Prominent Doses of Nitrogen Enhance Mulberry and Silk Cocoon Productivity

Nitrogen (N) has potential to improve leaf yield and quality of mulberry plant. However, optimum doses of N for mulberry cultivation have not been updated for long times on the newly developed mulberry varieties in Bangladesh. A study was conducted at the research field and laboratories of Bangladesh Sericulture Research and Training Institute (BSRTI), Rajshahi to determine the nitrogen (N) requirements and optimum age of mulberry plants to get higher leaf yield, better quality of leaves, successful silkworm rearing performance and suppresses of foliar diseases in mulberry plant. The six treatments executed for trials on N requirements of mulberry plants were: N: 0, 80, 160, 240, 320 and 400 kg/ha/yr. The blanket doses of P & K for N trial were fixed as per recommended doses of BSRTI. Research results indicated that the added nutrient elements (N) favored in increasing growth, leaf yield, improving quality of mulberry leaves, suppresses foliar diseases as well as improved silk cocoon productivity. The leaf yield increased with increased rates of N application. The highest leaf yield was 51.88 Mt/ha/yr found in older plants of 6-10 years of age with the application of N @ 400 kg/ha/yr which was 6.57% higher than the maximum average yield of less than 5 years ages of mulberry plant. All the growth and quality parameters of leaves viz: moisture, chlorophyll-a, chlorophyll-b, total sugar, soluble carbohydrate, reducing sugar and crude protein exhibited the best performance with the better silkworm rearing performances viz: wt. of 10 matured larval (g), effective rate of rearing by number, single cocoon wt. (g), single shell wt. (g), SR%, highest filament length (m), rendita and cocoon yield/100 dfls (kg) through the treatment of N400 P150 K100 kg/ha/yr (T5) with four split doses in 6-10 years ages of mulberry plant, where the cocoon productivity was 57.85% greater than the control treatment. Furthermore, the average incidence percentages of leaf spot, tukra and powdery mildew diseases were also reduced for the increasing doses of nitrogen. This study concluded that elevated N enhances mulberry leaf yield, quality, silk cocoon productivity as well as suppresses the foliar diseases incidence of mulberry plant.