Study On Photosynthetic Pigments Of Several Main Shrub Species In The Dry Valley Of The Upper Minjiang River

With the research object of the main shrubs distributed in typical dry valley on the banks of the Zagunao River in the upper reaches of the Minjiang River as the research object,by means of field investigations and laboratory experiments,this paper mainly studies four species of shrubs on the sunny slope,including Rabdosia,Campylotropis macrocarpa,Ajania achilleoides,Caryopteris glutinosa,and five species of shrubs on the shady slope,including Rabdosia,Campylotropis macrocarpa,Ajania achilleoides,Artemisia gmelinii,and Sophora davidii.In addition,the paper makes researches on the commonly-owned three species’ change regulations of photosynthetic pigments in the course of sowing,different seasons and slopes on the sunny and shady slope,namely,Rabdosia,Campylotropis macrocarpa and Ajania achilleoides,as well as discusses about the effect of environmental factors towards chlorophyll such as illumination,water content and soil nutrition.The adaptation mechanisms of plants in responding to different environmental changes will be analyzed from the perspective of plant physiology,and then the restoration and protection of vegetation ecology will be strengthened to provide an essential basis for the ecological environment construction in the region.The results show:(1)When different shrubs suffer from various environmental factors from spring to autumn in the dry valley of the upper reaches of Minjiang River,every photosynthetic pigment indication in shrubs presents different seasonal change.Chlorophyl a,carotenoid and chlorophyl volume in Rabdosia,Campylotropis macrocarpa,Ajania achilleoides,Caryopteris glutinosa and Artemisia gmelinii will vary with seasons and showcase the same change tendency,which illustrates these five shrubs have the appropriately same adjustment mechanism to adapt to the external environmental change.(2)Despite of the same slope,different shrubs photosynthetic pigment content varies and average levels of total chlorophyll volumes of four shrubs on sunny slope are ranked according to superiority: Rabdosia(1.615 mg.g-1)>Ajania achilleoides(1.503 mg.g-1)>Campylotropis macrocarpa(1.347 mg.g-1)>Caryopteris glutinosa(1.137 mg.g-1);while on shady slope average levels of total chlorophyll volumes of five shrubs on sunny slope are ranked according to superiority: Sophora davidii(2.939 mg.g-1)>Campylotropis macrocarpa(2.403 mg.g-1)>Artemisia gmelinii(2.088 mg.g-1)>Rabdosia(1.660 mg.g-1)>Ajania achilleoides(1.641 mg.g-1).(3)Compared differences of the photosynthetic pigments in the same shrub in different slopes,the total amount of chla,chlb,car and chl(a+b)in the different seasons of Rabdosia had no significant difference between the two slopes(P>0.05);the total amount of chla,chlb,car,and chl(a+b)in the shady slope of Campylotropis macrocarpa was significantly higher than that in the sunny slope(P<0.01);the total amount of the chla,chlb,car,and chl(a+b)in the Ajania achilleoides in autumn on the shady slope was significantly higher than that on the sunny slope(P<0.05).What’s more,there was no significant difference between the two slopes in other seasons(P>0.05).(4)The correlation between soil organic carbon and total nitrogen and photosynthetic pigments of shrubs was relatively high,especially nitrogen had a greater impact on photosynthetic pigments.Within a certain range,uplifting soil nutrients can increase the chlorophyll content of the shrubs,promote shrub growth so as to improve the adaptability of shrubs in adverse environments.(5)The leaf water potential and photosynthetic pigments of the same shrubs had a certain correlation in different seasons.The relationship between the leaf water potential and the photosynthetic pigments in Rabdosia and Campylotropis macrocarpa reaches into a high correlation level mainly in the summer,but the Ajania achilleoides was in highly correlation level mainly in summer and autumn.Those seasons with high correlations belong to the flower seasons,which indicates shrubs has a larger requirement towards water in the stage of flower seasons than other stage and it is more easy to influence photosynthetic pigments of plants.(6)Comparison of drought resistance of several main shrubs in the upper reaches of Minjiang River: Rabdosia>Sophora davidii>Caryopteris glutinosa>Ajania achilleoides>Campylotropis macrocarpa>Artemisia gmelinii.