白桦最佳施肥配方的筛选及其各元素的作用分析

选一个半同胞家系的1、2和3年生白桦实生苗，进行3种（T1、T2、T3）配方施肥，比较各配方肥对不同年龄白桦开花结实的影响，筛选获得最佳施肥配方。在此基础上，进一步开展最佳配方中氮、磷、钾各元素对白桦生长发育的影响，为白桦强化种子园和培育速生丰产林等不同用途的人工林提供施肥依据。结果表明:1）T3显著促进并提高白桦开花结实量，是白桦强化种子园施肥的最佳选择。2）在最佳施肥配方中，氮肥对白桦营养生长的作用最突出，使3年生树高和地径达3.08 m和25.76 mm，分别较对照提高了19.38%和 39.17%。3）氮肥也显著促进白桦开花结实，使3年生白桦的开花率达到了49%，而单独施用磷、钾肥的仅为4%和1%，对照没有开花；但是，氮肥处理与最佳施肥配方相比在开花率上存在显著差异，最佳施肥配方处理的白桦开花率达到了90%。4）白桦由营养生长期进入生殖生长期，部分营养被用于开花结实，影响了当年高生长，而地径的当年生长量没有受到影响。 

Selection of the optimum fertilizer formula and the effects of nutrient elements on growth and flowering performance of Betula platyphylla.

Three fertilizer formulae (T1,T2 and T3) of various nitrogen,phosphorus and potassium levels were applied to 1-,2-and 3-year-old Betula platyphylla seedlings of a half-sib family,respectively,with the objectives of comparing their effects on seedling flowering and fruiting and selecting the optimum one.Then,we investigated the effects of each element (N,P and K) of the optimum formula on growth and development of B.platyphylla seedlings.Results showed that:1) all formulae significantly increased flowering,compared with no fertilizer (control),with the great response occurring at T3.2) In T3,nitrogen was most effective in improving vegetative growth,making the 3-year-old trees reach 3.08 m in height and 25.76 mm in ground diameter,increased by 19.38% and 39.17% respectively than control.3) Nitrogen fertilizer promoted flowering more effectively than phosphorus or potassium fertilizer.Applying nitrogen improved the flowering rate of 3-year-old trees to 49%,compared with only 4%,1%,and 0 by applying only phosphorus,potassium or without fertilizer.However,applying T3 produced significantly more flowers than applying nitrogen alone,increasing the flowering rate to 90%;4) During the development from vegetative growth to reproductive growth,some nutrition was allocated for reproductive growth,which reduced the height growth but not diameter growth of the current year.