NaHCO3 impairs the growth and fruit yield of tomato plants

Abstract

Underground water enriched in NaHCO3 is used in farms of the Buenos Aires province for tomato crop irrigation. This farming practice leads to salt accumulation and soil impairment after several seasons of cultivation inside the greenhouses. This work assayed the effect of NaHCO3 on tomato fruit production. Plants of the Elpida variety of Solanum lycopersicum L were grown in a hydroponic system. The presence of NaHCO3 (from 5 mM, as measured in the underground water to 10 or 20 mM) reduced K+/Na+ ratio and whole plant biomass and fruit yield; however, no effect was observed on fruit quality parameters. To test the participation of ascorbic acid in the tolerance to this stress, two slggp1 Micro-Tom mutant lines deficient in this antioxidant were used. In these experiments plants were treated with 0, 5 and 10 mM NaHCO3 causing an impairment of K+/Na+ ratio, photosynthesis, fruit yield, leaf and shoot dry weight (but without effect in root biomass) and delaying of fruit ripening time. Wild type and mutants plant responses showed no differences at stress conditions. Although NaHCO3 treatments caused a similar impairment in ascorbic acid mutants and wild type plants, these results reinforced the physiological importance of ascorbic acid levels to optimize plant growth under non-stressful conditions. Taken as a whole, the results presented here demonstrated the importance of avoiding the accumulation of this salt in greenhouse soils to optimize tomato production.