Antibacterial activity of Leonurus sibiricus aerial parts     

Ahmed F  Islam MA  Rahman MM 《Fitoterapia》2006,77(4):316-317

Different solvent extracts (carbon tetrachloride, chloroform, acetone and methanol) of Leonurus sibiricus were studied for their antibacterial activity. Carbon tetrachloride and chloroform extracts showed a broad spectrum of antibacterial activity.  相似文献   

Influence of nitrification inhibitors on nitrification and nitrous oxide (N₂O) emission from a clay loam soil fertilized with urea     

Deli Chen  Helen C. Suter  Arshad Islam  Robert Edis 《Soil biology & biochemistry》2010,42(4):660-664

Laboratory incubation experiments were conducted to compare the effects of the nitrification inhibitors 3,4-dimethylpyrazole phosphate (DMPP) and 2-Chloro-6-(trichloromethyl)-pyridine (N-serve) on nitrification and nitrous oxide (N₂O) emission from a Vertosol from southern Australia, under controlled moisture and temperature. Nitrification rates in the control soil were strongly influenced by the temperature and moisture, increasing by a factor of 3.6 for each 10 °C increase between 5 and 25 °C. DMPP inhibited nitrification effectively for 42 days at 5-15 °C and 40-60% water filled pore space (WFPS). DMPP also slowed nitrification appreciably at 25 °C when the soil was at 40% WFPS, but was less effective at 60% water filled pore space. N-serve inhibited nitrification effectively for 42 days under all test conditions. Emissions of N₂O from the urea treatment (no inhibitors) significantly increased with increasing temperature and moisture. The ratio of total N₂O emission to total nitrification was not constant and varied from around 0.03% at 5 °C and 40% WFPS to 0.12% at 25 °C and 60% WFPS. DMPP and N-serve reduced cumulative N₂O emission over 42 days by more than 65% under all the imposed conditions.  相似文献   

Production of mahogany sawdust reinforced LDPE wood-plastic composites using statistical response surface methodology     

Sofina-E-Arab  Md.Azharul Islam 《林业研究》2015,26(2):487-494

We produced wood–plastic composite board by using sawmill wastage of mahogany(Swietenia macrophylla) wood and low density polyethylene.We used multi-response optimization to optimize the process parameters of composite board production including mixing ratio,fire retardant(%) and pressing time(min).We investigated the effects of these three process parameters in the mechanical and physical properties of the composite board.Afterwards,Box–Behnken design was performed as response surface methodology with desirability functions to attain the optimal level of mixing ratio,fire retardant and pressing time(min).The maximum modulus of elasticity(MOE) and modulus of rupture(MOR) were achieved at the optimal conditions of wood plastic mixing ratio of60:40,pressing time of 9 min and zero fire retardant percentage.The optimized MOR and MOE were 13.12 and1,781.0 N mm-2,respectively.  相似文献   

Evidence for a ‘uniculm effect’ in spring wheat (Triticum aestivum L.) in a mediterranean environment     

T. M. T. Islam  R. H. Sedgley 《Euphytica》1981,30(2):277-282

Summary The concept of the uniculm habit as an important feature of a wheat ideotype for a mediterranean environment was evaluated under field conditions. A uniculm plant produces a single shoot and when sown in a stand exemplifies a non-tillering crop with a fixed density of shoots throughout the growing season. Yield and harvest index of normal tillering spring wheat was compared with that of the same crop surgically detillered throughout the growing season to a constant density of 2 shoots per plant. The use of a biculm, whilst retaining the uniculm principle of a fixed density of shoots throughout the growing season, permitted comparison on a single crop sowing at normal field density.The control plots followed the usual pattern of tillering for the region attaining a maximum of about 4.0 shoots per plant by early spring. Shoot number declined to 2.3 and 2.6 per plant by maturity in 1978 and 1979, respectively.Detillered plots outyielded the controls by 14 per cent in 1978 (2.05 v. 1.80 tonnes ha^-1) and 22 per cent in 1979 (1.84 v. 1.51 tonnes ha^-1). Harvest indices were 0.39 v. 0.35 in 1978 and 0.30 v. 0.24 in 1979 for detillered and control plots, respectively.Higher leaf area indices and better water relations after anthesis in biculm stands indicated more efficient water use when shoot population was controlled at near optimum level. Irrigation at anthesis reduced the difference in yield between detillered and control plots.Although the uniculm principle was demonstrated with biculms in practice control of shoot number will require the use of genetic uniculms.  相似文献   

Field efficiency of biofertilizers on the growth of okra (Abelmoschus esculentus [(L.) Moench])     

M. Nuruzzaman  M. Ashrafuzzaman  M. Zahurul Islam  M. Rafiqul Islam 《植物养料与土壤学杂志》2003,166(6):764-770

An experiment was carried out at the Farm of the Department of Crop Botany, Bangladesh Agricultural University, Mymensingh from March to July, 2001 to investigate the effect of biofertilizers on morpho‐physiological characters of okra. The experiment was laid out in a randomized complete block design with four replications. There were nine treatments such as T₀ (control), T₁ (Azotobacter biofertilizer), T₂ (Azospirillum. biofertilizer), T₃ (Azotobacter + Azospirillum. biofertilizers), T₄ (Azotobacter + Cowdung 5 t ha^–1), T₅ (Azospirillum + 5 t ha^–1 cowdung), T₆ (Azotobacter + Azospirillum + 5 t ha^–1 cowdung), T₇ (5 t ha^–1 cowdung), and T₈ (60 % N). The experimental results revealed significant variations among the treatments in respect of morphological characters, e.g. plant height, number of leaves per plant, stem base diameter, tap root length, and physiological characters like root dry weight, leaf area index, and crop growth rate. Number of leaves per plant, stem base diameter, root length, root dry weight, leaf area index, and crop growth rate were larger in T₄, T₅, T₆, and T₈ than the others. In all the parameters, T₈ gave the similar result with biofertilizers in combination with cowdung treatments, and T₇ was identical with T₀ (control). These experimental results revealed that morpho‐physiological characters of okra could be modified by the application of biofertilizer + cowdung. However, biofertilizers + cowdung treatments were comparable to T₈ (60 % N) in this study. This suggests that T₄ or T₆ or T₅ were more benificial in environmentally friendly okra cultivation and may be used as an alternative of inorganic N by saving cost of production and sustaining productivity.  相似文献   

Seed compositional and disease resistance differences among gene pools in cultivated common bean   总被引：5，自引：0，他引：5  

F.M.A. Islam  K.E. Basford  C. Jara  R.J. Redden  S. Beebe 《Genetic Resources and Crop Evolution》2002,49(3):285-293

It is widely accepted that two major gene pools exist in cultivatedcommon bean, one Middle American and one Andean. Recently another gene pool,designated as North Andean and a fourth group (not considered to be adistinct gene pool) have been reported by the senior author and hiscolleagues. Many of the agronomic and seed compositional attributes of the twomajor gene pools are well known, but the seed compositional value and diseaseresistance of the North Andean gene pool has not yet been characterized. Torectify this situation, the seed compositional characters, percentage of proteinconcentrations (phaseolin, lectin and -amylaseinhibitor), the nutrient elements (calcium, phosphorus, iron andzinc) and the disease and pest attributes (angular leaf spot,anthracnose, common bacterial blight and empoasca damage) were considered.The Middle American gene pool gave higher lectin, calcium, phosphorus, sulfurand zinc than the Andean gene pool but lower phaseolin and iron. The NorthAndean gene pool is more like the Andean gene pool for phaseolin, resistance toangular leaf spot and anthracnose from Andean pathogen isolates, but more likethe Middle American gene pool for lectin, zinc, sulfur and resistance toanthracnose from Middle American pathogen isolates. On the other hand, it hadthe highest iron concentration and was more resistant to common bacterialblight. These results indicate the potential value of this gene pool in a commonbean breeding program.  相似文献   

Freeze-dried soil extraction method for the measurement of microbial biomass C     

K. R. Islam  R. R. Weil  C. L. Mulchi  S. D. Glenn 《Biology and Fertility of Soils》1997,24(2):205-210

A new method for the measurement of microbial biomass C by direct extraction of freeze-dried soil with either 0.5M K₂SO₄ or 0.5M NaHCO₃ was evaluated. The underlying principle of the method is that rehydrating a freeze-dried soil releases cytoplasmic organic compounds from desiccated and disrupted microbial cells. Nineteen soils under various management regimes were sampled to test the proposed method, in which each soil sample was split into two subsamples. One subsample was kept in the field-moist condition at 4°C. The other subsample was brought to 100% water-holding capacity and frozen at –20°C for 24h. The frozen soil was then freezedried. Both subsamples were extracted with 0.5M K₂SO₄ or 0.5M NaHCO₃ at a soil-to-extractant ratio of 1-to-4 (w/v) and organic C determined in the extract (C_{K2 SO4} or C_NaHCO3). The net freeze-dry stimulated increase in extracted C was correlated (r ²=0.98 for C_{K2 SO4} or 0.93 for <$>\rm C_{NaHCO_3})<$> more closely with microbial biomass C (C_MB) measured as net evolution of CO₂–C by chloroform fumigation incubation (CFI) than with total C (r ²=0.42 for C_{K2 SO4} or 0.47 for C_NaHCO3). Based on linear regression equations, extraction efficiency coefficients (K _EC) were used to calculate C_MB from C_{K2 SO4} or C_NaHCO3 as follows: C_MB=C_{K2 SO4}/0.152±0.004 C_MB=C_NaHCO3/0.257±0.01 The relationship between the C_MB and the flushes of C extracted after rehydration of freeze-dried soil showed that the K _EC values were more consistent for C_{K2 SO4} than C_NaHCO3. The freeze-dried soil extraction was a fast, precise, reliable and safe method for measuring microbial biomass C in soil. Received: 27 May 1996  相似文献   

Arsenic Accumulation in Rice (Oryza sativa L.) Varieties of Bangladesh: A Glass House Study   总被引：1，自引：0，他引：1  

M. Azizur Rahman  H. Hasegawa  M. Mahfuzur Rahman  M. Nazrul Islam  M. A. M. Miah  A. Tasmin 《Water, air, and soil pollution》2007,185(1-4):53-61

A glass house study was conducted to investigate the accumulation of arsenic in tissues of five widely cultivated rice (Oryza sativa L.) varieties of Bangladesh namely BRRI dhan 28, BRRI dhan 29, BRRI dhan 35, BRRI dhan 36, BRRI hybrid dhan 1. Arsenic concentrations were measured in straw, husk and brown and polish rice grain to see the differential accumulation of arsenic among the rice varieties. The results showed that the concentrations of arsenic in different parts of all rice varieties increased significantly (p?<?0.05) with the increase of its concentrations in soil. The rice varieties did not showed significant differences in arsenic accumulation in straw, husk, brown and polish grain when the concentrations of arsenic in soil was low. However, at higher concentrations of arsenic in soil, different rice varieties showed significant differences in the accumulations of arsenic in straw, husk and grain. Significantly higher concentrations of arsenic in straw and husk of rice were observed in BRRI hybrid dhan 1 compared to those of other verities. The BRRI dhan 28 and 35 concentrated significantly higher amount of arsenic in brown and polish rice grain compared to those of other rice varieties. The results imply that arsenic translocation from root to shoot (straw) and husk was higher in hybrid variety compared to those of non-hybrid varieties. Arsenic concentrations in brown and polish rice grain of five rice varieties were found to follow the trend: BRRI dhan 28 > BRRI dhan 35 > BRRI dhan 36 > BRRI dhan 29 > BRRI hybrid dhan 1. The order of arsenic contents in tissues of rice was: straw > husk > brown rice grain > polish rice grain.  相似文献   

Yield and water relations of wheat as influenced by irrigation and depth of tillage     

S. M. Rahman  A. Islam 《Irrigation Science》1991,12(2):67-71

Summary Development of a ploughpan has been reported in Bangladesh for almost all ploughed soils which are puddled for transplanted rice cultivation. Field information on the water requirement of dryland crops such as wheat and the effects of loosening the dense layer on crop yield and water use efficiency are very limited. Field experiments were, therefore, conducted in the grey floodplain soil of Sonatala series (Aeric Haplaquept) to study the irrigation and tillage effects on the yield and water relations of wheat (Triticum aestivum L. cv. Sonalika). The split plot design experiment comprised four irrigation treatments in the mainplots viz. W₀ = no irrigation, W₁ = irrigation of 5 cm at 4 weeks after planting, W₂-W₁ + irrigation(s) of 5 cm each at irrigation water to cummulative pan evaporation (IW/CPE) ratio of 0.75 and W₃- W₁ + irrigation(s) of 5 cm eacht at IW/CPE ratio of 0.50. The sub-plot tillage depth treatments were: A-7.5 cm (traditional), B-15 cm, C-22.5 cm, D-22.5 cm practised in alternate wheat seasons. Measurements were made of grain and straw yield, soil water depletion and water expense efficiency.Irrigation had no effect on grain or straw yield. Tillage to 15 cm increased wheat yield by about 15% over traditional depth to ploughing. In general, deep tillage coupled with one irrigation at four weeks after planting produced the largest wheat yield.Soil water depletion (SWD) in the 0–90 cm profile was greatest in the treatment receiving two irrigations, one at 4 weeks and again at IW/CPE ratio of 0.50. The average SWD in this treatment was 113 in 1982–83 and 82 mm in 1983–84. Plots receiving traditional tillage (7.5 cm) had the greatest SWD. Total water expense were the greatest in treatments receiving three irrigations. The maximum water expense efficiency (WEE) of wheat was observed in the non-irrigated plots in 1982–83 and 1983–84, respectively. Deep tillage treatments, in general, had significantly greater WEE than those under traditional ploughing. Intensive irrigation and efficient soil and water management are important factors in enhancing crop productivity. The former not only permits judicious water use but also better utilization of other production factors thereby leading to increased crop yield which, in turn, helps stabilize the farming economy. The best way to meet increasing demand for water is to adopt efficient water management practices to increase water use efficiency.Irrigation should aim at restoring the soil water in the root zone to a level at which the crop can fully meet its evapo-transpiration (ET) requirement. The amount of water to be applied at each irrigation and how often a soil should be irrigated depend, however, on several factors such as the degree of soil water deficit before irrigation, soil types, crops, and climatic conditions (Chaudhury and Gupta 1980).Knowledge of movement of water through the soil is imperative to efficient water management and utilization. The presence of a dense pan impedes water movement into the sub-soil. As a result, the top soil becomes saturated by irrigation and sensitive dryland crops can fail as this plough layer impedes the penetration of roots into deeper soil layers and decreases water extraction. Crops growing in these soils often undergo severe water stress within 5–8 days after rainfall or irrigation (Lowry et al. 1970). Due to decrease rates of water flow, the lower soil layer may remain unsaturated and as a result, the recharge and soil water storage in the profile are considerably decreased (Sur et al. 1981).In Bangladesh, ploughpans develop to varying degree in almost all ploughed soils (Brammer 1980). They are particularly marked in soils which are puddled for transplanted rice cultivation where the pan is usually only 8–10 cm below the soil surface and 3–5 cm thick. Its presence is generally regarded as advantageous for cultivation of transplanted rice in that it prevents excessive deep percolation losses of water. But in the same soil this cultivation for a subsequent dryland crop would adversely affect yield. A slight modification of the plough layer could enable good yields of both rice and a dryland crop to be obtained in the same soil in different seasons (Brammer 1980). The sub soils have a good bearing capacity, both when wet and dry and the pan can easily be reformed, if desired, for cultivating transplanted rice after a dryland crop like wheat.Professor of Soil Science, Dhaka University, Dhaka, Bangladesh  相似文献   

Corchorus pascuorum: transmission of chemically induced fruit formation with environmental change     

A S Islam  R Mughal 《Science (New York, N.Y.)》1969,164(877):315-316

When Corchorus pascuorum (Tiliaceae), native to Australia, was grown in the arid region of West Pakistan, it flowered abundantly but produced no fruit. It was induced to form fruit by treatment with 25 percent sucrose solution containing indolebutyric acid (300 parts per million). When plants were raised from the induced fruits, they fruited without any further treatment and retained the ability to produce fruits in two subsequent generations, whereas those raised from the original seeds produced no fruit.  相似文献