Effects of Stumping Season on the Relationship between Sprouting and Endogenous Hormones of Pinus yunnanensis Seedlings

PurposeTo explore the effects of different stumping seasons on the sprouting ability of Pinus yunnanensis seedlings, so as to provide a theoretical basis for hormone regulation of sprouting and tillering of P. yunnanensis.

MethodsThe growth indexes and the changes of endogenous hormone contents and values of IAA, GA₃, ZT and ABA in P. yunnanensis seedlings in different stumping seasons were measured, and the relationships among endogenous hormone contents and ratios and seedling height, ground diameter, number of sprouts, sprout length and sprout biomass were analyzed.

ResultsStumping in different seasons had an effect on the growth and sprouting of P. yunnanensis seedlings. The seedling height, ground diameter, sprout length and its biomass were the highest in spring, while the seedling and sprout growth were poor in summer, and the number of sprouts was the highest in autumn. The stumping season had significant effects on endogenous hormones. The contents of endogenous hormones GA₃ and ZT were higher at 60 and 90 days after stumping; the values of IAA, GA₃, ZT, IAA/ABA, GA₃/ABA, ZT/ABA, (IAA+GA₃+ZT)/ABA were the largest in autumn, and ABA content was the highest in spring. The principal component analysis and cluster analysis showed that the seedling growth in autumn was significantly different from that in spring and summer; in principal component analysis, (IAA+GA₃+ZT)/ABA, IAA/ABA, ZT/ABA and GA₃/ABA had a great effect on the number of sprouts, among which (IAA+GA₃+ZT)/ ABA had the largest eigenvector; GA₃ and GA₃/ABA had a great effect on the sprouting length; ZT, ABA and IAA had a great effect on the sprouting biomass, and the eigenvector of ZT was the largest.

ConclusionStumping season has a significant effect on seedling sprouting, and seedling sprouting is the result of joint regulation of multiple hormones. Compared with spring and autumn, stumping in summer has no advantage in the content and ratio of endogenous hormones. The needs of seedling production and use will be comprehensively considered to select the stumping season, and corresponding measures can be taken to improve the sprouting ability according to the research results.