The use of incidence counts for estimation of aphid populations. 1. Minimum sample size for required accuracy

In attempts to reduce the time required for monitoring cereal aphid populations, it has been suggested that direct counting be replaced by the use of incidence counts: estimation of aphid density from the proportion of wheat tillers infested. It is important, however, that the use of this simpler and more rapid method does not result in a loss of accuracy. This paper calculates the minimum sample size (number of tillers to be inspected) required to yield a given accuracy, using the two alternative sampling methods. Over the range of aphid densities close to the economic thresholds for pesticide application, the use of incidence counts does not require a much greater sample size than that needed for direct counting.Samenvatting Teneinde de bemonsteringstijd voor graanluizen te reduceren en een eenvoudige betrouwbare bemonsteringsmethode te ontwikkelen wordt telling van het aantal individuen per halm vaak vervangen door bepaling van het bezettingspercetage. Deze eenvoudige methode mag evenwel niet leiden tot een onaanvaardbaar verlies in nauwkeurigheid. Daarom wordt voor de directe telmethode en de methode met infectiepercentages de minimale monstergrootte bepaald bij een van te voren vastgestelde nauwkeurigheid. Het blijkt dat bij bladluizendichtheden, die dicht bij de economische schadedrempel liggen, de monsters bij de twee methoden niet in groote behoeven te verschillen.     

The use of incidence counts for estimation of aphid populations. 2. Confidence intervals from fixed sample sizes

Two approaches have been used in the monitoring of local populations of cereal aphids: direct counting of aphids on a number of tillers, and the less time-consuming assessment of incidence levels (the proportion of tillers infested). This paper compares the accuracy of these two methods, using a fixed sample size, as is desirable in a practical monitoring system. It is shown that the two methods are equally reliable over a range of incidence levels, but that the confidence intervals for the population density are very broad. Reduction of these sampling error requires a considerable increase in sample size, so they should instead be taken into account in the management decision-making process.Samenvatting Er worden doorgaans twee methoden gebruikt om de dichtheid van graanluizen vast te stellen: directe telling en bepaling van het bezettingsperentage. De nauwkeurigheid van deze twee methoden wordt hier vergeleken bij een constante monstergrootte, die gewenst is bij praktische waarnemingssystemen. De beide methoden zijn even betrouwbaar over een reeks van bezettingspercentages, maar de betrouwbaarheids-intervallen zijn erg ruim. Verkleining van deze bemonsteringsfouten vereist een aanzienlijke toename van de monstergrootte, zodat het waarschijnlijk beter is deze fouten in het beslissingsproces voor de bestrijding te betrekken.     

发芽、温度及pH对麦类籽实中植酸酶活性的影响

在25℃的条件下发芽 ,小麦东农123、小麦东农973821、大麦垦啤2号在第3天植酸酶活性达到最高 ,分别为原来的2.04、2.55、4.63倍 ;小黑麦92021、小黑麦5305及黑麦2号在第1天即达到最大 ,为发芽前的1.36、1.82和2.45倍。小黑麦5305中植酸酶的适宜温度为50℃ ,在40℃～60℃范围内可保持较高的酶活 ;适宜pH为5.5 ,低于4.0或高于7.0 ,酶活性基本丧失。温度与pH对植物植酸酶活性的影响存在互作效应     

饲粮物理有效纤维与谷物瘤胃可降解淀粉平衡影响奶牛咀嚼活动和养分表观消化率

饲粮物理有效纤维是一个兼顾物理特性和化学特性表达饲粮纤维营养价值的指标,它对奶牛咀嚼活动、瘤胃功能、机体健康状态等具有重要作用。谷物中含有的瘤胃可降解淀粉是微生物合成菌体蛋白的主要能量来源。饲粮物理有效纤维与谷物瘤胃可降解淀粉之间存在一定的平衡关系。本文对饲粮物理有效纤维和瘤胃可降解淀粉以及二者的组合效应对奶牛咀嚼活动和表观消化率的影响进行了综述,以期进一步加深对饲粮碳水化合物的平衡关系的理解。     

动物源性食品中氟喹诺酮类药物残留色谱质谱检测技术研究进展

兽药残留检测已成为全球动物源性食品安全的重要组成部分,色谱与质谱是兽药残留分析中最常用的检测方法。由于兽药各种类之间在理化性质、残留状态、限量要求等方面差异较大,导致在仪器分析环节存在一定的技术困难。为进一步了解该技术领域的研究进展,本文综述了动物源性食品中氟喹诺酮类药物残留色谱和质谱检测方法,指出了各种方法的优缺点并对检测技术的发展进行了展望,以期为氟喹诺酮类药物的残留检测提供技术支持和理论依据。     

Evaluating the effect of calcium,magnesium and sodium supplementation of Merino ewes on their lambs' growth

Our study aimed to investigate responses to supplementation of calcium (Ca), magnesium (Mg) and sodium (Na) to lactating ewes and lambs grazing barley forage from lamb marking to weaning. A 10-ha paddock sown to barley was subdivided into eight plots as four replicates of two treatments. Merino ewes (n = 104) with lambs at foot were stratified to the eight plots (13 ewes and 21 lambs/plot) based on number of lambs (twin or single) and ewes' weight. Supplemented groups had access to mineral supplements (30 g/ewe/day) supplying 12 g/ewe/day ground limestone, 12 g/ewe/day Causmag® and 6 g/ewe/day coarse salt in a ratio of 2: 2: 1 by weight (as fed) from day 0 (a day before lamb marking) after sample collection. Control groups were not supplemented with minerals. Blood, milk and urine samples from ewes and blood from lambs were collected at different time points, namely, a day prior to lamb marking (day 0), 14 days after the commencement of study (day 14), and 28 days after the commencement of study (day 28). Weight of the lambs was also recorded at each time point. We found that the concentration of the forage minerals (Ca, Mg and potassium (K)) was lower on day 28 than on day 0 (P < 0.025). Liveweight gain was greater in the first 14 days compared with the second weight gain period (P < 0.001). The interaction of time and treatment was significant for liveweight (P < 0.001). Due to the improvement in weight gain of supplemented lambs, we recommend that mineral supplementation during late lactation is beneficial considering the low cost of minerals, even though the mineral content of the forage was not deficient.     

秸杆中半纤的维素结构及分离新方法综述

主要介绍了秸秆中半纤维素与木质素，纤维素和蛋白质之间的化学连接方式，以及碱抽提、碱性过氧化氢抽提和辅助碱抽提等3种新型半纤维素分离方法，综述了近年来农作物秸秆半纤维素分离方法的研究新进展。     

山西省小杂粮生产现状与发展思路

论述了山西省小杂粮的生产优势、生产概况和存在的问题,提出了小杂粮产业发展的思路。     

微胶囊技术及其在功能性食品中应用的研究进展

微胶囊技术是21世纪的重点高新技术之一,应用非常广泛,尤其在功能性食品方面备受青睐。阐述了微胶囊壁材、微胶囊制备方法以及微胶囊技术在功能性食品方面的应用,并展望了微胶囊技术的应用。     

安徽颍上县禾谷类孢囊线虫发生与危害

为了解安徽皖北麦区及颍上县禾谷类孢囊线虫(cereal cyst nematode,CCN)发生和危害情况,用"zig-zag"法在皖北不同麦区采集小麦根际土样60份,利用Fenwick&Oostenbrink法分离CCN孢囊,统计卵密度发生频度。依据孢囊阴门锥等形态特征,鉴定颍上县CCN种类。利用扩散系数法判断CCN田间平面分布型,利用系统观察法,动态监测小麦生长季节0～300mm土层的2龄幼虫(J2)虫口变化。通过酸性品红染色方法监测早期侵染;选择CCN密度中等田块,以涕灭威作播前土壤处理,比较‘泛麦5’等品种的药剂处理间的株高和产量差异。结果表明,在皖北麦区,62%的田块CCN卵发生密度为1～10个/g土;经鉴定发生在颍上县的CCN为禾谷孢囊线虫(Heterodera avenae),颍上黄桥镇双楼村禾谷孢囊线虫在田间为块状分布;在颍上监测到J2对小麦侵染的最早时间在3月18日,当感染田块卵密度在2.5～20.5个/g土时,产量损失为9.8%～14.9%,其中‘泛麦5’产量损失显著,达14.9%。