Vegetative phase change among sweet corn (Zea mays L.) hybrids varying for reaction to common rust (Puccinia sorghi Schw.)

In maize, timing of vegetative phase change has been implicated in the response to certain pests and environmental stresses. Common rust is the most serious disease of sweet corn in the north central United States. Sweet corn hybrids differing for resistance to common rust were evaluated for vegetative phase change traits. There were significant differences among hybrids for all vegetative phase change traits measured, as well as resistance to common rust. Certain hybrids displayed rapid transition (within two leaves) from juvenile to adult vegetation, while others displayed prolonged transition (within four leaves). There were no significant correlations between vegetative phase change traits and common rust severity among the commercial sweet corn hybrids evaluated in this experiment.     

基于CLIMEX模型的玉蜀黍霜指霉菌入侵风险分析

为明确我国禁止进境的植物检疫性有害生物——玉蜀黍霜指霉菌Peronosclerospora maydis在中国的适生性以及入侵风险,采用CLIMEX 2.0软件分析其适生性,用ArcGIS 10.2软件确定其适生范围和适生程度,并采用多指标综合评判法量化分析其入侵我国的风险等级。结果表明,玉蜀黍霜指霉菌在我国的适生范围主要分布在长江以南的西南山地丘陵玉米种植区和南方丘陵玉米种植区,高适生区主要分布在云南、贵州、四川、重庆、广东、广西、湖南、江西、福建、海南和台湾等省 （区、市）。玉蜀黍霜指霉菌作为专性寄生菌,可在玉米整个生长季侵染危害,经多指标综合评判法分析并计算得到其风险综合评价值R为2.12,表明该病菌入侵我国的风险等级属高度危险,一旦入侵,势必对粮食安全、农业安全和生态安全带来巨大威胁,建议加强检疫监测,严防该病菌入侵。     

Incidence and geographical distribution of downy mildew on maize caused by Peronosclerospora sorghi in Nigeria

Abstract

Incidence and geographical distribution of downy mildew (Peronosclerospora sorghi) on maize (Zea mays) were determined in a systematic survey of 181 maize fields in the major maize‐growing regions and ecological zones of Nigeria. Downy mildew was observed in the forest and Guinea savanna ecologies, but no disease was detected in other ecologies. Highest levels of disease incidence (63%) were observed in the forest zone, and progressively less disease incidence was found at the southern and northern Guinea savanna zones. Spatial pattern analysis indicated an aggregation and randomness of infected plants in the northern Guinea savanna and the forest zone, respectively. Disease incidence was positively correlated with the presence of downy mildew infected sorghum plants and relative amount of sporulation on infected sorghum (Sorghum bicolor) but negatively correlated with plant age and cropping pattern. Relative sporulation on maize plants was negatively correlated with age of maize plants. Higher levels of disease incidence were observed when the previous crop was either maize or sorghum than when previous crops were cassava, okra, tomatoes, or rice.     

高粱乌米的营养功能与加工利用研究

高粱乌米富含多种营养成分,是天然的营养保健食用菌和功能性食品基料,具有广阔的开发应用前景。介绍国内外对高粱乌米在营养价值方面的研究情况,分析其营养功能,阐述其加工利用方向,为高粱乌米相关食品的开发提供参考。     

Assessment of loss in yield due to sorghum downy mildew (Peronosclerospora sorghi) of maize in Nigerian guinea savanna

Abstract

The losses in yield due to sorghum downy mildew of maize induced by Peronoscleospora sorghi were assessed from 1982 to 1984 in the epidemic‐prone area of Nigeria. Plots of maize with different downy mildew incidences were obtained by planting seedlots containing different percentages of metalaxyl‐treated seeds. The losses in yield were directly proportional to the incidence of the disease. There was highly significant negative correlation between the incidence of downy mildew and grain yield.     

高粱黑粉菌多糖降脂作用研究

为探讨高粱黑粉菌多糖的降脂作用，以小鼠为试验对象，采有对比试验的方法，研究高粱黑粉菌多糖对小鼠体重和脂肪指数的影响。试验结果表明：高粱黑粉菌多糖具有一定的减肥作用，且290mg／kg剂量的抑制作用较100mg／kg明显；高粱黑粉菌多糖能降低肥胖小鼠的脂肪指数。     

河南霜霉菌新记录

报道了河南高梁霜指霉菌新组合１种；霜霉菌新记录１２种，其中单轴霜霉菌２种，假霉霉菌１种，霜霉菌９种，它们寄生于１７科、４１属、５５种寄主植物上。     

Improvement of maize populations for resistance to downy mildew

Upgrading levels of disease resistance are a primary objective of maize breeding programmes. Efficacy of S₁ recurrent selection in improving levels of resistance to downy mildew (DM) infection was assessed in Nigeria from 1997 to 2000 in six maize populations. Improvement procedures consisted of evaluating S₁ progenies under artificial infection with DM spores and in disease‐free environments and using a selection index to combine selection for reduced DM infection with appropriate agronomic characters from more than one environment. Three to four cycles of selection were completed in each of the populations. Products from the different cycles of selection were evaluated and data collected on DM infection parameters and agronomic traits. Result obtained showed 3–4 cycles of selection were adequate to reduce DM infection levels significantly and increase grain yield. Downy mildew infection decreased by between 58 and 100% while grain yield increases ranged from 10 to 98% for the 2‐4 cycles of selection relative to the C0 (original). Selection increased grain yield with acceptable changes in plant height while maintaining maturity in disease‐free environments.     

Seed transmission of maize downy mildew (Peronosclerospora sorghi) in Nigeria

In an area of Nigeria where downy mildew of maize is present, histological assessment of maize seed revealed the presence of mycelium and oospores of Peronosclerospora sorghi in the kernels. Seed transmission of downy mildew of maize was demonstrated when grain purchased at local markets gave mean seedling infection rates of 12·3% (untreated seeds) and 10·0% (in metalaxyl-treated seeds) within 7 days of emergence, after storage in a desiccator for 30 days. When untreated seeds taken from nubbin ears of systemically infected plants from four states in southern Nigeria were planted at 9 days (17–22% moisture content) and 27 days (9–22% moisture content) after harvest, 20·0% infected seedlings resulted in both trials. Seeds from Borno state in northern Nigeria had 26·6% systemic seedling infection after 9 months of storage at 11% moisture content. When seeds harvested from maize plants inoculated with P. sorghi through silks were examined histologically, hyphae of P. sorghi were observed mostly in the scutellum of the embryo. Transmission of disease to seedlings was observed when the silk-inoculated seeds (9% moisture content) were planted in pots in a greenhouse; however, no disease transmission was observed when such seeds were planted in the field. The epidemiological significance of seed transmission is discussed with particular reference to survival of inoculum and development of epidemics. Also noteworthy is the overall significance of seed transmission in Nigeria, where the major source of seed is that saved by farmers from their grain crop, occasionally supplemented by seed bought from the local market.     

玉米锈病初侵染来源的研究

玉米锈病初侵染来源的研究马桂珍，暴增海，杨文兰（河北农业技术师范学院农学系，昌黎０６６６００）关键词玉米锈病；初侵染来源；孢子萌发ＳｔｕｄｙｏｎＰｒｅｌｉｍｉｎａｒｙＩｎｆｅｃｔｉｏｎＳｏｕｒｃｅｏｆＰｕｓｓｉｎｉａｓｏｒｇｈｉＳｃｈｗ￥ＭａＧｕｉｚ...