Application of Plackett-Burman Experimental Design for Investigating the Effect of Eight Phytohormones on Malt Quality Parameters

Barley is the major raw material for the malting and brewing industries. Seed germination is a fundamental process for malting and is affected by physical and chemical factors, especially plant hormones. It is well recognized that the phytohormones gibberellic acid (GA) and abscisic acid (ABA) are the primary hormones that antagonistically regulate barley germination. Other plant hormones, including auxin (IAA), ethylene (ET), brassinosteroid (BR), jasmonic acid (JA), salicylic acid (SA), cytokinins (CTKs), and strigolactone (SLs) also regulate seed germination by mediating the ABA/GA balance. In this study, the effects of eight hormones added during barley germination were investigated. An efficient design of the experimental method was employed to assess the effect of eight factors (alpha-amylase, beta-amylase, limit dextrinase, beta-glucanase, wort sugar profile, FAN, and beta-glucan content) on epicotyl and root elongation. Almost all studied phytohormones played a significant role on barley epicotyl elongation. GA, ET, BA (benzylaminopurine), and zeatin (ZEA) exerted an increased effect, while ABA, SA, and BR showed a decreased effect for alpha-amylase, beta-amylase, limit dextrinase, and beta-glucanase activity. Results showed that in addition to GA and ABA, that SA, ET, BR, BA, ZEA, and JA also had significant effects on malt quality. The balance between these phytohormones is vital to the malting quality of barley. Future applications of these results could improve current recognition about the effects of phytohormones on malting and provide concrete ideas for enhancing malt quality.