Effect Of GA₄ On Growth Physiology And Quality Of Dendrobium Offcinale

GA₄ is one of the species with high physiological activity among the gibberellins?GAs?,the plant growth regulators,and plays an important role in plant growth.Dendrobium offcinale is one of the most precious Chinese herbal medicine,which mainly functions to enhance human immunity by reducing blood sugar and blood pressure.Its main medicinal component is Dendrobium polysaccharide.However,there remains problems associating with D.offcinale,such as the shortage of wild resources,slow growth under artificial cultivation and low percentage of effective component content.Therefore,we aim to improve the cultivation efficiency and quality of D.offcinale in this paper.In order to explore the effect of GA₄ on the growth physiology and quality of D.offcinale,the growth index and polysaccharide content of D.offcinale were measured after GA₄ treatment,the dynamic changes of endogenous hormones,sugars and sucrose metabolizing enzyme activities were studied,and the correlation between growth and quality index,polysaccharide content and enzyme activites were analyzed.The main experimental results are shown as follows:1.GA₄ can significantly improve the growth and quality of D.offcinale.It has a significant effect on the increase of plant diameter and the amount of Dendrobium polysaccharide yield.The growth index with the greatest correlation to quality improvement is plant diameter and biomass.Plant height,plant diameter,biomass,polysaccharide content and total amount increased with the increase of GA₄ application concentration,and most of them were significantly different from CK and GA3.2.GA₄ has better effect in promoting the growth of D.offcinale than GA3,which showed narrow promoting ability towards the longitudinal elongation of D.offcinale.Briefly,the plant height of D.offcinale treated with GA3 was significantly higher than that of the control group,but there was no significant difference in other indicators.However,GA₄ can promote the growth of height and diameter of D.offcinale at the same time.3.Gibberellin has a significant effect on the breaking of D.offcinale seeds dormancy in summer.It showed an increase of endogenous hormones GA3,IAA and ZT after 100 days of GA3 application,and this might account for the reasons of another growth of D.offcinale.4.D.offcinale mainly relies on sucrose metabolism.Sucrose phosphate synthase?SPS?and sucrose synthase?SS?are enzymes that play an important role in this metabolism.The correlation analysis showed that the contents of sucrose and reducing sugars were positively correlated with those of SPS,SPS,AI and NI.This research can broaden the application of GA₄ on D.offcinale yield and provide reference for the development and utilization of GA₄ on other precious plant species.