Impact of Shading on Tomato Yield and Quality Cultivated with Different N Doses Under High Temperature Climate

Summary

This greenhouse study investigated the interaction between shade cloth application and nitrogen fertilisation in tomato production under extreme heat (up to 45 °C). The findings indicate that optimal nitrogen dosing differs between shaded and unshaded conditions; whilst unshaded plants showed yield increases with higher N rates, shaded plants achieved maximum yield at intermediate N (7 mM), suggesting that shading reduces nitrogen requirements. Notably, shade cloth increased fruit lycopene content irrespective of nitrogen treatment, whilst nitrogen doses require downward adjustment when deploying shading to mitigate high-temperature stress.

Regional applicability

This work addresses climate adaptation in horticultural production, relevant to United Kingdom protected cropping systems facing increasing heat extremes. However, the extreme temperatures tested (up to 45 °C) exceed typical UK greenhouse conditions, limiting direct applicability; the nutrient management principles may transfer to UK growers adopting shade strategies in response to climate warming, but cultivar selection and thermal management practices differ substantially between Mediterranean and temperate climates.

Key measures

Total fruit yield, mean fruit weight, fruit lycopene concentration, air temperature reduction (~11 °C with shade cloth), direct sunlight attenuation (~50% with AOL S40 shade cloth)

Outcomes reported

The study measured total fruit yield, mean fruit weight, and fruit lycopene concentration in tomato plants grown under different combinations of shading treatments and nitrogen doses (3, 7, and 14 mM N) in high-temperature greenhouse conditions. It examined how shading and nitrogen management interact to affect both productivity and nutritional quality under heat stress.

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