Adaptability Studies On The Six Species Spiraea Under Weak Light Treatment And Weak Light Dis-treatment Environment

The plant must receive the influences from the multitudinous environment factors in the growth process.The light is the direct energy of photosynthesis,which is the most important factor to maintain the plant survival and promote plant growth.Therefore the research to mechanism of plants beared the weak light and the discussion on the luminous intensity adaptation scope were very important,which can provide gist for plants' application in different environment in city garden.This research selected six spiecies outstandingly Spiraea:Spiraea thunbergii Sieb,Spiraea×bunmalba cv.Goldmound,Spiraea×bunmalba cv.Goldflame,Spiraea frits chiana Schneid,Spiraea thichocarpa Nakai and Spiraea media Schmidt.The research took the natural illumination as the comparison,carried on the weak light as 60%-65%,40%-45%,10%-15%that adopted the way which the shade net covered.Then it removed the shade net,and resumed the natural light It determined the shape structure targets,the physiological biochemi-stry targets and the photosynthesis targets under different weak light treeatment and the 10^th,20^th day during weak light dis-treatment.It comparaed and analysised this 6 spiecies' viarance characterristics and rule of the shape dissection characteristics,the physiological biochemistry characteristics,and photosynthesis characteristics under difference strength of light.It further inquired into their restore ability and adaptiveness to the different luminous intensity.Through to the system research of plants under adverse light circumstance and the comparative analysis to plants under differrence luminous intensity,the test obtained the main determination factor to judge plants' ability to bear the weak light.The test sorted the ability to bear the weak light of the 6 spiecies Spiraea,which to apply in the different botanical garden environment.The test was to screen to the illumination compatibility strong botanical garden plant,provide the theory basis and the application foundation for the north botanical garden construction.This research's main conclusions were as follows:1.The 6 spiecies spiraea displayed obvious photosynthesis diurnalvariation rule.When luminous intensity for natural illumination 60%-65%,40%-45%Pn daily variation changed into the splitb-lip curve;the first peak value was higher than the second peak value.They had the obvious phenomenon of "Midday depression of Pn".When luminous intensity for natural illumination 10%-15%Pn daily variation changed into the unimodal curve,not obvious "Midday depression of Pn".6 spiecies Spiraea's Pn,LCP,LSPand Rd were weakened along with the luminous intensity reduced,but AQY performanced opposite tendency. 2.Chlorophyll contents and carotenoid contents were increased with the light quality decreased. Chla/Chlb were decreased with the light quality decreased.Compared with the comparison the relative electronic conductivity rate and the proline contents increased under weak light treatment; SOD increased along with the weak light degree increasing.Under weak light treatment ABA contents reduced.The soluble sugar and the soluble protein both had the drop compared with the comparision.The 6 species Spiraea had the specificity protein under the weak light forces except Spiraea media Schmidt.This kind of protein's molecular weight concentrated much between 66kDa-45.0kDa.3.The test to leaves anatomical structure research discovered that the 6 spiecies Spiraea's leaves changed thiner,the top and bottom epidermal cell changed smaller,the stockade organization and sponge organization thickness changed thiner,the sponge organization cell space changed bigger,the two ratio reduced along with the light weaken.P/S was obviously inverse correlation with bearing the weak light ability.4.When the weak light treatment relieved the test discovered that,after 60%-65%and 40%-45%transmittance treatment the plants had certain restoration ability when restored the natural illuminetion.When the luminous intensity was only natural illumination 10%-15%,the recovery ability was weak.5.The reasearch evalued the influences of the 6 spiecies Spiraea to bear the ability to bear weak light synthesisly and the objectively.It obtained:relative specific leaf weight,the ratio of the stockade organization and the sponge organization thickness,the chlorophyll a/b and Pn were important targets to value plants' ability to bear the weak light.Among them the chlorophyll a/b value was the remarkable inverse correlation with the ability to bear weak light,relative specific leaf weight,the ratio of the stockade organization and the sponge organization thickness and Pn were obviously being connected with the ability to bear the weak light.6.Based on the determination result,this research used subordination function methods in the utilization fuzzy mathematics,and sorted the 6 spiecies Spiraea's ability to bear the weak light as: Spiraea×bunmalba cv.Goldflame＞Spiraea×bunmalba cv.Goldmound＞Spiraea thunbergii Sieb＞Spiraea media Schmidt＞Spiraea fritschiana Schneid＞Spiraea thichocarpa Nakai.