氮在柠条不同刈割处理后补偿生长中的作用

柠条对外界的扰动具有一定的忍耐能力.在地上组织破坏后,从根颈或剩余枝条产生大量的萌蘖枝.本文对柠条刈割处理分6种:对照(CK),去除主枝长度的30%,60%,去除主枝分枝数的25%,50%,100%.刈割处理植株当年生枝生物量显著高于对照;100%RSN处理没有开花结果,其他处理植株籽粒生物量、果荚生物量和所有刈割处理叶生物量高于对照或与对照差异不显著.籽粒氮质量分数、果荚氮质量分数、一年生枝氮质量分数与对照相似,但生长后期叶片氮质量分数高于对照.除100%RSN处理外,刈割处理植株在座果期根系氮质量分数低于对照,表明植物将大量的根系储存的氮供应地上组织生长.在果实采收期刈割植株根系氮质量分数迅速增加,可能是根系固氮能力或吸收能力增强的结果.在整个生长季节中,刈割植株向地上组织氮的输出量高于对照.

The role of nitrogen in compensatory growth of shrub, Caragana korshinskii Kom., following different clipping treatments

Caragana korshinskii, as a resprouter, has a strong ability to tolerate damage, such as grazing, clipping, frost, trampling or windthrow. It typically develops a stout tap-root, from the crown of which multiple shoot sprouts arise following destruction of aboveground shoots, and remaining shoots still grow, flower and maintain fruit production. In a population with a high level of damage, we removed 0%, 30% and 60% main shoot length, 25%, 50% and 100% main shoot number from shrubs. The current year shoot biomass Was higher in clipping treatments than in control. Seed biomass per shrub, pod biomass per shrub and leaf biomass per shrub were higher than or similar to those of control. Seed and pod nitrogen contents were similar between all treatments, so were current year shoots during the late growth season, but leaf nitrogen contents in clipping treatments were higher than control before leaf abscission. Root nitrogen contents of clipping treatments, with the exception of 100% RSN, were lower than control during fruit set, suggesting that more nitrogen was mobilized from root to supply to above ground growth, and late quick accumulation of nitrogen in roots compared to control may have resulted from the increase of the fixing ability and/or absorption ability. During the growth period, the mobilization of nitrogen biomass from root to shoot in clipping was higher.