Diurnal Variations in Photosynthesis,Stomatal Conductance and Leaf Water Relation in Sorghum Grown with or without Silicon under Water Stress

Sorghum [Sorghum bicolor (L.) Moench] was grown hydroponically with or without 50 ppm silicon (Si), and exposed to water stress from 10 days after sowing (DAS). At 15 and 23 DAS, we measured dry weight and diurnal variations in photosynthetic rate (P _N), stomatal conductance (g _s), transpiration rate (T), leaf water potential (ψ _L), and water uptake rate (23 DAS only). The reduction in dry weight at 23 DAS caused by water stress was ameliorated by silicon. Under water stress, silicon-treated seedlings showed higher g _s, P _N, and T than untreated ones. ψ _L remained almost constant within treatments throughout the daytime. Water uptake rate was reduced by water stress, but the reduction was ameliorated by silicon. We conclude that silicon enhanced water uptake and g _s, improving water supply to the leaves. These effects of silicon occurred soon after exposure to water stress.     

承德市坝上高原典型土壤的系统分类研究

中国土壤分类尚处于发生分类占主体、系统分类快速发展的并用阶段。为了解承德市坝上高原典型土壤在中国土壤系统分类中的归属,本文在该区域栗钙土、灰色森林土、黑土等发生分类土壤类型区,挖取8个具有典型代表性的土壤剖面,进行土壤形成条件调查,并分层取样进行理化性状分析。结果发现：（1）8个土壤剖面具有的诊断表层有：有机表层、暗沃表层、淡薄表层;诊断表下层有：钙积层、雏形层;诊断特性有：半干润土壤水分状况、湿润土壤水分状况、滞水土壤水分状况、潮湿土壤水分状况、冷性土壤温度状况、纤维有机土壤物质、半腐土壤有机物质、潜育特征、氧化还原特征、盐基饱和度。（2）按照《中国土壤系统分类检索（第3版）》,8个土壤剖面归属为3个土纲（雏形土、有机土、新成土）、4个亚纲、5个土类、6个亚类。按照《中国土壤分类系统》,8个土壤剖面归属为5个土纲、6个亚纲、7个土类、8个亚类。（3）8个土壤剖面在发生分类与系统分类中发生分异的分类级别存在明显差异,两种分类体系的不同分类级别之间关系较为复杂,并不呈简单的、一对一的对应关系。     

Detection and characterization of QoI resistance in Pyrenophora tritici-repentis populations causing tan spot of wheat in Argentina

Tan spot, caused by the fungus Pyrenophora tritici-repentis (Ptr), is a disease that has become more prevalent and intense in wheat crops in Argentina in recent years. Failure to control the disease with strobilurin fungicides, which were once effective, has been observed in different zones where wheat is grown. However, whether or not true resistance is present in the pathogen population in the region is not scientifically confirmed. This study evaluated the sensitivity of numerous Ptr isolates to representative QoI fungicides used in Argentina through in vitro and in planta assays, as well as through molecular analysis. Eighty-two monosporic isolates obtained in different locations in the north and south of Buenos Aires province in 2014, 2016, and 2018 were tested to determine sensitivity to selected QoI fungicides in conidial germination and mycelial inhibition assays, as well as in molecular analysis. Conidial germination was not inhibited at 1 µg/ml of azoxystrobin, trifloxystrobin, and pyraclostrobin. On the other hand, mycelial growth was inhibited by 59%, 56%, and 86% at 100 µg/ml of azoxystrobin, trifloxystrobin, and pyraclostrobin, respectively. The molecular analysis detected the G143A mutation in the cytb gene of all the 82 Ptr isolates, but the F129L and G137R substitutions were not present. This study documents the G143A mutation conferring QoI resistance in Ptr in South America. The findings of this study are key for future decisions regarding use of fungicide and rotation in the region.     

我国部分省域甘蓝主要产区黑腐病菌鉴定及致病力分析

 为了明确我国甘蓝主栽区黑腐病菌株种类与致病力水平,为优化抗病性鉴定方法、筛选抗病品种及抗病品种的合理布局提供依据,分别采集了10个省域的黑腐病病叶,经过分离纯化与分子鉴定,获得了26个典型甘蓝黑腐病菌株;选用5个甘蓝抗、感品种作为鉴别寄主,以甘蓝黑腐病菌株的悬浮液为接种体,采用喷雾接种法测定致病力。结果表明:来源于不同省域的黑腐病菌株致病力存在显著差异,致病力最强的是YU,病情指数平均值为38.31;致病力最弱的是SH,病情指数平均值为17.03。来源于不同海拔高度的甘蓝黑腐病菌株致病力最强的是G1500,病情指数平均值为37.93;最弱的是G800,病情指数平均值为19.80。根据鉴别寄主抗感反应将26个黑腐病菌株划分为12类致病型,发现来自不同地域的甘蓝黑腐病菌株间存在着显著的致病性分化现象,对甘蓝品种的致病力存在着显著性差异,其中菌株YU致病力最强,菌株YU可作为甘蓝抗病性鉴定的主要致病菌株,指导抗病品种的选育。     

温度对螺旋藻突变株(SP-Dz)生长及藻胆蛋白含量的影响

研究了不同温度条件对直线型钝顶螺旋藻突变株(SP-Dz)生长和藻胆蛋白含量的影响。结果表明,螺旋藻(SP-Dz)的最适生长温度为30~35℃,在30℃条件下培养的螺旋藻积累藻胆蛋白最多。     

沙地榛园金龟子防治技术试验

针对章古台地区引栽平欧杂种榛过程中出现的金龟子危害突出的现象进行防治技术研究。通过化学防治、无公害防治以及生物防治进行试验分析,结果表明:化学防治中喷施乐斯本乳油效果可达到98.3%,但药物防治对益虫和天敌均有毒杀效果,故化学防治方法慎用;通过对灯光诱杀和糖醋酒液2种无公害防治方法比较,考虑防虫效果及投入成本等多因素后得出高效宽谱诱虫灯可作为一种控制虫口密度的有效手段;生物防治将在未来害虫防治技术中发挥主导作用,通过对蓖麻杀虫效果的观察和记录,证实了蓖麻对金龟子有效的毒杀作用。     

精氨酸对笼养育雏期蛋鸭生产性能及抗氧化功能的影响

试验旨在研究饲粮中添加不同水平精氨酸对0~4周龄笼养蛋雏鸭生长性能及抗氧化功能的影响,探讨笼养育雏期蛋鸭适宜的精氨酸添加水平。试验采用单因素完全随机分组设计,选择健康1日龄金定蛋雏鸭180只,随机分为5组,每组6个重复,每个重复6只鸭,对照组饲喂基础日粮,试验组饲喂在玉米-豆粕型基础饲粮基础上分别添加0.10%、0.20%、0.30%、0.40%精氨酸的试验饲粮,试验期4周。结果表明：①饲粮中添加精氨酸平均日增重Ⅲ组显著高于其他各组(P<0.05),Ⅱ、Ⅳ、Ⅴ组间差异均不显著(P>0.05),Ⅱ、Ⅳ组显著高于Ⅰ组(P<0.05);平均日采食量以Ⅰ组最高,但各组间差异均不显著(P>0.05);料重比以Ⅲ组最低,显著低于其他各组(P<0.05),Ⅱ、Ⅳ、Ⅴ组间差异不显著(P>0.05),同时,Ⅱ、Ⅳ、Ⅴ组显著低于对照组(P<0.05)。②Ⅲ组血清和肝脏总抗氧化能力(T-AOC)与对照组相比差异显著（P<0.05),Ⅱ组血清谷胱甘肽过氧化物酶(GSH-Px)活性与对照组相比差异显著(P<0.05);Ⅳ组肝脏超氧化物歧化酶(SOD)活性与对照组相比差异显著(P<0.05);Ⅱ、Ⅲ、Ⅳ组肝脏丙二醛(MDA)含量与对照组相比差异显著(P<0.05),根据试验中有效评价精氨酸营养需要量的抗氧化指标,估测精氨酸添加水平分别为0.183%、0.198%、0.093%、0.208%。由此可见,蛋雏鸭采食玉米-豆粕型基础饲粮,精氨酸的适宜添加水平为0.093%~0.208%。     

不同因子对玛纳斯河流域农田土壤盐分的影响

选取玛纳斯河流域内玛纳斯灌区和莫索湾灌区为研究区．利用遥感影像和GPS定位技术布设土壤盐分采样点,研究分析土壤质地、作物类型及地形因子对农田土壤盐分的影响。结果表明,研究区农田表层土壤（0～20cm层、20～40cm层）的盐分含量大小为：粘壤土〉粉壤土〉砂壤土;不同作物种植条件下农田土壤盐分状况表现为：棉花地〉葡萄地〉玉米地;不同地形部位农田土壤盐分含量表现为：冲积洪积扇下部〉冲积洪积扇中部〉沙漠边缘〉冲积洪积扇上部,各地形部位农田土壤盐渍化程度均表现为轻度盐渍化;不同海拔农田土壤盐分状况表现为：400500m〉500～700m〉400m以下,土壤盐分含量随着海拔的升高呈先增加后降低的趋势。     

牛传染性鼻气管炎的分离鉴定和灭活条件的优化

从疑似牛传染性鼻气管炎病毒感染的牛鼻腔中分离出1株病毒,通过PCR方法和MDBK细胞病变观察对其进行鉴定,确定该分离株为牛传染性鼻气管炎毒株。通过对该毒株的增殖条件和甲醛灭活条件的优化研究,为制备牛传染性鼻气管炎细胞源灭活疫苗提供参考依据。结果表明该毒株接毒18h后病变细胞达70％开始收毒,病毒液在0．2％的甲醛37℃灭活36h灭活效果最好。     

X65管线钢焊接接头抗H2S应力腐蚀开裂性能

中海石油(中国)有限公司天津分公司在渤海湾某油田开展了天然气利用项目,天然气外输海管选用国产X65管线钢手工电弧焊接敷设完成.随着油田不断深入开发,伴生天然气中H2S含量持续增长,该海底管道特别是焊接接头等薄弱部位在运行过程中面临着H2S应力腐蚀开裂风险.根据NACE相关标准方法研究了X65管线钢焊接接头抗HB/HIC/SSCC性能,并对SSCC发生机制进行了探讨.研究结果表明:该天然气外输管道所选的国产X65钢焊接接头具有优良的抗H2S应力腐蚀性能,在管道敷设达标及目前运行工况条件下发生硫化物应力腐蚀开裂的风险较小.