Improved weed management for transplanted aman rice

Rainfed transplanted rice grown in the monsoon aman season accounts for more than 50% of the total area planted to rice in Bangladesh. Because of rising input costs, including labor, farmers are searching for ways to maintain income, by either increasing yields or reducing costs or both. On-farm trials in the High Barind Tract indicated that one-third of the farmers would be able to gain 0.5 t ha–1 or more additional grain by undertaking more intensive or timelier weeding than is usual under current management practices. Higher yields were observed on-farm from a preemergence application of butachlor(1.25 kg a.i. ha–1) compared with hand weeding twice. In Comilla District, trials of a range of weed management practices demonstrated that the yield advantage over the farmers’ practice, either one or two hand weedings, was on average 355 ± 18 kg ha–1 for Rifit (pretilachlor), 281 ± 39 kg ha–1 for Machete (butachlor), and 210 ± 34 kg ha–1 for Ronstar (oxadiazon), each followed by one hand weeding in aman 2003. Partial budgets calculated for inputs and returns showed that hand weeding was less profitable than herbicides in rainfed rice,incurring US$72 ha–1 lower return. Use of a push weeder plus one hand weeding was less profitable than herbicides, incurring$49 ha–1 lower return. To date, herbicides have been largely promoted for irrigated rice in Bangladesh. The trial results demonstrate that under rainfed conditions early in the aman season, water levels are adequate for herbicides to work effectively. The use of herbicides allows timely weed control when there is a shortage of labor and avoids transaction costs, such as the provision of meals and time needed to source laborers. Herbicides are likely to be adopted by growers experiencing labor shortages, particularly on large farms and for farmers seeking to reduce input costs. Sharecroppers and tenant farmers who pay rent are primarily concerned about obtaining a high aman yield, so innovations that raise aman yields (such as herbicides that will have a similar effect as a timely first weeding) are also likely to be adopted on sharecropped plots, even when costs are not shared between the landlord and tenant

Entropy generation for MHD natural convection in enclosure with a micropolar fluid saturated porous medium with Al2O3Cu water hybrid nanofluid

This contribution gives a numerical investigation of buoyancy-driven flow of natural convection heat transfer and entropy generation of non-Newtonian hybrid nanofluid (Al2O3-Cu) within an enclosure square porous cavity. Hybrid nanofluids represent a novel type of enhanced active fluids. During the current theoretical investigation, an actual available empirical data for both thermal conductivity and dynamic viscosity of hybrid nanofluids are applied directly. Numerical simulation have been implemented for solid nanoparticles, the volumetric concentration of which varies from 0.0% (i.e., pure fluid) to 0.1% of hybrid nanofluids. Heat and sink sources are situated on a part of the left and right sides of the cavity with length B, while the upper and bottom horizontal sides are kept adiabatic. The stated partial differential equations describing the flow are mutated to a dimensionless formulas, then solved numerically via the help of an implicit finite difference approach. The acquired computations are given in terms of streamlines, isotherms, isomicrorotations, isoconcentraions, local Began number, total entropy, local and mean Nusselt numbers. The data illustrates that variations of ratio of the average Nusselt number to the average Nusselt of pure fluid Num+ is a decreasing function of Ha and φ, while e+ is an increasing function of Ha and φ parameters of hybrid nanofluid

Comparative study of physical and elastic properties of jute and glass fiber reinforced LDPE composites

Jute fiber reinforced low density polyethylene (LDPE) composites and glass fiber reinforced LDPE composites were prepared at variable proportions using compression molding technique at 120 °C. Few physical and mechanical properties such as bulk density, water absorption%, tensile strength, elongation at break (Eb%), Young’s modulus, flexural stress and strain and tangent modulus of both composites were studied and compared. Throughout the study, it was revealed that glass composites had better mechanical stability as compared to LDPE jute composites

Effect of sowing dates on yield and yield-attributes of some sunflower hybrids

To determine the optimum sowing date for some sunflower hybrids i.e. A11 x Rf7, A11 x Rf9, A12 x Rf9, A8 x Rf10, A11 x Rf10, A8 xRf12, A9 x Rf12, A15 x Rf12, A2 x Rf20 and the check variety Sakha 53, along with to assess their genetic variability and to determine selection criteria for improving their yield. These materials were sown at four adjacent field represent four sowing dates i.e. 20th of April, 20th of May, 20th of June and 20th of July using randomized complete block design with three replications at the experimental Farm of El Mattana Agricultural Research Station, (latitude of 25.17o N and longitude of 32.33o E), Luxor Governorate, during the two successive summer seasons 2018 and 2019. Results revealed that early sown plants on 20th of April had high yield potential compared to other sowing dates. The promising sunflower hybrid for seed yield feddan-1 and more yield attributes was A12 x Rf9 when sown on 20th of April and across sowing dates, whereas A15 x Rf12 when it sown on 20th of July and across sowing dates was the best for seed oil content. Considerable genetic variability was detected among sunflower genotypes, and hence the selection would be effective to genetic improvement of seed weight plant-1 for these materials, which can be achieved through selecting genotypes having the largest head diameter and the heaviest weight of 100-seed.

Nonenzymatic Exogenous and Endogenous Antioxidants

Nonenzymatic exogenous and endogenous antioxidants play an important role in human health and act as preservatives for cosmetics, pharmaceuticals, and food products. This chapter will discuss the chemical structure and mechanism of action of the most important nonenzymatic small exogenous and endogenous organic molecules that act as antioxidants. The chapter will focus on the structural features, functional groups, properties, biosynthetic origin, and mechanism of action of such antioxidants. It also covers damages that free radicals create and the mechanisms by which they are neutralized by the various antioxidants. The scope of this chapter will be limited to nonenzymatic exogenous and endogenous antioxidants since enzymatic antioxidants have been discussed extensively in several reviews

Study of physical, mechanical and thermal properties of unidirectional jute fiber reinforced PVC film composites

This paper presents the physical, mechanical and thermal properties of unidirectional jute fiber reinforced polyvinyl chloride (PVC) film composites. Composites (wt % of fiber) of jute fiber reinforced PVC matrix were prepared by compression molding at 160⁰ C. Variable weight ratios of these composites namely 100:0, 95:5, 90:10, 85:15 and 80:20 were prepared and then physical, mechanical and thermal properties were studied. The tensile strength of composites increases with the increase of fiber addition and percentage of elongation at break decreases with increase of fiber addition. Thermal analysis of PVC-jute fiber composites show that thermal degradation of PVC film starts ahead of jute fiber and the degradation of composites was occurring in two stages

Studies on geo-morphology, ecology and fish production of the 92 rivers of Rajshahi Division, Bangladesh

Geo-morphology, ecology and fish production of the 92 rivers of Rajshahi division have been presented in this paper. Fifteen rivers are dead and 11 rivers have severe erosion problem. Siltation has increased in 66 rivers and depth has decreased in 11 rivers. Sixty nine rivers are suffering from low flow conditions. Fish diversity has decreased in 20 rivers while fish production has declined in 75 rivers. A total of 31 fish species have extinct, 25 species are under threat of extinction and 43 species have low production. Siltation and pollution are the major causes of fish habitat loss. Recommendations are made to protect and conserve fish habitat and riverine fisheries of Rajshahi division