Improving the fruit quality of Sichuan-pepper (Zanthoxylum bungeanum Maxim.) 'Dahongpao' by optimized GA3 treatments

To improve fruit quality, application of plant growth regulators as gibberellic acid (GA(3)) has emerged as a significant cultivation and management method. In the study, different concentrations of GA(3) solutions (25, 50, 75, and 100 mg L-1) were sprayed on Sichuan-pepper (Zanthoxylum bungeanum Maxim.; Rutaceae) 'Dahongpao' trees at fruit setting and enlargement stages. Spraying 75 mg L-1 GA(3) was most effective at both stages: vertical diameter, transverse diameter, hundred-grain weight, and number of oil sacs on the peel increased by 12%, 5%, 12%, and 42%, respectively, at fruit setting stage; and the aforementioned indexes increased by 14%, 11%, 12%, and 35%, respectively at fruit enlargement stage. Spraying 100 mg L-1 GA(3) at fruit setting stage, the content of total volatile oil, pungent compounds, non-volatile ether extracts, and total flavonoids significantly increased by 28%, 6%, 10%, and 3%, respectively; spraying 75 mg L-1 GA(3) at fruit enlargement stage, the indexes increased by 33%, 27%, 13%, and 11%, respectively. The comprehensive evaluation results based on Technique for Order Preference by Similarity to an Ideal Solution (TOPSIS) indicated that GA(3) treatment in a concentration of 75 mg L-1 could improve the quality of 'Dahongpao' fruits, thereby providing novel insights for the cultivation and management of such plant. Although spraying GA(3) may change fruit quality of Z. bungeanum, influencing mechanism of GA3 treatments on the external and internal quality of Z. bungeanum fruits remains unclear.