Economic analysis of tilapia farming in some selected area of Dinajpur District: A comparison between monoculture and polyculture

The study was conducted to assess the cost and return from tilapia farming. Fifty homestead aquaculture ponds practicing monoculture and polyculture of tilapia (25 farmers from each category) were selected for this study. Data had been collected through face to face interview by using a structured questionnaire during April to September 2015 from the selected farmers of Dinajpur districts. The results from the survey revealed that both the tilapia monoculture and polyculture farming were profitable. However, the average total cost per hectare per production period was found higher (Tk. 332,712.08) in tilapia monoculture than tilapia culture with carps (Tk. 241,722.34). Moreover, the net margin was also found higher in tilapia monoculture with benefit cost ratio 1.51. Whereas, the benefit cost ratio in polyculture farming was 1.34

Active and break spells of summer monsoon over Bangladesh

This study examines the intraseasonal variability of the southwest summer monsoon over Bangladesh using rainfall data from rain gauge stations of the Bangladesh Meteorological Department (BMD) collected over 30 years (1988–2017). In this paper, active and break spells are defined as periods during the peak monsoon months of July and August, in which the daily precipitation lasts for three or more days at 0.5 above and below the daily climatological cycle. The active and break phases of the monsoon over a period of 10 years (2008–2017) were also analyzed by The Weather Research and Forecasting (WRF) model simulation for analysing synoptic conditions. The model simulations for each year were done for the period of 1 May to 30 September with 1 May as the initial condition with a single domain of 30 km resolution and 19 vertical levels. The final operational global analysis data from the Global Forecasting System of National Centers for Environment Prediction (NCEP-FNL) with resolution 1° × 1° is used for model simulation. The model-simulated daily rainfall, Sea Level Pressure (SLP), wind pattern at 850 hPa, 200 hPa, and Outgoing Longwave Radiation (OLR) are compared with the observations from Tropical Rainfall Measuring Mission (TRMM), ERA5 (ERA5 is the European Centre for Medium-Range Weather Forecasts fifth-gen global atmospheric reanalysis data), and Kalpana-1. This study also finds that the increase in rainfall is concurrent with a southwesterly wind and the decrease of rainfall simultaneously occurs with a southeasterly wind. Active days were found to have lower OLR values and lower SLP than break days

Biocontrol efficiency of microencapsulated Trichoderma harzianum coupled with organic additives against potato stem rot caused by Sclerotium rolfsii

Potato (Solanum tuberosum L.), world's fourth most carbohydrate supplying crop is often challenged by numerous pathogens among which Sclerotium rolfsii remains one of the most damaging during both growth and storage. As biocontrol is being preferred for their safety and sustainability, the present experiment was conducted for testing the biocontrol effectiveness of microencapsulated Trichoderma harzianum application in combination with organic additives against S. rolfsii. Five combinations (no T. harzianum+no organic additive [control]; T. harzianum+no organic additive; T. harzianum+rice husk biochar; T. harzianum+mustard oil cake; and T. harzianum+tea waste) were tested against two levels of S. rolfsii (absence [control] and presence) under a polyhouse environment. Prior to that, hyper-parasitism of T. harzianum against S. rolfsii was tested in vitro which showed 63.2% growth inhibition for the later. Polyhouse study revealed 16%, 25%, 19%, 21%, 38%, 27%, 9%, 13%, 28%, 20% and 9% average increase in plant height, branch number plant–1, leaf number plant–1, shoot dry matter, root dry matter, healthy tuber, total tuber yield, leaf greenness, net photosynthetic rate, total phenolic content and total antioxidant activity respectively with a subsequent reduction of 49% unhealthy tuber and 32% disease severity index due to T. harzianum+organic additive treatments. Disease suppression and growth recovery of S. rolfsii inoculated potato plants were found significantly better when T. harzianum was applied with organic additives compared to solitary application. The results of this study would provide useful information in strategizing T. harzianum formulation preparation for effective biocontrol of potato stem rot caused by S. rolfsii

Sett priming with salicylic acid improves salinity tolerance of sugarcane (Saccharum officinarum L.) during early stages of crop development

Sugarcane (Saccharum officinarum L.), a globally cultivated carbohydrate producing crop of industrial importance is being challenged by soil salinity due to its glycophytic nature. Water stress coupled with cellular and metabolic alterations resulting from excess sodium (Na+) ion accumulation is irreversibly damaging during early crop developmental stages that often results in complete crop failure. This study therefore aimed to explore the potential of salicylic acid as a sett priming material to mitigate the negative effects of salt stress on sugarcane during germination and early growth stages. Five doses of salicylic acid (0 [hydropriming] [control], 0.5 mM, 1 mM, 1.5 mM and 2 mM) were tested against three levels of salinity (0.5 dS m−1 [control], 4 dS m−1, and 8 dS m−1) within a polyhouse environment. Results revealed 11.2%, 18.5%, 25.4%, and 38.6%, average increase in final germination, germination energy, seedling length and seedling vigor index respectively with a subsequent reduction of 21% mean germination time. Investigations during early seedling growth revealed 21.6%, 17.5%, 27.0%, 39.9%, 10.7%, 11.5%, 17.5%, 47.9%, 35.3% and 20.5% overall increase in plant height, total leaf area, shoot dry matter, root dry matter, leaf greenness, relative water content, membrane stability index, proline content, total antioxidant activity and potassium (K+) ion accumulation respectively with a subsequent reduction of 24.9% Na+ ion accumulation and 35.8% Na+/K+ ratio due to salicylic acid priming. Germination, seedling growth and recovery of physiochemical traits were highly satisfactory in primed setts than non-primed ones even under 8 dS m−1 salinity level. This study should provide useful information for strategizing salinity management approaches for better productivity of sugarcane