Intercropping Maize with Climbing Beans, Cowpeas and Velvet Beans

When one of the crops is a legume, intercropping has potential to reduce fertilizer nitrogen (N) needs and increase food quality. Total dry matter (DM) and grain yields of different plant populations of intercropped maize ( Zea mays L.) and climbing beans ( Phaseolus vulgaris L.), cowpeas ( Vigna unguiculata [L.] Walp.), or velvet beans ( Mucuna pruriens [L.] DC. var utilis [Wight] Bruck.) were compared in two experiments. Maize populations were 40,400 and 50,500 plants ha⁻¹ in combination with climbing bean populations of 0, 20,200, 40,400 and 80,800 plants ha⁻¹ in Experiment 1. In the second experiment, climbing beans, cowpeas and velvet beans at 215,200 plants ha⁻¹ were intercropped with maize at 64,600 plants ha⁻¹. Climbing beans contributed up to 5% to total DM yields in the first experiment. In the second experiment legume contributions to total DM were 20% for climbing beans, 12% for cowpeas and 8% for velvet beans. Increasing populations of maize and climbing beans increased grain and DM yields. Dry matter yield of maize was lowered by intercropping. However, DM yields of the intercrop were not different to maize sole cropped. Maize/cowpeas produced more total DM than maize/climbing beans. Cowpeas increased the total yield of crude protein by over 15% without lowering total DM yield of the intercrop compared to maize alone and are promising as a legume for intercropping with maize. Climbing beans show little promise as a possible legume for intercropping with maize.     

Non-target effects of dimethoate and acephate against Eusieus tularensis Congdon and Aphytis melinus DeBach on lemons in California

Understanding the non-target effects on pesticides used in crop production systems is essential for the development of IPM programmes in those systems. Two organophosphates for control of citrus thrips in citrus were compared at commercial field rates in a lemon orchard for their effect against a predacious mite and a parasitic wasp, both of which have a significant role in coastal lemon IPM. Dimethoate and acephate greatly reduced populations of both beneficial insects, holding them to below detectable levels for 8 weeks post-treatment. Moreover, citrus red mite, a secondary pest, developed beyond the economic treatment threshold in both the dimethoate and acephate plots 10 weeks and 4 weeks post-treatment, respectively. In addition to predatory mite mortality, hormoligosis is suspected in both instances, and especially with acephate, of causing this secondary pest problem.     

芽胞杆菌与嘧菌酯协同应用对葡萄叶部微生物群落及霜霉菌线粒体功能的影响

为明确生防菌剂枯草芽胞杆菌Bacillus subtilis HMB20428与化学杀菌剂嘧菌酯协同应用对葡萄霜霉菌Plasmopara viticola的抑制机制,结合生物学测定与显微表型观察方法分析其对葡萄霜霉病菌及活孢子囊的抑制作用,采用高通量测序技术分析其对葡萄叶部微生物种群多样性的影响,通过测定生理生化指标研究其对葡萄霜霉菌线粒体功能的作用。结果显示,枯草芽胞杆菌HMB20428与嘧菌酯协同应用对葡萄霜霉病菌的抑制作用显著,对活孢子囊的抑制率为99.05%;两者协同应用对微生物细菌种群有显著影响,枯草芽胞杆菌的优势占位作用明显;但对微生物真菌种群无显著影响;两者协同应用造成葡萄霜霉菌线粒体膜通透性转运孔开放度增加至90.59%,对跨膜电位的抑制率为94.29%,呼吸链酶复合物Ⅰ～Ⅴ的活性分别显著下降56.39%、22.47%、47.90%、60.52%和90.91%,说明葡萄霜霉菌线粒体膜在受到明显损伤和出现代谢功能障碍的同时,呼吸链酶活性明显被抑制,从而导致葡萄霜霉菌的能量代谢和生长受阻。表明枯草芽胞杆菌HMB20428与嘧菌酯协同应用时主要通过促进枯草芽胞杆菌竞争占位和增...     

Intrinsic and extrinsic drivers of life‐history variability for a south‐western cutthroat trout

The impacts of climate change on cold‐water fishes will likely negatively manifest in populations at the trailing edge of their distributions. Rio Grande cutthroat trout (Oncorhynchus clarkii virginalis, RGCT) occupy arid south‐western U.S. streams at the southern‐most edge of all cutthroat trout distributions, making RGCT particularly vulnerable to the anticipated warming and drying in this region. We hypothesised that RGCT possess a portfolio of life‐history traits that aid in their persistence within streams of varying temperature and stream drying conditions. We used otolith and multistate capture–mark–recapture data to determine how these environmental constraints influence life‐history trait expression (length‐ and age‐at‐maturity) and demography in RGCT populations from northern New Mexico, United States. We found evidence that RGCT reached maturity fastest at sites with warm stream temperatures and low densities. We did not find a strong relationship between discharge and any demographic rate, although apparent survival of mature RGCT decreased as stream temperature increased. Our study suggests plasticity in trait expression may be a life‐history characteristic which can assist trailing edge populations like RGCT persist in a changing climate.     

鱼腥草不同地理群体遗传结构与变异的研究

采用SRAP分子标记技术对湖南省怀化地区16个野生鱼腥草群体的遗传特征进行了分析。结果表明,16个鱼腥草群体的多态位点比例(PPB)为53.66%~85.35%,Nei基因多样性指数(h)为0.07~0.23,Shannon表型信息指数(I)为0.10~0.34,说明在鱼腥草群体水平上有相对较高的遗传变异;群体间的基因分化系数(Gst)为0.51,表明大部分的遗传变异均存在于群体间,同时群体内具有一定频率的基因流(Nm=0.326)。UPGMA聚类分析表明,16个群体在遗传距离为0.5处分为五大类群,并且有一定的地缘关系。相关性分析表明,虽然16个鱼腥草群体的遗传结构与生境因子相关均不显著,但基因分化系数(Gst)和基因流(Nm)随海拔的增加有上升而随着纬度和经度的增加有下降的趋势。     

Pod Yield Comparison of Pure-Line Peanut Selections Simultaneously Developed from Georgia and Zimbabwe Breeding Programs

Crosses were made between two widely grown U.S. peanut (Arachis hypogaea L.) cultivars, ‘Florunner’ and Florigiant’, and two genotypes adapted to growing conditions on the plateau of tropical Africa, ‘Makulu Red’ and 486 GKP. F₂ seed populations were equally divided between Georgia and Zimbabwe. Subsequently, pedigree selection was practised simultaneously at both locations in the early segregating generations. The highest yielding pureline selections were then interchanged, and combined yield evaluations were determined over three growing seasons at each location. ‘Florunner’, ‘Florigiant’, and the Georgia pureline selections tested at the Georgia location had significantly higher pod yields than ‘Makulu Red’, 486 GKP, and the Zimbabwe selections. Conversely, the mean yield of the Zimbabwe selections tested m Zimbabwe was significantly higher than that of the Georgia selections. Thus, the breeding environment under which selection is conducted among cross populations strongly influences the yield adaptability of selected peanut genotypes.     

Population dynamics and economic threshold of the nematodes Radopholus similis and Pratylenchus goodeyi on banana in Australia

To help banana growers to decide when to apply nematicide, economic thresholds were determined for tropical north Queensland, subtropical south-east Queensland and northern New South Wales, Australia. This was done by monitoring nematode populations, root damage and growth parameters of bunching pseudostems in several commercial crops for several years. There was no significant consistent change in the disease index in consecutive years in any of the regions, although there was great variation between crops. However, on two crops in the tropics, the disease index of roots increased. To reduce the risk of not applying nematicide when required, the economic threshold was adjusted down to allow for this increase on some crops. In the tropics with a crop value of $25 000 ha^?1 year^?1, the economic threshold occurred at a root disease index = 9.2-15.6. In the subtropics with a crop value of $10 000-15 000, the economic threshold occurred at a root disease index = 20.5-35.5. In the subtropics, Radopholus similis (burrowing nematode) was as pathogenic as Pratylenchus goodeyi (lesion nematode) as measured by root necrosis. However, both nematodes were less pathogenic in the subtropics than was R. similis in the tropics. In the subtropics, R. similis tended to be more numerous in warmer months and P. goodeyi in cooler months.     

The Mikania Problem

Abstract

Nine insecticides were evaluated for the management of blossom thrips, Megalurothrips usitatus on pigeonpea. The study revealed that when the population of blossom thrips exceeded 15 individuals per flower, spraying with deltamethrin, monocrotophos, chlorpyrifos, phenthoate or ethofenprox can be considered, and the longest residual action was obtained with deltamethrin.     

Developing Groundnut Lines with Resistance to Seed Colonisation by Toxin-producing Strains of Aspergillus Species

Abstract

Evidence for the possible development of groundnut (Arachis hypogaea L.) cultivars with favourable agronomic characteristics and resistance to aflatoxinproducing strains of Aspergillus species is presented. In studies of F₂ and F₃ progenies from crosses of resistant and susceptible genotypes data on the frequency distribution and least square estimates of genetic effects showed the possibility of selecting for resistance to seed colonisation by the fungus. Yield, value and seed quality data for seven advanced lines developed by using pedigree selection from crosses showed that potential favourable groundnut cultivars may be developed.     

Use of random regression model as an alternative for multibreed relationship matrix

A random regression model is presented as an approximation for multibreed variance model. The approximation is derived using the splitted multibreed model where the single breeding value is split to the breed specific and their segregation terms. The random regression model allows extending the multibreed information easily to genomic data models. We present the approach by a simple example.