广西主要蔗区宿根蔗根际土壤微生物群落结构分析

探讨了广西主要蔗区宿根蔗根际土壤微生物的分布情况,结果表明：宿根蔗根际土壤微生物数量总体上表现为：细菌〉真菌〉放线菌。但宜州市和北海市土壤中真菌数量〉放线菌;崇左市土壤中真菌和放线菌相当。     

我国超级稻根系特性及根际生态研究现状与趋势

以超级稻为代表的一批超高产水稻研发成功使水稻单产获得大幅度提高。较大的根系生物量、根重密度、根长、根长密度和根直径,根系偏向纵深分布且土壤深层根系生物量增大是超级稻根系生物学主要特征;高的单株根系氧化力、总吸收表面积、活跃吸收表面积、根系细胞分裂素(玉米素与玉米素核苷)含量是超级稻扩库增产的重要根系生理基础。生产中的施肥管理、水分管理、种植方式和根际土壤生态环境pH、氧、微生物、氮素形态等均可显著影响水稻根系的生长发育。通过适当的技术措施调控水稻根际生态环境向有利于水稻生长生理需求方向发展,以促进水稻根系健壮生长,实现水稻增产。水稻高产群体根系构型的形成与根际土壤生态因子匹配原理与调控,高产水稻地下根系、根际生态因子与地上群体的互作机制与调控路径,水稻根系定量化等方面是今后水稻根系深入研究的主要方向。     

Susceptibility of Brazilian populations of Diatraea saccharalis to Cry1Ab and response to selection for resistance

The sugarcane borer, Diatraea saccharalis (F.), is a key pest of sugarcane and other grasses, which is a current focus of research aiming to develop transgenically resistant genotypes. However, the current susceptibility of Brazilian populations of the sugarcane borer to Bt toxins is unknown. Laboratory assays were carried out to characterize the susceptibility of sugarcane borer to the Bt toxin Cry1Ab and to select a resistant strain for additional studies on Cry1Ab resistance. Susceptibility was characterized by exposing neonates of different Brazilian colonies of sugarcane borer to different concentrations in meridic diet using surface application of Cry1Ab toxin. Selection for Cry1Ab resistance was carried out by exposing neonates to Cry1Ab-expressing maize (MON 810). The resistance of the borer populations to Cry1Ab was variable with LC₅₀ and EC₅₀ values reaching about 30-fold. The larvae responded positively to Cry1Ab selection exhibiting a 55-fold increase in resistance after four generations. This suggests the suitability of using leaves containing Bt-expressing genes for selection and the existence of variability of Bt-resistance in populations of the sugarcane borer.     

Repeated solarization and long-term effects on soil microbiological parameters and agronomic traits

Innovative methods less invasive for man and environment are needed to solve the problem of weeds, pests and diseases in cropping systems. Soil solarization is one practice that involves passively heating soil covered by a thin clear plastic film for several weeks during the periods of high solar radiation before the crop is planted. Soil solarization treatments were repeated to verify their long-term effectiveness on soil microbial biomass and its respiration activities, in addition to yield response and root-knot nematodes control in tomato and melon crops following soil heating. Experiments in greenhouse were carried out in Southern Italy (40°24′ N, 16°28′ E) during the summer of 1998, 1999 and 2000 on soil infested by the root-knot nematode Meloidogyne javanica. Crop yields and fruit quality of all vegetable crops were positively affected by repeating solarization for two and three years, compared to an untreated soil and soil treated once in 1998. Solarization was effective in controlling root-knot nematode damage, but solarization affected the soil biota populations and their activities as a consequence of repeated treatments.     

不同供磷水平对柱花草和黑籽雀稗根际生理活性的影响

以热带柱花草和黑籽雀稗为材料,通过盆栽试验,研究不同磷水平对其根际酸性磷酸酶、微生物数量及根系活力的影响。结果表明：2种牧草根际酸性磷酸酶(ACP)活性随着磷浓度的增加而降低,在低磷(P0)处理时达最高,柱花草的ACP活性为603.24 mg/(kg·h),黑籽雀稗为367.21 mg/(kg·h)。当高磷浓度处理时,柱花草根际ACP活性较黑籽雀稗低。各处理中,柱花草的根际微生物总量较黑籽雀稗高,柱花草根际真菌的数量随磷浓度的增加而减少,处理间差异达极显著水平,低磷处理时土壤真菌数量较多,这有利于根瘤菌的形成。2种牧草的根系活力随着施磷浓度的增加而递减。黑籽雀稗根系活力P0处理极显著高于P3和P4处理,显著高于P2处理。黑籽雀稗根系活力受供磷水平的影响大于柱花草。     

The Impact of Roads on the Redistribution of Plants and Associated Arthropods in a Hyper-Arid Ecosystem

The construction of vehicular roads likely affects the distribution of natural resources. Although the effects of roads on different ecosystem aspects have been extensively studied, studies in arid and, particularly, in hyper-arid ecosystems are scarce. In drylands, where water is the main limiting factor, the effect of roads on the redistribution of water may have strong subsequent effects on the ecosystem, especially when roads cross natural water flow paths. To fill this knowledge gap, we studied the effects of a road that runs across a slope on the distribution of plants and animals in a hyper-arid environment. Changes in shrub cover, below and above the road, were quantified by remote sensing and image classification, while plant-associated arthropods were vacuum-sampled from shrub canopies and from open (inter-shrub) areas. We found that the spatial distribution of shrubs, a vital resource facilitating many other organisms, was affected by the road, with an increase in the shrub cover immediately above the road and a decrease below it. Arthropod abundance generally followed shrub cover, but the exact pattern depended on the specific group sampled. While some arthropod groups (e.g., aphids, parasitic wasps and barklice) thrived under the disturbed conditions above the road, other arthropod groups (e.g., mites and true bugs) were less abundant in the disturbed patches. Our results highlight the strong effects of human-made structures on the distribution of flora and fauna in arid ecosystems.     

不同健康状态咖啡根际环境特征比较研究

咖啡是世界三大饮料之一,具有广泛的营养价值、经济价值和药用价值.咖啡产业已成为我国热带经济作物优势产业之一.咖啡是多年生经济作物,随着其种植年限的增加,老咖啡园更新换代的时候,咖啡产生了严重的再植病,已成为影响咖农增收,制约产业可持续发展的严重问题,亟待解决.为揭示咖啡再植病产生机理,本研究分别在澄迈、琼海和万宁选择代...     

Effectiveness and chemical pest control of Bt-cotton in the Yangtze River Valley, China

The paper determines what might be the factors beneath the limited or reduced effectiveness being observed in China. The analysis is based on the data collected for several years from many locations in the Yangtze River Valley Varietal Experiment Network. All varieties declared to be Bt-cotton were confirmed to have the Bt-gene, the expression of which was assessed in three ways: through the analysis of Bt-protein production and through indoor and outdoor bioassays. Gene expression varied substantially between varieties and between years for the few varieties which were tested in two subsequent years. The Bt-cotton varieties being sown cannot control bollworms totally and this led to spray chemicals regardless of the real infestation level. Farmers are hence paying high prices for varieties which are not totally resistant to bollworms and pest control costs are not reduced to the extent that they might expect, lowering the profitability of cotton production.     

籼型两用核不育系水稻培矮64S的育性表达——幼穗发育过程中的NAD+-MDH和AP同工酶的变化

 以籼型两用不育系水稻培矮64S和常规稻粳籼89为材料，采用PAGE分析同工酶的方法，比较水稻幼穗发育过程中花粉母细胞形成期、减数分裂期和花粉完熟期NAD+-MDH和AP同工酶的变化，以期了解不育系的育性转换与表达机理。结果表明，在1993年2月25日、3月10日和3月30日三期播种的水稻培矮64S均表现不育，花粉不育度在99.7%以上，结实率在0.3%以下，1994年8月1日播种的培矮64S表现可育，结实率在19%以上，而同期播种的常规稻粳籼89均能得到正常结实，结实率在68%以上。同时发现1993年培矮64S的不育性在花粉完熟期与颖花及花药的NAD⁺-MDH活性的显著降低关系较大。在花粉母细胞形成期—减数分裂期与颖花AP的活性及同工酶组成的变化关系较密切。1994年表现可育的培矮64S与粳籼89相比不存在这种差异。由此可认为培矮64S育性表达可能与花粉发育前期的脂肪代谢以及花粉发育后期的呼吸代谢有关。     

Potato production on wide beds: Impact on yield and selected soil physical characteristics

Planting three rows of potatoes in a bed the width of two conventional rows offers an easily managed way to increase seed piece populations, with the potential of increasing tuber yield and enhancing tuber quality. A wide bed production system (3 rows of potatoes planted on a 1.9 m flat-topped raised bed) was compared to a conventional-ridged system (1 row of potatoes in sharply sloped ridges on 96 cm centers) in 1996 and 1997 on a Norfolk sandy loam soil and a Portsmouth fine sandy loam soil in eastern North Carolina. Potato plant stands, leaf area index at approximately 9 WAP, yield, and quality were measured. Soil temperature, soil moisture, and cone index, as a measure of soil penetration resistance, were also measured, wide beds were more moist than conventional ridges early in the season. Cone index was greater throughout the root profile in wide beds in two of three tests. The row on the west side of an individual wide bed was most similar to conventional ridges in daily soil temperature fluctuations between minimum and maximum temperatures, and had greater fluctuations than the middle and eastern rows of the wide bed. Total yield and yield of grade A potatoes were not significantly different between wide beds and conventional ridges at either site. At one site, yield of grade B potatoes was significantly less in the wide bed; among the three rows in the wide bed, the eastern row had significantly lower yield of grade B potatoes. Conventional ridges had a higher percent of green grade A potatoes than the wide beds in one of three trials. Under North Carolina conditions, changing production systems would be unadvisable for most growers because wide beds do not increase yield enough to justify spending the money for more seed and to change equipment.     

Influence of rotation system on siderophere-producing microorganism(SPM) in rhizosphere soil of southern China

Soil siderophores are important for crop growth,benefit ferric iron absorption of root,and are affected by cropping patterns.The objective of this study was to evaluate the quantity of siderophores in soil of 2 continuous crop rotation patterns over 30 years in Anren country,China.Quantity and siderophore-producing capability of microorganisms in rice-riceoilseed rape(DDY)rotation and rice-rice(DD)rontinuous cropping rhizosphere soil were tested and analyzed by chrome azurol S method.Isolated strains were used to identify siderophore-producing microorganism(SPM)by PCR amplification and DNA sequencing.Results showed that 9 siderophore-producing bacteria strains were isolated from DDY rhizosphere soil while 7 strains were identified from DD rhizosphere soil.The mean solubility index which representing siderophore-producing capability of strains was 3.05.PCR amplification results indicated that bacterial were the major SPM in soil.This research indicates that crop rotation systems could drive microorganisms to produce siderophores and enrich them in bacterial communities.     

球孢白僵菌在玉米根际的定殖及对根际微生物的影响

通过分生孢子诱变法获得了球孢白僵菌抗多菌灵突变株,测定球孢白僵菌不同抗性突变株对多菌灵的抗性水平及遗传稳定性.选择其中对多菌灵EC50为245.0697,抗性水平指数达到229.29的抗性突变株BC-8菌株作为定殖菌株.采用盆栽接种试验和涂抹平皿法测数等方法研究球孢白僵菌抗性突变株BC-8菌株在玉米根际的定殖能力及对根际微生物数量的影响.结果表明:BC-8菌株可以在玉米外根际和根表定殖,但未在根内分离到;玉米移栽后28 d,外根际、根表的分离数量达到最大值;用BC-8菌株分生孢子悬浮液处理玉米幼苗后,玉米根际细菌、真菌及放线菌的数量均比对照减少;玉米移栽后14d,根际细菌、真菌、放线菌的数量与对照相比都有大幅度的减少;移栽后28 d,根际各种微生物的数量都有所增加,但与对照相比,仍呈减少趋势;移栽后42 d,根际微生物的数量趋于稳定.     

大叶丁香丙酮提取物对皮氏叶螨的毒力及代谢酶活性的影响

采用叶片浸渍法和分光光度法研究了大叶丁香(Eugenia caryophyllata Thunb)丙酮提取物对皮氏叶螨(Tetranychus piercei McGrvgor)的毒力及其代谢酶活性的影响。试验结果表明:大叶丁香丙酮提取物对皮氏叶螨具有良好的毒杀作用,处理后72 h LC50值为4.31 mg/mLL;其13.33 mg/mL对皮氏叶螨的48 h和72 h校正死亡率分别为81.82％和95.35％,其6.67 mg/mL对皮氏叶螨的72 h校正死亡率为75.58％;大叶丁香丙酮提取物在5.0、4.0、3.0、2.0、1.0 μg/mL的质量浓度下,对皮氏叶螨酯酶、羧酸酯酶、碱性磷酸酯酶的活性均有抑制作用,作用大小均随处理浓度的增加而增强,但大叶丁香丙酮提取物对酸性磷酸酯酶则有一定程度的激活作用。      

免耕对土壤理化性状和直播稻生长及产量形成的影响

为探明免耕直播稻的生长规律和免耕直播的环境效应,研究了稻田免耕直播对土壤理化性状和水稻生长及产量形成的影响.结果表明,稻田免耕后,土壤容重降低和孔隙性得到改善,土壤养分在土壤表层富集.与翻耕直播相比,免耕直播稻分蘖能力较弱,但无效分蘖较少,成穗率高.直播条件下,免耕更有利于叶面积的扩展.除齐穗期外,其它生育时期免耕稻的根系活力强,平均比翻耕提高4.45%.在最高分蘖期,免耕直播稻的根冠比和单蔸根干重高于翻耕直播稻.在翻耕和免耕条件下,干物质积累量及在茎、叶和穗中的分配比例无显著差异.免耕直播稻的实际产量为8.6 t/hm2,比翻耕直播稻增产5.8%.另外,免耕直播稻的收获指数比翻耕直播稻高,增幅为13.3%,但未达到5%的显著差异水平.     

水稻根际环境与氮素利用的关系研究进展

氮素高效利用是实现水稻高产和建立环境友好型农业的关键一步.根际环境与氮素能否高效利用密切相关,也是近年来栽培、土壤及生态学领域的研究热点.本文总结了水稻根际环境的定义及范畴,解析了水稻氮素吸收利用的相关机制,阐述了根际土壤、根系以及根际微生物与氮素利用的关系,分析了目前存在的问题和对未来研究的展望.     

中国道地药材研究现状与展望

运用生态学理论阐述了我国道地药材学术思想的形成过程、道地药材研究的概况，以及道地产区药用植物的生态位作用。运用现代生物技术，阐明药用植物次生代谢途径中的关键酶系的表达和控制。旨在更好地把握道地药材形成的综合环境和社会条件，为制定SOP提供理论依据，保障我国道地药材行业可持续地发展。     

Long-term effect of tillage systems on soil microbiological,chemical and physical parameters and the incidence of charcoal rot by Macrophomina phaseolina (Tassi) Goid in soybean

A 20-year field experiment was employed with the aim of evaluating the effect of tillage systems on biological, chemical and physical aspects of the soil, and to establish whether there was a correlation of these parameters with the incidence of charcoal rot (Macrophomina phaseolina) of soybean and crop yield. The tillage systems evaluated were direct seeding (DS), DS + scarifier (DS + S), minimum tillage (MT) and conventional tillage (CT). DS presented higher values than CT in culturable total fungi (26.33 × 10⁵ vs. 2.33 × 10⁵ CFU g⁻¹ dry soil), total bacteria (182 × 10⁷ vs. 64 × 10⁷ CFU g⁻¹ dry soil), microbial respiration (0.77 mg CO₂ g⁻¹ week⁻¹ vs. 0.45 mg CO₂ g⁻¹ week⁻¹) and fluorescein diacetate (FDA) hydrolysis (4.17 ug fluorescein g⁻¹ h⁻¹ vs. 1.70 ug fluorescein g⁻¹ h⁻¹ in CT. Fungal and bacterial community fingerprints, by terminal restriction fragment length polymorphism (T-RFLP) analysis, of Intergenic spacer regions of rRNA and 16S rRNA genes, respectively, were influenced by the tillage system. Also FAME (fatty acid methyl ester) profiles showed that microbial community structure in DS and CT was clearly different. DS samples contained significantly higher total microbial biomass than the other tillage treatments, but there were no significant differences in fungal biomass or any consistent trend with respect to stress index. Our results showed that microbial communities were more abundant and active in DS than in CT in response to high nutrient content in soil. Indeed, DS systems presented higher soil OM, total N, K and Ca than CT. Electrical conductivity and aggregate stability (AS) were also improved by DS. Soybean grown in high-quality soil was not affected by charcoal rot, however, under CT, disease incidence in soybean was 54%. These differences were correlated to the higher microbial abundance and activity under DS, the biological component being a key factor determining soil capacity to suppress the soilborne pathogen.