不同倍性白桦无性系苗期最佳施肥量的确定

Best Fertilizer Rate of Different Ploidies Birch Clonal Seedling

以2年生的白桦四倍体和二倍体共19个无性系苗木群体为试验材料,用前期筛选的施肥配方配制成1/1 000质量浓度的混合营养液对根部进行浇灌施肥,分别7(处理1)、10(处理2)、15 d(处理3)的间隔期施肥,以不施肥为对照(处理4)。试验采用完全随机区组设计,重复3次。施肥自5月1日起始,8月31日结束。苗高、地径调查每隔15 d调查1次,自5月15日起,10月1日结束。结果表明:在3种施肥及对照条件下不同倍性白桦的生长均呈现"慢-快-慢"的"S"型,生长速度及生长期随着施肥量的递增而递增,苗高、地径生长量较对照分别提高42.46%、32.14%;在3种施肥处理及对照条件下不同倍性白桦无性系间生长量差异明显,二倍体高生长较四倍体提高了20.30%,在施肥处理1的条件下四倍体的地径生长较二倍体提高了3.71%。由3种施肥及对照处理条件下无性系的平均高径比、配方肥的用量及用工成本等综合分析,确定施肥间隔为15 d的处理3为白桦苗木培育时的主选施肥方案。无性系的不同对施肥量的要求不同,本项目分别为19个白桦无性系确定了精确施肥量。综合各无性系在各种施肥处理条件下苗高、地径生长量,初步选择3个二倍体、1个四倍体为优良无性系,它们分别为2Bz3、2Bz18、2B353和4B44,其平均苗高、地径较未施肥对照时分别提高了40.60%、32.26%。

With 19 2-a different clones birch （include diploid and tetraploid） seedlings group, the optimum fertilization formula was used to make 1/1 000 nutrient solution irrigated root fertilization for 7 d （Treatment 1 ）, 10 d （Treatment 2）, 15 d （Treatment 3）, with no fertilization as the control （Treatment 4）, and then set same fertilizer concentration to each seed- ling every time. The test was performed in a completely randomized block design and repeated three times. Fertilization be- gan on May 1 and end on August 31. The investigation of seedling height and ground diameter was conducted from May 15 th to October 1 st. All treatments birch seedlings growth rhythm showed a ＂slow-fast-slow＂ pattern, the growth rate and growth period were increased with the increasing of fertilizer rate, comparing with control, the height and ground diameter of Betula platyphylla grown in fertilization treatments were increased by 42.46% and 32.14%, respectively. There was a significant difference in the growth of B. platyphylla under different fertilization treatments. The diploid height increased by 20.30% compared with the tetraploid, but the tetraploid was obviously coarser. The fertilization of Treatment 1 was 3.71% higher than diploid. According to the average height-diameter ratio and fertilizer rate under different treatment and the labor costs, the fertilization interval of 15 d （ Treatment 3 ） was the best choice as the main fertilization scheme. Different clones required different fertilizer rates, the test determined each clone＇ s precise fertilization rate for 19 clones. Integrated the growth of seedling height, ground diameter under the condition of different fertilization treatments, there were four clones （ 2Bz3, 2Bz18, 2B353 and 4B44） selected as excellent clones, and the average seedling height and ground diameter were increased by 40.60% and 32.26% higher than the clones without fertilization, respectivly.