| Phosphorus is an essential element for plant growth, and is the structural composition material of many kinds of biomolecule (nucleic acid, phospholipid, phosphoric acid, glucose, catalytic coenzyme), therefore plays a crucial role in stabilizing the cellular membrane structure, improving the efficiency of material metabolism and regulating enzyme activity. However, the bioavailable phosphorus in the soil seldom meets the needs of plant growth. At present, most of the soil around the world is in bad lack of phosphorus. The area of aphosphagenic soil in China is approximately 6.72×107 ha, especially in the large distribution area of red soil in southern China, which belongs to subtropical monsoon climate zone, where the soil weathering is intensely, and by the proccess of stronger eluviation, the soil is distinct desilisification and allitization, has strong effect on phosphorus-fixation. After a long period of acclimation under stress environment, plant had evolved their own adaptive mechanism. For example, adjusting the growth pattern of roots to avoid soil patches that contain toxic Al3+, or exudate low molecular weight organic acids to chelate Al3+ and increase the availability of P. In recent years, in order to establishing a high efficiency, low waste sustainable production system of agriculture and forestry, scientists in the field of plant nutrition had devoted to introduce and select plant genotypes that can grow and develop well on the acid soil by genetic breeding.Masson pine is an Chinese special local tree species as well as an important industrial material wood in subtropical zone of China, possesses excellent characteristics such as fast growing, high yield, good comprehensive utilization and fine fiber quality, therefore, is an important pillar for forest industry, papermaking industry and forest product industry. Masson pine is widely distributed in China and has strong adaptability, spreads over 15 provinces, where exist many high mountains and big rivers throughout its entire distribution area, and the geographical environment is always changeable. Under the long-term natural selection and reproductive isolation, there is considerable genetic variation within the sample of masson pine, and reflects its great capability of adapting to low-phosphorus red soil. Therefore, development of genetic resources, screening and cultivating acid-tolerance P-efficient genotypes of masson pine provides a new way to ensure the sustainable production of plantation, while understanding the low-P tolerance mechanism of masson pine is required. For this reason, the further study of low-P tolerance mechanism of masson pine is of important theoretical significance and practical value. Based on this background, this research was carries out with eleven superior families of Pinus massoniana, which were provided by Wuyi forest farm of Zhangping county, Fujian, and sand culture experiment at four P levels were conducted to observe and explore their differences in utilizing the insoluble phosphate. The activated adaptation mechanism for insoluble phosphate in acid soils and genetics of P efficiency were expatiated primarily, and five families were screened out as ideal family to plant widely on acid red soil of south China. The main results are as follows:1. Sand pot experiments indicated that the 11 families of masson pine had a significant variation in cellular antioxidation capacity and enzymatic activity. The free proline concentrations in the leaves of No.335, No.474 and No.388 was relatively high, therefore these three families had greater capabilities for maintaining the cell pressure potential, keeping the cell's internal environment in steady-state. No.2 had relatively higher content of MDA, lower content of Pro and CAT, therefore, indicated that its cellular membrane structure was damaged in deep degree, and its ability in scavenging active oxygen was poor. No.335, No.568, No.242 and No.658 had relatively higher content of CAT, indicated that they hadremarkable scavenging effects against H2O2. 2. Under phosphorus stress, masson pine promotes the activity of Apase in the roots and leaves to activate and absorb organic phosphorus in the rhizosphere soil and multiple reuse the limited P inside plant tissues. Results of this study show that the activity of Apase in the leaves was significantly greater than that in the roots. When applying hard-soluble P, the activity of Apase in the leaves of masson pine was raised, while the activity in the roots was reduced.3. Under adversity stress, the gene expression of masson pine was changed and some induced proteins were produced in plants. P5 treatment had increased the soluble protein content of masson pine, while under P20 treatment, the inceasing Al3+ in the sand had toxic effects on plants, therefore each family had encountered more or less reducing of soluble protein.4. The root exudates of masson pine had certain ability to mobilize insoluble Fe-P and Al-P. After applying sparingly soluble phosphate into soils with low available phosphorus, each fimily can absorbed large amounts of phophorus, making P accumulation in vivo increase significantly. Masson pine secreted much more oganic acid, and its root exudates increased the pH value of the rhizosphere, chelating the toxic Al3+, therefore inproving the availability of phosphorus in the rhizosphere.5. Among the 11 tested masson pine families, No.474 has high cellular antioxidation capacity, and moreover, its phosphorus use efficiency is relatively high, therefore is an ideal provenancethat can tolerance low phosphorus. No.2 also has relatively high phosphorus use efficiency, while its cellular antioxidation capacity is relatively poor. Therefore under the single P stress, its growth performance maybe is a great satisfaction. But if it met complex Al-P stress, that the result may have potential risk. No.335, No.568 and No.658 have stationary utilization efficiency of insoluble phosphates, attributed to their relatively high decomposing capacity of activated oxygen, therefore these three family could grow and develop well on the strong weathered soil with rich aluminum and effect of phosphorus fixation.
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