Rice seedling blight is an important disease caused by a complex of fungi including to the fungal genera of Fusarium, Pythium and Rhizopus species. These were consisting of F. roseum and F. solani, P. graminicola, P. spinosum, P. irregulare and P. sylvaticum, R. chinensis, R. oryzae and R. javanicus. A modified MIDI method was used for extraction of fatty acids and fatty acid methyl ester (FAME) profiles were characterized relating to the rice seedling pathogens. Total 83 isolates were used in this experiment. All tested isolates were subjected by the principal component analysis and cluster analysis based on the cellular fatty acid compositions to generate qualitative and quantitative variations. A total of 14 fatty acids were detected and FAME profiles showed quantitative and qualitative variations within different species levels of belonging to same genus. In this experiment, the possibility of utilization as the chemotaxonomic tools based on FAME profiles was discussed.
This study evaluated important agronomic and morphological characteristics of twelve local papaya varieties that had been collected in Viet Nam in 2008. The results showed that the collection of papaya varieties had a plant height of from 94 cm to 169 cm, number of leaves of from 17.6 to 21.8, canopy diameter of from 146.7 cm to 188.3 cm, stem diameter of from 6.5 cm to 8.6 cm, and insertion height of fruit of from 43.7 cm to 84.4 cm. This study also revealed that the total content of soluble solids in fruit of the local varieties ranged from 10.37% to 12.48%, while the color of fruit flesh included red and yellow. There were six types of papaya flowers including pistillate, hermaphrodite (pentendria, carpelloid, elongata and barren) and staminate, as well as two kinds of populations (gynodioecious and dioecious) among the varieties used in the experiment. This paper provides useful information on the agronomic and morphological characteristics of twelve local papaya varieties that will be exploited as one of the genetic resources for breeding new papaya varieties in Viet Nam.
An experiment was carried out at the Sher-e-bangla Agricultural University, Dhaka during 2007-2008 to study the role of arbuscular mycorrhizal fungi (AMF) on red amaranthus grown in arsenic amended soil. Plants were grown with or without AMF inoculation in soil amended with three levels of arsenic (10, 100 and 500 ppm). The higher concentrations of arsenic in soil significantly affected seed germination. The germination of seeds of red amaranthus was completely inhibited in the 500 ppm arsenic amended soil. A positive response of AMF on germination was observed. The study revealed that root length, shoot height, leaf number, fresh and dry weight of shoot and root, mycorrhizal root colonization, vigor, and nutrient (N, P, K and S) uptake were increased significantly by mycorrhizal association, while the parameters were decreased significantly with increases in arsenic concentration. Mycorrhizal inoculation reduced arsenic concentration in shoots of red amaranthus.
This experiment was carried out at the Regional Agricultural Research Station, Ishuirdi, Pabna during the growing season from 2009-10 to delineate better management practices, the optimum plant sex density and suitable harvesting stage of pointed gourd for higher yield and quality of pointed gourd. The experiment consisted of two management practices viz.: mulch with wheat straw and Bamboo pandal, three plant sex densities (female: male) viz.: 15:1 (T1), 10:1 (T2), and 5:1 (T3) and three harvesting stages at 8, 12 and 16 days after female flower atheists. The highest yield (36.86 t/ha) was obtained in the management practice of bamboo pandal. The highest yield (33.61t/ha) was produced at the 15:1 plant sex density. The highest yield (32.33 t/ha) was recorded in the harvesting at 8 days after female flower anthesis (H1). The combined effect was reflected as the highest yield (39.99 t/ha) obtained in the bamboo pandal coupled with 15.1 plant sex density and harvesting at 8 days after female flower anthesis (S2-T1-H1).
A radish variety named Tasaki Mula was used to investigate the effect of climatic factors on the development of Alternaria disease under field conditions. The average data of 2 crop seasons (2004/05-2005/06) revealed that 20-day-old plants transplanted on 20 December showed less number of spots and conidia, and their numbers increased with the age of the plants. The conidia and spot ratio was 290:1-593.10:1 from disease initiation to final assessment in 50-day-old plants. Correlation analysis of the association of the number of conidia landing and numbers of spots per leaf with weather factors at different growth stages revealed that maximum (23.48°C) and minimum (11.14°C) temperatures and sunshine hours (5.00 h) had significant positive correlation, while relative humidity (78.28%) and fog hours (4.39 h) had significant negative correlation with conidia landing and number of spots per leaf in 50-day-old transplanted plants. Total rainfall and number of rainy days had no significant association with conidia landing and number of spots per leaf. Prediction equations were developed for 4 different observations. The R2 values for the association of weather factors with number of conidia landing and number of spots per leaf showed variation of 54-93% and 44-81%, respectively, in radish seed crop infected with Alternaria brassicae. This indicated that some unknown factors might be involved in conidia production and number of spot formation, and some climatic factors played a significant role in disease development.
We performed pot experiments to study the effects of different combinations of arbuscular mycorrhiza (AM), Rhizobium (R), and different sources and doses of phosphorus on the growth and yield of mungbean. Different fertilizer treatments had a significant effect on AM root colonization and sporulation. Full doses of chemical fertilizers uppressed AM colonization and the number of spores. The highest root colonization (90.00%) and population of spores in the rhizospheric soil (290.25 spores·100 g-1 soil) of mungbean were recorded for half of the recommended dose of triple superphosphate plus AM and R. This treatment also produced the maximum number and weight of nodules, length and weight of roots and shoots, number of branches and pods, and seed yield of the crop.
Effect of ethanol (ET) on vase life of Bougainvillea was investigated at the Plant Physiology Section, Horticulture Research Centre, Bangladesh Agricultural Research institute (BARI), between December and February of 2010-2011. The optimum concentration of ET required for increasing bougainvillea flower longevity and delaying senescence under storage condition was determined. Young and fresh flowers were randomly harvested from 4-year-old bougainvillea trees. The flowers were treated with 4, 8, 12, 16, 20, 30, 40, and 50% ET. The longest vase life of 7 days was recorded for flowers treated with 8% ET, followed by vase life of 6 days for flowers treated with 12% ET. The vase life of control flowers was 4 days. High concentrations (16-50%) of ET drastically reduced the vase life of bougainvillea. The quantum yield (Fv/Fm) was higher in flowers treated with 8% and 12% ET than in those treated with other ET concentrations. Our results suggested that the vase life of bougainvillea flower was significantly affected by ethanol treatment, and the longevity was higher in flowers treated with 8% and 12% ET than in those treated with water (control) and other ET concentrations.
The sheath pathogen complex, comprising Rhizoctonia solani, R. oryzae, R. oryzae-sativae, and Sclerotium hydrophilum, causes a significant loss of rice yield in Asia. This study was carried out to characterize the causal agents of rice sheath diseases in Myanmar and to study the relationship among different isolates of R.solani from Myanmar, Japan, and Vietnam. Diseased rice stems, including those with unidentified symptoms in the field, were collected from different rice growing areas. The number of isolates of R. solani, R. oryzae, R. oryzae-sativae, and S. hydrophilum was 89, 110, 137, and 25, respectively. Genetic characterization of Rhizoctonia spp. was performed using the repetitive element PCR assay. R. solani AG-1 IA, R.oryzae, and R. oryzae-sativae collected from Myanmar were classified into two, two, and three different population types, respectively. The isolates of R. solani from Myanmar, Japan, and Vietnam were characterized into four distinguishable groups (RS1-4). RS1 isolates were a Myanmar-specific group, while the other groups were found in all of the tested regions.
This study was conducted to evaluate the physical and chemical properties, constraints, and management and conservation of organic peat soils for sustainable crop production in Bangladesh. Peat soils are found between the Ganges river floodplain and the Ganges tidal floodplain in Gopalgonj, Bagerhat, and in the adjoining parts of Khulna, Barisal, and Jessore districts, occupying an area of about 224,700 hectares (1.6% of the total area). The mineral content of peat soils is an important factor to determine their fertility since mineral particles are the sources of nutrients. In peat soils, organic matter content and all macronutrients and micronutrients, except Zn, are present in very high amounts. Peats on river flats, however, can have considerably higher mineral content if sediments are deposited during a flood. In Bangladesh, peat soils are seasonally flooded, poorly to very poorly drained, very dark greyish brown to black, and organic in nature. These soils have alternate layers of peat and muck, and peat and mineral layers sometimes occur on the top of the profile. The main limitations of the soil are requirement of deep ploughing, perennial wetness, and low-bearing capacity; thus, managing these soils by improving drainage is difficult. Two popular indigenous management techniques, namely, Sharjan and Gher procedures, are practiced in the areas having peat soils. Because of the presence of highly to partially decomposed organic matter and sulphur in peat soils, there is a possibility of root injury by the production of H2S gas. The fallow lands with peat soils are mainly used for cultivating broadcast aman, mixed Aus and broadcast aman, boro rice along with shrimp culture, and boro rice and transplanted aman along with shrimp culture. Locally, these soils are also used for fuel. These soils, which have a mineral layer at the top of the profile, can be improved by allowing the sediments from the adjoining tidal rivers to settle down on full organic soils. Organic matter-rich peat soils could be developed for agricultural purposes through the sedimentation process. The data obtained from this study are valuable for establishing more effective approaches for the management of peatlands and the development, preservation, and restoration of the peat soil area in Bangladesh.