【作者】 那守海；

【导师】 阎秀峰；

【作者基本信息】 东北林业大学 ， 生态学， 2008， 博士

【摘要】 兴安落叶松（Larix gmelinii）是我国东北地区重要的用材树种,在东北林区,由于气温低、冬季时间长,凋落物的分解及有机物的矿化过程较为缓慢,林地氮、磷营养常常成为落叶松生长的限制因子。因此,研究不同氮、磷营养供给下落叶松的氮、磷素的吸收利用及对其生长的影响,对于提高落叶松林生产力,丰富森林培育理论具有重要的理论意义。本研究在温室中,采用砂配技术培养落叶松一年生幼苗,并设置了不同梯度的氮、磷素供应,对不同氮、磷处理下的落叶松幼苗的生长指标进行了测定,分析了落叶松幼苗对氮、磷素的吸收、积累与转运过程,主要研究结果如下:（1）氮、磷养分供应与落叶松幼苗氮、磷素的积累与转运的关系。在不同的氮、磷营养水平条件下,施氮显著提高了落叶松幼苗叶、茎、根的氮浓度,其中叶氮浓度最高,且随氮供给水平的增加,变化幅度也最大。供磷水平未影响幼苗对氮素的吸收。低的磷供应尽管没有降低针叶磷浓度,但却导致茎和根中磷浓度降低,说明供磷不足减少了幼苗对磷的吸收。增加供磷可提高茎、根中的磷浓度。在不同浓度氮素处理水平下,根的氮转运量、转运效率和氮转运贡献率最高、茎次之、叶最低,并均随供氮水平的提高而增加。在磷处理水平为0.5 mmol·L^-1时,根、茎的氮转运量、氮转运效率和氮转运贡献率的最高,但在低于或高于该处理浓度时相关指标降低;叶的氮转运量和转运效率同样也在供磷水平为0.5 mmol·L^-1时最高,在高于或低于上述供磷水平时,均可导致相关指标降低,但其氮转运贡献率在供氮水平为1mmol·L^-1时最高。从氮收获指数看,叶最高、根次之、茎最低,叶的氮收获指数随氮和磷处理水平的升高而升高,而根却降低,茎的反应不显著。在不同的氮素处理水平下,根的磷转运量和磷收获指数最高、叶次之、茎最低,而磷转运效率和转运贡献率则是根最高、茎次之、叶最低;供磷水平对茎的磷转运量、转运贡献率和磷收获指数影响不显著,而对根和叶的影响比较显著。（2）氮、磷素营养对落叶松幼苗根系碳、氮积累与分配的调控。氮素的影响较为显著研究结果表明:落叶松幼苗根系中的碳浓度随氮处理水平的增高而降低,而碳积累,量和碳收获指数则随氮处理水平的升高而升高;在不同级根中,落叶松幼苗的碳浓度和积累量也表现出随根序升高而增加的趋势;全根的碳积累量、氮积累量与生物量对氮素供应水平的响应基本一致,表现出随氮素供应水平提高而增加的趋势;氮素的积累量只有在高氮供应条件下才显著提高(32 mmol·L^-1);氮收获指数与碳收获指数表现出类似的规律。各级根的C/N值均随氮处理水平的升高而呈下降的趋势,但不同级别的根差异不显著。供磷水平对落叶松幼苗根系的碳含量影响不显著,而碳积累量则表现为从2级根到5级根的逐渐升高,当供磷水平为1 mmol·L^-1时,高级根和低级根的碳积累量不同。正常供磷水平时,落叶松幼苗的氮含量最高:在不同供磷水平下,1级根的氮收获指数最高。（3）氮、磷素营养对落叶松幼苗生物量和碳分配的调控。氮、磷供给不足显著抑制落叶松幼苗地上部的生长,但对根的生长无影响。施加氮、磷对幼苗的地上部生长有很大的促进作用,过量的供磷对幼苗的生长有抑制作用。氮、磷供给不足时,落叶松幼苗均表现出将更多的碳分配到地下以促进根系的生长,扩大根系对养分的吸收表面积,这可能是落叶松幼苗对于低的养分供给的一种适应策略。（4）氮磷营养与落叶松光合作用的关系。氮素营养的供给与落叶松幼苗的光合特性有很强的相关性。氮素供应不足,显著降低了幼苗的叶绿素含量、类胡萝卜素含量、可溶性蛋白含量和反映植物光合能力的光饱和净光合速率（Pmax）,Fv/Fm和中Φ_PSⅡ显著下降。而施氮可有效的提高光化学效率,减缓光抑制现象。另外,随着供氮水平的降低,落叶松幼苗的qP下降,同时伴随着NPQ的增加,说明氮缺乏时植株捕获的光能不能被有效利用,而是更多的以热的形式被耗散掉了。相比之下,磷对光合作用的影响较小。磷缺乏没有引起光合色素含量及可溶性蛋白含量的下降,Pmax也仅小幅度下降。另外,供磷水平对叶绿素荧光参数的影响也不显著,这也说明了磷对落叶松幼苗幼苗的光合特性影响较小。更多还原

【Abstract】 Larch（Larix gmelinii） is the one of the most important timber species in northeastern China,and its growth is often limited by nitrogen and phosphorus shortage because slow decomposition rate of litter results by low temperature and long winter in boreal forest. Therefore,it is important practice and theory significance of improving productivity of larch forest and enriching silviculture to study the effect of nitrogen and phosphorus supply level on assimilation and utilization of nitrogen and phosphorus in larch.In this study,the experiment was conducted in green house,the Larch seedlings were cultured in sand to supplied with different levels of nitrogen and phosphorus.The growth index of Larch seedlings on the condition of different levels of nitrogen and phosphorus supply was determined,and the process of assimilation and accumulation of nitrogen and phosphorus in larch seedlings was analysed.The results of the study were summarized as follows:（1） The relationship·between nitrogen and phosphorus supply with accumulation and translocation of nitrogen and phosphorus in larch seedling.Additional nitrogen supply significant increased needle,stem and root nitrogen concentration in larch seedling,and needle nitrogen concentration was highest and have the most change extent with the increase of nitrogen supply.Phosphorus supply level has no effect on the nitrogen absorption of larch seedling.Low phosphorus supply didn’t decrease the needle phosphorus concentration,but it did indue a decline of stem and root phosphorus concentration,these suggested that insufficient phosphorus supply decreased the phosphorus assimilation of larch seedling. Inereasing the phosphorus supply may increase stem and root phosphorus concentration.The value of nitrogen translocation amount,nitrogen translocation efficiency and nitrogen contribution in roots were higher than shoots,and which in shoots were higher than needles with different nitrogen supply,and all raised with the increase in nitrogen supply.The value of nitrogen translocation amount,nigrogen translocation efficiency and nitrogen contribution in roots and shoots were the highest with the 0.5 mmol·L^-1 phophorus supply same as the translocation amount and nitrogen translocation efficiency in needles,however the value of the nitrogen contribution in needles was the highest with the 1.0 mmol·L^-1 phosphorus supply,and the related values above all declined while increasing or decreasing phosphorus supply.The value of nitrogen harvest index（NHI） of needles was the highest,and which of the roots take the second place,which of the shoots was lowest;the value of NHI of needles was increased with the increase in phosphorus supply while which of the roots declined,however which of effects on shoots was no significant.（2） The effect of nitrogen and phosphorus supply levels on accumulation and allocation of carbon and nitrogen in larch seedlings root.The results showed that with the increase in nitrogen supply,the carbon concentration in the larch roots were declined,while the carbon accumulation amount and carbon harvest index were increased;The carbon concentration and accumulation were increased with the nitrogen supply increasing while the root order ascending;The carbon accumulation,nitrogen accumulation in whole root of larch seedlings were up with the increase in nitrogen supply;meanwhile the biomass of whole root were raised. Nitrogen accumulation amount increased significantly while the nitrogen supply level increased to highest(supplied with the nitrogen supply level of 32 mmol·L^-1).Same as the carbon harvest index,the nitrogen harvest index in larch roots were raised with the nitrogen supply increasing.However,the C/N ratio in roots were declined with increase in nitrogen supply.The phophorus translocation amount and harvest index of root was higher than needle and shoot with the different level of nitrogen supply,and the value above of the shoot was lowest.While the value of phosphorus contribution and efficiency of root was higer than shoot,and the value of shoot was higer than needle.The effect of phosphorus supply on phosphorus translocation amount,translocation contribution and phosporus harvest index was not significant while was significant with root and needle.（3）The effect of nitrogen and phosphorus nutrition on biomass and carbon distribution in larch seedlings.Deficient nitrogen and phosphorus supply significant restrained shoot growth of larch seedlings,but had no effect on root growth.Increased nitrogen and phosphorus supply obviously improved the shoot growth of larch seedlings,and excessive phosphorus supply restrained growth of seedlings.Partitioning of carbon to roots was enhanced in order to inerease root growth and enlarge absorption surface to nutrition with the deficient nitrogen and phosphorus supply,It maybe a adaptive strategy of larch seedling to low nutrition supply.The effect of phophorus supply on carbon concentration of larch seedling was not significant,and the carbon accumulation was increased from root order 2 to order 5.The carbon accumulation of higer order and low order root were different while the phosphorus supply was 1 mmol·L^-1.The nitrogen concentration of larch seedling was higest with the normal phosphorus supply;The nitrogen harvest index of order 1 root of seedling was higest with the different phosphorus supply.（4） The relationship between nitrogen and phosphorus nutrition with photosynthesis of larch seedlings.There was a strong correlation between nitrogen supply and photosynthesis of larch seedlings,deficient nitrogen supply reduced chlorophyll content,carotenoid content total soluble protein content of needle of larch seedling and result in light-saturated net photosynthetic rate（Pmax） which reflect plant photosynthetic ability decreased,the Fv/Fm and Φ_PSⅡ decreased significantly.Whereas increased nitrogen supply can significantly improve photochemistry efficiency and alleviate photoinhibition.In addition,with the decease of nitrogen supply level,qP of larch seedling also decrease,and this change was accompanied by a increase of NPQ,these suggest that under nitrogen deficiency,the light energy which have been captured by plant can not be used effcetively,but more of them is dissipated in heat. Compared with the effect of nitrogen,phosphorus had little effect on photosynthesis of larch seedling.Phosphorus defieieney didn’t indue in deceased of photosynthetic pigment content and to total soluble protein content,and P_max only decrease slightly.On the other hand, phosphorus supply level either had a significant effect on chlorophyll fluorescene parameters, it also indicated that the effect of phosphorus on photosynthetic characteristics of lareh seedling is slight.更多还原