Effects of L-tert-leucine on Quality and Storage of Gala Apple

ZHANG Sipu; ZHOU Qianqian; CUI Wei; ZHANG Ke; HAN Lixin; QU Zhenfang; LU Yunfeng; TANG Cunduo; NIU Jiajia

doi:10.15933/j.cnki.1004-3268.2023.12.019

Abstract：In order to improve the quality and storage of Gala apples,exogenous L-tert leucine was sprayed on the leaf for three times during the fruit development period,with concentrations of 0(water,control),50,100,500,1000,and 5000 mg/L,respectively.The effects of L-tert-leucine concentration on harvest quality and low temperature storage at(0±1)℃of Galala apple were investigated.The fruit hardness,total soluble solid(TSS)content,titratable acid(TA)content,soluble protein content,free amino acid content,peroxidase(POD)activity,and superoxide dismutase(SOD)activity were determined respectively.The results showed that foliar spraying of exogenous L-tert leucine significantly promoted the yellowing color and brightness of Gala apple fruits,and increased fruit hardness,TSS content,TA content,soluble protein and free amino acid content to varying degrees.The treatment with concentration of 500 mg/L significantly increased the single fruit weight(247.58 g),which was 8.3% higher than the control(228.55 g).All treatments were beneficial to the maintenance of fruit firmness,TSS content and soluble soluble protein content,inhibited the decrease of TA content,and the increase of free amino acids,and lower POD activity and higher SOD activity were maintained during cold storage of Gala apple.After 75 days of storage,the 50 mg/L treatment had the highest TA content(4.69 g/L),the 100 mg/L treatment had the highest hardness(7.13 kg/cm2)and the 1000 mg/L treatment had the lowest free amino acid content(1248.1 mg/kg).The 500 mg/L L-tert leucine treatment had no soften fruit flesh,the soluble protein content(116.7 mg/kg)and SOD activity[29.64 U/(min·g)]were the highest,POD activity[8.09 U/(min·g)]was the lowest,and free amino acid content(1940.0 mg/kg),hardness(6.74 kg/cm2),TSS content(15.20%),and TA content(4.65 g/L)were significantly better than the control.In summary,multiple applications of 500 mg/L L-tert leucine during fruit development could significantly improve the harvesting quality and storage capacity of Gala apple.