| Phosphorus is an essential nutrient element for plant, which is the composition of a number of important compounds in plants, and it participates in a variety of metabolic processes. The phosphorus is one of the important factors which restrict the wood productiveness. Plants mainly absorb phosphate by uptaking orthophosphate.However,phosphorus in soil is easily fixed into some insoluble Fe-P,Ca-P and Al-P compounds which are difficult to use for plants in the south of China. Although,the phosphorus content in southern is high, most of them are useless and distribute heterogenousely. So that how to use difficult dissolving phosphorus in the southern soil becomes a great subject in forestry production. A large number of studies show that some plants can use difficult dissolving phosphorus to grow under the P deficiency condition, and this endemic ability of seeking phosphorus is heritable. And this conclusion provide the possible way to screen plant genotypes which is high phosphate use. Eucalyptus is one of three famous fast growing species in the world , and is widely planted in the south of our country .It consume most of the nutrient in a short time for the continuous planting of Eucalyptus plantation for a long time, and phosphorus deficiency turn to a important factor which restrict the Eucalyptus plantation productiveness.There are many studies of Eucalyptus making use of phosphorus recently, but the studies most all about the single Eucalyptus variety with same quality phosphorus deficiency and lack of the comparative studies of different varieties with different quality phosphorus deficiency. In view of this, this paper bases on the research method of stress botany and take eight introduce Eucalyptus varieties in the south as research objects, design a heterogeneity phosphorus stress experiment to simulate phosphorus status under natural conditions.And then determine morphology and physiology indicators of different Eucalyptus species under heterogeneity phosphorus stress.In order to compare the different ability of different Eucalyptus varieties to seek for nutrient under heterogeneity phosphorus stress and reveal adaptive mechanism of different Eucalyptus varieties to heterogeneity phosphorus stress.So that provide scientific basis for screening high phosphate use Eucalyptus varieties. The main result and conclusions presented in this thesis are as follow:1. In the heterogeneous environment, the differences of the height, diameter growth and change in volume, dry matter accumulation and dry matter distribution between different eucalyptus are significant. E.grondis×E.urophylla 9,E.wetarensis×E. camaldulensis 3 and E. urophylla×E.grandis DH-32-29 change more than other eucalyptus under the same group test conditions, while E.dunnii,E.urophylla camaldulensis,UG and E. urophylla×E.grandis DH-32-16 change less, and E.geandis 5 and E.geandis 9 are at the middle. The result also shows that height, diameter, dry matter accumulation in heterogeneous increased significantly in three different treatments, especially E. urophylla×E.grandis DH-32-29,E. urophylla×E.grandis DH-32-16,E. urophylla×E.grandis DH-32-16. The order of root-shoot ratio in different Eucalyptus is opposite compare to height, diameter, dry matter accumulation. The root-shoot ratio in heterogeneous shows consistent with that in non-p homogeneous, it means that as long as the deficiency state of some roots showed the response of P deficiency.2. In P-heterogeneous conditions, the difference of root length, root surface area, root volume, root average diameter in different eucalyptus is significant. E.geandis 5,E.grondis×E.urophylla 9,E.geandis 9 and E.wetarensis×E. camaldulensis 3 is in turn reduced root length, and their root surface area and root volume are all above the average, while the root indexs of E. urophylla×E.grandis DH-32-29,E.dunnii,E.urophylla camaldulensis, UG and E. urophylla×E.grandis DH-32-16 are all below the average. The root length, root surface area and root volume of E. urophylla×E.grandis DH-32-29 increase a lot with the P-content, so E. urophylla×E.grandis DH-32-29 is sensitive to phosphorus concentration. Root average diameter in each treatment and each Eucalyptus are almost the same. Root morphological indices of E.geandis 5,E.geandis 9,E.wetarensis×E. camaldulensis 3 and E.grondis×E.urophylla 9 shows better in varieties of P-conditions, and higher root growth in both sides in heterogeneous. These four kinds of eucalyptus have greater chance to absorb nutrients and adjusted to low phosphorus environment more easily. The roots of E. urophylla×E.grandis DH-32-29,E.geandis 9,E.wetarensis×E. camaldulensis 3,E.urophylla camaldulensis,UG and E.dunnii proliferate in P side, while E. urophylla×E.grandis DH-32-16,E.geandis 5 and E.grondis×E.urophylla 9 proliferate in non-P side.3. The P-content of leaf of E.geandis 9,stem of E.dunnii and root of E.grondis×E.urophylla 9 are high in P-heterogeneous conditions. The P-contents in the stem of E.geandis 9,E.wetarensis×E. camaldulensis 3 and E.dunnii, and root of E. urophylla×E.grandis DH-32-16 and E.wetarensis×E. camaldulensis 3 in heterogeneous are higher than that in P homogeneous. Roots of E. urophylla×E.grandis DH-32-29 and E.geandis 5 are higher P-content in P-side, while the other Eucalyptus are not. In P-heterogeneous conditions, E.dunnii is highest in transport efficiency, while the lowest is E. urophylla×E.grandis DH-32-16; P-utilization in Eucalyptus decreases with the content of P in matrix. P-utilization shows the order: stem>root >leaf in non-p homogeneous and heterogeneous, while the order is root >stem >leaf in P homogeneous. P-utilization in the stem and leaf of E.geandis 5 and the root of E.urophylla camaldulensis,UG are high, the same as E. urophylla×E.grandis DH-32-29.4. In P-heterogeneous conditions, content of Chlorophyll A, B and total chlorophyll are high inE.geandis 9, E.wetarensis×E. camaldulensis 3 and E.grondis×E.urophylla 9 is high, keeping the advantage in non-p homogenous. E.dunnii increase greatly in chlorophyll content. E. urophylla×E.grandis DH-32-29,E.grondis×E.urophylla 9 and E.dunnii are higher compared to that in p- homogeneous, it means that they can take up nutrients more easily in P-heterogeneous conditions. Chlorophyll A/B increasing with the P content in matrix, so Chlorophyll A affected more strongly by phosphorus. However, the difference of Chlorophyll A among treatments is not sinificant.5. The malondialdehyde(MDA) of E.grondis×E.urophylla 9 and E.dunnii is the highest and lowest in P-heterogeneous conditions, while the others is middle. MDA in E. urophylla×E.grandis DH-32-16,E.geandis 5,E.geandis 9 and E.dunnii is lower in heterogeneous than in homogeneous, so their ability to repair themselves is more strong. MDA in heterogeneous is sinificantly different from the other treatments, while the difference between Eucalyptus have no significantly difference.6. The difference of soluble protein is insignificant among different treatment. May be it is because Eucalyptus use a small amount of phosphorus to synthetical protein and maintain a high metabolism. Content of soluble protein E.wetarensis×E. camaldulensis 3,E.urophylla camaldulensis,UG and E.dunnii is higher in heterogeneous compare to other treatment ,while others is not. E. urophylla×E.grandis DH-32-29 content more soluble protein in homogeneous.7. In P-heterogeneous conditions, APase activity in leaf of E.geandis 9 is the highest, while the highest one in root is E. urophylla×E.grandis DH-32-29. Apase activity in Eucalyptus leaf is higer in heterogeneous than that in homogeneous, besides E. urophylla×E.grandis DH-32-16 and E.grondis×E.urophylla 9. The result shows that some roots of Eucalyptus impacted by deficiency state in P-heterogeneous condition, react deficiency physiological responses and then strengthen their P-utilization. Apase activity of root in P-side is higher than in non-P side.8. In P-heterogeneous conditions, the difference of rhizosphere PH is insignificant. Excepted E. urophylla×E.grandis DH-32-29, the rhizosphere PH in different treatment is insignificant also.9. Summing the index evaluation above, in P-heterogeneous conditions, E.grondis×E.urophylla 9 and E.wetarensis×E. camaldulensis 3 are higher,more strengthen,more thick of ground diameter,larger change of dry matter accumulation and longer root. So morphological growth index perform well in these two Eucalyptus. E. urophylla×E.grandis DH-32-29,E.geandis 5 and E.geandis 9 are at the middle, while E.dunnii,E.urophylla camaldulensis,UG and E. urophylla×E.grandis DH-32-16 are not so well. Incording to further physiological measurements, E. urophylla×E.grandis DH-32-29 and E.grondis×E.urophylla 9 show stronger absorption ability and higher P-utilization efficiency. But their moderate level of metabolic rate and poor capacity of antioxidant. E.geandis 5 and E.wetarensis×E. camaldulensis 3 also show high P-utilization efficiency but poor absorption ability and moderate level of metabolic rate. E.urophylla camaldulensis,UG and E. urophylla×E.grandis DH-32-16 show higher P-utilization efficiency than E.geandis 9 and E.dunnii. but poor capacity of antioxidant and poor absorption ability,... |
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