| In south China, Eucalyptus (SPP) is the windbreat strategical tree species, Eucalyptus together with poplar and pine trees were called the three fast-growing tree species of world. Due to it's fast-growing and remarkable benefit characteristic, in south China provinces,the scale of Eucalyptus plantation has been unceasingly expanded, therefore the phenomenon of seedling shortage also often happened. Accelerated the cultivation of qualified Eucalyptus container seedling can effectively relieve the problem, but at present cultivated the container seedlings of Eucalyptus mainly use light matrix, which capacity to keep and releases nutrients is low, cannot satisfy the seedling rapid growth. Therefore, nutrition regulation in seedling growth stages has become a key technology to fast cultivate qualified Eucalyptus seedling. Currently in seedling index growth stage commonly used empirical fertilization, and supplied concentrated or cycle, but this kind of traditional nutrition control technologies exist defects, such as the added nutrients doesn't fit with seedling growth; After one-time fertilization will cause high root medium total concentration of nutrient solution in short-term, which will directly restricts the potential of seedling growth, lower quality of seedlings, even cause the waste fertilizer, environmental pollution, etc. Therefore, seek more precise nutrition control technology has become an important tesk to be solved in the Eucalyptus seedling technique system.Therefore, the subject will aim at present the existence of Eucalyptus seedling, applicated the advanced plant mineral nutrition steady-state theory and technology, further research the steady-state nutrition regulation technology of Eucalyptus container seedling. Mainly discussed how the total nutrition and way of index fertilization (that is in the same situation of fertilization amount, in seedling stage, according to the exponential increase nutrient add mode supplemented the total nutrition, matched the seedling stage growth rhythms, try to keep nutrient concentration of plant body stable and balanced, not like traditional fertilization made nutrient dilution along with increasing biomass) affect the growth characteristics, root morphology characteristics, biomass allocation pattern, nutrient absorption and utilization efficiency, root medium environment nutrition characteristic, fertilizer use efficiency, etc; meanwhile, for the fertilize starting point, fertilize cycle (or fertilize length) and the main nutrient elements matching made a further optimization study.The purpose of this study is to fully excavate the seedling growth potential and create the highest rate, shorter seedling period, improve seedling quality, and can effectively save fertilization, reduce the environment pollution caused by fertilization, and puts forward a set of precise nutrition control technology system for rapid cultivating high quality seedling. This has important significance to build new fertilize technology system for cultivating Eucalyptus containers seedling by factory nursery in greenhouse. Specific research conclusions are as follows:(1) Fertilization mode has obvious effect to growth of Eucalyptus seedling cultivated in light matrix container. At the end of the experiment (The first 10 weeks after fertilization), the Eucalyptus nursery seedling's height, ground diameter, biomass and root biomass of 4 kinds application mode, basically were significantly higher than that of no-fertilization (CK), in one particularly the growth of 50mg N per-plant total nutrition index fertilization model was best. Compared with the traditional mode, each growth index in 50mg N per-plant total nutrition index fertilization, 25mg N per-plant total nutrition index fertilization and 50mg N per-plant total nutrition concentrated fertilization these tree fertilization mode were all have a remarkable increased, this fully illustrated that total nutrition concentration fertilization and total nutrient index fertilization greater promoted Eucalyptus seedling growth. But, we can see from its dynamic growth and relative growth rate that 50mg N per-plant total nutrition concentrated fertilization mode growth better on early and later growth rate began to fall, appeared lack of momentum, meanwhile, seedling growth of 50mg N per-plant total nutrition index fertilization and 25mg N per-plant total nutrition index fertilization had obvious superiority and persistent. Therefore, in the nutrition regulation of Eucalyptus container seedling which was cultivated in light matrix, the 50mg N per-plant total nutrition index fertilization and 25mg N per-plant total nutrition index fertilization mode was a better choice.(2) In the mass the dynamic change law of Eucalyptus seedling height, ground diameter, biomass and root biomass in different fertilization mode showed trend that slower growth in the first 4-6 weeks and later rapid growth, the dynamic growth process matched with exponential growth model. After fertilization began in first 4-6 weeks, the difference of each growth index of Eucalyptus seedling among different fertilization mode was relatively small, and then the difference was gradually widened, expecially the difference from the 50mg N per-plant total nutrition index fertilization to the traditional mode and no-fertilization.(3) The seedling morphological characteristics of Eucalyptus container seedling had certain differences among different fertilization mode. At the end of the experiment (The first 10 weeks after fertilization), Eucalyptus seedling leaf number, root length and lateral root number of four fertilization mode basically all higher than that of no-fertilization, in which biggest leaf number and root length both were 50mg N per-plant total nutrition index fertilization, the maximum number of lateral root was 50mg N per-plant total nutrition concentrated fertilization; while the leaf specific weight of four mode were all lower than that of no-fertilization, the minimum was that of 50mg N per-plant total nutrition index fertilization, this showed that fertilization will increase leaf number, root length and lateral root number but obviously reduced the leaf specific weight, especially for 50mg N per-plant total nutrition index fertilization and 25mg N per-plant total nutrition index fertilization these two mode. The effect of fertilization mode to Eucalyptus seedling crown-root ratio and leaf-root ratio was small, but fertilization will significantly improve the shoot-root ratio of Eucalyptus seedling, especially for 50mg N per-plant total nutrition index fertilization and 25mg N per-plant total nutrition index fertilization these two mode too. This may be related to fertilization had a large improvement on aboveground biomass of Eucalyptus seedlings (especially stems) than that of the underground.(4) At the end of the experiment (The first 10 weeks after fertilization), Eucalyptus seedling quality index of four fertilization mode were significantly higher than that of no-fertilizer (CK), which indicated that fertilization can effectively improve the quality of nursery stock. But compared with the traditional fertilization mode, the total nutrition concentration fertilization mode and total nutrition index fertilization mode could much more improve the quality of nursery stock, particularly the 50mg N per-plant total nutrition index fertilization.(5) Fertilization could obviously improve Eucalyptus seedling chlorophyll-a and chlorophyll-(a + b) content, but only had a certain stimulative effect to its chlorophyll-b and carotene content. Compared with the traditional fertilization mode,the total nutrition index fertilization mode was more advantageous to increase Eucalyptus seedling chlorophyll content, especially 50mg N per-plant total nutrition index fertilization which chlorophyll-a, chlorophyll b, chlorophyll-(a + b) and carotenoids content were all most.(6) The effect of fertilization mode to the content of each element in seedling was relatively complicated, had great impact on N, P, K elements content of seedling but small on Ca,Mg elements content; the dynamic change of N, P, K elements content in two total nutrition index fertilization mode performed relatively steady trend, but that in two concentrated fertilization mode performed major fluctuations and gradually declined, and demonstrated the phenomenon which was higher than that of two total nutrition index fertilization mode in early period and later lower than theirs, expecially for the 50mg N per-plant total nutrition concentrated fertilization mode. This was probably because of the total nutrition index fertilization mode had obvious advantages and sustainability to the growth of Eucalyptus seedling.(7) Fertilization have significant effect on N, P, K, Ca and Mg elements accumulation of seedlings. Compared with the traditional fertilization mode,the total nutrition concentration fertilization mode and total nutrition index fertilization mode had advantages for seedling to absorb nutrient elements, so that could effectively increase the N, P, K, Ca and Mg elements accumulation of seedling, particularly for 50mg N per-plant total nutrition index fertilization. Except the N,K and Mg elements accumulation of 50mg N per-plant total nutrition concentrated fertilization had some descend, with the passage of time, the N,P,K,Ca and Mg elements accumulation of four fertilization mode in general presented rapid increase on early period and slowly later, but no-fertilization was basically showed a slower increase trend. Both the total nutrition index fertilization mode were better to maintain nutrients balance in Eucalyptus seedling, the ratio of nutrient elements was similar to that of applied nutrient solution, and the two concentrated fertilization mode and no-fertilization would easily led to nutrient imbalance in seedlings.(8) The fertilizer use efficiency of different fertilization mode was obvious difference.The fertilizer use efficiency of two total nutrition index fertilization mode both in some degrees higher than that of two mode of total nutrition concentrated fertilization and no-fertilization, in which The fertilizer use efficiency of 50mg N per-plant total nutrition index fertilization was the highest. This showed that total nutrition index fertilization mode would better improved the fertilizer use efficiency.(9) At the end of the experiment (The first 10 weeks after fertilization), fertilization mode had certain effect to the N, P, K, Ca and Mg element content in light matrix, the greatly influences was K element content, the smaller influences was Mg element content. By the comparison from before and after fertilization, the N element content of all fertilization mode all appear to drop; the P element content mostly appear to increase excepted the no-fertilization; the K element content only appear to drop in the traditional mode and no-fertilization, others were all rised; the Ca and Mg element content both increase in some degrees. Besides,compared with other fertilization mode, the nutrient elements content in light matrix of 50mg N per-plant total nutrition index fertilization mode and 25mg N per-plant total nutrition index fertilization mode, which decrease or increase rate was relatively small, could be better to make the nutrient elements content keep relatively stable, while other fertilization modes could not. Excessive drop may cause empty the nutrition of matrix, which would against fertility maintaining and late seedling growth, Excessive increase may cause large nutrient residue in the matrix, not only waste fertilizers but also could cause secondary moderate growth and environment pollution.(10) Orthogonal test results showed that, in the total nutrition index fertilization mode, the N applicationrates and fertilization starting point had big effect to seedling height, ground diameter and plant biomass, while the length of fertilization time didn't effect much. In seedling height, ground diameter, biomass and seedling quality index of evaluation indexes, the optimal combination respectively were A1B1C2,A1B1C2,A1B1C1 and A1B1C1.(11) Applied DRIS nutrition comprehensive diagnosis method to analysis the nutrition in light matrix of eight test. Nutrition diagnosis results indicated that the processing of nutrient unbalance index from high to low order was : 5#>3#>4#>test3>2#>test2>1#>test4, this showed that the nutrition of 5# no-fertilization was the most unbalanced one. From the order of requiring fertilizer by nutrition diagnosis, 3#,4# and 5# were all scarce for N, K fertilizer. In general, the proportion of nutrient elements of 1#,2#, test2, test3 and test4 were relative balance, which explain the total index fertilization was more favorable to keep the balance of nutrients in the plant.(12) In seedling height, ground diameter, biomass and seedling quality index of evaluation indexes, orthogonal test results of main nutrient elements ratio in total nutrition index fertilization mode showed that, only the Ca ratio had obvious effect to seedling growth others all didn't work, this indicated that in the total index fertilization mode of this test, which adopts the main nutrient nutrition elements ratio was more reasonable. The corresponding relatively optimal combination for seedling height, ground diameter, biomass and seedling quality index was A2B2C2D2,A1B1C2D3,A3B3C3D3 and A3B3C2D2.(13) The cultivate matrix of eucalyptus container seedling had an obvious effect to growth, but there was different between growth index and fertilization mode. In the no-fertilization and 25mg N per-plant total nutrition index fertilization mode, the seedling height and biomass of Eucalyptus seedling cultivated by yellow soil were both higher than that cultivated by light matrix, but it was opposited in the 50mg N per-plant total nutrition index fertilization mode. In three kinds of fertilization mode, the Eucalyptus seedling diameter and quality index of light matrix were shown better than that of yellow soil.The best fertilization mode would be different in different cultivate matrix. The 25mg N per-plant total nutrition index fertilization mode in the cultivate matrix of yellow soil performed best, of which the Eucalyptus seedling height, ground diameter, biomass and seedling quality index were all the highest, and also showed that 25mg N per-plant total nutrition index fertilization mode > 50mg N per-plant total nutrition index fertilization mode >no-fertilization(CK); Meanwhile the 50mg N per-plant total nutrition index fertilization mode in light matrix performed best, of which the Eucalyptus seedling height, ground diameter, biomass and seedling quality index were all the highest. It had important practical significance to production of Eucalyptus seedling in the future.The cultivate matrix had a significant effect to the element content of N, P, K, Ca, Mg in Eucalyptus seedling, especially for N,K elements. In the cultivate matrix of yellow soil, of three fertilization modes, element content of N in Eucalyptus seedling in 25mg N per-plant total nutrition index fertilization mode was the highest, other elements content were basically higher in 50mg N per-plant total nutrition index fertilization mode. This was different from the light matrix. The cultivate matrix had a significant effect to the element accumulation of N, P, K, Ca, Mg in Eucalyptus seedling. In the cultivate matrix of yellow soil, of three fertilization modes, element accumulation of N, P, K, Ca, Mg in Eucalyptus seedling in 25mg N per-plant total nutrition index fertilization mode was the highest; but 50mg N per-plant total nutrition index fertilization mode was the best in light matrix. This variation was similar to seedling growth index.
|
PDF Full Text Request