土壤紧实度对玫瑰幼苗生长及根系氮代谢的影响

 以盆栽玫瑰（Rosa rugosa）‘珲春’实生苗为试材，研究土壤紧实度对其生长和根系氮代谢的影响。结果表明，玫瑰幼苗生长指标及生物量在不同土壤紧实度下的大小顺序为：1.30 g · cm^-3处理 > 1.50 g · cm-3处理 > 1.10 g · cm^-3处理；根冠比随土壤紧实度的增加而下降，1.50 g · cm^-3处理下降显著。土壤紧实度的增加抑制了地下部的生长，表现为根系长度、侧根数量、主根直径等均随土壤紧实度的增加而降低，根系平均直径和总面积有所增加；根系活力以土壤紧实度为1.30 g · cm^-3的处理最高，1.50 g · cm^-3处理最低；根系中硝态氮、氨态氮含量和硝酸还原酶活性变化趋势一致，均是土壤紧实度为1.30 g · cm^-3的处理最高，1.50 g · cm^-3处理次之，1.10 g · cm^-3处理最低；谷氨酰胺合成酶活性随着土壤紧实度的增加而升高。土壤紧实度显著影响玫瑰幼苗氮代谢活动，进而影响植株对养分的吸收和利用，1.30 g · cm^-3的土壤紧实度较适宜于玫瑰的生长。

Effect of Soil Compaction on Growth and Root Nitrogen Metabolism of Rosa rugosa Seedlings

Experiment was conducted with potted seedlings of Rosa rugosa，for studying the effect of soil compaction with 1.10 g · cm^-3，1.30 g · cm-3，1.50 g · cm^-3 soil bulk density（SBD）on growth and root nitrogen metabolism of the seedlings. The results showed that the values of growth index and biological yield under different soil compaction were 1.30 g · cm-3 > 1.50 g · cm^-3 > 1.10 g · cm^-3. The ratio of root/top （R/T）of plant was decreased with soil compaction increasing，and the R/T of the 1.50 g · cm^-3 SBD was significantly lower than that of the 1.10 g · cm^-3 and 1.30 g · cm^-3 . The root growth of the potted seedlings were inhibited as the soil compaction increasing，including root length，lateral root number and tap root iameter，but the average diameter and surface area of root was increased. The root activity，NO₃^--N and NH₄⁺-N contents，NR activity in root were the largest in the 1.30 g · cm^-3SBD，then the 1.50 g · cm^-3 SBD and the 1.10 g · cm^-3 was the lowest. GS activity in root was increased as the soil compaction increasing. The experiment indicated that the soil compaction was a crucial factor to affect nitrogen metabolism and influence the absorption and utilization of nutrients in plant. 1.30 g · cm^-3 SBD was favorable for plants to grow.