Effect of sodium alginate-based superabsorbent hydrogel on tomato growth under different water deficit conditions

Abstract

The main challenge facing agriculture today is water scarcity. At present, agriculture consumes around 70 % of the planet's freshwater, much of which is lost through evaporation, leaching and runoff. This wastage, combined with the increased frequency and severity of droughts linked to climate change, is having a considerable negative impact on crops. As a result, the food security of people living in regions with limited water resources is threatened. In this regard, efficient water management using water-saving materials and soil additives such as superabsorbent polymers (SAPs) are recognized as an effective strategy to boost water use efficiency by plants and improve agricultural productivity. The present study fits with this strategy and aims to investigate the effect of new sodium alginate-based hydrogel-treated sandy loam soil on seed emergence and growth of tomatoes as a crop model under different water-deficit stress levels. A set of pot experiments was conducted in a greenhouse chamber using sandy loam soil amended with two levels of hydrogel (0.1 % and 0.5 % by weight) along with untreated control, all under water-deficit stress at three levels: 30 % of the daily amount of required irrigation water (DARW) for different growing cycles (severe stress), 70 % DARW (mild stress), and 100 % DARW (normal irrigation conditions). The germination test showed the absence of phytotoxicity of the developed hydrogel and confirmed its suitability in protecting seedlings from drought stress. Greenhouse experiment results demonstrated that water stress and levels of applied hydrogel significantly (P < 0.05) affected plant growth parameters such as plant height, stem diameter, number of leaves, chlorophyll content, fresh weight, and dry weight compared with the treatments without SAPs. The developed sodium alginate-based SAPs showed relevant agronomical benefits under drought stress by retaining more water and nutrients, thus it had the potential to be used in agriculture for better water management along with significant environmental benefits.

Keywords: Drought stress; Plant growth; Soil amendments; Soil water retention; Superabsorbent polymers; Tomato; Water holding capacity.