Development of New Submergence Tolerant Rice Variety for Bangladesh Using Marker-Assisted Backcrossing

Submergence tolerant high yielding rice variety was developed using BR11 as a recipient parent applying foreground, phenotypic and background selection approaches. Recombinant selection was found essential to minimize linkage drag by BC2F2 generation. Without recombinant selection, the introgression size in the backcross recombinant lines(BRLs) was approximately 15 Mb on the carrier chromosome. The BRLs were found submergence tolerance compared to the check varieties under complete submergence for two weeks at Bangladesh Rice Research Institute, and produced higher yield compared to the isogenic Sub1-line under control ed submerged condition. The BRL IR85260-66-654-Gaz2 was released as BRRI dhan52 in 2010, which was the first high yielding submergence tolerant variety in Bangladesh. BRRI dhan52 produced grain yield ranging from 4.2 to 5.2 t/hm2 under different flash flood prone areas of Bangladesh in three consecutive seasons. The study demonstrated the efficiency of recombinant selection and better adaptability of the newly released submergence tolerant high yielding variety in flash flood prone different areas of the country with respect to submergence tolerance and yield potential.     

Morphological and Genetical Variability among Rhizoctonia solani Isolates Causing Sheath Blight Disease of Rice

Eighteen isolates of Rhizoctonia solani collected from infected rice plants in four different locations of Bangladesh were studied by using morphological characters and molecular markers. Anastomosis study with a reference isolate confirmed that all the isolates belonged to R. solani. Significant variation was observed in sclerotial size, shape and distribution. Un-weighted pair group method with arithmetic mean dendrogram constructed based on the Gower's general similarity coefficient showed that these isolates were grouped into four clusters at the 0.68 similarity coefficent according to morphological characters. Cluster I was a major cluster consisting of 13 isolates, while clusters Ⅱ to Ⅳ consisted of 1 or 2 isolates. Analyses by variable number of tandem repeat and amplified fragment length polymorphism markers showed that the isolates were grouped into five and three clusters at a similarity coefficient of 0.64 and 0.69, respectively. Although most of the variability was found between isolates from different regions as expected, significant variation was observed within the isolates collected from similar agro-ecological regions. Our results suggest the presence of different races of R. solani within the same local geographic regions.     

Monitoring of spatial variations of particulate matter (PM) pollution through bio-magnetic aspects of roadside plant leaves in an Indo-Burma hot spot region

Particulate matter (PM) is an important air pollutant because of its adverse impacts towards human health. The existing and conventional methods of PMs monitoring are found to be inadequate in feasibility, which paved the way of magnetic biomonitoring approach. The magnetic measurement carried through the plant leaves is useful means in assessing the PM pollution. Plant species are found to be an effective biomonitors and may act as natural filters by trapping and retaining the PM on their leaf surfaces. Therefore, the aim of this communication is to demonstrate the magnetic properties [magnetic susceptibility (χ), anhysteretic remanent magnetization (ARM) and saturation isothermal remanent magnetization (SIRM)] of two roadside plant leaves (Hibiscus rosa-sinensis and Mangifera indica) at four spatially distant sites. The study measures and compares the capabilities of these plants to accumulate and retain the PMs. The study also assesses the PM pollution at selected sites and establishes the relationship between magnetic properties and PM in the city of an Indo-Burma hot spot region. The results indicated a significant correlation between the concentration of ambient PM and magnetic measurement (χ, ARM and SIRM) of both the roadside plant leaves. Similarly, reasonably good correlations are obtained between magnetic parameters (χ, ARM and SIRM) and Fe content in PMs. Present study is, perhaps, a novel contribution in the area of bio-magnetic monitoring studied with several magnetic parameters viz., χ, ARM and SIRM. Results indicated that the bio-magnetic monitoring is applied for environmental geomagnetism which act as proxy for ambient PM pollution and further employed as an eco-sustainable tool for environmental management in urban and peri-urban regions.     

Ant community associated to citrus canopy in Southern Portugal over a century after the invasion by the Argentine ant

The Argentine ant Linepithema humile (Mayr) established in Algarve, Portugal, about 120 years ago. In this work we assess the current impact of this invasive species on ant communities of citrus orchards and compare the invasibility between different ecological sub-regions in relation to some biotic and abiotic requirements. A novel extensive sampling approach in citrus canopy (including the trunk) along 49 orchards in three ecological subregions was performed. In total 21 species were observed, covering 81% of the species reported for the region. Despite the same habitat, ant species composition differed in contiguous subregions with particular significance to the absence of Argentine ant in the inner subregion. Based on the results we hypothesized the existence of ecological factors at regional scale preventing the establishment of L. humile in this subregion, related to anthropogenic factors and geologically unfavorable sites. At a local scale, its establishment and dominance is associated with ant community composition and a lack of dominant native ant species, which can be responsible for straightening the spread of one of the world most invasive ant species.     

First record of the pepper tree psyllid, <Emphasis Type="Italic">Calophya schini</Emphasis> Tuthill (Hemiptera,Calophyidae), in the Palaearctic region

The presence of the psyllid Calophya schini infesting the Peruvian pepper tree, Schinus molle, was detected in several localities in the region of Lisbon, in Portugal. This is the first record of this jumping plant-louse in Europe and the Palaearctic region.     

高效液相色谱法测定蔬菜中7种氨基甲酸酯类农药残留研究

[目的]建立一种氨基甲酸酯类农药残留分析方法。[方法]对市场上蔬菜随机抽样,采用配荧光检测器和柱后衍生系统的高效液相色谱仪测定了蔬菜中涕灭威砜、涕灭威亚砜、灭多威、3-羟基克百威、涕灭威、克百威、甲萘威7种氨基甲酸酯类农药的多残留,对每种农药进行了3种不同浓度(0.05、0.10、0.50 mg/kg)的添加回收率试验。[结果]蔬菜中7种农药的回收率在74.6%～107.6%,精密度在10%以内。[结论]该方法可用于大白菜、黄瓜、番茄、辣椒、芹菜等样品中氨基甲酸酯类农药残留分析。     

Arsenic Stress Responses and Tolerance in Rice: Physiological,Cellular and Molecular Approaches

Arsenic (As), a potentially toxic metalloid released in the soil environment as a result of natural as well as anthropogenic processes, is subsequently taken up by crop plants. In rice grains, As has been reported in Asia, North America and Europe, suggesting a future threat to food security and crop production. As³⁺ by dint of its availability, mobility and phytotoxicity, is the most harmful species of As for the rice crop. Specific transporters mediate the transport of different species of As from roots to the aboveground parts of the plant body. Accumulation of As leads to toxic reactions in plants, affecting its growth and productivity. Increase in As uptake leads to oxidative stress and production of antioxidants to counteract this stress. Cultivars tolerant to As stress are efficient in antioxidant metabolism compared to sensitive ones. Iron and selenium are found to have ameliorating effect on the oxidative stress caused by As. Microbes, even many indigenous ones, in the plant rhizosphere are also capable of utilizing As in their metabolism, both independently and in association. Some of these microbes impart tolerance to As-stress in plants grown in As contaminated sites.