| Camellia olifera is one of the world’s four woody oil trees, and it’s also edible oil treespecies native to China, which prefers warm and humid climatic conditions with theannual average temperature of14~22℃, annual rainfall of800mm or more, and is moreadaptable to different soil conditions. The tree species not only has high economic value,but also plays an important role in biological fireproof, water and soil conservation, andecological environment improvement.Anhui is located in the northern margin of the distribution of C.oleifera in China.Compared with the annual rainfall of C. oleifera suitable area, that of the northern marginC.oleifera meets basic needs of its growth. Sometimes there may be inadequate rainfallwhich leads to water stress. C.oleifera container seedlings and C.oleifera trees wereselected as experimental materials to study the effect of water stress or rainfalldifferences on growth and physiological and biochemical characteristics of C.oleifera inthis paper. The main results are as follows:1. Water stress of container seedling:The leaf water content does not fall but rise, rising from60.3%to73.3%when thedehydration degree was0%-30%. The leaf water content gradually decreased from73.3%to30.3%when dehydration degree was31%-70%.When dehydration degree of leaf was0%-30%, the resistance value of root and stemwas0%-25%respectively, which showed a decreasing trend. On the contrary, theresistance value increased, especially when dehydration degree was above60%, theresistance value raised rapidly. When dehydration degree was below50%, the resistancevalue of container substrate increased slowly, oppositely, the value raised rapidly.The leaf relative conductivity first decreased then increased as dehydration degreeincreased with the relative conductivity reached its lowest value at the20%dehydrationdegree, followed by a sharp increasing trend.CAT and POD activity first decreased then increased and finally inactivated as thedehydration degree increasing, and the enzyme activity reached its peak when thedehydration degree was40%.The tests showed that the physiology activity of seedlings was optimum when thedehydration degree was20%. Therefore, the dehydration degree of container substrateshould be controlled in20%in the process of cultivating container seedlings of C.oleifera in the future. 2. Water control planting of container seedling:When dehydration degree was0%-15%（Processing I）,16%-30%（Processing II）,31%-45%（Processing Ⅲ）,46%-60%（Processing Ⅳ） and61%-75%（Processing Ⅴ）,the seedling survival rate was100%,92%,75%,25%and0%respectively.Number of new leaves and the growth of shoots of C. oleifera container seedlingswere both in a “slow-fast–slow” growth pattern, which growth curve was in a regular“S” shape. Seedling shoots of Processing Ⅱ was4.31cm followed byProcessing Ⅰwith3.93cm. The ground diameter of Processing Ⅱreached3.19mm, which was thethickest, followed by Processing III,3.12mm. Length and width of leaves ranked themost with Processing Ⅱ, which was4.30×2.35cm, followed byProcessing Ⅰ,whichwas4.17×2.15cm. The root length and number of fibrous roots were Processing III>Processing II> Processing I> Processing IV> Processing Ⅴ.Of the five water control measures, the C.oleifera container seedlings ground andbelow-ground biomass first increased then decreased with the rising of water stress.There was significant difference of C.oleifera container seedlings root/shoot ratio at0.01under different water control processing.The relative conductivity, the malondialdehyde, soluble sugars, and the free prolinecontent of the seedling leaves first decreased and then increased with the rising of waterstress; the leaf relative conductivity of ProcessingⅡ was the lowest. There was significantdifference of inclusion content at0.01among different water control processing. Thechlorophyll a, chlorophyll b and chlorophyll total content first increased and thendecreased, Processing Ⅳ sharply decreased.C.oleifera container seedling netphotosynthetic rate (Pn), the stomatal conductance (Cond), and the transpiration rate (Tr)first increased then decreased, while the intercellular CO2concentration (Ci), firstdecreased and then increased.3. Comparative study on the different annual rainfall ecotypes of C. oleifera:Average annual rainfall of the three regions in eastern Anhui, western Anhui, andsouthern Anhui were904.4mm,1100.0mm and1601.1mm, which length of C. oleiferaspring shoots were7.32cm,9.17cm and10.24cm; the number of leaf were5.2,6.3and7.8; length and width of leaf were5.71cm×2.80cm,5.25cm×2.60cm and5.78cm×2.76cm; the leaf thickness were1.222mm,1.155mm and1.177mm; the leaf weightwere0.547g,0.533g and0.558g respectively.The length of spring shoot, number of leaf,length and width of leaf, and the leaf weight of C. oleifera of the three regions roughlyincreased as average annual rainfall increased; And the leaf thickness was quite the contrary.There was positive correlation between the annual rainfall and leaf water content; theannual rainfall was negatively related to the bound water/free water ratio. However, therewas no significant difference of the three areas (Pleaf water content=0.684>0.05; Pleaf boundwater/free water=0.712>0.05). There was negative correlation between the annual rainfalland the leaf resistance value.In all tested samples, the range of the content of benzene-ethanol extracts,holo-cellulose, cellulose, lignin vary respectively from10.8%-26.2%,0.28%-0.57%,0.12%-0.25%and0.13%-0.28%. In the same rainfall ecotype, the content ofbenzene-ethanol extracts of leaf was higher than that of shoot, and the other materialcontents were quite the contrary. In the three rainfall ecotypes, the content ofbenzene-ethanol extracts, the cellulose and lignin were the highest and the holo-cellulosecontent of shoot was the lowest of the most northern edge(Fengyang) of C. oleifera.In the future production of C. oleifera of northern edge, many different cultivationmeasures such as improving the content of benzene-ethanol extracts and the cellulose andlignin, reducing water content and holo-cellulose content were taken to improve the stressresistance of C. oleifera. |
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