Selection for improvement of desirable traits will be successful only when it is performed based on reliable genetic parameters. An experiment was conducted by segregating populations of eight intra-hirsutum hybrid combinations. Genetic parameters including mean, range, phenotypic coefficient of variation (PCV), genotypic coefficient of variation (GCV), heritability, genetic advance (GA), GA as percentage of mean, skewness and kurtosis in F₂ generation and heritability parameter in F₃ generation of eight intra-hirsutum hybrids were assessed for yield components. To assess the breeding value of genotypes selected based on genetic parameters; their progenies were evaluated in the F₃ generation. The study revealed that F₂ generation of the cross combination TCH 1628 × Gh 493 exhibited the highest mean, GCV, PCV, heritability, GA, GA as percentage of mean and negative kurtosis for seed cotton yield. The F₂ population of the crosses such as MCU 12 × Gh 488 (ginning outturn) TCH 1452 × MCU 5 (boll weight) and TCH 1628 × Gh 493 (boll number and plant height) and SVPR 2 × Gh 488 (sympodial number) were exhibited excellent variability for the respective traits. F₃ progenies raised out of selected single plants recorded more than 98% of heritability for traits viz., seed cotton yield and ginning outturn. Remarkably higher expression of these heritability values in F₃ progenies than their respective F₂'s indicated the stable inheritance and improved breeding value of selected individuals under genetic parameters based selection. Hence, genetic selection implies its worthiness through an expression of high mean values for different biometrical, important fiber quality and seed cotton yield traits in 21 elite F₃ progenies selected.

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The maximum phosphorus adsorption (S_max) and Phosphorous saturation index (P_sat) of a soil provide information for the proper management of the P fertilizer of the soil. The objective of this investigation was to determine S_max and develop a P_sat for 14 rice soils. Soil samples were analyzed for pH, clay content, dithionite extractable Fe (Fe_D), Mehlich-3 (M3) extractable P (PM3), and Fe (FeM3). The S_max value and P_sat based on M3 extractions were determined. The S_max value ranged from 110 to 625 mg kg^-1, and correlated with sand (r =-0.70, P>0.01), silt (r =0.70, P>0.01), clay (r =0.59, P>0.05) and Fe_D (r =0.71, P>0.01). Soil pH_H2O and organic carbon content were not correlated (P>0.05) with S_max, while pH_KCl was negatively correlated (r =-0.64, P>0.05) with S_max. Multiple regression found that the combination of pH_KCl and Fe_D were the two most important soil properties related to the S_max of the soils studied. Conventional adsorption equations, such as the Langmuir, Freundlich and Temkin equations, satisfactorily described the P sorption of the soils. The P sorption capacity of the studied soils varied from 80 to 316 mg kg^-1. The calculated energy of adsorption of the soils ranged from 0.18 to 1.56 mg L^-1, and there was apparently a negative correlation between the energy of adsorption (k) and the observed S_max values. Buffering capacity ranged from 14 to 69. Phosphorus saturation indices (P_sat) of the tested soils varied from 1.82 to 28.21%, and were correlated with sand (r =0.56, P>0.05) and silt (r =-0.59, P>0.05), but not with the other soil properties we studied.

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The quality of surface water (canal and pond water) and groundwater (well water) was monitored with an interval of 6 months from 2002 to 2005 at two farming villages near Ha Noi, Viet Nam. In the villages, two rice and one winter crop were cultivated within a year, in which massive amounts of chemical fertilizer-N were applied consecutively. The ammonium-N concentration ranged from 0.01 to 11.6 mg/L for surface water and from trace level to 5.6 mg/L for groundwater. The nitrate-N concentration ranged from 0.04 to 0.95 mg/L for surface water and from 0.01 to 1.2 mg/L for groundwater. These concentrations did not increase with time. It was considered that surface water must be carefully used for the irrigation of agricultural crops, because the ammonium-N plus nitrate-N concentration exceeded a threshold value of 5 mg/L at several times during the monitoring period, above which some damage for crop growth might happen. The ammonium-N concentration of groundwater was proportional to the annual amount of chemical fertilizer-N applied at the villages, suggesting a positive effect of the application of chemical fertilizer-N on an ammonium-N concentration of groundwater. Groundwater was unsuitable for drinking, because the ammonium-N concentrations mostly exceeded a level of 0.78 mg/L, above which human internal organ systems might be damaged. The nitrate-N concentration of groundwater satisfied the water standard for drinking use.

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Growth and mortality parameters, exploitation rates, annual recruitment patterns and length-weight relationships were estimated from monthly length-frequency and weight samples of Ilisha filigera, captured mainly by set bag nets (SBNs), from the upper Bay of Bengal off the Bangladesh coast using the FiSAT program. The objective of this study is to estimate growth parameters, mortality rates, and the exploitation rate and recruitment pattern of I. filigera for sustainable management. The von Bertalanffy growth parameters, asymptotic length L₈ (cm) and growth constant K (per year), were found to be 48.90 and 0.80, respectively. The L₈ and Z/K estimates provided by the Wetherall plot were 48.487 cm and 2.517. The annual rate of fishing mortality (F = 0.91) was low compared to the relatively high natural mortality (M = 1.35). The value of the exploitation rate (E = 0.40) suggested that the species was not over-exploited by SBNs operation in the region. About 53.33% of I. filigera were found to be recruited during the August-October period, and 46.67% during the March-May period. The growth performance index (φ') was 3.28. The total length and body weight relationship was found to be W = 0.0318 L^2.5803 suggesting that the growth rate displayed a negative allometric pattern (b < 3). The growth parameters derived in the current study were found to be comparable with previous estimates available for the same species from the Bay of Bengal and from other localities.

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This study was conducted to determine the impact of irrigation on income distribution among farm families in the drought-prone Barind Tract in the Rajshahi district of Bangladesh. We performed a decomposition analysis of the Gini measures of inequality in order to quantify the relative importance of the various component of income in accounting for overall income inequality. This analysis provided some information about how different farm and non-farm income sources (agriculture, livestock, fisheries, business and off-farm jobs, and agricultural wages) in irrigated and non-irrigated villages were distributed across farm households. Finally, we compared the Gini ratios for overall income and the various components of income for irrigated and non-irrigated situations in order to ascertain the effect of irrigation on income distribution. The overall Gini ratio that we computed was slightly higher in irrigated situations than in non-irrigated situations. This implies that increased production efficiency due to irrigation may slightly increase income inequality in the irrigated villages where land income tends to be unequally distributed among households, farm income contributed the lion's share of this income.

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We have assessed the leaching of heavy metals from the contaminated sediments of the To-Lich and Kim Nguu river systems in Hanoi, Vietnam We used different solutions such as distilled water (pH 5.5), nitric acid (HNO₃), acetic acid (CH₃COOH) and Ethylene diamine tetra acetic acid (EDTA) in a batch leaching test. The average concentrations of heavy metals leached were: (1) using H₂O: 63.4% of Cd, 10.6% of Cr, 5.3% of Cu, 33.6% of Ni, 1.6% of Pb and 6.2% of Zn; (2) using HNO₃: 67.2% of Cd, 10.6% of Cr, 5.0% of Cu, 34.1% of Ni, 1.3% of Pb and 5.5% of Zn; (3) using CH₃COOH: 65.0% of Cd, 12.7% of Cr, 5.1% Cu, 45.2% of Ni, 1.2% of Pb and 5.4% of Zn; and (4) using EDTA: 70.5% of Cd, 15.6% of Cr, 17.0% of Cu, 59.5% of Ni, 7.2% of Pb and 33.0% of Zn. The EDTA had high heavy metal leachability compared to water, acetic acid, and nitric acid. The average potential leachability decreased in the following order: Cd > Ni > Cr > Cu = Zn > Pb. The leachability exhibited a tendency to decrease with increasing organic matter for heavy metals other than Cr and Zn.

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A sustainable water resources management has become a major concern all over the world. In agricultural areas, water quality degradation occurs due to excessive application of fertilizer especially where high yielding crops are cultivated. To make the balance between food production and environmental conservation, it is essential to evaluate the effects of agricultural activity on water environments and ecosystems. As is widely known, water temperature plays a major role in water quality dynamics through biogeochemical processes. The present study, therefore, aims to develop a mathematical model for simulating daily water temperature in paddy fields. In the model, only three meteorological data of air temperature, sunshine duration and relative humidity, and crop information of leaf area index (LAI) are required. Sensitivity analyses were conducted on each input variable for identifying the contribution of these variables to the water temperature estimation. As a result, the present model showed high applicability in estimating water temperature in paddy fields. Air temperature was found to have the strongest effects on water temperature, which was followed by relative humidity, sunshine duration and LAI. Despite the low contribution to the water temperature, LAI affected all of the heat fluxes, which would suggest the importance of the crop growth model. An integration with hydrological and water quality models are recommended for further application of the present model.

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Tomato is cultivated during the dry winter season in Bangladesh with scarce rainfall. Poor farmers can not afford enough money to apply irrigation as well as other costly inputs. Conventionally, rice straw is used as mulch to conserve soil water during the crop cultivation of dry season. The availability of rice straw is not sufficient to meet the demand because it is also used as fuel, house making and cattle feed. Nowadays, agroforestry is practiced in many parts of the country and there is an opportunity to use tree leaves as mulch. The study was aimed to examine the effectiveness of tree leaf (Senna siamea) mulch comparing with the conventional mulch (rice straw) and no mulch for saving irrigation water in tomato cultivation. Irrigation water (IW) (40, 20 and 10 mm) were applied when cumulative pan evaporation (CPE) exceeded 40 mm, thus the irrigation levels were IW/CPE 1.0, 0.5 and 0.25, respectively. Senna leaf mulch conserved more soil water than straw mulch and no mulch. Number of fruits per plant, fruit length and fruit yield of tomato were the highest in Senna leaf mulch, which did not vary significantly with rice straw mulch but varied significantly with no mulch. Tomato yield obtained from Senna leaf mulch was 4.6 and 13.7% higher than straw mulch and no mulch, respectively. All these parameters increased with irrigation level. Ascorbic acid content of fruit was relatively high in no mulch with lower irrigation level, while β-carotene was increased with irrigation level irrespective of mulches. Weed dry weight was significantly higher in no mulch plot compared to straw and Senna leaf mulch plots. Results indicate that Senna siamea leaf can be used as effective mulch and 50% irrigation water can be saved without significant yield loss for tomato cultivation during the dry season.

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