| Larix spp. is deciduous coniferous tree which belongs to Larch Pinaceae and is the main plantation species in the Northeast, North, and Southwest mountain area of China. Improved varieties and strong seedlings are the substance precondition for the cultivation of Fast-growing and High-yield Plantaion, While, water and fertilizer management is the key technique during the peroid of seedling culturation. There are significant differences in mineral nutrition absorption between species, families, and clones. The achievement of genetic improvement of larch is obvious, However, the technical system of strong seedling cultivation has not been completed yet especially for effects of water and fertilizer on seedling growth in species, hybrid and clone levels. The related levels of influences of water and fertilizer on seedlings and cuttings of larch were observed in the research. The mine results were as follows:1. Water is the first factor to limit the growth of Larix spp.. It not only obvious influence the height and diameter growth but also significantly affect biomass of single seedling and parts(above-ground and down-ground) of seedling especially in the distribution of root biomass and the nitrogen, phosphorous and potassium content in different organs. The most beneficial water content of soil is 55% field capacity under which the root collar diameter of seedling, water content in needles, content of chlorophyll b, carotenoids and soluble protein, and the activity of glutamine synthetase(GS) were all higher than the other treatments.2. Compared with water, nitrogen is the second factor that influences Larix spp. cuttings growth. The height, single biomass and parts(above-ground and under-ground) biomass, and the ratio of root took of the cuttings were all affected by nitrogen added. However, nitrogen does not obviously have an effect on root collar diameter for the cuttings. The differences of nitrogen, phosphorous, and potassium content in different organs from the cuttings were significant between treatments. Middle does of nitrogen(2g·seedling-1) added would accelerate both the rate of photosynthesis and transpiration. The stomatal conductance of needle was widest with no nitrogen added while it was the narrowest with the high does(4g·seedling-1) nitrogen supplied. Water use efficiency were highest no matter with no nitrogen offered or with high does supplied. However, the transpiration rate was large with high does nitrogen supplied. So, the water use efficiency was not really high.3. The inter effect of water and nitrogen on height, root collar diameter, single biomass, parts(above-ground and down-ground) biomass and content of nitrogen, phosphorous and potassium in different organs of Japanese seedlings and cuttings was also obvious. The growth and content of nitrogen, phosphorous and potassium in needles of larch seedlings and cuttings under the treatment of 55% field capacity with 2 g N·seedling-1 added were highest compared to other treatments. And the photosynthesis of this treatment was also higher than others.4. The treatment of 75% water content of substrate with nitrogen added is the most suitable condition for larch seedlings growth. The total growth of seedlings from Larix kaempferi(Lamb.) Carr. and Larix principis-rupprechtii Mayr were highest with the treatment of 75% water content of substrate with nitrogen added(30 mg N·seedling-1) under which the biomass increment of Larix principis-rupprechtii Mayr and Larix olgensis Henry were more compared with other conditions. While, the level of 75% water content of substrate with nitrogen added(60 mg N·seedling-1) would be able to accelerate the biomass increment of larch seedlings especially for the above-ground biomass of Larix principis-rupprechtii Mayr and Larix olgensis Henry. The nitrogen, phosphorous and potassium content in needles and stem of Larix kaempferi(Lamb.) Carr. and Larix principis-rupprechtii Mayr were higher under the treatment of nitrogen added(30 mg N·seedling-1) while that of Larix olgensis Henry were higher under the treatment of 60 mg N·seedling-1. The root length, root surface area, ratio of root to shoot were all larger both under the treatments of 75% substrate water content and 75% substrate water content with nitrogen added(30 mg N·seedling-1). On contrast, both the treatments of 100% substrate water content and 75% substrate water content with nitrogen added(60 mg N·seedling-1) obviously decreased the ratio of root to shoot of larch seedlings. However, the mineral content of larch seedling with the treatment of 75% substrate water content with nitrogen added(60 mg N·seedling-1) were the highest which displayed the root mineral level of larch seedlings has been to the luxury state.5. The treatment of 55% + N not only could improve the height, root collar diameter, above-ground biomass and content of chlorophyll a and b but also obviously increased the accumulation of nitrogen, phosphorous and potassium content in different organs of cuttings. But it did not improve the phosphorous content of above-ground of those cuttings. The interesting is the activity of glutamine synthetase(GS) and superoxide dismutase(SOD) enzyme in needle was lower and the accumulation of malondialdehyde(MDA) was less with the treatment of water content at 55% field capacity which displayed that the physiological activity was strong. And the root characteristics of cuttings under the treatment of water content at 55% field capacity exceeded the other treatments also explained the suitable growth condition for root is moderate drought.Clone 6 was more tolerance to drought than others while clone 8 preferred to slight drought condition and clone 8 performed better under 55% field capacity with nitrogen added(2g N·seedling-1) not only than that of other clones but also than that of itself with the other condition.6. The growth and needle physiological activities of transplanting larch seedlings would be affected during the first year after fertilization. However, the growth, biomass, physiological indexes, photosynthesis indexes, and mineral content of the species and the hybrid of them in the second year after fertilized revealed that indexes mentioned above of the suitable fertilzered treatment displayed better than that of control. The hybrid of Hua 30 * Ri kuan 10 and Ri kuan 10 species in the treatment of C2 [(8g N+10g P)/m2] were better than other treatments including control. While, Hua 30 species grown faster and it’s needle physiological activities were higher with the treatment of C3[(11g N+13g P)/m2]. The growth and physiological traits of Hua 30 * Ri kuan 10 hybrid displayed better than that of it’s paratents.7. The formulation 2 would be the suitable controlled-released fertilizer for larch seedling according to the difference analysis of the growth law, total growth, biomass, chlorophyll content, mineral content in seedling and available mineral content in substrate and the mineral proportion, release period, and the prices of the formulations. Compared the seedling growth, physiology and mineral content, the suitable formulation for seedlings of Larix kaempferi(Lamb.) Carr., Larix olgensis Henry and Larix principis-rupprechtii Mayr is formulation Y2(the improvement of formulation 2 mentioned above). |
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