Effects of Exogenous Spermidine and its Synthetic Inhibitor on the Development of Bulbils on Herbaceous Peony ( Paeonia lactiflora Pall . )

In this study, the herbaceous peony cultivar ‘Zifengyu’ was sprayed with the exogenous spermidine (Spd) and the spermidine biosynthesis inhibitor D‒argimine (D‒Arg). The bulbils of each treatment were selected every 10 days to investigate the dynamic changes of endogenous hormones and polyamines, the activity of enzymes and contents of soluble protein and soluble sugar. The development state of bulbils was observed with paraffin section in winter. Then the unearthed date, budding rate, blossoming season, plant height and flowering rate of the peonies in each treatment were statistically analyzed. The results showed that in petal primordium differentiation phase, Spd treatment increased the contents of enogenous Spd, putrescine (Put) and gibberellin A3 (GA3), whereas the D‒Arg decreased their contents. But Spd and D‒Arg treatments both accelerated the change speed of the antioxidant enzyme activities and reduced MDA content, enhanced the accumulation and utilization of soluble sugar and soluble protein, and raised the contents of zeatin (ZT) in the early development of bulbils and then declined later. At the same time, the contents of indole‒3‒acetic acid (IAA), abscisic acid (ABA), ethylene (ETH) were reduced and shorten petal primordium differentiation phase, extend stamen primodium differentiation phase. Spd treatment was not conducive to budding rate and blooming and plant development, D‒Arg treatment had no significant effect on plant height, and could improve budding rate and blooming of herbaceous peony. © 2019 Friends Science Publishers