不同降雨型桉树种苗期特性研究

Study on Growing Features of Eucalypt Seedling from Different Rainfall Types

以新引入四川的20个桉树品种71个种批号种子为材料,开展了育苗试验及苗期生长发育特性观察,重点观察了分别代表冬雨、夏雨、均匀降雨型的品种王桉、大花序桉、白腊树桉的苗期特性。结果表明:不同品种种子萌芽所需的温度、湿度是不一致的,在相同的温湿度条件下,各个品种发芽期、发芽率不同,但苗期发育特性基本相同。苗木的个体发育前期是根的快速生长,苗木高、地径、根的生长量随叶片数量增加而增加;夏季播种的夏雨型品种和部分均匀降雨型品种出苗整齐,出苗率一般在85%左右;冬雨型品种发芽极不整齐,发芽期从8月延续到翌年3月。同一品种秋季和初夏育苗的效果也不一致。

Growing features during seedling stage of three newly different rainfall types Eucalyptus species were studied.E.regnans,E.cloeziana and E.fraxinoides were selected to stand for the winter rainfall type species,summer rainfall type species and well-distributed rainfall type species differently to illustrate their growing characteristics by tabulating.The results showed that their root systems grew very rapidly,their root length was two or three times more than their height in the emergence and embryonic stages of seedling.During their main leaf growing period,the growth of seedling height,ground diameter and roots increased with the increasing of leaf blades.Their increments were not along with the changes of air temperature and moisture because the growth biotem-peratures among seedling were uneven.The results showed that the relatively differences were found in the seedling emergence rate and seedling-forming rate of various species and species batch number when they were sown at the same time.The summer rainfall type and partly well-distributed rainfall type species sown in summer had an even seedling emergence and a high emergence rate,generally being 85% or so,and sometimes their germination rate could reach 100% at most.The winter rainfall type species had an uneven germination,and their germination period began from the seventh day after sowing and last until March next year.The seeds of the same species and the same species batch number also had uneven cultivating seedling effects when they were sown in different seasons such as autumn and early summer.