光照和氮交互作用对水曲柳幼苗生长、生物量和氮分配的影响

Interactive effects of light intensity and nitrogen supply on Fraxinus mandshurica seedlings growth,biomass,and nitrogen allocation

采用温室沙培方式,对水曲柳幼苗进行了不同光强(2个水平)和氮浓度(4个水平)处理,分析了其生长、生物量和氮分配对环境变化的响应.结果表明:与全光照处理相比,低光处理下水曲柳幼苗冠根比(S/R)和净氮吸收速率(NNUR)极显著提高(P<0.01),但相对生长速率(RGR)和净同化速率(NAR)极显著下降(P<0.01);低光处理下的幼苗根、茎、叶和整株生物量分别较全光照处理降低了36.8%(P<0.01)、1.7%、12.7%(P<0.05)和24.3%(P<0.01);低光处理使幼苗分配到根系的氮比例明显下降,而叶片的分配比例增加.无论光强大小,氮对幼苗生长都具有十分明显的促进作用,而且幼苗S/R和叶片的氮分配比例都随氮供给浓度的增加而明显提高.光强和氮浓度对水曲柳幼苗的基径、S/R、RGR和生物量(根和叶)分配比例具有显著的交互作用(P<0.05).

With sand culture in greenhouse, the responses of Fraxinus mandshurica seedlings growth, biomass, and N allocation to 2 levels of light intensity and 4 levels of N supply were studied. The results showed that under low light intensity, the seedlings shoot/root ratio （S/R） and net N uptake rate （NNUR） increased significantly （P 〈 0. 01 ）, but their relative growth rate （RGR） and net assimilation rate （NAR） had a significant decrease （ P 〈 0. 01 ）. The biomass of root, stem, leaf, and total plant under low light was decreased by 36. 8% （P 〈0. 01 ）, 1.7%, 12. 7% （P 〈0. 05）, and 24. 3% （P 〈0.01 ）, respectively, and the N allocation to leaf increased but that to root was in adverse. At the two light levels, N supply had an obvious promotion effect on the seedlings growth, and the S/R and the N allocation to leaf were increased obviously with increasing N supply. Significant interactive effects of light and N supply were observed on the seedlings diameter, S/R, RGR, and biomass allocation.