Standardization of agrotechniques for vertically trained watermelon [Citrullus lanatus (Thunb.)Matsum. & Nakai]

Abstract

The experiment entitled “Standardization of agrotechniques for vertically trained watermelon [Citrullus lanatus (Thunb.) Matsum. & Nakai] under rain shelter” was carried out at Department of Vegetable Science, College of Agriculture, Vellayani, Kerala, during the period 2021-2022, to study the effects of spacing, training and pruning on yield and quality of watermelon hybrid ‘Saraswati’ under rain shelter. The treatments were factorial combinations of three planting densities viz., D1- 1.5 m × 0.6 m, D2- 1.5 m × 0.45 m and D3-1.5 m × 0.3 m; two training levels viz., T1– nipping into single vine and T2– nipping into double vine) and two pruning heights viz., P1- pruned at 2 m and P2- unpruned) arranged in randomized block design with two replications and control with horizontal training of vines in open condition. Planting densities significantly influenced all growth parameters while training affected only flowering characters and number of leaves. Plants at wider spacing, D1 recorded longest vine (3.84 m), earliest flowering (15.56 for male flower and 22.41 for female flower), lowest node of flowering (4.68 for male flowers and 13.64 for female flowers), highest number of leaves (14.21 at 20 DAT and 34.63 at 45 DAT), highest chlorophyll content (1.69 mg 100 g-1 at 20 DAT and 2.93 mg 100 g-1at 45 DAT) and highest dry matter production at harvest (29.15 g). Highest leaf area per plant (2211.50 cm2 at 20 DAT and 2266.02 cm2 at 45 DAT) and longest internodes (7.84 cm) were recorded in closer spacing, D3. The chlorophyll content was found to be higher in open condition (3.00 mg 100 g-1) than under rain shelter. All yield parameters other than rind thickness, fruits per plant and seed characters were significantly influenced by spacing. Plants at wider spacing recorded highest value for fruit equatorial diameter (15.15 cm), fruit polar diameter (18.90 cm), fruit weight (2.84 kg), yield per plant (5.50 kg), harvest 86 index (0.79) and longest crop duration (102.62 days). Medium spacing noted least days to first harvest (46.84 days). Closer spacing, D3 had fruits at lower nodes (15.31) and recorded highest values for yield per plot (78.37 kg). Training to single vine recorded earliest flowering (16.79 days for male flower and 23.14 days for female flower) and lowest node of flowering (5.36 for male flowers and 14.36 for female flowers). Training to two vine noted highest number of leaves (13.37 at 20 DAT and 34.43 at 45 DAT) and highest dry matter production at harvest (28.14 g). Plants trained to single vine produced fruits with highest fruit weight (2.84 kg) and longest polar diameter (18.17 cm). However, plants trained to double vine recorded highest number of fruits (2.56), yield per plant (5.28 kg), yield per plot (72.32 kg) and harvest index (0.79). Pruning had significant influence on vine length, days to flowering and number of leaves at 45 DAT. Unpruned plants recorded longest vine (5.00 m), higher number of leaves at 45 DAT (32.98) and highest dry matter production (27.88 g). Pruned plants noted earliest flowering (16.88 days for male flower and 23.24 days for female flower). Pruned pants recorded highest value for fruit polar diameter (18.39 cm) and fruit weight (2.56 kg) while unpruned plants had highest number of fruits per plant (2.26), yield per plant (3.03 kg), yield per plot (69.47 kg) harvest index (0.74) and longest crop duration (115.38). Seeds per fruit and weight of 100 seeds were not significantly influenced by any of the treatments. Among treatment interactions, D×T significantly influenced chlorophyll content at 45 DAT, leaf area index, days to first harvest, number of fruits per plant, fruit weight and dry matter production at harvest. D×P combinations had significant effect on vine length, fruit polar diameter chlorophyll content at 45 DAT, days to first harvest, number of fruits per plant, fruit weight, yield per plant, yield per plot and harvest index. Interaction of P×T and D×T×P influenced chlorophyll content at 87 45 DAT, number of fruits per plant, yield per plant, yield per plot and harvest index. On analysis of economic parameters, highest net returns (Rs. 10,06,729) and B:C ratio (3.02: 1.00) were recorded in double vine unpruned plants at closer spacing (D3) under rain shelter. The study revealed growing watermelon vertically trained watermelon at 1.5 m × 0.3 m resulted in highest yield per unit area (78.37 kg) and B:C ratio (3.02: 1.00). Unpruned plants trained as two vines recorded highest number of fruits per plant, yield per plant, yield per plot and harvest index. So, the present study suggests cultivation of vertically trained watermelon under rain shelter as double vine at closer spacing without pruning the main vine