Effects Of Drought Stress On Growth And Development Of Camellia Oleifera

6-year-old Camellia oleifera forests were test materials and the 4 treatments were natural condition,drought stress,covering straw and loosing soil.The test was to explore the effects of drought stress on the growth and development of Camellia oleifera and the effects of covering straw and loosing soil to alleviate drought stress.The main results are as follows.(1)The differences of air temperature,humidity,light and soil temperature among different treatments were not significant(P>0.05).The soil moisture content difference between natural condition and drought stress was very significant.The soil moisture content of covering straw and loosing soil had no significant difference with that of natural condition and the soil moisture content difference with that of drought stress was significant.Alleviating measures played a role.(2)With the extension of drought stress time,the soluble sugar content in leaves showed a rising trend.Covering straw and loosing soil had a certain ease on the soluble sugar content in leaves,but the effects was not significant.The soluble protein content in leaves increased firstly and then decreased.The soluble protein content was higher than the initial level in the later experiment stage experiment.The measures had no significant effect on soluble protein content.Under drought stress IAA and ZR/IAA content decreased,ZR content showed a decreasing trend,GA content rised and decreased at the end of the experiment.The change of endogenous hormone content and ratio in leaves regulated the growth and development of Camellia oleifera.Covering straw and loosing soil could alleviate the effects of drought stress on IAA,ZR and GA contents and the effects of ABA content and ZR/IAA were not significant.Under drought stress condition,soluble sugar content in leaves was inversely proportional to soil moisture content.In the initial period changes was small and in the late the rise was rapidly.It was exponential function relation between soluble sugar content and soil moisture content.With the soil moisture decreased the soluble protein content was fluctuating trend,and the relationship between them was polynomial function.(3)Fruit width decreased by 89.29%under drought stress compared with the natural condition,and it increased by 81.25%,84.09%respectively under covering straw and loosing soil.The 2 measures can effectively alleviate the effects of drought stress on fruit width.The fruit height growth was negative under drought stress,and that of natural condition,covering straw and loosing soil were 0.95 mm,0.87 mm,0.55 mm respectively.The growth of flower width under drought stress was lower than other treatments after October 16th when the soil water content was 16.5%.The growth of flower height under drought stress was lower than other treatments after October 1st when the soil water content was 17.2%.Flower height was more sensitive to soil moisture content.Flower width decreased by 24.79%under drought stress compared with the natural condition,and it increased by 26.24%,24.15%respectively under covering straw and loosing soil.Covering straw and loosing soil could effectively alleviate the effects of drought stress on fruit width and fruit height and they could alleviate the effects of drought stress on the flower width and flower height in a certain extent.Flower bud continued to grow under drought stress condition.The growth simulation equation of flower height and flower width was exponential function and the growth of flower height was greater than that of flower width.(4)The difference of canopy structure under 4 kinds of treatments was not significant because test materials were 6 years old and their roots was large which could be able to absorp the soil moisture in the depths to resist drought stress.So the comparison test of different age class Camellia oleifera forests was conducted.The effect of drought stress on the canopy structure of sapling forest was much greater than that of immature timber.In the canopy structural parameters,the influence of average leaf angle was the biggest then the transmission coefficient and the leaf area index was the last.(5)The effects of drought stress on the chlorophyll content in spring shoots was different from that in autumn shoots.The chlorophyll content of spring shoots under drought stress declined seriouslyand that of the 4 treatments were increased in the late stage.The effects of covering straw and loosing soil on the chlorophyll content in spring shoots were not significant.In the experiment stage the leaves in autumn shoots were rapidly growing and the chlorophyll content was in the accumulation period.The chlorophyll content greatly rised under natural condition,covering straw and loosing soil.The chlorophyll content increased less compared with other 3 treatments,the effect of drought stress on the chlorophyll content of the leaves in autumn was effectively alleviated.Covering straw and loosing soil could effectively alleviate the effects of drought stress on chlorophyll content in autumn shoots.Under drought stress condition,with the decrease of soil moisture content the chlorophyll content in spring shoots decreased and the chlorophyll content showed an upward trend because it wwas in the growth stage.Leaf thickness of spring shoots was less than that of autumn shoots.The effect of drought stress on leaf thickness of autumn shoots was more significant.There was no significant difference on the upper epidermis,palisade tissue,spongy tissue and lower epidermis,The ratio of palisade tissue was less than spongy tissue ratio.The proportion of upper epidermis in spring shoots was larger than that of lower epidermis,but the autumn shoots were opposite.(6)The difference of kernel oil rate under 4 kinds treatments was not obvious,but the performance was obvious in the yield of Camellia oleifera seeds and oil.The effect of drought stress on dry weight of per seed,oil yield of dry seed and fruit moisture content influenced the yield of Camellia oleifera.Fresh seed weights of per mu under different treatments were 327.97 kg,230.70 kg,256.25 kg and 272.34 kg and dry seed weights of per mu were 1.98.68 kg,142.23 kg,165.03 kg and 161.77 kg.Oil weights of per mu were 52.45 kg,35.99 kg,42.25 kg and 41.17 kg.The oil weight under drought stress decreased by 31.38%compared with the natural condition.The yield of camellia oil under covering straw and loosing soil increased by 14.82%,12.58%compared with the drought stress.The measures could alleviate the effects of drought stress on yield of camellia oil and camellia oil yield could be improved.(7)Using PCA(Principal Component Analysis)to decrease the number of the related indexes and get 8 principal components.Fat and fatty acid composition of fruit,moisture content of fruit,organic contents in the leaf,the growth of fruit and flower bud these principal components reflect 90.18%information of the origin varieties.