秸秆覆盖免耕对土壤细菌群落区系的影响

多年连续秸秆覆盖免耕对土壤细菌群落影响很大,免耕可提高０－１０ｃｍ土层土壤细菌总数、放线菌数、棒状细菌数和贫营养细菌数量,特别是免耕土壤能使芽孢杆菌数量增多几倍。     

不同控草措施对高温季节华南地区蔬菜田杂草群落的影响

华南地区高温季节从6月持续到10月,田间杂草危害严重,当前高温季节田间杂草群落发生格局相关的研究资料积累不足。因此在广州高温季节于标准化菜田通过田间杂草调查、小区控草试验和室内土壤培养,研究了杂草群落发生规律和菜田不同清园和土壤处理控草措施对田间杂草群落短期防效和后续影响。结果表明,试验田休耕50 d后,田间杂草群落中禾草类杂草种类较少但发生量明显占优,阔叶类杂草种类较多而危害总体较轻,莎草类杂草种类较少,发生量与阔叶草相当;牛筋草(Eleusine indica)呈现明显的单优势,光头稗(Echinochloa colona)、千金子(Leptochloa chinensis)、碎米莎草(Cyperus iria)、草龙(Ludwigia hyssopifolia)等的盖度也较高。休耕后取田间土壤在不同温度条件下培养的结果亦表明,高温促进禾草类杂草的出苗和幼苗生长(尤其是40℃/35℃)而15℃恒温培养14 d几乎仅有阔叶类杂草出苗。不同控草措施处理的田间试验结果表明,百草枯处理(900 g a.i./hm~2)后阔叶类杂草总盖度上升的趋势被扭转为禾草类杂草持续占优势;喷施百草枯并铲草处理30 d后杂草盖度即恢复至60%以上,而配合喷施丁草胺(1350 ga.i./hm~2)、乙草胺(750 ga.i./hm~2)、精异丙甲草胺(750 ga.i./hm~2)或二甲戊灵(600 ga.i./hm~2)进行土壤处理30 d后可使杂草盖度与仅喷施百草枯处理分别下降72.9%、84.6%、83.9%和77.5%;土壤处理前配合浅翻耕可明显提升控草效果。典范对应分析(CCA)结果表明,控草处理70d后,百草枯、铲草和翻耕处理均对试验田间杂草群落结构具有显著影响(P0.01),田间各主要杂草在CCA排序图中明显分为两个类群:1)光头稗、牛筋草、千金子、马唐(Digitaria sanguinalis)、水虱草(Fimbristylis miliacea)和三头水蜈蚣(Kyllinga triceps);2)草龙、胜红蓟(Ageratum conyzoides)、鳢肠(Eclipta prostrata)、马齿苋(Portulaca oleracea)等阔叶类杂草和碎米莎草。     

秸秆覆盖免耕土壤细菌和真菌生物量与活性的研究

土壤微生物生物量在土壤生态系统中具有非常重要的作用。大量的试验研究表明 ,土壤微生物生物量是植物营养元素的一个重要的源与库 ,生物量对土壤养分的调控作用 ,已经成为土壤培肥、耕作制度改革和作物栽培实践中的重要理论依据之一。自从Jenkinson提出了测定土壤微生物量的原理和概念以来 ,Jenkinson和 Powlson提出了测定微生物生物量的方法[16] ,Van De Werf和 Verstraete提出了土壤微生物生物量可以分为全微生物量和活动微生物量[10 ] ,Anderson和 Domsch提出了生物量与生物活性中细菌与真菌的比例为 2 2 /78% [8]。虽然生物量的研…     

多点接种方法计数土壤细胞生理类群的研究

多点接点计数方法是根据细菌分解固体培养基上不同的有机化合物的能力确定为不同的生理类群,由有机化合物的降解点数和根据MPN方法进行计数,对不同的耕作方法进行了测定表明,秸秆覆盖免肾够明显提高土壤中分解淀粉,木聚糖,纤维素,果胶,几丁质,卵磷质,脂类和蛋白质类群的细菌数量。     

长期免耕不同秸秆覆盖量对玉米产量及其稳定性的影响

阐明长期免耕不同秸秆覆盖量下玉米产量变化趋势及其稳定性差异,可为建立和评价长期保护性耕作模式、促进粮食持续生产提供理论支撑.本研究基于我国东北黑土区长期保护性耕作定位试验(始于2007年),以传统垄作(RT)为对照,分析了免耕无秸秆覆盖(NT0)、免耕33％秸秆覆盖(NT33)、免耕67％秸秆覆盖(NT67)和免耕10...     

休闲期深翻覆盖对旱地小麦土壤水分及籽粒蛋白质积累的影响

采用大田试验研究旱地小麦休闲期不同时间深翻不同材料覆盖对土壤水分、籽粒蛋白质形成的影响及其生理机制。结果表明:前茬小麦收获后45 d深翻覆盖较15 d可提高播前120～300 cm土壤蓄水量,而降低开花期0～300 cm(除80 cm土层外)土壤蓄水量;显著提高籽粒蛋白质及其组分含量、蛋白质产量、谷/醇比,提高旗叶GS活性及花后10～15 d、25 d旗叶GOGAT活性,均以渗水地膜覆盖效果较好。结果还表明,播前80～200 cm、开花期260～280 cm土壤蓄水量与旗叶GS、旗叶GOGAT活性显著相关,且与旗叶GS活性关系更密切。籽粒蛋白质组分含量、谷/醇比、蛋白质产量与旗叶GS、旗叶GOGAT活性显著相关,且与旗叶GS活性相关性较密切,尤其是谷/醇比。播前和开花期120～300 cm土壤蓄水量与籽粒蛋白质及其组分含量显著相关,播前60～220 cm、开花期240～300 cm土壤蓄水量与谷/醇比显著相关。总之,休闲期等雨后深翻覆盖有利于蓄积休闲期降雨,有利于提高播前深层土壤水分,最终提高籽粒蛋白质品质及质量,且采用渗水地膜覆盖效果最好。     

Age-related Feeding by the Parthenium Beetle Zygogramma bicolorata on Sunflower and its Effect on Survival and Reproduction

Freshly emerged adults of Zygogramma bicolorata Pallister (Coleoptera: Chrysomelidae), introduced for biological control trials against the noxious weed Parthenium hysterophorus , were seen to feed and lay eggs on sunflower leaves under confined conditions in the laboratory. The time taken for initiation of feeding was found to be positively correlated with adult age, while survival after feeding on the crop was negatively correlated. However, adults that had fed on sunflower even for 1 day on P. hysterophorus were incapable of ovipositing, and young larvae could not feed on the crop. Under field conditions, newly emerged adults were only attracted to feed on plants that were treated either with a crude aqueous extract of leaves or pollen grains of P. hysterophorus , indicating that the chances of Z. bicolorata becoming a pest of sunflower are negligible. Age-related Feeding by the Parthenium Beetle Zygogramma bicolorata on Sunflower and its EVect on Survival and Reproduction     

Organic mulches vs. black plastic in organic strawberry: does it make a difference for ground beetles (Col., Carabidae)?

Abstract:  Carabid beetles were sampled by pitfall traps in May–September 2002 and 2003 in an experimental organic strawberry field in seven different mulching row treatments and in fescue-growing row spaces to determine the effect of mulches on carabid activity–density and species composition. There were no differences between treatments or row spaces in total numbers of all carabid species in either season. Of the 67 identified species and 4374 individuals, the most trapped ones were Clivina fossor (11.7% of total catch), Dyschirius globosus (10.2%), Patrobus atrorufus (9.3%), Pterostichus niger (8.8%), Bembidion properans (7.4%), Pterostichus melanarius (6.0%), Bembidion lampros (5.7%), Pterostichus crenatus (5.7%), Amara communis (4.1%), Trechus secalis (3.9%), Pterostichus strenuus (3.9%), Loricera pilicornis (3.1%), Harpalus rufipes (2.8%) and Carabus nemoralis (2.6%). Large carabid species P. niger and P. melanarius were trapped more in all mulched rows than in row spaces, and C. nemoralis was trapped more in the mixture of pine woodchip/buckwheat husk mulch than in row spaces, barley straw and birch woodchip mulch. The small but abundant species P. atrorufus was trapped more in buckwheat husk mulch than in row spaces and B. properans in row spaces than in buckwheat husk mulch. H. rufipes , being also a pest in strawberry, was trapped more in cut grass mulch than in row spaces. The Shannon H' diversity index was significantly higher in the mixture of pine woodchip/buckwheat husk mulch than in black plastic, buckwheat husk mulch or in row spaces, and in birch woodchip and cut grass mulches than in row spaces. The results of trapping studies show the species preference to the specific mulches, and reflect positive or negative effect of mulches on carabid diversity with consequences to plant protection.     

银胶菊(Parthenium hysterophorus)中抗TMV活性成分的分离及活性测定

采用活性跟踪法从银胶菊中分离获得抗病毒活性物质,经质谱和核磁共振分析,确定该物质为小白菊内酯.采用半叶枯斑法和叶圆盘法测定了其对烟草花叶病毒(Tobacco mosaic virus,TMV)的抑制效果,结果表明:0.2 mg/mL的小白菊内酯在混合接种和药液浸泡两种处理中均表现出较好的体外抑制TMV活性,其抑制率分别为69.0%和72.1%;在离体条件下对烟草叶圆盘中的烟草花叶病毒复制也具有良好的抑制效果,抑制率为72.3%.     

Effects of Crop Residue on the Persistence of Steinernema carpocapsae

We determined the effects of crop residue on the persistence of an entomopathogenic nematode, Steinernema carpocapsae. During 2 consecutive years, nematodes were applied at rates of 2.5 × 10₄ and 1.0 × 10⁵ infective juveniles/m² to small field plots planted with corn. Nematode persistence was monitored by exposing Galleria mellonella larvae to soil samples from plots with and without crop residue (approximately 75% coverage of soybean stubble). Persistence of S. carpocapsae was significantly greater in crop residue plots than in plots without residue. In crop residue plots that received the higher rate of nematode application, larval mortality did not significantly decrease during the study period (3 to 5 days) and remained above 85%. In nematode-treated plots without crop residue, however, larval mortality fell from over 96% to below 11% and 35% in the first and second trials, respectively. The increased crop residue may have benefited nematode persistence through protection from desiccation or ultraviolet light. We conclude that increased ground cover in cropping systems (e.g., due to reduced tillage) may lead to increased insect pest suppression with entomopathogenic nematodes.     

Size-based intraspecific variations along altitudinal gradient and follow of Bergmann’s rule in Parthenium beetle,Zygogramma bicolorata Pallister

Body size in insects is coupled with numerous physiological, life-history and ecological traits. Its variation along temperature gradient is widely studied. However, information regarding variations in body size of insects along altitudinal gradient is limited. Present study was designed considering hypothesis that there would be an increase in body size of Parthenium beetle, Zygogramma bicolorata Pallister (Coleoptera: Chrysomelidae) with increasing altitude and decreasing in temperature. To achieve the objectives, beetles were collected from three eco-climatic zones of NEPAL [Kathmandu (1400 mts, 24 °C; warm temperate zone), Chitwan (415 mts, 25 °C; upper tropical/sub-tropical zone), and Mahendranagar (229 mts, 34 °C; humid subtropical zone)], and one of INDIA [Varanasi (81 mts, 36 °C; humid subtropical zone)] for their morphometric analysis (body length and body biomass). Results revealed that the size of beetles in all eco-climatic zones increased with increasing altitude and decreasing temperature. While adults of Kathmandu were largest, followed by Chitwan and Mahendranagar, but those of Varanasi were smallest in size. The sex ratio was female-biased in Kathmandu and Varanasi, but was male-biased in Chitwan and Mahendranagar. Irrespective of temperature and altitude, females were larger than males in all eco-climatic zones. Our results affirmed our hypothesis and were in compliance with Bergmann’s rule. The findings may be helpful in understanding phenotypic plasticity and distribution pattern of Z. bicolorata adults in Indian sub-continent under global climate change scenario.     

Does Zygogramma bicolorata Pallister really affects the growth,density and reproductive performance of Parthenium hysterophorus L?

Zygogramma bicolorata Pallister (Coleoptera: Chrysomelidae) is a satisfactory potential candidate for controlling Parthenium hysterophorus L. The study was conducted in order to evaluate the bio-control potential of Z. bicolorata to satisfactory reduced the density of parthenium weed in natural field conditions. Therefore, beetles were released in the twelve study sites @ 12 adults and/or larvae/m² in their respective sites on 5th, 10th, 15th and 20th day after initial field releases. Observations were made on defoliation by the beetle, perthenium plant height, plant biomass, leaf injury rating and soil seed reservoir. Present study showed that field releases of Z. bicolorata considerably lowering down the parthenium density at all treated sites. At larval release sites by the 60th day of observation a complete defoliation was noted, however at adult release sites it took 80 days for complete defoliation. Moreover, significantly higher number of developmental stages i.e. eggs, larvae and adults were noted in the adults released sites than to larval released sites and the controls. It was also noted that plant height and its density, flowers & leaves production, biomass of parthenium plant and seed reservoir in soil was negatively affected in treated sites as compared to untreated sites. Thus, we have concluded that adults can be utilized in biocontrol program because population build-up was greater in those sites where adults were released.     

向日葵组织培养研究进展

向日葵(Helianthus annuus)是世界主要的油料作物之一.近几年来有关向日葵的研究很多,其中向日葵组织培养研究越来越受到重视.本文从向日葵外植体培养、植株再生影响因素、组培过程中存在的问题及解决方法等方面进行了综述.