遮荫对白枪杆苗期生长性状和光合色素的影响

Effect of Shading on the Growth Traits and Photosynthetic Pigment of Fraxinus malacophylla Seedlings

研究遮荫对白枪杆Fraxinus malacophylla 幼苗生长、生物量及其分配等指标的影响,为今后白枪杆苗木培育和石漠化植被恢复提供优质种苗。试验以1年生白枪杆实生苗为材料,采用单因素随机试验方法,设置不遮荫(F_(1))、25%±5%遮荫(F_(2))、50%±5%遮荫(F_(3))、75%±5%遮荫(F_(4))4个处理,试验开始后每隔30 d测定白枪杆幼苗的地径、苗高、株幅等生长指标,生长期结束后称量白枪杆幼苗的生物量,并对生长指标进行比较分析。结果表明:不同遮荫处理会对白枪杆幼苗的生长、生物量及分配产生显著影响,随着遮荫程度增加,白枪杆幼苗的苗高生长量、地径生长量、冠幅生长量、总生物量和各器官生物量均先增加后降低,且均在中度遮荫处理下达到最大值;根生物量分配比和根冠比总体随着遮荫程度增加而下降,茎生物量比随着遮荫程度增加而增加,叶生物量分配比变化不显著;随遮荫程度的增加,白枪杆幼苗光合色素含量增大,而叶绿素a与叶绿素b的比值(Chla/Chlb)下降。研究表明,中度遮荫下一年生白枪杆幼苗生长最好,具有较高的耐荫性;因此,白枪杆幼苗在育苗和石漠化生态恢复过程中的利用应充分考虑其耐荫蔽能力。

To study the effects of shading on growth,biomass and its distribution of Fraxinus malacophylla seedlings,so as to provide high quality seedlings for future cultivation of Fraxinus malacophylla seedlings and restoration of rocky desertification vegetation.1-year-old Fraxinus malacophylla seedlings were used as materials,and the single-factor randomized experiment was adopted.4 treatments were set,such as no shading (F_(1)),25±5% shading (F_(2)),50%±5% shading (F_(3)) and 75%±5% shading (F_(4)).The growth indexes of Fraxinus malacophylla seedlings such as ground diameter,seedling height and plant width were determined every 30 days after the experiment.After the end of the growth period,the biomass of Fraxinus malacophylla seedlings was weighed,and the growth indexes were compared and analyzed.The results showed that:different shading treatments had significant effects on the growth,biomass and its distribution of Fraxinus malacophylla seedlings.With the increase of shading degree,the seedling height growth,ground diameter growth,crown width growth,total biomass and biomass of various organs of Fraxinus malacophylla seedlings all increased first and then decreased,and all reached the maximum under moderate shading treatment;root biomass distribution ratio and root-shoot ratio decreased with the increase of shading degree,while stem biomass distribution ratio increased with the increase of shading degree,leaf biomass distribution ratio did not change significantly.With the increase of shading degree,the photosynthetic pigment content of Fraxinus malacophylla seedlings increased,while the ratio of Chla to Chlb decreased.The results showed that the 1-year-old Fraxinus malacophylla seedlings the best growth and high shading-tolerance under moderate shading.Therefore,the shading-tolerance of Fraxinus malacophylla seedlings should be fully considered in the utilization of seedling raising and rocky desertification ecological restoration.