Spraying potassium silicate and sugar beet molasses on tomato plants minimizes transpiration, relieves drought stress and rationalizes water use

Abstract

Transpiration is a physiological phenomenon in which water is lost from the plants in the form of water vapors. Under the global shortage of water, transpiration reduction is an efficient and a necessary procedure for conserving irrigation water with keeping the plant survival and protecting foliage against drought harms and consequently increasing water productivity. One of the main strategies to reduce the transpiration rate and reduce the deleterious impacts of drought stress is the foliar application of antitranspirants. The impacts of foliar application of five antitranspirants (potassium silicate, sugar beet molasses, kaolin, abscisic acid, or linseed oil) as well as water-sprayed plants on growth, some physiological parameters, yield components and water use efficiency of tomato plants cv. 023 grown under three irrigation levels (100, 80 or 60% of the estimated crop evapotranspiration, ETc) were studied. The field experiment was conducted during 2014 and 2015 seasons at the Experimental Farm of Horticulture Department, Faculty of Agriculture, Ain Shams University, Shoubra El Kheima, Qalyubia Governorate, Egypt. Results revealed that decreasing irrigation level from 100% to 60% of ETc reduced the vegetative growth parameters, SPAD readings, leaf relative water content, leaf osmotic potential, N, P, K and Ca percentages in leaves, yield components, and water use efficiency, while leaf electrolyte leakage was increased in both growing seasons. Foliar applications of antitranspirants exhibited varying responses in relation to alleviating of the negative effects of drought stress. Potassium silicate and sugar beet molasses were the most effective antitranspirants for attenuating the severity of water deficit. On the contrary, both ABA and linseed oil had significant inhibitory effects on some parameters, while kaolin had moderate and neutral effects. In conclusion, potassium silicate or sugar beet molasses can be used as effective antitranspirants and ameliorative substances for alleviating the hazardous effects of water deficit on tomato plants.