Studies On Cultivars Selection Of Ground-cover Chrysanthemum And Drought Resistance Of Primula Forbesii In Kunming

Ground-cover Chrysanthemum is a group of novel and beautiful chrysanthemum cultivars, which applies to landscape use with wide coverage,strong adaptability and excellent ornamental value.Kunming is the nationwide flower producing base; however,suitable ground-cover chrysanthemum varieties have not been selected for this area so far.Primula forbesii are Chinese unique germ plasma resources which have beautiful appearance and are promising for application and exploitation.It has been studied in recent years because of its various advantages,but those researches mainly focused on biological characteristic and heredity field,no research was conducted on drought resistance physiology of Primula forbesii.In the view of the situation mentioned above,the author firstly selected 10 varieties from 70 introduced varieties base on the performance of their growth rates on the barren soil; and then based on the result of seedling stage experiment and florescence experiment,6 varieties were selected from 10 and considered as suitable varieties for the application in Kunming,with relevant cutting and cultivation techniques involved.The drought resistance physiology of Primula forbesii was studied base on the change rules of different physiological indexes such as relative conductance,MDA,soluble protein,dissociate amino acid,proline, chlorophyll,photosynthetic rate,transpiration rate,and stomatal conduction under four levels of soil water content.The four soil water content levels were;W1(50%～70%,water sufficient),W2 (40%～50%,light water stress),W3(30%～40%,moderate water stress),W4(20%～30%,severe water stress).The main results were as follows;1.The research lasted for 15 months from June 2006 to August 2007.During this period, according to the indexes of photosynthesis,physiology and morphological character in seedling stage, the research emphasized on the examination of the adaptability of different ground-cover chrysanthemum varieties; while during florescence stage,the author used ground-cover chrysanthemum varieties' character grading criteria to appraise the overall admiring valuation and adversity-tolerance.Based on the analysis of soil chemical element,the climate in Kunming and the results of seedling stage and florescence experiment,'Beilinhong','Jinbuhuan','Luojinqian', 'Wanfen','Xinhong','Zuixishi' were selected.2.In this study,statistical result showed that the living rate of softwood cutting was 99% far beyond hardwood cutting with many advantages.Compared of the growth of two plant density,the better row spacing of ground-cover chrysanthemum was 30cm.3.Primula forbesii experienced a series of physiology changes under water stress;when suffered from light water stress MDA increased 23% and relative conductance enhanced 42% under moderate water stress,the leaf cell membrane was injured from membrane lipid per-oxidation for the first step during soil water stress.Meanwhile,the osmotic adjustment substance accumulated in large quantity. Dissociate amino acid and proline increased 110% and 90% separately under light water stress,they were the main osmotic adjustment substance in this stage.Under moderate water stress soluble protein,dissociate amino acid and proline increased 123%,193% and 259% respectively,they took part in osmotic adjustment and physiological function together.When suffered from severe water stress only dissociate proline accumulated constantly,it added to 499% compared to soil water sufficient.The relationship between soluble protein and soil water content was not significant, however,soluble protein showed significant relationship with dissociate amino acid,hence,the physiological function of soluble protein was mainly performed while suffered from soil water stress. Photosynthetic rate,transpiration rate and stomatal conduction descended while soil water content decreased,transpiration rate had the strongest relationship with soil water content,soil water deficit would cause transpiration rate descending foremost.Chlorophyll content and stomatal conduction had significant relationship with photosynthetic rate,the decrease of photosynthetic rate of Primula forbesii was the consequence of stomatal limitation and non-stomatal limitation working together.The appearance of Primula forbesii was changed under soil water stress,it was temporary wilting under moderate water stress and would recover rapidly after rewatering; when suffered from severe water stress,it would be wilting permanently. 4.Physiological indexes could reflect drought resistance in a certain extent.In the study, Primula forbesii had some characters such as accumulating osmotic adjustment substance rapidly, protein metabolized energetically,sensibility of stomatal conduction,chlorophyll merely decreased and strong recovering capability from drought when suffered from soil water stress,which indicated its strong drought resistance.Consequently,the result showed that Primula forbesii had certain drought-resistance abilities in some extent.Further studies on the quantity demands of water still need to be conducted.6 varieties were selected in the research which could be extending in Kunming and 200 thousand ground-cover chrysanthemum commercial seedlings had been breeded.Meanwhile,the drought resistance of Primula forbesii was confirmed primarily.The conclusion of this study would also provide reference for the application and popularization of ground-cover chrysanthemum and Primula forbesii in Kunming.