Management of Cercospora leaf spot of groundnut (Arachis hypogaea L.) with a single fungicidal spray

Field trials were conducted during the rainy seasons of 1993/94 for chemical control of groundnut leaf spot using a single spray. A fungicide mixture ofcarbendazim 0.05%+mancozeb 0.2% was applied once in different treatments. Spray timings varied from 30 d.a.s. to 80 d.a.s. at 10-day intervals. Spray application reduced the percent disease index in all treatments. A statistically significant increase in pod yield was obtained in treatments sprayed up to 50 d.a.s. in 1993. The yield data were not significantly different in 1994. Sprays at 40 d.a.s. in 1993 and 50 d.a.s. in 1994 gave maximum returns. The cost of treatmentdid notvary significantly. The benefitto cost ratio oftreatments ranged from 1.1 to 8.1 in 1993 and 4.1 to 5.5 in 1994.     

牡丹红斑病病原鉴定与ITS序列分析

牡丹红斑病是危害牡丹的最重要病害之一.本研究欲通过对病原菌进行鉴定并明确其分类地位.采用形态学方法结合分子标记法对牡丹红斑病病原进行鉴定,利用Mega5软件对枝孢霉属进行系统发育树分析.结果表明：该病致病菌为牡丹枝孢霉,序列与GenBank登录号为GQ395812.1的ITS序列同源性最高,同源性大于99％.聚类分析发现,枝孢霉属可分为7个聚类组,样品菌株与牡丹枝孢霉为一类.分子鉴定与形态学鉴定结果一致,该研究为牡丹红斑病的快速诊断与防治提供了依据,并为枝孢属的系统发育和分类鉴定提供了参考.     

Farmer participatory evaluation confirms higher grain yields in spring wheat using a selection index for spot blotch resistance, maturity and kernel weight

Wheat (Triticum aestivum L.) cultivars for the warm regions of South Asia must produce high yields and possess resistance to spot blotch (Cochliobolus sativus), early maturity and high kernel weight. A study was conducted to determine the effectiveness of selecting for high grain yield based on a selection index for spot blotch resistance, maturity and kernel weight in four wheat crosses involving a susceptible cultivar and resistant genotypes. Initial selection of 40 progeny lines in each cross had been made using a selection index based on disease severity, days to heading and kernel weight as reported by Sharma and Duveiller [{Crop Sci 43 (2003) 2031}]. The five highest grain-yielding progeny lines from among the 40 lines in each cross, their parents and five popular commercial cultivars were evaluated in field trials at two sites in Nepal in the 2002 and 2003 wheat seasons. Multiple spot blotch assessments were made to determine the area under disease progress curve (AUDPC). Grain yield, thousand-kernel weight (TKW), days to heading and plant height were examined. The wheat genotypes in the farmer's field were also ranked on the basis of cultivar preference criteria by the local farmers. The 20 progeny lines always showed a higher (+11 to +125%) grain yield and heavier (+10 to +44%) kernels than their parents and a lower (−83 to −89%) AUDPC than the susceptible parent. The progeny lines showed 98–100% grain yield, 97–100% TKW and 66–78% AUDPC compared to the highest grain-yielding commercial cultivar. Based on the farmers' preference criteria for a desirable wheat genotype, the best progeny lines ranked from 3rd to 5th, whereas the two commercial cultivars ranked 1st (Gautam) and 2nd (BL 1473). Results indicated that selection was effective in combining adaptation genes present in a local cultivar with some level of tolerance to spot blotch and resistance genes from exotic genotypes, which translated into improved agronomic performance and disease resistance. The selection index and farmer participatory approach used in this study could serve as a guideline in breeding efforts targeted for high yielding genotypes for wheat-growing conditions in South Asia where spot blotch is a serious biotic constraint to yield.     

Stay green trait: variation, inheritance and its association with spot blotch resistance in spring wheat (Triticum aestivum L.)

One thousand four hundred and seven spring wheat germplasm lines belonging to Indian and CIMMYT wheat programs were evaluated for stay green (SG) trait and resistance to spot blotch caused by Bipolaris sorokiniana during three consecutive crop seasons, 1999–2000, 2000–2001 and 2001–2002. Disease severity was recorded at six different growth stages beginning from tillering to late milk stage. SG trait was measured by following two approaches: difference for 0–9 scoring of green coloration (chlorophyll) of flag leaf and spike at the late dough stage (GS 87) and a new approach of leaf area under greenness (LAUG). Germplasm lines showed a wide range (7–89) for LAUG and were grouped into four viz., SG, moderately stay green, moderately non-stay green and non-stay green (NSG). However, very few (2.2%) lines showed high expression of SG trait, i.e., LAUG >60. LAUG appeared to be a better measure of SG trait than a 0–9 scale. Mean spot blotch ratings of SG genotypes were significantly lower than those of NSG genotypes at all growth stages. Two spot blotch resistant genotypes (Chirya 3 and Chirya 7) having strong expressions of SG trait were crossed with NSG, spot blotch susceptible cv. Sonalika. Individually threshed F₂ plants were used to advance the generations. SG trait and spot blotch severity were recorded in the parents and F₁, F₃, F₄, F₅, F₆ and F_6–7 generations under disease-protected and inoculated conditions. SG trait in the F₁ generation was intermediate and showed absence of dominance. Evaluation of progenies (202–207) in the segregating generations revealed that SG trait was under the control of around four additive genes. Lines homozygous for SG trait in F₄, F₅, F₆ and F_6–7 generations showed significantly lower mean area under disease progress curve (AUDPC) for spot blotch than those with NSG expression. A positive correlation (0.73) between SG trait and AUDPC further indicated a positive influence of SG on severity of spot blotch. The study established that variation for SG trait exists in spring wheat; around four additive genes control its inheritance in the crosses studied and there is positive association between SG trait and resistance to spot blotch.     

巷道堆垛类机械式停车系统

在介绍智能立体停车的基础上，论述了巷道堆垛类机械停车库的机械系统和控制系统，着重论述了巷道堆垛类机械停车库的机械系统构成及其设计原则，并对该机械停车系统的工程应用前景进行了探讨。     

广州白云山昆虫种类调查和森林害虫防治对策

1998-2000年期间，对白云山风景区进行了昆虫调查和标本采集，并初步鉴定有12月61科105属111种其中有林木害虫17种，天敌昆虫33种，根据景区虫情，提出了控制其森林虫害不成灾的对策。     

香梨果萼黑斑病菌Alternaria alternata遗传转化体系的建立及GFP标记菌株的获得

 为建立香梨果萼黑斑病菌链格孢(Alternaria alternata)的原生质体遗传转化体系,本实验以香梨果萼黑斑病菌强致病性菌株LI1为供试材料,研究菌龄、酶系统、酶解时间等对链格孢菌原生质体制备的影响。链格孢菌菌丝在CM液体培养基中培养20 h,以0.7 mol·L^-1 NaCl为稳渗剂,1%裂解酶+1%崩溃酶+1%蜗牛酶的酶液组合下,28 ℃酶解4 h,原生质体制备效率最高。通过PEG/CaCl₂介导法将含有潮霉素B抗性基因和绿色荧光蛋白基因的质粒转入链格孢菌LI1,转化子生长表型及外源基因的PCR鉴定结果表明抗性基因已成功整合到香梨果萼黑斑病菌中。成功建立了香梨果萼黑斑病菌链格孢菌的原生质体遗传转化体系,并成功获得GFP标记菌株,为病原菌侵染定殖过程及致病机制研究奠定了基础。     

广州白云山几种森林群落的物种丰富度和多样性

研究了广州白云山风景名胜区森林群落的物种多样性，利用Simpson指数和Shannon-Wiener指数，按群落类型计算了各群落的总体多样性指数和均匀度，不同层次和不同径级的多样性指数和均匀度，各群落的Simpson多样性指数为4.5379-9.3591，均匀度为0.1782-0.4288,Shannon-Wiener多样性指数为2.7672-3.6691，均匀度为0.6637-0.8119，其数值下鼎湖山和粤北南岭国家级自然保护区天然林的相关研究接近，但物种丰富度则较低，多样性指数值的高低与各群落所受干扰程度有关，受干扰程度最小的“荷木＋中华锥－九节”群落，其Shannon-Wiener多样性指数最高，同时各群落的幼苗层均具较高的多样性指数，显示出群落有较强的天然更新潜力。     

己唑醇悬浮剂防治桃树褐斑病试验

通过田间药效试验,结果表明,已唑醇3000倍、4000倍、5000倍三个浓度处理对桃褐斑病的防效均高于对照药剂代森锰锌处理,且差异性显著;已唑醇3000倍和4000倍处理防效均在90%以上,二者之间无差异显著性,但与已唑醇5000倍处理间在5%水平上存在显著性差异;试验结果还显示250g/L己唑醇悬浮剂不仅对桃褐斑病防治效果好,不污染果面,而且安全性好,可在果树花期、幼果期使用,增强叶片的光合作用,是目前防治桃褐斑病的理想药剂。     

Economic returns from fungicide application to control foliar fungal diseases in winter wheat

Fungicides are commonly applied to control foliar fungal diseases of winter wheat in the central Great Plains of the United States and often are routinely recommended. However, economic benefits from fungicide application in winter wheat have rarely been quantified in this region. A total of eight field experiments were conducted in 2006 and 2007 in Nebraska, USA to quantify yield increases from fungicide applications to control foliar fungal diseases in winter wheat. Experiments were conducted at the same four locations (Mead, Clay Center, North Platte and Sidney) in both years. The fungicides used were azoxystrobin + propiconazole, pyraclostrobin, propiconazole, azoxystrobin and trifloxystrobin + propiconazole applied at varying rates and growth stages. Average wheat prices were calculated from data provided by the United States Department of Agriculture (USDA) Agricultural Marketing Service. Average fungicide and fungicide application costs were obtained through surveys of local retailers, chemical manufacturers and commercial applicators. These prices and costs were used to calculate net returns from fungicide treatments. The probability of a positive net return was 0.60, 1.00 and 0.80 in 2006 (dry, low disease severity), 2007 (wet, moderate to high disease severity) and both years combined, respectively. Net returns ranged from $−101 ha⁻¹ to $172 ha⁻¹ in 2006 and from $60 ha⁻¹ to $294 ha⁻¹ in 2007. Net returns were at least two times the total cost ($2 return on $1 investment) in 4 out of 60 or 6.7% of treatments in 2006 and 51 out of 60 or 85% of treatments in 2007. In 2006, the best net returns occurred at Mead and Clay Center and resulted from the treatments 1) azoxystrobin + propiconazole applied at Zadoks growth stage (GS) 31 (first node detectable) at a rate of 0.58 l ha⁻¹ and 2) azoxystrobin + propiconazole applied at GS 31 at a rate of 0.58 l ha⁻¹ and again at GS 37 (flag leaf just visible) at the same rate. In 2007, the treatments that resulted in the best net returns were 1) azoxystrobin + propiconazole applied at GS 39 (ligule/collar of flag leaf just visible) at a rate of 1.02 l ha⁻¹, 2) pyraclostrobin applied at GS 39 at a rate of 0.66 l ha⁻¹, 3) propiconazole applied at GS 39 at a rate of 0.29 l ha⁻¹, and 4) trifloxystrobin + propiconazole applied at GS 39 at a rate of 0.73 l ha⁻¹. For the same fungicide applied at the same rate at GS 31 and GS 39 in 2007 (wet, moderate to high disease severity), the GS 39 application generally resulted in a higher net return than the GS 31 application. Averaged across treatments and locations, net returns were $6 ha⁻¹ and $183 ha⁻¹ in 2006 and 2007, respectively. The results from this study indicate that foliar fungicide application to winter wheat can be profitable in years with moderate to high disease severity; however, net loss can result if fungicides are applied in years with low disease severity.