Vegetative Growth and Foliage Nutrient Content of Super Chief Apple under Different Irrigation and Fertigation Schedules in NW Himalayan Region

In the scheduling of nutrient supply programs, analysis of plant nutrient status has been found to be useful to prevent the deficiency or toxic effects of nutrients in any horticultural crop. So the present study was framed to assess the foliage nutrient content and vegetative growth under different irrigation and fertigation combination modules. Recently apple (Malus ×domestica) orchards in the state Himachal Pradesh of India have converted from the traditional royal delicious orchard at 6 × 6 m spacing with rainfed/basin irrigation to early spur varieties on dwarfing rootstock with drip irrigation, both with or without fertigation. An experimental field trial was started at the end of 2018 in a ‘Super Chief’/MM106 orchard at an experimental farm of the department of Soil Science & Water Management, Dr. YS Parmar University of Horticulture and Forestry, Nauni, Solan (HP). A factorial experiment with 16 treatment combinations of 4 irrigation levels viz. I₁ – drip irrigation at 100% ETc, I₂ – drip irrigation at 80% ETc, I₃ – drip irrigation at 60% ETc, I₄ – conventional irrigation, and four fertigation levels viz. F₀ – No fertilizer application (absolute control), F₁ – 100% of AD (NPK), F₂ – 75% of AD (NPK) and F₃ – 50% of AD (NPK) were replicated thrice with 3 plants in each replication. Vegetative growth parameters and leaf nutrient contents were affected by both fertilization and water rate. Irrigation and nutrient levels and their interactions exhibited significant effect on leaf N (3.10%), P (0.28%), K (1.77%), and S (0.44%) contents. Significantly maximum contents were observed in the irrigation level I₁ (DI at 100% ETc). Among fertigation level, F₁ [100% AD (NPK)] recorded highest contents of leaf N (3.17%), P (0.29%), K (1.80%), S (0.46%). Interaction I₁F₁ registered maximum leaf N (3.36%), P (0.36%), K (1.92%) and S (0.63%). With an increase in the water volume and an increasing dose of NPK, vegetative growth parameters, i.e., tree height, plant spread, tree volume, trunk girth, and annual extension growth were noted to increase proportionately. Treatment DI at 100% ETc (I₁), increased the tree height by 9.41, plant spread (EW by 32.0, NS by 16.3), tree volume by 61.36, trunk girth by 8.05, and annual extension growth by 14.22% over conventional irrigation (I₄). Drip fertigated trees with F₁ [100% AD (NPK)] reported the highest growth parameters. The results of two years apple trial suggested a positive effect of fertigation on enhanced effectiveness of fertilization and improved foliage nutrient content and vegetative growth.