Effects of Minimum Air Temperatures at Seedling Stage on Plant Growth, Yield, and Fruit Quality of Tomatoes Grown on a Single-Truss System.

Summary

This controlled trial examined the effects of seedling-stage minimum temperatures on tomato development and commercial performance in single-truss winter cultivation. Seedling vigour increased with warmer minimum temperatures (optimum 20°C), and leaf expansion was proportional to accumulated thermal time irrespective of minimum temperature regime. However, cooler seedling temperatures (5–10°C) paradoxically increased flower and fruit number but triggered substantial fruit shape abnormalities and reduced marketable yield; fruit sugar content improved significantly with warmer seedling conditions, suggesting a trade-off between yield quantity and quality.

Regional applicability

The findings are directly applicable to protected horticulture in temperate climates including the United Kingdom, particularly for winter glasshouse tomato production. The single-truss system and winter cultivation context are standard practices in UK commercial protected cropping, though the specific temperature thresholds and variety responses should be validated for UK cultivars and growing conditions.

Key measures

seedling fresh weight, plant height, leaf area, cumulative temperature-driven leaf expansion, flower number, individual fruit weight, malformed fruit incidence, marketable fruit yield, soluble solids (sugar) content

Outcomes reported

The study examined how minimum air temperatures (5, 10, 15, 20°C) during seedling stage affected subsequent plant growth, flower and fruit development, yield, and fruit quality in single-truss tomato production. Key measurements included seedling fresh weight, plant height, leaf area, flower number, individual fruit weight, fruit shape abnormalities, and sugar content.

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