Absorption and emission of CO2 by ponded water of a paddy field

In the daytime, the CO₂ concentration in the air close to the water surface of a ponded paddy field was lowest and it increased with the distance above the water surface, while an inverse relation was observed in the nighttime. On the other hand, the pH of the ponded water changed significantly throughout a day and was expected to affect atmospheric CO₂ in the vicinity of the water surface, because the solubility of CO₂ in water depends on the pH. In this study, we investigated the relationship between the changes in the pH of the ponded water and the response of the CO₂ concentration in the air above the water. The pH of the ponded water of the paddy field increased in the daytime and decreased in the nighttime, so that the water was alkaline in the daytime and weakly acidic in the nighttime. We found that the daily changes in the atmospheric CO₂ concentration gradient almost corresponded to the daily changes in pH. The increase of the pH of the ponded water in the daytime was due to the absorption of dissolved CO₂ by photosynthetic bacteria and micro-algae within the ponded water. Furthermore, we compared the pH with RpH, defined as the pH at which the CO₂ concentration of the water is in equilibrium with that of the air, to determine whether CO₂ was absorbed by or emitted from the ponded water. In the daytime, the pH value of the ponded water was higher than that of the RpH, and the water could therefore absorb CO₂ , whereas during the nighttime, since the pH value of the ponded water was lower than that of the RpH, the water was expected to emit CO₂. These results show that the ponded water absorbed CO₂ from the air above the water surface in the daytime and emitted CO₂ in the nighttime.     

Soybean preference for Bradyrhizobium japonicum for nodulation

For examining the probability of increase in the occupation ratio of inoculated rhizobium in nodules, various Rj-soybean cultivars including the Rj ₂ Rj ₃ Rj ₄-lines of soybean were grown in a field of the Kyushu University Farm. Bradyrhizobium japonicum USDA110 that carries uptake hydrogenase (Hup⁺) was used as an inoculum. The relative efficiency of nitrogen fixation generally increased by the inoculation. However, there were no significant differences in the effects among the genotypes of the host plants. The occupation ratio of serogroup USDA110 in the nodules on the taproot of the inoculated plants was in the range of 77–100%, suggesting that the B. japonicum strain USDA110 infected taproots immediately after inoculation. The occupation ratios in the nodules on the lateral roots were 53–67, 40–86, 63–83, and 62–77% in inoculated plants of the non-Rj-, Rj ₂ Rj ₃-, Rj ₄-, and Rj ₂ Rj ₃ Rj ₄-genotypes, respectively, and they decreased in all the genotypes with the progression of growth. At the time of the first sampling, the occupation ratios on the lateral roots of these Rj ₂ Rj ₃ Rj ₄-genotypes showed values intermediate between those of IAC-2 (Rj ₂ Rj ₃) and Hill (Rj ₄) , which were the parent cultivars of the Rj ₂ Rj ₃ Rj ₄-lines, B340, B349, and C242. The reduction in the occupation ratio of the serogroup USDA110 for about 1 month after the first sampling was the lowest (0.13–0.16) in the Rj ₂ Rj ₃ Rj ₄-genotypes, excluding B349, followed by the non-Rj- and Rj ₂ Rj ₃-genotypes and highest (0.52–0.69) in the Rj ₄-genotypes, excluding Hill. Therefore, it was considered that the population of compatible rhizobia with host soybean plants increased in the rhizosphere with the progression of the development and growth. The results showed that with the expansion of the root area of host plants, the occupation ratio of type A rhizobia including the serogroup USDA110 was high. Therefore, the Rj ₂ Rj ₃ Rj ₄-genotypes were superior to other Rj-genotypes in terms of the inoculation effects of nodulation type A rhizobium, B. japonicum USDA110. However, the preference of the Rj ₂ Rj ₃ Rj ₄-genotype for serogroup USDA110 is not sufficient to rule out the competition with the other serogroups in this study. Therefore, the study should be centered on the isolation of more efficient (Hup⁺) and highly compatible rhizobial strains with the Rj ₂ Rj ₃ Rj ₄- genotypes.     

Effect of N. sativa oil on impaired glucose tolerance and insulin insensitivity induced by high-fat-diet and turpentine-induced trauma

The aim of this study was to investigate the effect of N. sativa oil on impaired glucose tolerance and insulin insensitivity induced by high-fat diet and trauma. Three dietary groups were used in this study; Rat-Chow (RC), N. sativa oil diet (Combination 4% N. sativa oil and 16% butter oil) (NSOD) and 20% Butter Oil Diet (BOD). Each group was subdivided in two groups; control and trauma. Diets were supplemented for five consecutive weeks body weight increase per week was calculated. At end of the dietary treatments, single dose (2 mL kg(-1) body weight) of turpentine was injected in the dorso-lumber region. Intravenous glucose tolerance test (i.v. GTT) was performed, insulinogenic index and insulin sensitivity was measured. The results showed butter oil diet significantly increased the body weights and visceral fats compared other two groups, respectively. Fasting glucose levels did not change in trauma induced rats while insulin levels increased significantly and it found highest in butter oil diet fed animals. Impaired glucose tolerance was found sever in BOD fed traumatized rats. N. sativa oil diet protected impaired glucose tolerance and insulin insensitivity induced either via saturated fatty acids or injury. In conclusion, N. sativa oil may be used in post surgery diabetic patients to prevent the long going adverse effects from surgical trauma.     

异速模型评估森林植被生物量有机碳储量

在孟加拉的吉大港南部森林地区,利用异速模型评估森林植被的有机碳的储量.异速模型被分别应用测试树木(被划分两个胸高直径级)、灌木和草本植物.采用基部面积估算胸高直径级为从> 5 cm 到 ≤ 15 cm 和> 15 cm树木的生物量有机碳储量模型最好,分别有很高的决定系数(胸高直径级> 5 cm 到 ≤ 15 cm 的r2 为0.73697,胸高直径级> 15 cm 的r2为0.87703),且回归系数(P = 0.000)显著.其它模型(包括采用树高,胸高直径,树高和胸高直径,以及综合树高、胸高直径和木材密度)的线性和对数关系都表现出很低的决定系数.分别建立了20种优势树种的异速模型,采用树木基部面积的模型都得到很高的决定系数值.单独采用灌木和草本植物总生物量的异速模型有较高的决定系数(灌木的r2 为0.87948,草本植物的r2 为0.87325),且回归(系数)性显著(P = 0.000).生物量有机碳的评估是复杂的和耗时的研究,本研究所建立的异速模型可以应用于孟加拉和其它热带(地区)国家的森林植被的有机碳储量的测算.     

Ecological and economical significance of homestead forest to the household of the offshore island in Bangladesh

An explanatory survey was conducted to assess the contribution of plant diversity to the ecological and socio-economic condition of the rural household in the offshore island of Bangladesh.Assessment was done by means of multistage random sampling.The homestead sizes of the study area were classified into 3 groups viz,large (>0.25 ha),medium (0.05-0.25 ha) and small (<0.05 ha) based on the result obtained from a preliminary survey,and a total of 45 homesteads,15 from each group,were selected randomly for the study.The average annual income from homestead's plant diversity varied from Tk 5730.00 (US$95.5) to Tk 17500.00 (US$291.67).The rural people were mainly dependent on their homegarden for woodfuel and nutritional requirement as forest was unavailable in the island.The rural people here also cultivated the plant species as a safety measure from frequent cyclone.Constraints hindering the development of homestead plantation were identified and suggestions were given such as the adequate supply of seedlings of fast growing native species and conservation of endangered species to meet the demand of the household as well as to keep ecological balance.     

孟加拉无机肥料对几种农林作物生物固氮和种苗生长的影响(英文)

比较了不同浓度无机肥料(尿素和重过磷酸钙)对四种农林作物(楹树、雨豆树、相思树和印度田菁)生物固氮和种苗生长的影响。种子萌发一个月后利用不同浓度肥料(尿素:40kg·hm-2,80kg·hm-2;重过磷酸钙:40kg·hm-2,80kg·hm-2;(尿素 重过磷酸钙)40kg·hm-2和(尿素 重过磷酸钙)80kg·hm-2)处理种苗。结果表明:中等浓度无机肥料促进了种苗的生长,但较高浓度无机肥料也不利于种苗的生长。当施加尿素时根瘤菌的数量大小明显受抑制,但随着增加磷肥(重过磷酸钙)根瘤菌的数量大小增加。本研究有助于农业人员利用无机肥料改善土壤提高农林作物的生物固氮和种苗生长。图2表6参33。     

Leaf litter decomposition of dominant tree species of Namdapha National Park,Arunachal Pradesh,northeast India

Rates of weight loss and nutrient (N and P) release patterns were studied in the leaf litter of the dominant tree species (Ailanthus grandis, Altingia excelsa, Castanopsis indica, Duabanga sonneriatioides, Dysoxylum binectariferum, Mesua ferrea, Shorea assamica, Taluma hodgsonii, Terminalia myriocarpa and Vatica lancefolia) of a tropical wet evergreen forest of northeast India. Nitrogen and phosphorus mineralization rate and decay pattern varied significantly from species to species. In general, the decay pattern, characterized by using a composite polynomial regression equation, exhibited three distinct phases of decay during litter decomposition—an initial slow decay phase (0.063% weight loss day⁻¹), followed by a rapid decay phase (0.494% weight loss day⁻¹) and a final slow decay phase (0.136% weight loss day⁻¹). The initial chemical composition of the litter affected decomposition rates and patterns. Species like D. sonneriatoides, D. binectariferum, and T. hodgsonii with higher N and P content, lower carbon and lignin content, and lower C:N ratio and lignin:N ratio exhibited relatively faster decomposition rates than the other species, for example M. ferrea, C. indica and A. grandis. A slow decay rate was recorded for species such as M. ferrea, C. indica, and A. grandis. The initial N and P content of litter showed significant positive correlations with decay rates. Carbon and lignin content, lignin:N, and C:N showed significant negative correlations with decay rates. Soil total N and P, and rainfall, soil temperature, and soil moisture had positive correlations with decay rates. The rapid decomposition rates observed in comparison with other different forest litter decay rates confirm that tropical wet evergreen forest species are characterized by faster decomposition rates, indicating a faster rate of organic matter turnover and rapid nutrient cycling.     

Antinociceptive activity of Derris uliginosa

The ethanol extract of leaves of Derris uliginosa given by oral route at dose of 250 and 500 mg/kg produced a significant inhibition on acetic acid-induced writhing in mice.     

The effect of indoxacarb and five other insecticides on Phytoseiulus persimilis (Acari: Phytoseiidae), Amblyseius fallacis (Acari: Phytoseiidae) and nymphs of Orius insidiosus (Hemiptera: Anthocoridae)

A laboratory study assessed the contact toxicity of indoxacarb, abamectin, endosulfan, insecticidal soap, S-kinoprene and dimethoate to Amblyseius fallacis (Garman), Phytoseiulus persimilis Athias-Henriot and nymphs of Orius insidiosus (Say). Amblyseius fallacis is a predacious phytoseiid mite and an integral part of integrated pest management (IPM) programmes in North American apple orchards. The other two beneficials are widely used in greenhouses to manage various arthropod pests infesting vegetable and ornamental crops. Indoxacarb is a slow-acting insecticide, so toxicity data were recorded 7 days post-treatment when the data had stabilised. It showed no toxicity to O. insidiosus nymphs or to A. fallacis or P. persimilis adults. The LC50 values for O. insidiosus nymphs and P. persimilis could not be estimated with their associated confidence limits, because the g values were greater than 0.5 and under such circumstances the lethal concentration would lie outside the limits. The LC50 for A. fallacis was 7.6x the label rate. The fecundity of P. persimilis was reduced by 26.7%. The eclosion of treated eggs from both species of beneficial mites was not affected adversely. Among the other pest control products, S-kinoprene and endosulfan affected adversely at least one species of the predators, whereas dimethoate, abamectin and insecticidal soap were very toxic to all three beneficials. Indoxacarb should be evaluated as a pest control product in IPM programmes.     

Detection of Cryptosporidium parvum and Cryptosporidium muris in soil samples

 The flotation procedure for the detection of Cryptosporidium parvum and Cryptosporidium muris oocysts in feces was adapted for use on soil samples. Soil samples were seeded with known amounts of purified C. parvum or C. muris oocysts and Cryptosporidium spp.-free bovine feces. The limit of detection for this procedure was determined at different levels of inoculation for each species. At each level of inoculation, 30 control samples were processed and the observer was blind to the status of the sample. All samples were examined for the presence of Cryptosporidium spp. oocysts using phase-contrast microscopy. The samples were seeded with the following estimated counts of C. parvum oocysts: 1000/g, 1250/g, and 1500/g. These levels had sensitivities of 88%, 90%, and 93%, respectively. All inoculation levels had a specificity of 100%. Thirty additional samples were inoculated with C. muris and the limit of detection was found to be 76 oocysts/g sample, with a sensitivity of 97% and a specificity of 100%. Received: 4 October 1999