Abstract
Ten experiments to investigate the effects of growth regulator and management practices in manipulating the harvesting time and increasing yield as well as quality of eight to ten years old mango (Mangifera indica) cv. Amrapali plants were conducted at the BAU Germplasm Centre, FTIP, Department of Horticulture, Bangladesh Agricultural University, Mymensingh in four fruiting seasons from 2005 to 2008. Soil drench application of paclobutrazol at 10000 ppm and 7500 ppm on 15 July or 15 October was more effective in reducing vegetative growth i.e. terminal shoot length, number of leaves and leaf area compared to control (water application). Both 7500 ppm and 10000 ppm paclobutrazol applied as soil drench on 15 October caused earlier panicle emergence by 19 days as well as harvesting by 15 days compared with control. Furthermore, paclobutrazol when applied at 7500 ppm or 10000 ppm on 15 July advanced panicle emergence and harvesting by 23 days and 22 days, respectively over control. Applying paclobutrazol at 7500 ppm on 15 July produced the highest number of fruits (185) as well as yield (55.05 kg) per plant and the heaviest fruit (303.67g) compared with the lowest number of fruits (67) and yield (11.72 kg) per plant and the lightest fruit (177.00g) in control. Paclobutrazol at 7500 ppm applied on 15 July or 15 October also resulted in higher edible portion, lower stone pulp ratio and peel pulp ratio, longer shelf life, higher TSS, increasing vitamin C, lower titratable acidity, higher dry matter, reducing, non-reducing and total sugar contents as compared to control plants. Irrespective of concentrations, KNO, advanced harvest date by 5 to 6 days over control. Both KNO, and urea at 4% were effective for profuse flowering, higher fruit retention per panicle, increasing yield and quality of mango over control. Deblossoming at 75% in 2005 caused earlier panicle emergence by 8 days and harvest by 5 days in the following fruiting season (2006) compared to the control plants. The treatment 50% deblossoming resulted in the highest yield (22.42 kg/plant) in 2005 and deblossoming at 75% had the highest yield (24.58 kg/plant) in the following year (2006). On an average of two years, 50% deblossoming gave the highest yield. Plants receiving 100% or 150% of the fertilizer dose (Cow dung 25 kg, Urea 750 g 250 g Gypsum 250 g and Zinc Sulphate 15 g per plant) in three installments caused delayed harvest by 9 or 11 days, respectively than the untreated control plants. Applying fertilizer at 150% of the fertilizer dose in three installments had the highest number of fruits and yield per plant as well as fruit quality over control. The plants irrigated twice on 15 October and 15 November produced maximum number of fruits as well as yield per plant. The heaviest fruit, higher TSS, lower stone pulp ratio and peel pulp ratio were recorded in plants irrigated on 15 of each month starting from October to March and the lowest values in control. Fruits from the plants of irrigation treatments irrespective of intervals were matured and harvested 10 days later as compared to that of control. Plants irrigated twice on 15 October and 15 November and then continued from fruit set to maturity at 7 day or 14 day intervals produced about two fold higher yields (22.15 kg/plant or 21.62 kg/plant, respectively) and better quality fruits over control. The combination of selected best treatments like soil drench application of paclobutrazol at 7500 ppm on 15 July +150% of the fertilizer dose applied in three installments + 4% KNO3 application on 15 November + Irrigation on 15 October and 15 November and then continued from fruit set to maturity at 7 day intervals resulted in the earliest panicle emergence by 49 days (20.12.07) and earlier harvest by 27 days (04.06.08) as compared to the latest emergence and harvest on 07.02.08 and 01.07.08 in control, respectively. The increased number of fruits (198) and yield (59.72 kg) per plant, heaviest fruit (307.75g) and fruits of good quality was attained from the same combination of selected best treatments over control, which had the lowest number of fruits (24) and yield (4.34 kg) per plant as well as the lightest fruit (191.00 g).