Location and characteristics of soil The experimental plot was under the agroecological zone of Old Himalayan Piedmont soil (AEZ-1). The area has irregular patterns of grey stratified, sands and silts. Those are moderately acidic throughout and parent alluvium is rich in minerals. Organic matter content is low and CEC is medium. Soil fertility level in general is low to medium. The selected experimental site was well-drained medium-high land. The soil was slightly acidic (pH 5.85). The percent organic carbon, nitrogen, total available boron and zinc were 1.29%, 0.07%, 0.39 and 3.0 micro gram per gram of soil, respectively (Soil Testing Laboratory, SRDI, Dinajpur). Climate The experimental area belongs to a subtropical climatic zone which is characterized by heavy rainfall, high humidity, high temperature and a relatively long day period during the “Kharif” season (April- September) and scarce rainfall, low humidity, low temperature and short day period during “Rabi” season (October-March). This climate is also characterized by distinct season’s viz., the monsoon or rainy season extending from May to October, the winter or dry season from November to February and the pre-monsoon period or hot season from March to April.
Plant materials The tomato variety used in the experiment was “Maharaja F1”.This is a high-yielding variety. The seedlings were collected from BADC in Dinajpur. Treatments of the experiment There were 9 treatments combinations consisting of both B (0, 1 and 2kgha-1) and Zn (0, 1 and 2 kgha-1) and every treatment received nitrogen as urea (300 kg/ha), phosphorus as triple superphosphate, TSP (200 kg/ha) and potassium as Meurate of Potash, MP (210 kg/ha) as basal doses. Design and layout of the experiment The two factor experiment was laid out in the Randomized Complete Block Design (RCBD) with 3 replications. In total, there were 27 unit plots. The unit plot was 1.2m x 2.4m in size with a distance between unit plots was 50 cm. Land preparation At first the land was ploughed with a power-tiller on 12 November 2017 and kept open to sunlight. The after the experimental plot was prepared by several ploughings and cross ploughings followed by laddering to break the clods and to level the soil. The weeds and stubble of previous crops were collected and removed from the plot. These operations were done to bring the land under good tilth for transplanting of tomato seedlings. The experimental plots were laid out in accordance with the experimental design. Application of fertilizer A basal dose of well-decomposed cow dung @ 10 t ha-1 was applied just after opening the land. TSP was applied at final land preparation. The urea and MoP were applied in two equal installments by band placement, first band after two weeks of transplanting and again after two weeks from the first band placement. The treatments of Zn as zinc sulphate and B as boric acid were properly distributed to 9 plots under 3 replications as per design of the experiment. Transplanting of seedlings Healthy and uniform-sized 30 day old seedlings were transplanted in the experimental plots in the afternoon of 21 November, 2017 maintaining a spacing of 40 cm and 60 cm between the rows and plants. Light watering was applied immediately after transplanting by using water can.
Caring after seedlings Gap filling was done in place of dead or wilted seedlings in the field using healthy seedlings of the same stock previously grown. Weeding was accomplished as and whenever necessary to keep the crop free from weeds, for better soil aeration and to break the soil crust. When the plants were well established, staking was given to each plant by Bambusa sticks to keep them erect. Within a few days of staking, the plants were pruned and thereafter only 2 or 3 main branches were kept before going to flowering stage. Irrigation was done whenever necessary. The young plants were irrigated by a watering can. Beside this, irrigation was given four times at an interval of 12 days depending on soil moisture content. At the early stage of growth, some plants were damaged by insect pests (mainly leaf miner), and malathion 57 EC was sprayed at the rate of 2ml/liter at an interval of 15 days. Tomatoes were damaged by leaf blight, and Acrobat MZ was sprayed at the rate of 2ml/liter at an interval 15 days, and non-discovered plants were removed from the plots and destroyed.
Sampling of tomato fruits Fruits were harvested at 3 days’ intervals during early ripe stage when they attained a slightly red color. The harvesting was started from 15 February to 24 March 2018. Tomato fruits were harvested in the morning. The collected fruits were carried in gunny bags and then half of the collected samples were immediately transferred to the storeroom. Proper care was taken while harvesting and handling to avoid any mechanical injury. Harvested tomato fruits were stored in safe place at Post Graduate Laboratory of the Department of Horticulture, Hajee Mohammad Danesh Science and Technology University, Dinajpur. Data collection Five plants were selected at random in such a way that the border effect could be avoided. For this reason, the outer two lines and the outer plants of the middle lines in each unit plot were avoided. Data were recorded periodically from the sample plants at 15 days’ interval.