The Response Of Camellia Oleifera Superior Clones Under Drought Stress And Drought-resisting Measures

The summer and autumn seasonal drought occurred frequently and intensity in Red Soil ofHilly Region, Soil water condition makes an important role as one of the main limitingenvironment factors in the production of agriculture and horticulture in the region. Camelliaoleifera is one of agroforestry pillar and advantage industry in the southern red soil hillyregion.To explore physiological response under the condition of the seasonal drought and theecological effect under the different management measures, reducing physical hazards and thenegative effect of yield and quality for oil-tea woody fuel economic forest from the red soildrought, and also provide theoretical basis and technological support for Camellia oleiferagarden cultivation in the red soil hilly region, The morphological indexes,physiological andbiochemical index,photosynthetic light response parameters of oil-tea clones seedlings underdrought stress were first surveyed by the method of continuous drought;Moreover,thedrought-resistance ability of Camellia oleifera nine clones were comprehensive evaluated andsame time,The variation of the photosynthetic physiological characteristics,fruit growthdynamics,economic characters,soil moisture and physical and chemical properties wereanalyzed under irrigation, coated, covered the grass to the hill measures for preventing thedrought, simulated sustainable drought conditions to full fruit period of Camellia during thesummer and fall drought period.Main research conclusions are as follows:1.The difference of camellia leaf relative water content, chlorophyll meter values, nitrogencontent and survival rate between the control and Oil-tea clones under light water stress is small,but leaf water content significantly decreased, chlorophyll values of the new and old leafletsdecline continues, the nitrogen content reduced rapidly with the nitrogen metabolism functiondeclined of the oil-tea, the survival rate significantly decreased in the period of mediumdrought and severe stress.Decline difference between different varieties of oil-tea wassignificant,The rate of nitrogen content decline in new leaves of oil-tea three was high than theold leaves during the stress of each period.In the process of water stress, the super oxidedismutase (SOD）and peroxidase (POD)activity of oil-tea leaves show its decreased after rising,The performance trends are basically identical during dry stress procession.The accumulation ofproline (Pro）content, malondialdehyde content (MDA), soluble sugar, soluble protein contentchange slightly during mild water stress, The increment is low,but the rising amplitudedifference between different clones during the medium drought and severe stress showsignificantly. 2.The day average of Pn, Tr and Gs of Oil-tea clones decreased continuously duringdrought stress，But the Tr drop is greater than the Pn overall，The double peak trends in thedaily change curve decline,or become single peak even disapper during the drought stress;WUE rise under light or medium drough,but decrease by the severe water stress. Gs and Trunder water stress show same tendency,Intercellular Ci and Pn decreased through stomatallimitation during the mild, moderate stress，but the phenomenon of CO2concentrationincreasing and the Tr decline by the non-stomatal limitation emerged in the severe t water stress.Pn,Tr,Ci与Gs of each oil-tea tree clone overall drop small under mild drought,change betweenclones are basically identical;The decreasing range increase sharply,and the difference betweenclone is obvious after moderate stress. Pnmax,AQY,LSP of Camellia oleifera SuperiorClonesGan84-8,Ganxin46,Ganwu15decline continutely but Rd rise in the process of droughtstress, the abilities of drought adaptability is Gang Wu15＞Gang Xing46＞Gang84-8.3.There was extremely significant positive correlation between Leaf RWC and leaf value,nitrogen content, Pn,Tr,Gs,but there was significantly negative correlation between Leaf RWCwith MDA, POD, SOD, soluble sugar and other physiological indexes and Ci,and There werewere extremely significant positive correlation between Pn,Tr,Gs with MDA, Pro content, andthe correlation coefficient was0.78,0.88respectively,but it show negative correlation with Ci;Tr was significantly positively related to Ci, and the correlation coefficient was0.82.Thedrought resistant ability of each oil-tea tree is Gang Wu15＞Gang Wu2＞Gang68＞Gang83-4Gang Xing46＞Gang Fu20＞Gang84-8＞Gang71＞Gang Wu11by evaluating synthetically theoil-tea clones ability to drought tolerance by membership function.4.The average daily volume moisture content of the soil0-40cm layer got29.70%,27.53%与25.52%after film mulching, straw covering,the control in the Oil-tea camelliawoodland during the summer, and all higher than the control(25.52%).The diurnal variationcoefficient of film mulching, straw covering were2.47%,7.87%,but the control was8.97%,so itimprove the water stability by the above measure; The soil water content under takingirrigationA, irrigationB, film mulching, covering grass respectively highter than the control by1.163times,1.158times,1.133times and1.112times; and18.27%during sumer and fall.Theeffect is most obvious adopting management measures of taking irrigation, filmmulching,covering grass in August and improve greatly than that of CK water content,It is47.45%,34.46%,23.27%respectly.It can make obvious effects in the growth of the content of zinc,calcium elements in thecamellia oleifera land by film mulching,Especially improving the content of organicmatter,iron,magnesium,calcium elements in the soil0－20cm layer; It is beneficial significantlyto enhance the content of total phosphorus,available phosphorus,iron magnesium,calciumelements in the soil0－20cm layer by cultural packet.It is helpful to increase the content oftotal potassium,available nitrogen,iron,manganese elements in the land by irrigation measures. But also contributed to the loss of the content of copper,zinc, magnesium and calcium elementsin the soil0－20cm layer;especially reduced the content of organic matter,zinc element in thesoil20－40cm layer5.The fruit diameter and height growth of Camellia oleifera Superior Clones Gan68,Gan84-3,Gan84-8, Gan71, Ganyong5, Gan8, Gan xin48all exceed than the contrast underirrigation、film coating and cover grast measures dure the different growth stage in July,andproducing significant differences between them;The effect of different drought resistingmeasures on the fruit diameter and high is irrigationA＞plastic membrane mulching＞irrigationB＞mulching with straw; There is the significant difference of the shape index, Irrigationenlarge the shape index,and make fruit shape more round and full.Pn, Tr,Gs, Ci and chlorophyllcontent in oil-tea tree were by irrigation, film covering and grass mulch to forest land to someextent, It is the most effective measures to improve the different phase photosyntheticproductivity by increasing irrigation amount during summer dry period.6.The single fruit weight of oil-tea clones were significantly increased to25.118%,10.899%,10.80%and7.077%by taking irrigation,plastic mulching, straw covering,culture stand measures during the summer and fall period;and the fresh seeds yield be increased1.179times,1.105times,1.092times and1.10times,and the dry seed oil content be improved29.983%,30.554%,18.474%and15.710%on average by the same time. It can be improved53.64%and86.11%to per plant yield compared with the control by plastic mulching and strawcovering,and be increased1.32times and1.75times to the crown yield per square metre; Theshort term effect for the oil-tea tree yield is plastic mulching,and long-term effect with strawcovered is superior to the film,and had a significant difference compared with the control. Thereis significantly positively relationship with per plant yield and the crown products, fresh seedyield, dry seed oil content,There was significantly positive correlation between the crownproduction with fresh seed yield, dry seed oil conten, the correlation coefficient were all beyond0.93, and there was also significantly significantly positive correlation between the fresh seedyield and dry seed oil content; The effect of different coverage measures on oil-tea clones isirrigation＞culture stand measures＞plastic mulching＞straw covering＞the control＞persistentdrought by evaluating synthetically.