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1.
对治理荒山荒坡常用的封育、补播、重新建植三种方法进行了对比、调查和分析。结果表明,采用补播措施治理荒山荒坡是较为有效的途径,也是合理开发利用荒山荒坡、尽快恢复植被、控制水土流失和改善生态环境经济实用而又可行的方法。 相似文献
2.
不同播期和不同肥力条件下向日葵干物质形成和物质分配对杂交种产量的影响 总被引:9,自引:4,他引:5
不同的播期明显影响向日葵籽实产量及病害发生的程度。通过调整播期,可防止或减轻叶部斑病和菌核病的发生,在向日葵生产上起着很大作用。向日葵不同品种干物质积累规律符合Logistic生长曲线,可用方程y=k/(1 ae^-bx)模拟。向日葵植株的器官平衡依次为:除空壳外,茎秆(28.5%)、籽实(24.5%)、叶片(22.5%)、葵盘(17.3%)、叶柄(4.9%)。土壤肥力对向日葵的器官平衡有较大影响。经济系数不高是向日葵的一个特点。栽培条件不同,经济系数差异较大。在一般情况下,春播条件下经济系数较高,夏播条件下经济系数较低。 相似文献
3.
4.
奎屯地区农七师位于天山北麓,准噶尔盆地的西南缘,总面积5986km2,其中作物种植面积120万亩,随着农七师产业结构的调整,2003年实施了“万头澳牛引进工程”,养牛业的发展使农七师畜牧业对玉米的需求量增加,尤其是澳牛养殖业对青贮玉米需求量更大,因此,研究分析气象要素对玉米播种及苗期的影响是重要工作之一。 相似文献
5.
应用断裂力学理论和实验技术,测定了重油催化再生器材料及焊缝的力学性能和断裂韧度值,按照《压力容器缺陷评定规范》(CVDA-84)对再生器下部筒体典型缺陷进行了评定。经分析计算获得了重油催化再生器下部筒体各部位各种裂纹类型缺陷的允许尺寸,可将其作为重油催化再生器无损检测时的缺陷评定指标。 相似文献
6.
分析了水稻机械化喷直播技术的特点和技术要求,介绍了水稻机械化喷直播技术的应用现状及其技术推广的制约因素.提出了推广水稻机械化喷直播技术的对策. 相似文献
7.
Field studies were undertaken to explore the weed management strategies for transplanted and direct wet-seeded rice in the Dera Ismail Khan district of North-west Frontier Province, Pakistan. The experimental design was a randomized complete block with a split plot arrangement. The main plots consisted of two planting techniques (transplantation and direct seeding), while weed control practises assigned to the subplots included the use of the granular herbicide Sunstar 15WG (ethoxy sulfuron), Machete 60EC (butachlor), conventional hand weeding, and the weedy check (untreated control). Data were recorded on weed dynamics and the agronomic parameters of the rice crop. Economic analyses on the data were also run. The weed density and biomass were lower in the transplantation plots than the direct-seeding plots. The herbicides ethoxy sulfuron and butachlor reduced the density over the weedy check, with a density comparable to hand weeding in 2002, but slightly higher in 2003. As a result of weed management by hand weeding and herbicides, the paddy yield and its components were significantly higher for the transplanted method compared to the direct-seeded method. The comparable yield of herbicides with hand weeding offers an option for the use of herbicides as an alternative management tool. In light of our findings, it is concluded that for good economic returns, rice crops may be transplanted rather than direct-seeded. The herbicides ethoxy sulfuron and butachlor offer a weed control cover comparable with hand weeding under the transplantation method, while butachlor is good for controlling weeds even under the direct-seeded conditions in the agroclimatic conditions of the area. 相似文献
8.
The establishment of predacious mites in commercial orchards may be accelerated by the transfer of pruned wood in winter and
summer from donor orchards to release orchards. Following winter pruning, 3-year-old and older wood is collected and transported
as soon as possible in bundles to a release orchard for distribution. If the release orchard is composed of dwarf trees, then
one or two bundles of 5 kg each are placed vertically at the base of the trunk of every tree in the block (0.5 to 1 ha); if
the trees are of standard size, then four or five bundles used. Following summer pruning, annual shoots and suckers are distributed
immediately in a release orchard composed of dwarf trees by placing 12–15 branches on the foliage of fruit-bearing branches;
if the release orchard is composed of standard trees, then 50 branches are used. The pruned wood should have 20–25 leaves
and not less than one predator per leaf. The release orchard should have a light infestation (two or three mites per leaf)
of pest tetranychids. These phytophagous mites would serve as food and help establish the predators. The release orchard grower
should develop a pest management program based on the same groups of pesticides used in the donor orchard.
http://www.phytoparasitica.org posting Aug. 31, 2005. 相似文献
9.
V. Sandilands F. Whyte L. K. Williams T. S. Wilkinson N. H. C. Sparks T. J. Humphrey 《British poultry science》2018,59(6):698-702
ABSTRACT1. Chicken-associated Campylobacter spp. are the cause of most food poisoning cases in Europe. In order to study the host–pathogen interactions, a reliable and reproducible method of colonising chickens with the bacteria is required.2. This study aimed to identify a more appropriate and less invasive method of colonisation (cf. gavaging) by seeding bedding material (litter) that commercial chickens are kept on with a mixture of Campylobacter spp., broth and faeces.3. The first phase of the study tested the longevity of Campylobacter spp. recovery in seeded litter over 24 h: significantly more Campylobacter spp. was recovered at 0 or 3 h post-seeding than at 6 and 24 h post-seeding, indicating that the pathogen can survive to detectable levels for at least 3 h in this environment.4. In the second phase, three groups of 10 broiler chickens (negative for Campylobacter spp. prior to exposure) were exposed at 21 days of age to one of three different Campylobacter jejuni and C. coli mixes (A, B, C), using the method above. At 28 days of age, birds were euthanised by overdose of barbiturate or cervical dislocation, and livers and caeca removed for Campylobacter spp. assessment.5. All liver and 28/30 caeca samples tested positive for Campylobacter spp., with mix A and C giving higher counts in the caeca than mix B. The method of euthanasia did not affect Campylobacter spp. counts.6. In conclusion, a successful method for reliably colonising broiler chickens with Campylobacter spp. has been developed which negates the need for gavaging and is more representative of how contamination occurs in the field. 相似文献
10.
采用基质盆栽试验,研究了铺地竹(Sasa argenteastriatus E.G.Camus)叶片对结球生菜(Lactucasativa L.var.capitata L.)种子萌发和幼苗生长的影响,结果表明,铺地竹叶片粉末对结球生菜种子的萌发和幼根生长具有一定的抑制作用,随着浓度的增加抑制作用增强,在50~200 g/m2的范围内,幼根抑制率为12.15%~28.91%。在50~100 g/m2的用量下,铺地竹叶片对结球生菜苗长表现为促进生长作用,而在200 g/m2时,则表现为抑制生长作用。施用铺地竹叶片后3 d、6 d、9 d和12 d,结球生菜幼苗的叶绿素含量特别是叶绿素a的含量显著减少,随着基质中叶片粉末浓度的增加,结球生菜叶绿素含量降低,叶绿素a含量高低依次为对照、低浓度处理、中浓度处理、高浓度处理。随着处理后时间的延长,竹叶对结球生菜叶片叶绿素a含量的影响减弱。这个结果进一步验证了自然条件下铺地竹叶片对植物生长的化感效应,说明其具有开发植物源除草剂的潜力,为研究铺地竹叶片中的化感物质提供了佐证。 相似文献