纵卷叶螟绒茧蜂在不同类型田的发生规律

为掌握纵卷叶螟绒茧蜂的发生特点,对纵卷叶螟绒茧蜂在单作稻田和水稻-玉米邻作类型田的发生规律进行了调查.结果显示:水稻-玉米模式中纵卷叶螟绒茧蜂的数量在玉米的扬花期明显高于单作稻田,最高值为单作稻田模式的3.36倍,但是田间纵卷叶螟绒茧蜂的寄生率并不高于单作稻田模式.在单作稻田未施药系统田,纵卷叶螟绒茧蜂的数量显著高于施药系统田;并且与稻纵卷叶螟幼虫的数量密切相关.不论在何种种植模式下,纵卷叶螟绒茧蜂的雌性比一直处于低水平,在单作稻田下,雌性比为0.2～0.3,在水稻-玉米邻作田,其雌性比为0.25左右.     

Allelopathy and the active metabolites of the endophytic fungus,Alternaria J46, from Platycladus orientalis

The endophytic fungus, Alternaria J46, was isolated from the stem of the medicinal plant, Platycladus orientalis. A suspension of Alternaria J46 mycelial segments and the culture filtrates of the fungi exhibited marked seed germination inhibition against the monocot wheat, large crabgrass, bromegrass, rice and barnyardgrass and weak inhibition against the dicot redroot pigweed and morning glory, but it was safe for use on soybean, rape, cucumber, tomato, lettuce and radish crops. It is possible to use J46 culture filtrates in order to prevent monocot weeds in dicot cropland. Three active metabolites were isolated from an extract of the fungus cultures and elucidated as 3‐acetyl‐5‐sec‐butyltetramic acid (1, tenuazonic acid), 3‐acetyl‐5‐iso‐butyltetramic acid (2, vivotoxin II) and cyclo‐(L‐leucyl‐L‐proline) (3). Among these three compounds, compounds 1 and 2 showed significant phytotoxic effects on the seed germination of large crabgrass, while compound 3 exhibited weak activity, and all were safe for lettuce at 100 μg mL^?1. Accordingly, compounds 1 and 2 were the main active metabolites that were responsible for endophytic fungus Alternaria J46's strong seed germination inhibition against monocotyledons.     

马铃薯甲虫空间分布型及序贯抽样

马铃薯甲虫Leptinotarsa decemlineata Say是一种重要的害虫,为明确其在新疆的空间分布,及时采取有效的防控措施,在田间调查的基础上,采取随机取样和Iwao回归分析法对新疆乌鲁木齐地区的马铃薯甲虫成虫、卵块和幼虫的空间分布型、理论抽样数及幼虫的序贯抽样方法进行了研究。结果表明,马铃薯甲虫各虫态空间格局的聚块性指标均大于1,空间分布型为普通群聚型;对低龄幼虫进行序贯抽样,当防治阈值为50头/样方、置信水平为1.96时,防治上、下限方程分别为:d1=50n+81n和d0=50n-81n,当百株虫量达到756头以上时需要进行防治。     

半干旱栽培稻田不同秸秆覆盖材料的产量效应

采用田间观测的方法,分析了不同覆盖材料对半干旱栽培条件下杂交水稻田间茎蘖数、干物质积累和土壤水分的影响,探讨了不同覆盖材料的产量效应。结果表明:(1)在川西北丘陵旱区进行秸秆覆盖有利于增加非灌溉期田间土壤贮水量,提高田间茎蘖数;秸秆腐烂所释放的养分,缓解了稻田磷钾供应相对不足的现状,有效提高了杂交稻的结实率、有效穗数和千粒重;覆盖处理稻田0~0.5 m土层贮水量较不覆盖处理增加2%~13%,田间茎蘖数增加4%~15%,有效穗数增加4%~8%,结实率增加3%~7%,千粒重增加0.6%~1.7%。(2)在灌溉水源没有保证的丘陵旱区,将半干旱栽培与秸秆覆盖相结合,可有效提高杂交水稻产量。冈优725和D优363实收产量平均值在油菜荚壳覆盖、麦草覆盖和麦糠覆盖处理下分别较对照增加10.2%、7.0%和7.7%。     

Characteristics and dynamics analysis of Populus euphratica populations in the middle reaches of Tarim River

Populus euphratica Oliv. is widely distributed along the Tarim River. Maintaining stability of P. euphratica population is important to local development. This study explored the static life table, survivorship curves and four function curves (survival rate, cumulative mortality rate, mortality density, and hazard rate), and development index of P. euphratica population in the middle reaches of Tarim River. The results indicated that the age structure of P. euphratica population belonged to positive pyramidal type, which meant young age-class individuals occupied most populations. The number ofⅠ-Ⅱage classes accounted for 66.2% of whole population, and this indicated that there were abundant subsequent seedlings resources to support the growth of P. euphratica population in the middle reaches of Tarim River. The survivorship curve of P. euphratica belonged to the Deevey Ⅲ (concave-type) and the development index was 47.72%. Four function curves revealed that the individuals of P. euphratica sharply decreased at the initial stage and then leveled off at the late stage of survival curve. Time sequence prediction models predicted that the number of midlife individuals would increase in future 10, 20, 30 years, and P. euphratica population grew steadily as a result of rich saplings.     

农药中毒的原因分析及防治对策

为探讨农业生产过程中农药中毒的发生原因及规律,我们在枣阳市的吴店、南城、兴隆和鹿头等乡镇进行了调查和试验,为广大农民科学掌握使用农药的方法进行了有益探索,并研究制定了科学有效的预防对策.     

不同盐浓度对芨芨草种子萌发过程中几种生理指标的影响

不同浓度的N aC l处理芨芨草种子后,通过研究其萌发过程中淀粉酶、超氧化物歧化酶、过氧化物酶活性以及可溶性糖含量的变化。结果表明:N aC l处理下芨芨草种子萌发过程中超氧化物歧化酶、过氧化物酶活性与对照相比均上升,且呈现双峰曲线的变化趋势。而淀粉酶活性、可溶性糖含量与对照相比均下降,并与N aC l处理浓度呈负相关。     

草莓根腐病病原菌分离与鉴定

为了有效防控草莓根腐病,采用组织分离法,对徐州地区草莓根腐病病原菌进行分离与鉴定,分离、纯化后获取了5个真菌菌株,经形态学与分子生物学碱基序列测定结果比对发现：CMGF-1是胶孢炭疽菌或其亚种,CMGF-2和CMGF-3是棒孢拟盘多毛孢或其亚种,CMGF-4和CMGF-5是串珠镰刀菌或其亚种。黑根根腐的致病菌主要是镰刀菌和拟盘多毛孢菌,而红中柱根腐的致病菌是胶孢炭疽菌。     

耐抽薹小白菜品种比较研究

以五月慢为对照,对4个耐抽薹小白菜品种(系)进行比较研究,选出耐抽薹,产量、品质等综合性状优良的品种(系)。试验结果说明,五月慢A×5-3-2组合是综合性状优良的新品系,适合在武汉地区种植。     

中国果树类病毒的发生及其研究进展(英文)

概述了在中国发生且己鉴定明确的5种果树类病毒,即苹果绣果类病毒(Apple scar skin viroid,ASSVd)、梨泡状溃疡类病毒(Pear blister canker viroid,PBCVd)、葡萄黄斑类病毒-1(Grapevine yellow speckle viroid-1,GYSVd-1)、柑橘裂皮类病毒(Citrus exocortis viroid,CEVd)和桃潜隐花叶类病毒(Peachlatent mosaic viroid,PLMVd)的研究进展,包括病害的首次发现、症状特征、发病规律、检测方法与防治对策以及这些类病毒的生物学与分子生物学特性。