An experiment was carried out to investigate per se performance, specific combining ability, heterosis and the interrelationships among them for yield and yield components in an eight-parent half diallel cross in rice. The parental genotypes used in the study were BRRI dhan29, BR4828-54-4-1-4-9, BRRI dhan28, IRB, Amol3, IR65610-38-2-4-2-6-3, Minikit and ZhongYu7, which were chosen for their genetic differences and diverse origins. The hybridization for the study was performed during Boro season, 2001-2002, while the evaluation of F₁'s was performed during the following Transplanted Aman season, 2002. The per se performance of 28 hybrid combinations exhibited that the highest grain yield was observed in the cross BRRI dhan29 x Amol3 due to a high number of panicles and a higher number of filled grains per panicle. The study of sca effects revealed that in most of the cases a combination of high x low or even low x low crosses exhibited high sca effects for most of the characters, rather than high x high cross combinations indicating the importance of gene interactions. The best specific combiners were Amol3 x IR65610 for earliness, Amol3 x ZhongYu 7 for panicles/plant and filled grains/panicle, BRRI dhan28 x Amol3 for 1000-grain weight and BRRI dhan29 x Amol3 for grain yield/plant. The nature and extent of heterosis in both types (over mid parent and better parent) were found to vary depending on cross combinations and the characters under study. Based on mean values of mid and better parental heterosis in 28 crosses, the highest magnitude of heterosis was obtained in grain yield/plant followed by panicles/plant and filled grains/panicle. Most of the cross combinations produced significantly positive heterosis for grain yield/plant. The maximum heterosis for grain yield/plant was displayed by the hybrid BR4828 x Amol3 followed by IR65610 x Minikit. There were highly significant positive correlations among per se performance, specific combining ability and heterosis for almost all the rice characteristics which clearly suggested that specific combining ability and heterosis of a hybrid combination could reliably be predicted by per se performance of the cross combinations.

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An incubation experiment was carried out in the laboratory at 30°C for 56 days to investigate the mineralization pattern and changes in microbial biomass in lowland paddy soil amended with four organic materials (OM). The organic materials were rice straw (Oryza sativa), dhaincha (Sesbania rostrata), water hyacinth (Eichhornia crassipes) and partially decomposed cowdung. Inorganic N (NH₄⁺, NO₃^-) released from the OM amended soils gradually increased and reached it's maximum during 42 to 56 days of incubation. N mineralization was negatively correlated with C: N ratios of the added OM. The critical C: N ratio value for N mineralization and immobilization was observed in water hyacinth (C: N=20: 1) where mineralization followed immobilization after a certain period. Microbial biomass formation gradually increased up to between 28 and 42 days of incubation and decreased thereafter. Biomass C formation ranged from 155 to 216 mg kg^-1 in OM amended soil and 95 to127 mg kg^-1 in control soil, and biomass N formation accounted for 30 to 43 mg kg^-1 in OM amended soil and 20 to 25 mg kg^-1 in control soil. No clear relationship was observed between biomass C and N formation and the C: N ratios with added OM. However, OM with high C: N ratios, like rice straw, showed higher contributions to biomass C and N formation than OMs with lower C: N ratios. The results suggest that OMs having higher C: N ratios would be better for the improvement of microbial biomass level as well as soil fertility under tropical conditions.

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Genetic divergence among 42 bottle gourd (Lagenaria siceraria Mol. Standl.) accessions was estimated using D² and canonical analysis. The accessions were grouped into five clusters. No clear relationship was observed between geographic origin and genetic diversity. The maximum intercluster distance was between cluster I and cluster II, and the minimum was between cluster III and cluster IV. Primary branches per plant, fruit length and weight, number of fruits and yield per plant contributed maximum to the total genetic divergence. The results obtained by D² analysis were also confirmed by canonical analysis. The accessions included in the most divergent clusters I and II, are promising parents for a hybridization programme for obtaining high heterosis and thus better segregants in bottle gourd.

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The biodiversity of arbuscular mycorrhizal (AM) fungi of agricultural crops in different ABZs was assessed through survey during 1999. A total of 26 crops were surveyed in 4 AEZs in Bangladesh. Among the selected crops, maize, wheat, sorghum, grasspea, chickpea, cowpea, groundnut, soybean and onion were highly mycotrophic. Poor or no mycorrhizal association was found in prosomillet, sweet potato, lentil, linseed, knolkhol, brinjal, safflower, cabbage, cauliflower and mustard. Variations in AM colonization and spore population were observed for different agricultural crops in different agroecological zones of Bangladesh. The AM fungal structures (hyphae, vesicles and arbuscules) in the root system of the selected crops varied, irrespective of crop species.

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The effects of Rhizobium inoculation on the nodulation, plant growth, yield attributes, seed and stover yields, and seed protein content of six mungbean [Vigna radiata (L.) Wilczek] varieties were investigated. The mungbean varieties were BARI Mung-2, BARI Mung-3, BARI Mung-4, BARI Mung-5, BINA Moog-2 and BU Mung-1. Rhizobium strains TAL169 and TAL441 were used for inoculation of the seeds. Two-thirds of seeds of each variety were inoculated with Rizobium inoculant and the remaining one-third of seeds were kept uninoculated. The number and dry weight of nodules/plant, plant height, root length, number of main branches/plant, number of pods/plant, pod length, 1000-seed weight, seed and stover yields, and seed protein content of the crop increased significantly due to inoculation of the seeds with Rhizobium strains. Among the varieties, BARI Mung-4 performed the best in all aspects showing the highest seed yield of 1135 kg/ha. Rhizobium strain TAL169 did better than TAL441 in most of the studied parameters. The number of pods/plant and 1000-seed weight had positive correlations with seed yield/ha. It was concluded that BARI Mung-4 in combination with TAL169 performed the best in nodulation, plant growth, seed and stover yields, and seed protein content.

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An ex ante rate of return analysis was conducted using the economic surplus model to estimate the Internal Rate of Return (IRR) by newly potato variety of Provento developed by Tuber Crops Research Centre (TCRC), BARI. The IRR of the total investment in Provento variety potato research was calculated at 34%. Sensitivity analysis revealed that the estimated Internal Rate of Return (IRR) of Provento variety potato ranges from 29%-39%. When the supply elasticity increased by 25%, the IRR was 30% and when the supply elasticity decreased by 25%, the IRR become 39%. Ex ante analysis indicates that the expenditure on the Provento variety potato of TCRC, BARI for research and development is a good investment.

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Soil temperature and heat flux were measured within a tropical rainforest, Lambir Hills National Park, Sarawak, Malaysia from March 2001 to April 2002. The vertical profile of soil temperature (-2~-50 cm depth) was measured by Copper-Constantan thermocouples at 4 different depths (-2, -10, -20 and -50 cm) and the soil heat flux was measured by a heat flow sensor at 10 cm below the forest floor. Clear seasonal variation was not seen in either temperature or heat flux. The daily range of soil temperature was the largest at the surface layer (-2 cm) and amplitude rapidly decreased with depth. The immutable layer (the highest layer of the daily temperature range < 0.1°C) of this study site estimated by the vertical profiles of the soil temperature was 41.35 cm below the forest floor. The daily range of soil heat flux was about ±5W/m², corresponding to less than 0.5 % of global solar radiation above the canopy. The soil temperature was highest in the surface layer during the period around noon; it was lowest during the period from midnight to early morning. According to the results of the soil heat conductivity analysis, it was suggested that the organic matter and water content were high within the upper soil layer (-10 cm depth). The estimated soil heat flux using a simple model was slightly higher for daytime and lower for nighttime than the observed levels. This discrepancy was assumed to be caused by the diurnal change of the soil water content in the upper layer.

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The call for the conservation of the environment through reduction of waste and promotion of recycling has been gathering strength for a number of years. In Japan, the Fukuoka Greenery Recycling Center was built with the intention of diversifying waste disposal methods and therefore making great contribution towards conserving the environment. The Fukuoka City Government has adopted the practice of amending soil with recycled materials. Two types of compost materials were used and their effects on plants and CO₂ concentration in soil were evaluated. The first type consisted of mixtures of perlite, peat moss and slow decomposing fertilizer (the traditional way of amending soil in Japan) and secondly, the newly developed recycled materials (RC) generated from mixtures of processed garden wastes/tree pruning, waste timber and sewage sludge collected from households. Mixtures of these materials were applied at different rates and application varied at depths of 0 (surface application), 0-25cm, 0-50cm and 0-100cm, with corresponding application concentrations of 100, 30, 15 and 7.5 percent, respectively.

The recycled compost had a positive effect on the growth of Cinnamomum camphora seedlings, particularly when soil was amended with 15 percent concentration (RC15%) applied at 0-50cm-soil layer, and even at lower concentration (7.5 percent) applied at 0-100cm. Among the treatments, RC15% showed significantly higher biomass production, and higher height growth was also observed in RC30% (718.2g and 154.3cm), as compared with the effect of mixtures of perlite, peat moss and slow decomposing fertilizer (200.1g in TC15% and 125.7cm in TC30%).

The observed temporal and spatial variations in soil CO₂ concentrations were attributed mainly to biotic (root respiration and microbial activity) and abiotic (soil temperature and soil moisture content) factors. Observed CO₂ concentrations vary according to time, depth and amount of compost applied. The highest concentration was observed in September 1999 under RC 7.5% (5.30 percent) at 60cm and the lowest during winter (January 1999) with 0.13 percent of the control treatment at 8cm depth. Soil CO₂ concentration has a strong positive correlation with temperature (r=0.95) and is also significantly correlated with moisture content (r=0.63) at 100 cm soil depth. Strong correlations of temperature at any given depth indicate temperature’s significant role in determining the level of CO₂ concentration. Moreover, compost applied to the deeper soil layer at a low concentration (RC 7.5%) greatly affected respiration rates, contributing to a higher CO₂ concentration in the deeper soil layers (40 ~100cm). However, it was found that the observed higher CO₂ concentration had no detrimental effect on the growth of plants studied.

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Ba Vi (1,296 m alt. at the highest peak) and Tam Dao (1,592 m alt. at the highest peak) are national parks located 50 km west of and 75 km north of Hanoi City, respectively. During the years 1998-2002 we surveyed ants in both areas. The present paper gives an inventory of the results, counting 218 species belonging to 56 genera in 11 subfamilies, though 133 species were left unidentified. The species number for each area is comparable, 151 in Ba Vi and 151 in Tam Dao, of which 84 species were observed in common. The result was assessed in terms of workload of surveys, species composition, comparing with the faunas of Cuc Phuong and Hoang Lien Son.

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The larval parasitoid Bracon hebetor (Say) is found to parasitize the larvae of pyralid moths in grain storages in Thailand. To determine effectiveness of this parasitoid as a biological control agent in the storages, we examined effects of temperature and food on adult longevity of a Thailand strain of B. hebetor in the laboratory. When nothing, water or 50% honey solution was provided at 15-25°C, females lived significantly longer than males, except for the treatments with nothing or water at 25°C. Longevity of both sexes provided with nothing, water or honey solution, increased with decreasing temperature, except for those with water or nothing at 20-25°C. Both sexes provided with honey solution lived longer than those with nothing or water at temperatures tested. That B. hebetor is abundant in storages where no food source exists may be due to this relatively long longevity in dry condition.

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