台湾稻螟发生期预测技术与应用     

蒙显标  陈强  陆寿成  陈永宁  刘忠调  麻显球 《植物保护学报》1997,24(2):133-136

作者采用室内外结合的方法,根据台湾稻螟幼虫、蛹、卵的形态特征,制定了台湾稻螟分龄分级标准,并按所测定的相应虫态历期,采用分龄分级法进行了3年的发生期预测验证,平均准确率达96.7％,用于指导大田防治1.93万hm~2,平均防治效果达85.8％。  相似文献   

优质牦牛肉肉质的综合评价   总被引：8，自引：0，他引：8  

冶成君 《青海畜牧兽医杂志》2004,34(4):18-19

2000-2002年对大通牛场40头6月龄不同性别的全哺乳牦牛的肉质进行了综合评价。对供试牦牛肌肉pH、嫩度、肌纤维细度、系水率、肉的贮存损失、肉的煮熟时间、熟肉率和烹饪损失率及肉色等进行了评价，分析了肌肉的化学成分，氨基酸及微量元素含量。结果表明该牦牛肉系水率强，肉的煮熟时间短，肉的贮存损失及烹饪损失较小，肌纤维较细，肉色深红。并具有蛋白质含量高，脂肪含量低及富含各种氨基酸的特点。  相似文献   

闭锁群体BLUP选择下遗传方差和近交系数的变化     

鲁绍雄  连林生  李明丽 《畜牧与兽医》2004,36(8):13-15

采用计算机随机模拟方法模拟了在一个闭锁群体内连续对单个性状进行 1 5个世代选择的情况。选择过程中世代不重叠 ,每个世代的种畜根据动物模型最佳线性无偏预测 (BLUP)法估计的育种值进行选留 ,并在此基础上系统地比较了不同群体规模、公母比例和性状遗传力对群体遗传方差和近交系数变化的影响。结果表明 ,扩大育种群规模、增加公畜比例以及对低遗传力性状进行选择时 ,群体遗传方差降低的速度和近交系数上升的速度会更慢 ,在长期选择时可望获得更大的持续进展和适宜的近交增量  相似文献   

葡萄品种浆果成熟期多样性及归类标准评价   总被引：5，自引：0，他引：5  

刘崇怀  潘兴  郭景南  樊秀彩  孔庆山 《果树学报》2004,21(6):535-539

对郑州葡萄圃内260个鲜食和153个酿酒品种的浆果成熟期进行了鉴定评价。在郑州地区,最早熟的葡萄种质材料早莎巴珍珠6月29日生理成熟,果实发育期48d;最晚熟的种质材料大宝10月12日成熟,果实发育期144d,在其间的103d时间里不断有成熟的葡萄品种,表现了丰富的多样性。酿酒葡萄的果实成熟期相对集中,大多数酿酒葡萄品种在8月中旬成熟,7月份和9月份成熟的葡萄品种所占的比例极少。果实发育期≤60d、61～80d、81～100d、101～120d、≥121d的品种次数呈正态分布,果实发育期81～100d的品种占收集品种的53.03%;果实发育期少于60d的极早熟品种和果实发育期多于120d的极晚熟品种所占比例较少。早、中、晚熟品种按照浆果发育期进行归类较为简便。  相似文献   

优质白菜新品种‘暑绿’     

侯喜林  曹寿椿  张蜀宁  张增翠  王建军  孙红霞 《园艺学报》2004,31(3):421-424

 ‘暑绿’系白菜一代杂种，亲本为SW-13和SU-124(矮×苏)。该品种株型直立、束腰，叶片近圆形、翠绿色，叶柄半圆、绿白色。品质佳，株型美观，叶片与叶柄质量比值为0.67，单株质量0.40 kg。高抗炭疽病，抗TuMV、霜霉病和黑斑病。适宜在喜食青梗菜的地区作夏菜、秋菜和秋冬菜栽培。  相似文献   

ANN在森林资源预测中的应用研究   总被引：4，自引：0，他引：4  

张锦宗  朱瑜馨 《干旱区研究》2004,21(4):374-378

人工神经网络(ANN)方法是基于实例的方法,不需要考虑数学模型的内部结构,不需要假设前提条件,不需要人为地确定因子权重,作为一个黑箱综合地映射研究对象的整体性。应用人工神经网络多步预测方法对甘肃连城林场吐鲁沟营林区有林地面积进行预测,网络模型的最大相对误差为0 080 8％,最小相对误差达到0 0089％,平均为0.038 6％,表明预测值与实际值吻合程度很好,因此模型的精度较高,并且建模简单经预测,林场2000-2004年有林地面积稍有下降趋势,分别为2 873.2 hm2,2 618 7 hm2,2 484.5 hm2,2 346 hm2,2 171 6hm2。  相似文献   

Including an additional systematic environmental effect within a generation in an evaluation model improves accuracy of prediction of breeding values in a closed herd of pigs     

Masahiro SATOH 《Animal Science Journal》2004,75(2):97-102

The present study evaluated the advantage of mixed‐model techniques over a selection index under different magnitudes of an additional systematic environmental effect (ASEE) in terms of accuracy of prediction and expected genetic gain. The data attempted to simulate a closed herd in a pig breeding program. The base population (G₀) consisted of 10 males and 50 females. Six generations (G₀ to G₅) were selected by using a selection index of three traits without overlapping. Additional systematic environmental constants with four levels in a generation were assigned from a uniform distribution at different ranges. Breeding values of animals in the last generation (G₅) were estimated on the basis of an index of individual phenotype (SI‐U), SI‐U adjusted for ASEE using a least‐squares mean (SI‐A), best linear unbiased prediction using an animal model excluding ASEE (AM‐E), and an animal model including ASEE (AM‐I). Accuracy of prediction and expected genetic gain were larger by the animal model than by the selection index, even if heritability of the traits selected was high and ASEE was set to zero. When ASEE was zero, the accuracy of prediction and expected genetic gain given by SI‐U and AM‐I were similar to those given by SI‐A and AM‐E, respectively. However, the differences in accuracy and expected gain between SI‐U and AI‐A and between AM‐I and AM‐E increased as the range of ASEE increased. It was concluded that selection based on an animal model was more effective than index selection, even if the herd environment was uniform and traits with high heritability were selected, and that it should be always included in an evaluation model, however slight any systematic environmental effect may be in a closed herd.  相似文献   

A perspective on the measurement of time in plant disease epidemiology   总被引：2，自引：1，他引：2  

D. J. Lovell †  S. J. Powers  S. J. Welham  S. R. Parker 《Plant pathology》2004,53(6):705-712

The growth and development of plant pathogens and their hosts generally respond strongly to the temperature of their environment. However, most studies of plant pathology record pathogen/host measurements against physical time (e.g. hours or days) rather than thermal time (e.g. degree-days or degree-hours). This confounds the comparison of epidemiological measurements across experiments and limits the value of the scientific literature.  相似文献   

The effect of sowing date, stale seedbed, row width and mechanical weed control on weeds and yields of organic winter wheat   总被引：1，自引：0，他引：1  

I A Rasmussen 《Weed Research》2004,44(1):12-20

Three field experiments were carried out in organically grown winter wheat in Denmark. The treatments were sowing time (normal or late sowing) and false seedbed, row width (12 and 24 cm) and weed control method [untreated; mechanical weed control (weed harrowing at 12 cm supplemented with inter‐row hoeing at 24 cm); and herbicide weed control]. Weed biomass in midsummer was greatest on plots sown at the normal sowing time (compared with delayed sowing) and was reduced by mechanical or chemical weed control (compared with untreated plots). Row width alone had no influence on weed biomass, but in the experiment with high weed pressure, the more intensive mechanical weed control used at a row width of 24 cm reduced weed biomass. Normal sowing time tended to give higher yields, but this was only statistically significant in one of the three experiments. Wide rows gave a yield decrease in the experiment with low weed pressure. The effect of weed control on yield was dependent on the weed pressure. At low weed pressure, mechanical weed control caused a yield decrease compared with untreated or herbicide treated. At intermediate weed levels there were no differences, whereas at high weed pressure, mechanical weed control and herbicide treatment caused a yield increase compared with untreated. False seedbeds were shown to contribute to a decrease in the soil seed reserve.  相似文献   

Pharmacokinetics of tiludronate in horses: A field population study          下载免费PDF全文

M. A. Popot  M. Jacobs  P. Garcia  B. Loup  J. Guyonnet  P. L. Toutain  L. Bailly‐Chouriberry  Y. Bonnaire 《Equine veterinary journal》2018,50(4):488-492

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