Development of a powder formulation of Pseudomonas fluorescens for control of rice blast

Pseudomonas fluorescens strain Pf1, inhibitory to the growth of the rice blast pathogen Pyricularia oryzae in vitro , was developed as a talc-based powder formulation. When rice seeds were treated with this formulation, the bacteria spread to roots, stems and leaves of the plants and protected against leaf infection by P. oryzae . When applied as a foliar spray, the bacteria survived on the leaves. The powder formulation controlled leaf blast under greenhouse conditions. In tests as a seed treatment and foliar spray in four field trials it effectively controlled the disease and increased grain yield.     

Role of acquisition and inoculation time in the expression of clonal variation for BYDV-PAV transmission in the aphid species Rhopalosiphum padi

Vector efficiency of 20 Rhopalosiphum padi clones, originating from Europe, North America and North Africa and exhibiting different types of life cycle, was evaluated by transmitting a French BYDV-PAV isolate to barley plants under five different acquisition/inoculation sequences (AAP/IAP). Differences between clones in transmission efficiency were found only when a short AAP was followed by a long IAP (6 h/120 h) and, to some extent, when a long AAP (48 h) was followed by a short IAP (6 h), but no differences were found when the conditions for virus transmission were optimal, i.e. long AAP followed by long IAP (48 h/120 h). There were no differences in transmission rates by clones of different geographical origins and with different life cycles. As a consequence, clonal variation is probably of little importance in the vector aspects of the epidemiology of PAV serotypes transmitted by R. padi , but the availability of a range of clones exhibiting transmission differences under limiting AAP or IAP conditions could be of interest for studies of virus–vector relationships.     

Modelling crop:weed interactions in wheat with ALMANAC

ALMANAC is a dynamic model for plant growth, water balance and soil nitrogen dynamics that can simulate on a daily basis two or more competing species. The simulation of competition for light is based on Beer's law, allowing a different extinction coefficient ( k ) for each species. Light is partitioned between species based on k -values, leaf area index and plant heights. Total hiomass is simulated with radiation use efficiency and grain yield with a harvest index approach, sensitive to water stress. The model simulates competition for water and nutrients based on each species current rooting zone and demand by each species. The effect of crop management on the competition issue can he simulated. The model was evaluated in Dijon (France) using 4 years of experimental data on wheat:oat mixtures, differing in oat ( Avena sativa L.) densities, the period of oat emergence, the date of weed suppression by herbicides and the wheat ( Triticun aestivum L.) genotype. Additional data on oilseed rape ( Brassica nupus L.) and vetch ( Vilcia sauiva L.) competition in spring wheat were also used. The wheat grain yield was reasonably simulated with a root mean square error (RMSE) of 0.10-0.35 t ha^-1. Corresponding values for oats were 0.10-0.55 t ha^-1. The competitiveness of oats, oilseed rape and vetch was correctly simulated. The model appears as a reasonable tool for estimating damage thresholds in integrated weed control programmes.     

长吻帆蜥鱼作为生物采集器探究海洋中深层生物微塑料污染特征

海洋中深层生物作为链接海洋上层与深层食物网的媒介,对维系大洋生态系统结构和功能的稳定有着不可替代的重要作用。由于样品采集的困难性,针对中深层生物微塑料污染研究十分缺乏。长吻帆蜥鱼(Alepisaurus ferox)具有特殊的消化机制,是优秀的生物采集器。本研究利用激光红外成像光谱技术,量化分析了长吻帆蜥鱼胃中保存的中深层物种体内微塑料的丰度和理化特征。共采集中深层鱼类和头足类7种,其肠道中检测出微塑料146个,检出率85.71%,丰度为10.43 ± 12.12个/尾, 粒径为20.34~309.89 μm(47.36 μm ± 43.41 μm)。微塑料以颗粒状(59.58%)和碎片状(36.30%)为主,聚合物成分主要是丙烯酸酯共聚物(Acrylate copolymer),占比60.27%。本研究首次证明了长吻帆蜥鱼作为生物采集器开展海洋中深层生物微塑料污染研究的可行性,研究结果对解析大洋生态系统微塑料污染及其潜在生态风险具有重要意义。     

南平市延平区马铃薯生产现状与发展对策

通过4a来对延平区马铃薯产业的调查研究,脱毒马铃薯品种的引进筛选,示范推广的实践,分析马铃薯产业现状,探讨存在的问题,提出发展对策,为进一步加快延平区的马铃薯产业发展提供依据。     

The arthropods associated with the decomposition of some common grass and weed species in the soil

The arthropod fauna associated with the decomposition of herbage of various species on the surface of the soil was studied. Litter of Rumex, Urtica, Ranunculus, Senecio and Lolium disappeared rapidly at first and thereafter at a slower rate. Dactylis disappeared more slowly than the other litters over the first 6$\text{1}\text{2}$ months but its rate of disappearance thereafter was greater than that of the other species. There were quantitative and qualitative differences between the microarthropod communities associated with the various litters. Highest populations of microarthropods were recorded from Dactylis. Dactylis and Lolium were the most similar in the species composition of their faunas. Changes occurred in the relative abundance of various arthropod groups and species during the course of decomposition in all litters.     

THE EFFECT OF HISTAMINE ON SILAGE DRY-MATTER INTAKE

The oral introduction of 0·5 g histamine as the diphosphate into the rumen of sheep produced no effect on the physiological condition of the animals. The feeding of histamine, as the dihydrochloride, in levels up to 1 g/day to sheep on silage diets did not affect the dry-matter intake.