Synergistic Effects of N P K Fertilizer Regimes and Plant Spacing on Morphological and Biochemical Traits of Bacterial Wilt-resistant Tomato Lines (Solanum lycopersicum L.)

Abstract

Tomato (Solanum lycopersicum L.) is a heavy feeder of NPK nutrients, and precise management of fertilizer regimes and plant spacing is essential to maximize growth, yield, fruit quality, and disease resistance. Bacterial wilt, caused by Ralstonia solanacearum Smith, has become a limiting factor in the cultivation of tomato in some pockets of Zone-I and Zone-II of Himachal Pradesh (Kangra Valley and surrounding areas of Mandi and Chamba districts). This is a soil borne bacterial disease and results in complete failure of the crop. This disease has also been reported from traditional tomato growing areas of Solan and Kullu valleys of Himachal Pradesh. The present investigation was undertaken to study the effects of N, P, K fertilizer regimes and plant spacing on morphological and biochemical traits of bacterial wilt–resistant tomato lines. The trial was laid out in a split–split–plot design comprising three fertility levels—F₁: 75%, F₂: 100% NPK (100 kg N, 75 kg P₂O₅, 55 kg K₂O/ha), and F₃: 125%—in the main plot; three spacings—S₁: 45 cm×45 cm, S₂: 60 cm×45 cm, and S₃: 75 cm×45 cm—in subplots; and three varieties—V₁: DPT-1, V₂: DPT-2, and V₃: Palam Pink—in sub-subplots at the Vegetable Research Farm of the Department of Vegetable Science and Floriculture, CSK HPKV, Palampur during the summer-rainy season 2022. Observations included growth and yield traits (days to 50% flowering, days to first harvest, number of fruits per cluster, fruit harvest duration, plant height, average fruit weight, pericarp thickness, locule number, marketable yield per plant), and biochemical parameters (TSS, lycopene content, titrable acidity, ascorbic acid). The highest lycopene content was recorded in treatment F₂S₂V₂, while the highest ascorbic acid content was observed in F₃S₁V₁, both significantly superior to all other treatments. The highest marketable yield (1.65 kg/plant) was achieved in the F₃S₃V₁ treatment (125% NPK, 75 cm×45 cm spacing, DPT 1).