Photosynthetic Physiological Responses Of Two Varieties Of Clematis To Flooding Stress

Clematis belongs to the genus Clematis L.of the Ranunculaceae family.Is has a large variety of colors,a high ornamental value,and a reputation as a “climbing plant queen”.Zhejiang Province belongs to subtropical monsoon climate zone.The soil here is too wet or waterlogged which is bad for the growth of clematis.Therefore,waterlogging stress becomes the main obstacle in the way to apply clematis in urban landscape and home gardening.This paper uses the Innocent Blush and Polish Spirit 2-year-old seedlings as materials to simulate the conditions of flooding in greenhouses.Two standards of waterlogging have been taken to compare with normal-irrigated clematis: half irrigation and full irrigation.Researches on waterlogging resistance,gas exchange parameters,photosynthesis-light curves and chlorophyll fluorescence parameters have been conducted with 7d,14 d,21d,28 d and 35 d.Chlorophyll fluorescence parameters were used to study the effect of different flooding levels and different flooding time on photosynthetic physiology of clematis.It provides a theoretical basis and reference for the introduction of the selection and application of foreign Clematis cultivars in Chinese gardens and the selection and breeding of native clematis ornamental species.The main findings are as follows:1)In the aspect of physiological indexes: flooding stress increases with time 2 clematis varieties Flooding Stress Index,relative conductivity,MDA,proline,soluble protein,POD and SOD content increased noticeably.Chlorophyll a,chlorophyll b and total chlorophyll content were gradually decreased,and chlorophyll a/b and carotenoids did not change significantly.2)In the later stage of half irrigation and early stage of full irrigation,waterlogging resistance,Pnmax,LSP,AQY,Rd,Fv/Fm,Fv'/Fm',qp,ERT,Gs,Tr and Ci have decreased significantly.The photosynthetic rate decrease of Innocent Blush in early stage was caused by stomatal factors while the decrease in later stage was caused by the lower photosynthetic activity and efficiency of non-stomatal factors.The decrease of Pn in Polish Spirit under waterlogging stress was mainly caused by stomatal factors.3)2 clematis varieties under flooding stress various physiological and photosynthetic parameters indexes showed different degrees of change,the correlation analysis showed that flooding stress index,chlorophyll a and chlorophyll b,total chlorophyll content,MDA,relative conductivity,proline,SOD,POD,Pnmax,LCP,AQY,Pn,AQY,Gs,Fv'/Fm',ERT parameters and clematis waterlogging resistance varieties with strong correlation,can response difference waterlogging resistance,suitable as a clematis waterlogging resistance evaluation factors.