Foliar applications of abscisic acid decrease the incidence of blossom-end rot in tomato fruit

Abstract

Various environmental stress factors, such as drought and high relative humidity, can cause calcium (Ca) deficiency and lead to physiological disorders such as blossom-end rot (BER) in tomato (Lycopersicon esculentum) fruit. Recent studies demonstrate that abscisic acid (ABA) triggers whole-plant and fruit-specific mechanisms to increase fruit Ca uptake and prevent BER development. The objective of this study was to examine the effects of foliar application of ABA and hydroponic Ca treatments in fertilizer solution on localized deficiency of Ca causing BER in tomato fruit. The application of 500mgL−1 ABA foliar spray treatment significantly decreased Ca in the leaf tissue. Ca decreased by 10.7% in the leaf tissue when comparing the foliar application of ABA to the control. In addition, decreasing Ca treatments from the 180mgL−1 to the Ca deficient treatment of 60mgL−1 decreased Ca concentration in the leaf tissue by 39.5%. The interaction of ABA and Ca treatments had a significant effect on Ca concentration in the fruit tissue. Ca concentration increased 25.7% when comparing the 180mgL−1 Ca and 0.0mgL−1 ABA treatment to the combination treatment of 180mgL−1 Ca and 500mgL−1 ABA treatment. In addition, ABA treatments had statistically significant effect on Ca in tomato fruit proximal and distal tissue and increased the concentrations 14.7% and 34.6% in, respectively. The incidence of BER in tomato fruit tissue was lowest with ABA treatments and Ca treatment of 180mgL−1. The incidence of BER decreased by 86.2% from the combination of 180mgL−1 Ca and 0.0mgL−1 ABA treatment to the combination treatment of 180mgL−1 Ca and 500mgL−1 ABA treatment. The results demonstrate that the application of ABA increased Ca in the fruit tissue as Ca treatments were decreased from the 180mgL−1 Ca. Furthermore, our results demonstrate that, despite reducing total plant Ca uptake in the leaf tissue, the 500mgL−1 ABA foliar spray treatments significantly reduced the incidence of BER development in tomato fruit. Thus, ABA could be an alternative treatment to increase Ca uptake into fruit and distribution into the distal tissue of the fruit relative to leaf uptake.