试验和1年生产试验,分析各品种的产量、品质、抗性及其他农艺性状,筛选满足市场需求适合广东种植的高产优质突破性甜玉米新品种。结果表明,广良甜31、粤甜28等6个甜玉米新品种产量均比对照品种粤甜16号增产5%以上,甜度高甜,果皮薄或较薄,两年品尝评分平均值均达87.5分以上,综合抗性好,是高产优质新品种。广良甜31产量最高,粤甜28品质最好,圣甜2号生育期最短。 相似文献
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利用辽宁省铁岭市蔡牛镇玉米生产农户2018～2019年连续跟踪实地调研数据,对春玉米条带耕作密植高产技术的应用经济效果进行分析,并基于随机前沿生产函数模型对农户玉米生产的技术效率进行评价。研究表明,种粮大户、合作社等有较大生产规模、农业收入占家庭总收入比重大、户主受教育程度较高的农户更倾向于应用技术,普通农户应用技术比例较低。不论是灾害年还是正常年,春玉米条带耕作密植高产技术显著提高了玉米生产农户的经济效益和技术效率,与正常年份比,在灾害年份更能发挥提高经济效益、技术效率的优势。政府应加大对该技术的宣传力度,提高农民专业素质,鼓励农户规模化经营,加大技术补贴力度,以提高春玉米条带耕作密植高产技术的应用。 相似文献
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以7个不同血缘的紫玉米杂交组合ZS11、ZS15、ZF39、FS11、SF38、FG01、68G1为试验材料,研究不同基因型紫玉米氮素吸收利用的基因型差异。结果表明,不同基因型紫玉米植株氮素含量和积累量均存在显著差异,紫玉米植株氮素含量在整个生育期间均呈逐渐下降趋势,氮素积累量呈上升趋势。7个品种中成熟期子粒产量高、吸氮总量大、氮素利用效率高的组合为SF38和68G1。通径分析和相关分析表明,氮素利用效率对不同品种产量的高低起主要作用,氮素吸收总量对产量的作用相对较小。从氮素的阶段积累与产量的关系来看,开花期至灌浆期吸氮量增加有助于紫玉米产量的提高,其次为大喇叭口期至开花期。 相似文献
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对"3414"田间试验各处理玉米产量和不同氮水平(N0=0、N1=93.75、N2=187.5、N3=281.25 kg/hm~2)下测定土壤无机氮,探究N、P、K不同配比施肥对玉米产量的影响和不同氮水平下土壤无机氮的变化特征。结果表明,施氮对玉米产量的影响达到差异显著水平,施磷、钾肥对玉米产量的影响差异不显著。随着施氮量升高,玉米产量先升高后稳定,通过方差分析确定当地最佳推荐施氮量变化范围为93.75～281.25 kg/hm~2。施氮可以提高1 m土壤中铵态氮和硝态氮的积累量。铵态氮易被固定,拔节期以后,土壤中铵态氮积累较为稳定。硝态氮在土壤中变异较大,尤其在高施氮量(281.25 kg/hm~2)时,1 m土体中硝态氮积累量显著增加。无机氮总量与施氮量显著相关,当施氮量为281.25 kg/hm~2时,大大增加中期(抽雄期)氮素损失风险,确定安全施氮量处于187.5～281.25 kg/hm~2。提高产量、减少氮素损失的生产目标,207.27 kg/hm~2的施氮量为当地经济安全施氮量。 相似文献