Asian Journal of Soil Science and Plant Nutrition

Background: Tomato production under naturally ventilated polyhouse conditions requires precise management of irrigation and nutrient supply to achieve high productivity while improving water and nutrient use efficiency. Drip irrigation scheduled according to crop evapotranspiration and fertigation can enhance the delivery of water and nutrients to the active root zone. However, the optimum combination of irrigation and fertigation levels for indeterminate tomato hybrids under such protected conditions remains insufficiently standardised

Aims: To determine the optimum drip irrigation regime and fertigation level, and their interaction, for maximising the growth, yield, fruit quality and nutrient use efficiency of hybrid tomato grown under a naturally ventilated polyhouse.

Study Design: Factorial randomised complete block design (FRCBD) with nine treatment combinations with three replications.

Place and Duration of Study: College of Horticulture, Bagalkot, University of Horticultural Sciences, Bagalkot, Karnataka, India, during 2025-26 under a naturally ventilated polyhouse.

Methodology: The indeterminate F₁ hybrid tomato 'Hamsa' was raised on raised beds at 90 x 60 cm spacing under drip irrigation. Three irrigation regimes based on crop evapotranspiration, I₁ (60% ETc), I₂ (80% ETc) and I₃ (100% ETc), were combined factorially with three fertigation levels, F₁ (80% RDF), F₂ (100% RDF) and F₃ (120% RDF; RDF = 300:300:300 kg ha^-1 NPK), giving nine treatment combinations replicated three times. Data on growth, flowering, yield, fruit quality, post-harvest soil nutrient status, nutrient and water use efficiencies were recorded and analysed statistically.

Results: Irrigation and fertigation levels and their interaction significantly influenced plant height at 60 days after transplanting (DAT), yield attributes and fruit quality. The treatment combination I₃F₃ (100% ETc + 120% RDF) recorded the tallest plants (139.67 cm), the highest number of fruits per plant (45.56), the heaviest fruit (122.06 g) and the highest fruit yield (126.35 t ha^-1), which was about 63% higher than the lowest-yielding combination I₁F₁ (77.67 t ha^-1). Fruit firmness and pericarp thickness were also greatest under I₃F₃ (3.14 kg cm^-2 and 9.93 mm), whereas total soluble solids showed an inverse trend, being highest under I₁F₁ (4.87 degrees Brix). Water use efficiency was highest under I₁F₃ (282.33 kg ha^-1 mm^-1).

Conclusion: Drip irrigation at 100% ETc combined with fertigation at 120% RDF is recommended as the most productive and remunerative schedule for tomato under naturally ventilated polyhouse conditions, whereas restricted irrigation with a higher fertigation dose (I₁F₃) offers a more resource-efficient alternative wherever water is the limiting input.