Effects of four pre-harvest foliar sprays with β-aminobutyric acid or salicylic acid on the incidence of post-harvest disease and induced defence responses in jujube (Zizyphus jujuba Mill.) fruit after storage

Abstract

SummaryIn order to evaluate the effects of pre-harvest foliar sprays with β-aminobutyric acid (BABA) or salicylic acid (SA) on the incidence of post-harvest diseases caused by Monillinia fructicola (G. Winter) Honey or Alternaria alternata (Fr.) Keissl in jujube (Zizyphus jujuba Mill. cv. Dongzao) fruit, 4.8 mM BABA or 2 mM SA was sprayed on trees four times, at approx. 30, 60, 90, and 110 d after full blossom (DAFB). The results showed that the development of both diseases in fruit inoculated with either pathogen at harvest were significantly inhibited (P ≤ 0.05) by pre-harvest BABA or SA sprays. The incidence of disease caused by M. fructicola was decreased by 29.5% or 41.7%, and that caused by A. alternata was lowered by 34.5% or 43%, by BABA or SA sprays, respectively. The inhibitory effect persisted in fruit stored at 0ºC. In addition, BABA or SA sprays also significantly reduced (P ≤ 0.05) the incidence of natural post-harvest decay by 19.3% or 26.1%, and delayed the index in fruit skin colour change from green-to-red by 38.4% or 34.2%, respectively, after 60 d in cold storage. The activities of β-1,3-glucanase and peroxidase increased, and the concentrations of phenolic compounds were enhanced by BABA or SA sprays in fruit during storage. Superoxide dismutase activity increased, but catalase activity was strongly inhibited by BABA or SA sprays. These results suggest that the induction of disease resistance by pre-harvest BABA or SA sprays may persist in fruit after harvest and can protect fruit against post-harvest losses.