Md. Moinul Hosain Oliver

BACKGROUND: Knapsack-type lever-arm sprayers are manually operated by farmers to apply chemicals in the field, which is time-consuming, labor-intensive, and costly. Prolonged use can cause discomfort in the hands, shoulders, and waist of operators, leading to fatigue. This problem can be affordably overcome by some mechanical maneuvers. AIM: This research aims to develop and evaluate a wheel-operated, knapsack-type sprayer machine suitable for row crops. METHODS: The machine integrates a lever-operated sprayer with a wheel-driven mechanism, transferring power via a chain and sprocket system. The sprayer’s performance was evaluated in both workshop and field conditions, considering factors such as nozzle discharge, spray angle, coverage area, swath width, and efficiency. RESULTS: The machine was made to serve at variable heights of crops, and its field efficiency was measured at 88.46%. A break-even analysis indicated 34.13 ha as the minimum acreage that must be sprayed for the sprayer to be profitable. The cost of fabrication (USD 105.93) was found to be affordable by marginal farmers of low- to middle-income countries. CONCLUSION: The developed wheel-operated sprayer is effective in field conditions, offering improved ease of use and reduced drudgery in pesticide application.

Pectin, a polysaccharide, is widely used as a gelling and thickening agent in the food industry. This study undertook optimization of pectin extraction from the peels of Baccaurea ramiflora Lour. (Burmese grape or lotkon), an abundantly grown wild fruit in Bangladesh. We applied the Box–Behnken Design of Response Surface Methodology with varied processing parameters including pH, time, and temperature. The Response Surface Methodology, employing a second‐order polynomial model, successfully optimized the extraction conditions for the maximum pectin yield. The model predicted a pectin yield of 10.73%, which closely matched the experimental yield of 10.56%. The optimal conditions for pectin extraction were determined as pH (2.4), extraction time (56 min), and temperature (76°C). Further analyses of the extracted pectin under optimized conditions confirmed its excellent potential for food applications. The pectin was characterized by its moisture content (10.42%), water activity (0.51), ash content (3.41%), equivalent weight (769.23 mg/mole), methoxyl content (7.75%), anhydrouronic acid content (66.88%), degree of esterification (65.79%), and acetyl value (0.39%). These determined parameters strongly support that the pectin extracted from the peels of Burmese grapes is of good quality.

Okra is a well-known and economically important vegetable grown in Bangladesh for consumption and seed production. The yield of okra is low compared to developed countries that can be increased using irrigation water efficiently. Traditional irrigation methods are used for okra cultivation in the developing countries, resulting in significant water loss. One of the options that appears to be promising for reducing this water loss is drip irrigation since it applies water directly to the plant’s root zone. However, farmers frequently complain about manual inspection and water wastage from the overhead tanks in small-scale microirrigation systems. An automated microirrigation system can help to solve this problem. This approach was developed at Bangabandhu Sheikh Mujibur Rahman Agricultural University to evaluate the performance of okra in terms of plant growth, seasonal water usage, and yield factors. For a better understanding of specialist crop irrigation management, the effectiveness of water utilization was also investigated. The experimental field was set up in a Randomized Complete Block Design (RCBD) from March to May 2021, with three different treatments such as T1 (Conventional irrigation), T2 (Drip irrigation) and T3 (Timer drip irrigation), for comparing the treatments with four replications. To construct an automated microirrigation system, a pump controller with sensing probes to regulate the water level in the irrigation tank and irrigation timers for watering the okra field depending on scheduling were used. According to the data, only the length of the pod varied significantly, whereas the other factors were non-significant. The yield components, such as the weight of pod per plant and yield, did not varied significantly among the treatments. The highest (12.95 kg/m3) and the lowest (10.47 kg/m3) water use efficiency were obtained in T3 (Timer drip irrigation) and T1 (Conventional irrigation) respectively. The study reveals that automated microirrigation technology can save 11% more irrigation water than conventional irrigation.

Concentrations of heavy metals in irrigation water and soil were examined to determine the level of contamination in a particular irrigation channel in Gazipur, Bangladesh. In this conduit, effluent from households, industries, and municipalities was combined with irrigation water. The study was carried out in order to estimate pollutant loads along a wastewater irrigation channel and to conceptualize seasonal changes in composite wastewaters. A total of six wastewater and nine contaminated soil samples were collected directly from the study area and analyzed for this project. From February to March, before the monsoon, the pH of the water is too low for this channel to be used for irrigation. At the end of the monsoon season, from April through May, all wastewater tests were within these parameters, making them suitable for irrigation. Considering the standard limits, Pb, Cr, and Cu concentrations in all wastewater samples were found unsuitable for irrigation and thus problematic for soils and crops. The concentration of Cd in the wastewater samples ranged from 27.82 to 88.36 mg/L, whereas the tolerance limit for Cd in irrigation water is 0.01 mg/L. In soil samples from the three places chosen, the levels of Pb were below the safe limit and the levels of Cr were above the safe limit. The heavy metal pollution index of all the sites crossed the safe limit. On the basis of the geo-accumulation index and the pollution index, Pb indicates no pollution and Cd indicates very high levels of pollution in all locations. The maximum enrichment factor was found for Cd, Pb, and Cu, which have minor enrichment, Ni, which has no enrichment, and Cr, which has moderate enrichment. The study also tried to link heavy metals in wastewater to their deposition in soil and seasonal and temporal variations. The study revealed that industrial effluent utilized for irrigation was closely related to the accumulation of heavy metals in soils. Since irrigated agricultural soils are likely to be exposed to harmful wastes, it is crucial that the effluents from the industrial region of Gazipur are appropriately controlled.

Pectobacterium carotovorum subsp. carotovorum [Pcc (formerly Erwinia carotovora subsp. carotovora)] PC1 causes soft-rot disease in a wide variety of plant species by secreting multiple pathogenicity-related traits. In this study, regulatory mechanism of air-liquid (AL) biofilm formation was studied using a cytR homolog gene deletion mutant (ΔcytR) of Pcc PC1. Compared to the wild type (Pcc PC1), the ΔcytR mutant produced fragile and significantly (P < 0.001) lower amounts of AL biofilm on salt-optimized broth plus 2% glycerol (SOBG), yeast peptone dextrose adenine, and also on King’s B at 27°C after 72 h incubation in static condition. The wild type also produced significantly higher quantities of AL biofilm on SOBGMg^– (magnesium deprived) containing Cupper (Cu²⁺), Zinc (Zn²⁺), Manganese (Mn²⁺), Magnesium (Mg²⁺), and Calcium (Ca²⁺) compared to the ΔcytR mutant. Moreover, the wild type was produced higher amounts of biofilms compared to the mutant while responding to pH and osmotic stresses. The ΔfliC (encoding flagellin), flhD::Tn5 (encoding a master regulator) and ΔmotA (a membrane protein essential for flagellar rotation) mutants produced a lighter and more fragile AL biofilm on SOBG compared to their wild counterpart. All these mutants resulted in having weak bonds with the cellulose specific dye (Calcofluor) producing lower quantities of cellulose compared to the wild type. Gene expression analysis using mRNA collected from the AL biofilms showed that ΔcytR mutant significantly (P < 0.001) reduced the expressions of multiple genes responsible for cellulose production (bcsA, bcsE, and adrA), motility (flhD, fliA, fliC, and motA) and type III secretion system (hrpX, hrpL, hrpA, and hrpN) compared to the wild type. The CytR homolog was therefore, argued to be able to regulate the AL biofilm formation by controlling cellulose production, motility and T3SS in Pcc PC1. In addition, all the mutants exhibited poorer attachment to radish sprouts and AL biofilm cells of the wild type was resistant than stationary-phase and planktonic cells to acidity and oxidative stress compared to the same cells of the ΔcytR mutant. The results of this study therefore suggest that CytR homolog is a major determinant of Pcc PC1’s virulence, attachment and its survival mechanism.

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