山东生态条件下纯作春棉的适宜密度研究

以常规抗虫棉鲁棉研28号为材料,在山东广饶、夏津和冠县三地大田条件下纯作种植,研究了不同密度（3.00～9.00株/m2）下的棉花产量及产量构成。结果表明,种植密度对纯作抗虫棉产量、产量构成以及熟相均有显著的影响,对经济产量的调控效应三个试验点大致相同,都随密度的增加呈现先升后降的趋势。即低密度（3.00株/m2）和高密度（9.00株/m2）处理的产量低,中高密度（4.50～7.50株/m2）的产量较高。三个点平均,6.00株/m2密度处理的籽棉和皮棉产量与4.50株/m2处理相当,但比3.00株/m2分别增产10.1%和12.0%,比9.00株/m2处理分别增产22.3%和22.8%。提高密度能提高单位面积的生物产量和单位面积铃数,但可显著降低棉柴比、铃重和早熟性。密度偏高和偏低都不能获得较高的经济产量和协调的产量结构,山东春棉纯作条件下适宜种植密度为4.50～6.00株/m2。     

伴生分蘖洋葱对番茄根际微生物群落结构的影响

以分蘖洋葱和番茄为材料,采用高通量测序研究伴生分蘖洋葱对番茄根际土壤细菌和真菌群落的组成和结构的影响。结果表明:与番茄单作相比,分蘖洋葱伴生处理改变了番茄根际土壤细菌和真菌群落的组成,变形菌门(Proteobacteria)、拟杆菌门(Bacteroidetes)、放线菌门(Actinobacteria)、酸杆菌门(Acidobacteria)、厚壁菌门(Firmicutes)、浮霉菌门(Planctomycetes)和绿弯菌门(Chloroflexi)为优势细菌门,子囊菌门(Ascomycota)、接合菌门(Zygomycota)和担子菌门(Basidiomycota)为优势真菌门;在纲水平上,分蘖洋葱伴生处理显著提高了具有有益潜力的α-变形菌纲(Alphaproteobacteria)的相对丰度,显著或极显著降低了粪壳菌纲(Sordariomycetes)和散囊菌纲(Eurotiomycetes)的相对丰度;在目水平上,分蘖洋葱伴生处理显著提高了鞘脂单胞菌目(Sphingomonadales)和丙酸杆菌目(Propionibacteriales)的相对丰度,显著或极显著降低了小囊菌...     

Can winter cover crops influence weed density and diversity in a reduced tillage vegetable system?

Weeds are a major constraint for organic crop production. Previous research has found that cover crops in reduced tillage systems can provide weed interference, subsequently reducing inputs and improving crop yield. However, questions remain about effects of cover crop species identity and cover crop biomass on weed suppression and crop yield. This four-year study investigated how winter cover crops grown alone or in mixture influenced weed presence and crop yield in a reduced tillage organic vegetable system. Treatments were barley (Hordeum vulgare L.), crimson clover (Trifolium incarnatum L.), mixed barley + crimson clover, and a no-cover crop control. Plots were flail-mowed and strip-tilled prior to planting main crops (2011 and 2012: broccoli Brassica oleracea L.; 2013 and 2014: crookneck squash Cucurbita pepo L.). We measured density, diversity, and community composition of weeds and viable weed seeds, changes in weed percent cover within growing seasons, and crop yield. We found that the presence of barley, crimson clover, or barley + crimson clover reduced weed density by 50% relative to the control. Cover crop biomass negatively influenced weed density and weed seed diversity, and positively influenced squash yield. Weed percent cover within growing seasons did not respond differentially to cover crop treatment. Cover crop treatment and cover crop biomass had no influence on weed or weed seed community composition. These results suggest that reduced tillage winter cover crops in mixture or monoculture can similarly suppress weeds and improve yield, primarily due to biomass effects.     

Response of winter rye to long-term monoculture under the conditions of varied chemical plant protection level

The response of winter rye to a 26-34 year monoculture cultivation was followed in 9-year investigations carried out on loess-based, dusty, medium-heavy soil in the years 1993-2001. Parallel rye cultivation in a 6-plot crop rotation was the control object. The study included 3 levels of chemical plant protection of the corn: O - no protection, H - protection against weeds, HF - protection against weeds and diseases. The mean rye grain yield in the crop rotation amounted to 6.22 t ha m 1 during the period of study. The monoculture decreased its productivity by 26.4% on average. A negative response of rye to being sown after itself was dependent on the protection level. The rye yield decrease in the monoculture became lower with an intensification of the crop protection: 0-38%; H-20.5%; HF-19.9%. Lower rye yields in the monoculture are the result of crop thinning and deterioration of the spike yield and grain size.     

Concentrations and seasonal dynamics of dissolved organic carbon in forest floors of two plantations （Castanopsis kawakamii and Cunninghamia lanceolata） in subtropical China

The concentrations and seasonal dynamics of DOC in forest floors of monoculture plantations ofCastanopsis kawakamii and Chinese fir (Cunninghamia lanceolata) were assessed in Sanming, Fujian, China (26°11′30″N, 117°26′00″E). Forest floor samples were taken in January, April, July and October in 2002 and divided into undecomposed material (horizon Oi), partially decomposed organic material (horizon Oe), and fully decomposed organic material (horizon Oa). Upon collection, DOC concentrations of samples were analyzed by a High Temperature TOC. The results showed that the annual average DOC concentration of Chinese fir (1341.7 mg·kg⁻¹) in the forest floor was higher than that ofCastanopsis kawakamii (1178.9 mg·kg⁻¹). Difference in DOC concentrations was observed among three horizons of the forest floor. DOC concentration of forest floor in the two forests was the highest in horizon Oe. Seasonal trends of DOC concentrations in different horizons of forest floors were similar and the maximal value occurred in autumn (or winter). The concentration and temporal change of DOC in studied forests were probably related to the variation in moisture, temperature, biological activity and quantity of organic matter in the forest floor. Foundation item: This study was supported by the Teaching and Research Award program for MOE P.R.C. (TRAPOYT) Biography: ZHANG Jiang-shan (1946-), male, Researcher in Fujian Normal University, Fuzhou 350007, P.R. China. Responsible editor: Zhu Hong     

耐阴与不耐阴大豆茎叶性状的变异及差异比较研究

大豆不耐阴品种的性状变异大于耐阴品种,茎叶性状中,叶形指数的变异最小、柄角的变异最大,表明叶形性状较稳定、柄角性状易受环境影响,对照单作,大豆间作后,节长增加,节径和柄茎变细,比叶鲜,干重下降,两类型大豆有着基本一致的消长趋势,但在消长平准上,不耐阴品种比耐阴品种显著。柄角,柄长和叶片的长、宽及面积等五性状,在中、高节位上的叶层变化及差异,表现了不耐阴品种对弱光环境反应的敏感和耐阴品种的钝性。耐阴     

我国蓝子鱼养殖模式探析

对我国蓝子鱼的养殖模式与养殖现状等进行了阐述,包括常见的蓝子鱼养殖品种、常规单养模式、生态混养模式和利用蓝子鱼的食性特点开展有害藻类生物防控等,分析了蓝子鱼养殖产业发展过程中存在的问题,并对蓝子鱼养殖产业发展前景和潜在的热点研究方向进行了展望。     

Saprophytic soil microflora in relation to yield reductions in soil repeatedly cropped with barley (Hordeum vulgare L.)

Summary The yield-depressing effect due to repeated cropping (monoculture) of barley reported from long-term field experiments was observed as a reduction in plant growth in short-term pot experiments. The nature of the monoculture effect was investigated by mixing field soils with different cropping histories in different proportions in the greenhouse, while the influence of rhizosphere microflora from the monocultured and crop rotation soils on barley growth was studied in gnotobiotic experiments. Indigenous bacterial populations and the pH of the test soils were also measured. Significantly more bacteria were found in the crop rotation soil compared to the monocultured soil, but the two soils did not differ in pH. Greenhouse experiments showed that in the monocultured soil, seed germination was delayed and plant dry weight reduced, and that these effects had a biological origin. Attempts were also made to induce the monoculture effect in the crop rotation soil by inoculation with known harmful bacteria. The results from the experiments with mixed soils and with soil inoculation indicated that where crop rotation was practised the soil was more sensitive to bacterial effects than the monocultured soil. The rhizosphere microflora from the monocultured soil did not affect plant weights in short-term gnotobiotic experiments, but it significantly stimulated the number of lateral roots compared with the crop rotation microflora. This stimulation could not be related to differences in bacterial counts, pH, or ion concentrations in the plant-growing medium.     

辽宁西部地区油松水土保持纯林改造与评价

辽宁省西部营造有大量用于水土保持的油松人工纯林。如何改造这些低效的纯林是生产实践中面临的一个严重问题。根据近自然林业思想,通过实践提出了带状皆伐栽植阔叶树,块状皆伐栽植阔叶树和林中空地、林缘等栽植阔叶树改造现有的油松纯林具体方法。论述了改造的对象和树种选择等问题,并详细介绍了每种方法的关键技术及其应用条件。通过实际调查和对比分析,对经过带状改造的油松林进行了评价。结果表明,16年后,采用上述方法改造的油松林具有明显的分层结构,林下植物物种多样性增加了23．5％-52．9％,土壤脲酶、磷酸酶和蔗糖酶活性比对照分别提高了6％-142％,46％-99％和31％-200％,松毛虫危害得到有效控制,水土保持功能也得到提高。图2表3参37。     

棉花抗枯萎病品种连作田微生物数量变化 Ⅱ棉花枯萎病抑病土成因

从棉花抗病品种连作3、6、8、9、10a的土样中分离出3830个真菌菌落,其主要类群归入11个真菌属.随着棉花抗病品种连作年限的增长,土壤中真菌和放线菌的种类和数量逐渐增加,而棉花枯萎菌的数量则逐渐减少.对棉枯萎菌抑制性较强的种类有:细黄链霉菌(Streptomyces microflavus)、球孢链霉菌黄色变种(S.globispvar.flavus)和紫链霉菌淡红变种(S.violaceus).供试土样中分离到的3315个细菌菌落按菌落特征可分为9个类型,其中Ⅲ型和Ⅸ型对棉枯萎菌有较强的抑菌作用,初步鉴定为枯草芽孢杆菌Bacillus subtilis.和B.sp.,它们在连作年限较长的土样中出现的频率较高,但土样中细菌的总数量与棉花抗病品种连作的年代成反相关.供试土样中分离出5种主要线虫,其中螺旋线虫、滑刃线虫、真滑刃线虫的数量也随抗病棉花连作时间的延长而增加.