Reducing irrigation does not always mean sacrificing a crop. In two protected-growing tomato cycles, researchers maintained yields comparable to conventional full irrigation while applying 20% less water alongside a seaweed-derived biostimulant.
What researchers studied
A Brazilian research team examined whether controlled water reductions and a plant biostimulant could improve tomato production efficiency. Their experiments compared irrigation at 40%, 60%, 80%, 100% and 120% of estimated crop evapotranspiration, a measure of the water a growing crop loses.
Each irrigation level was tested with or without an extract derived from the seaweed Ascophyllum nodosum. The researchers assessed tomato production, photosynthesis, plant water status, water-use efficiency and the energy associated with irrigation over two crop cycles under protected cultivation.
This was a controlled horticultural experiment rather than a survey of commercial farms.
What they found
The most promising combination was irrigation at 80% of crop evapotranspiration plus the biostimulant. Across both cycles, it sustained yields comparable to plants receiving 100% replacement without the extract, while reducing irrigation water by one fifth.
For the 80%-plus-extract treatment, photosynthetic rates were reported to improve by as much as 5.7% to 7.8%, and energy productivity was approximately 0.70–0.72 kilograms of tomatoes per megajoule.
Excessive irrigation offered little advantage. At 120% replacement, the study reported an additional 0.6 megajoules of energy per plant and water-use-efficiency reductions of up to 15.7%–16.9%.
What it means
Water efficiency is a central question for growers facing rising energy costs and more variable water supplies. The results suggest that careful irrigation scheduling, potentially combined with targeted biostimulants, deserves attention as an alternative to simply maximising water application.
Importantly, the finding concerns a particular treatment combination. It does not show that reducing irrigation by 20% without the extract would have achieved the same yield.
Important limitation
The experiments involved tomatoes under protected cultivation and only two production cycles. Results may vary with soil, climate, variety, irrigation equipment and the cost or composition of the biostimulant. Commercial-scale validation is needed before treating the approach as a universal prescription.
Source Information
Study: Every drop counts: optimizing water use efficiency for sustainable tomato production
Authors: Vinícius Villa e Vila, Gabriel Villela Bedum, Mateus Silva Gelain, André Luiz da Mata Melo Junior, Tamara Maria Gomes, Roberto Fray da Silva and Patricia Angélica Alves Marques
Journal / Source: Scientific Reports
Published: 20 October 2026
