Study On Characteristics Of Growth,Endogenous Hormone Content And Oxidase Activity Of Inverted Populus Yunnansensis

To identify the growth characteristics,endogenous hormone content and oxidase activity changes,with upright cuttings of Populus yunnanensis Dode as control,the lateral branch numbers,lengths,diameter and ground diameter of inverted cuttings were recorded.The leaf samples were collected from top,middle and bottom of current-year cuttings and from the top of main branch of one-year-old cuttings.Four endogenous hormones?IAA,ABA,GA₃ and ZT?and three oxidase activities?IAAO,PPO and POD?were analyzed with high performance liquid chromatography?HPLC?and UV-spectroscopy respectively to explore the difference of morphological and physiological between upright andinverted P.yunnanensis.These analyses aimed to provide a preliminary research foundation of the effects which polarity bringing to plant growth and development.The main results were as follows:1.The growth characteristics,endogenous hormone content and oxidase activities of current-year upright and inverted P.yunnanensis.?1?The height growth of upright cuttings was larger than that of inverted cuttings,and their differences were small in May and June,the largest in July,and decrease from August to November.For the increase of girth growth,the values of both upright and inverted cuttings were the largest from May to June.They were higher main branch diameter and ground diameter in inverted cuttings than in upright cuttings.The lateral branch number decreased in morphology from top to bottom of upright cuttings,while the top and bottom of inverted cuttings could both keep branches.?2?The IAA content of leaves decreased from top to bottom of upright cuttings in May and July,while the rank order for parts of inverted cuttings were middle?top?bottom in May and bottom?top?middle in July.These all changes were significant.The ABA content was not significant for parts.The difference of GA₃ content among parts of both upright and inverted cuttings was similar,and the top part was the highest with followed by middle and bottom in turn.Among months,the IAA content of leaves on the top of upright cuttings decreased with time,while the IAA content of other five parts was highest in July.The ABA and GA₃ content of upright and inverted cuttings was the highest in May.?3?The IAAO activity of middle part on inverted cuttings was highest among months without significance.The PPO activity of inverted cuttings was higher than that of upright cuttings in May without significance.The rank order for POD activity among parts of upright cuttings in July was bottom?middle?top,while it was top?middle=bottom for inverted cuttings.Among months,the differences of IAAO and PPO activity were not significant.Except bottom of upright,POD activity of others was highest in September,but there were significant differences among months.2.The growth characteristics,endogenous hormone content and oxidase activities of one-year-old upright and inverted P.yunnanensis.?1?The height growth of upright cuttings was higher than that of inverted one,and their differences were increased from March to July.Compared with upright,their girth growth was higher for inverted cuttings,and there were increased tend with time at their differences.In each period,the ground diameter of inverted cuttings was higher than that of upright.There was decreased tend with time for the numbers of lateral branch,in which the branches were centred on the top of upright cuttings and the bottom of inverted one.?2?Using upright cuttings as control,the IAA and GA₃ contents of inverted cuttings were higher in May,August and October,but the difference was not significant for IAA content and was significant for GA₃ only in May and August.The ABA and ZT content of inverted cuttings were higher except in September,with significance for ABA in May and for ZT in May,August and October.Among months,the differences of IAA content was not significant,while it was significant for ABA with the highest in September and for GA₃ with the highest in July.Whether the cuttings were inverted or not,the ZT content was highest in July and the difference among months was significant,?3?The IAAO activity of inverted cuttings was higher than that of upright,and their difference was significant only in May.Compared with upright,the PPO and POD activity of inverted cuttings in each period was also higher,and the significant was found for PPO in August and for POD in August and September.There were significant differences among months for IAAO activity of both upright and inverted cuttings,and the values were highest in July and lowest in May.For upright cuttings,the PPO activity was highest in May with significant to other months,while this was also highest for inverted one in May without significant to August and October.The POD activity of both upright and inverted cuttings was the highest in May and there was significant difference among months.