Study On The Growth Of Seedling,the Variation Of Endogenous Content And Enzyme Activity Of Inverting Populus Yunnanensis

In order to clarify the change law of IAA content in different parts of bark and lateral buds of inverting Populus yunnanensis during rooting process,upright cuttings made of one-year-old main stem of P.rootlings as control,statistics analysised the morphological index of water culture,high performance liquid chromatography(HPLC)was used to measure the IAA content with polar transport characteristics and GA3,ABA and ZT content with nonpolarity.Meanwhile,the growth,endogenous hormone content and oxidase activity,etc.of inverting and upright P.yunnanensis and P.deltoides during the growth process,were analyzed to discuss the morphological and physiological differences between inverting and upright P.yunnanensis during the growth and development,in the hope of providing an early research basis for auxin polar transport mechanism in depth.The main findings are as follows: 1.The dynamic changes of morphological characteristics and endogenous hormones content of inverting P.yunnanensis during rooting process.(1)Root primordium brokethrough epidermis and formed white protuberances from upright P.yunnanensis on 4th day of water cultured.On 6th day,white radical grew out from the root primordium.Root primordium brokethrough epidermis and formed white protuberances from the base of inverting P.yunnanensis on 5th day.On 7th day,white radical grew out from the root primordium.Leaves on upright P.yunnanensis withered 7 days earlier than the inverting one.Both the number of adventitious roots and length of root of upright P.yunnanensis were higher than the inverting one.Their differences reached an extremely significant level.The changes in the number of leaves and length of lateral branch in different parts of inverting and upright P.yunnanensis tended to be consistent and decreased in morphology from top to bottom sequentially.During rooting(49 days in the present study),the apical dominance of inverting P.yunnanensis did not change.(2)4 types of endogenous hormones in lateral buds decreased in morphology from top to bottom sequentially,consistent with the length of lateral branch and the number of leaves,that is,the content was the highest in exuberant sites.IAA content in the bark of upright P.yunnanensis increased from top to bottom sequentially,while IAA content in the bark of inverting P.yunnanensis decreased from top to bottom sequentially.They presented the same change rule in the same morphological direction and complied with the principle of IAA polar transport.GA3,ABA and ZT content in the bark increased from top to bottom sequentially and obeyed the gravitation.2.The change law of morphological characteristics and physiology of inverting P.yunnanensis and P.deltoides during the growth process.(1)Both the bough thickness and seedling height of upright P.yunnanensis and P.deltoides were extremely significantly higher than inverting ones.The thickness and height growth law between upright and inverting P.yunnanensis and P.deltoides were consistent,both of which grew fastest in Jul.~ Aug.,followed by Aug.~ Sep.and grew slowest in Sep.~ Oct..But the growth of inverting cuttings of 2 species was weaker,and their increments throughout the periods were smaller.Particularly,inverting P.yunnanensis almost stopped growing in Sep.~ Oct.,with thickness grew less than 1 mm and the height grew less than 10 mm.(2)IAA content of upright P.yunnanensis was higher than the inverting one in Jul.~ Oct..This was not significant in Jul.~ Aug.,but significant in Sep.~ Oct..Although IAA content of upright P.deltoides was higher than the inverting one in Aug.,their difference was not significant.In Jul.,Sep.and Oct.,IAA content of inverting P.deltoides was higher than the upright one and the difference was extremely significant.GA3 content of upright P.yunnanensis was not significantly different from the inverting one in Jul..In Aug.,GA3 content of inverting P.yunnanensis was significantly higher than the upright one,but it's opposite in Sep.~ Oct..GA3 content of upright P.deltoides in four periods were all higher than the inverting one,and the difference was significant or extremely significant.ABA content of upright and inverting P.yunnanensis was similar.In the first 2 periods,inverting P.yunnanensis was slightly higher,while in the last 2 periods,upright P.yunnanensis was slightly higher.But both of their differences were not significant.ABA content of upright P.deltoides was not significantly different from the inverting one in Jul.and Oct.,but extremely significantly higher than the inverting one in others.(3)Gave a comparison of IAAO activity between different cutting methods,the result showed that,upright P.yunnanensis was higher in Jul.,Sep.and Oct.,while inverting P.yunnanensis was higher in Aug..The difference was all extremely significant.Upright P.deltoides was higher in Jul.~ Sep..The difference was extremely significant in the first 2 months,but not significant in Sep..The IAAO activity of inverting P.deltoides increased sharply in Oct.and was extremely significant higher than the upright one.The POD activity of upright P.yunnanensis and P.deltoides was quite high in four periods,and the difference from inverting ones was extremely significant.Although the POD activity of upright P.yunnanensis and P.deltoides were higher than inverting ones in 4 periods,but the significant degree was not different.Among them,the difference between upright and inverting P.yunnanensis was extremely significant in Jul.,significant in Aug.,and not significant in Sep..In Oct.,the activity of upright P.yunnanensis still went up sharply,while the activity of inverting P.yunnanensis reduced.The difference was the greatest and reached an extremely significant level.The PPO activity of P.deltoides was not significantly different in Jul.~ Aug..In Sep.~ Oct.,the activity of upright cutting went up more quickly,and the difference from the inverting one was extremely significant.