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。     

Changes in a wetland plant association induced by impoundment and draining

In 1977 a newly constructed gravel access road blocked water flow across a shrub swamp in Tewksbury, Massachusetts, draining one section and impounding another. Within one year, the vegetation in the drained area shifted substantially toward a denser and more species-rich association. After three years the changes slowed, but they had not stopped after six. Many of these changes would not be expected to reverse themselves once a more normal flooding pattern was established. In the newly flooded area there was little changes for the first three years, but after that time many species began to decline in numbers, with the most pronounced effect occurring after five years. Even short-term alterations in the flooding cycle can be expected to have substantial and long-lasting effects on wetland vegetation.     

Optimum tilt angles for solar collectors in clear sky conditions

Solar collectors have to be tilted properly to maximize solar energy collection. Optimum tilt angles for collectors at various latitudes are determined for all 12 months of the year. These results are also applicable to collectors with a cylindrically-curved transparent cover.     

硅肥对甘蔗叶片一些光合特性的影响

探讨了硅肥对甘蔗叶片光合特性的影响,尤其对上部叶和下部叶进行比较,测定了叶绿素含量、硝酸还原酶活性、叶面积指数、叶片的夜间光合产物输出量。结果表明:施硅能增加甘蔗的叶绿素含量,尤其是下部叶的叶绿素含量;能提高下部叶的硝酸还原酶活性;能延长叶片的功能期,增加群体叶面积系数;增加了中下部叶片的夜间光合产物输出量。传统上对于甘蔗生理生化性状的研究一般都是取 1叶进行测定,本研究发现硅肥对于甘蔗上下部叶作用的差异性,有必要对甘蔗下部叶作更多的研究;在甘蔗生产中有剥除老叶习惯的地方,施用硅肥之后,可以多留1片叶。     

Modified plant architecture to enhance crop disease control: genetic control and possible value of upright fruit position in cucumber

Plant architectural features can facilitate disease control by creating unfavourable environments for pathogen growth or limiting pathogen contact with the host. In the case of Phytophthora capsici infection of cucumber (Cucumis sativus), the susceptible fruit typically lie in contact with soil under warm, moist conditions of a full canopy, an ideal location for exposure to inoculum and disease development. We have shown that increased row spacing, trellising and architectural variants that allow for more open canopies, such as shorter vines, reduced branching, or smaller leaves, can modify microclimate as assessed by temperature at the location of developing fruits. However, only trellising reduced infection rates (<3 % infection vs. 22 % for control). A cucumber accession PI308916, with extremely short internodes and resulting upright position of young fruit, also exhibited reduced disease. Fruit of PI308916 were susceptible when inoculated with P. capsici, indicating that reduced infection likely resulted from decreased soil contact. The compact trait is inherited as a single recessive gene, cp. Like many architectural traits, cp may be pleiotropic; PI308916-derived breeding lines were reported to have poor seedling emergence. PI308916 exhibited inconsistent apical hook formation that co-segregated with short internodes in F₂ and backcross generations, and disorganized internodal cortical cell arrangement. The combined phenotypes suggest either pleiotropy or very tight linkage of genes affecting hormone balance or cell division. The narrow chromosome region recently defined by QTL analysis includes candidate gene homologs of meristem related genes modulating cell division or spacing of lateral shoot organs and genes associated with brassinosteroid signaling or cytokinin content.     

广东省稻瘟病菌生理小种的消长动态

１９９０～１９９７年,用中国稻瘟病菌鉴别寄主鉴定了广东省稻瘟病菌单孢菌株１５７４份,共鉴定出８群４３个生理小种。其中ＺＣ群一直是广东省的优势种群,其出现频率平均为５０.２％;ＺＣ_１３一直是优势小种,其出现频率平均为２７.４％,其次是ＺＧ_１（１８.８％）、ＺＣ_１５（１４.５％）和ＺＢ_１３（９.１％）小种。不同地区不同年份优势小种的类型及其组成不同。     

Combined treatment of aminoethoxyvinylglycine (AVG) and 1-methylcyclopropene (1-MCP) reduces melting-flesh peach fruit softening

The effects of postharvest application of aminoethoxyvinylglycine (AVG) and 1-methylcyclopropene (1-MCP) on ethylene production and fruit quality, and thus on transportation and shelf-life, were evaluated in melting-flesh peaches. AVG (150 mg L⁻¹) significantly reduced ethylene production, and the effect was enhanced in combination with 1-MCP (1 μL L⁻¹). However, fruit treated with AVG alone softened to untreated control levels 2 d after harvest (DAH). Treatment with 1-MCP significantly reduced the rate of softening until 2 DAH, but the fruit rapidly softened thereafter, and reached untreated control levels by 4 DAH. A combination of AVG and 1-MCP significantly reduced fruit tissue softening throughout ripening. The effect of each chemical on flesh firmness indicated that 1-MCP affected fruit response in the early stages of ripening up to 4 DAH, and AVG significantly reduced softening in the latter stages from 4 to 9 DAH. Peaches treated with AVG and 1-MCP retained their ground color during ripening, but the effect of each chemical on color is unclear. The present study indicates that combined treatment with AVG and 1-MCP significantly delays the ripening of melting-flesh peaches.     

Development ofNew InDel Marker to Detect Genotypes of Conferring Fertility Restoration of BT-Type Cytoplasmic Male Sterility inRice简

Restorer line breeding is an important approach to enhance the heterosis and improve the yields of japonica hybrid rice. To improve the selection efficiency of restorer lines for BT-type cytoplasmic male sterility (CMS) in japonica rice, a functional marker InDel-Rf-1a based on the difference of nucleotide sequence in Rf-1a locus between BT-type CMS lines and restorer lines was developed to detect the genotypes of different rice materials. Conventional indica rice varieties, restorer and maintainer lines without 574 bp deletion could restore the fertility for BT-type CMS in japonica rice. By contrast, most conventional japonica rice varieties except Aichi 106 and Yijing 12, with genotype of rf-1arf-1a showed the 574 bp deletion maintained sterility for BT-type CMS lines. To further verify the effect of genotyping detection in Rf-1a locus, this marker was also used to amplify the genomic DNA in different japonica rice restorer lines, CMS lines, hybrids and F₂ segregation population, and three genotypes in Rf-1a locus could be distinguished distinctly. Therefore, the marker InDel-Rf-1a could be widely used for genetic identification and marker-assisted selection (MAS) in breeding japonica restorer lines.