Synergistic regulation of photosynthesis, antioxidants, and fruit weight in greenhouse-grown tomato as affected by substrate type and exogenous additives

Summary

This greenhouse study in the Gobi region investigated how different growing substrates interact with exogenous additives (surfactant, nano water-retaining agent, or combined) to regulate tomato physiology and productivity under water-limited conditions. Substrate type determined the effectiveness of specific additives: surfactant alone enhanced photosynthesis and antioxidant defence in coconut coir and mixed substrates (28–42% increases in net photosynthetic rate and POD activity), whilst the combined treatment optimised photosynthesis in washed sand. Fruit weight gains of up to 12.4% were achieved through strategic substrate–additive matching, with POD activity emerging as a key physiological correlate of both photosynthetic performance and yield.

Regional applicability

The findings are geographically specific to the Gobi region's arid conditions and may have limited direct application to UK greenhouse horticulture, which operates under different water availability, climate, and energy regimes. However, the mechanistic insights into substrate–additive interactions and water-use efficiency optimisation could inform UK protected cropping practice, particularly regarding substrate selection and potential use of wetting agents or water-retaining amendments in water-stressed production systems.

Key measures

Net photosynthetic rate, stomatal conductance, peroxidase (POD) activity, superoxide dismutase (SOD) activity, malondialdehyde (MDA) content, average fruit weight

Outcomes reported

The study measured effects of different substrates (coconut coir, washed sand, peat + perlite mix) combined with surfactant and nano water-retaining agent treatments on tomato photosynthesis, antioxidant enzyme activity, oxidative stress markers, and fruit weight. Fruit weight gains of 4.1–12.4% were achieved through optimised substrate–additive combinations.

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