Animal-based organic nutrition induces comparable fruit quality to that of inorganic fertigation in soilless-grown grape tomato

Summary

This soilless cultivation trial compared three OMRI-certified organic nutrient solutions (variously combining animal-based nitrogen sources with potassium sulphate) against Steiner's inorganic control for their effects on grape tomato fruit quality. Organic fertiliser applications increased total hydrolysable and condensed polyphenol content relative to the inorganic control, whilst environmental stressors (temperature >30°C and sub-optimal light) suppressed carotenoid content and colour attributes. An organic blend containing animal-based nitrogen, ammonium sulphate and potassium sulphate produced morphology and colour comparable to conventional fertigation, though the inorganic control yielded highest carotenoid levels.

Regional applicability

This study was conducted in Mexico under high-temperature, controlled soilless conditions that differ substantially from UK outdoor or protected horticulture systems. The findings on organic nutrient solution formulation and phenolic enhancement may be transferable to UK producers using protected cropping, though UK's cooler climate and lower light stress mean carotenoid outcomes may differ; direct comparison of UK organic and conventional tomato production in local conditions would strengthen applicability.

Key measures

Total hydrolysable polyphenols, condensed polyphenols, carotenoid content, fruit morphology (size and shape via Tomato Analyzer software), fruit colour parameters (digital image analysis via Color Test), air temperature, light intensity

Outcomes reported

The study compared polyphenol, carotenoid content, and morphological and colour attributes of organically and conventionally fertilised soilless-grown grape tomatoes. Environmental factors (high temperature and sub-optimal light) and nutrient solution type were evaluated for their effects on fruit quality metrics.

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