Effect of Biostimulants on Drought Tolerance of Greenhouse-Grown Tomato

Summary

This greenhouse trial examined how two biostimulants—a plant-derived polyhydroxy acids extract (B1) and Sargassum seaweed extract (B2)—mitigate drought stress in tomato production across three irrigation levels. Whilst drought reduced key physiological traits by up to 58%, both biostimulants enhanced net photosynthesis (up to 44%), chlorophyll content (up to 33%) and, for B2, water use efficiency (up to 43%). However, these physiological improvements did not translate to increased fruit yield or quality, suggesting a limited practical benefit for production under the tested conditions.

Regional applicability

The findings are relevant to UK horticultural practice, particularly for protected tomato cultivation where water availability and drought management are increasingly important under climate change. However, transferability depends on UK-specific growing conditions, substrate types, and cultivar responses; local validation trials would be advisable before recommending biostimulant applications as a drought mitigation strategy for commercial production.

Key measures

Stomatal conductance, net photosynthesis, quantum yield, chlorophyll content index, intrinsic water use efficiency, plant height, stem thickness, number of leaves, fruit yield, fruit number, fruit weight, quality indices, bioactive compounds, antioxidant activity

Outcomes reported

The study measured physiological traits (stomatal conductance, net photosynthesis, chlorophyll content, water use efficiency), agronomic traits (plant height, stem thickness, leaf number), and post-harvest parameters (fruit yield, fruit number, weight, quality indices) in tomatoes exposed to three drought levels and treated with two biostimulants. Drought stress significantly reduced physiological and agronomic performance, whilst biostimulants enhanced certain physiological responses but showed limited effects on fruit production.

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