【摘要】 钾对植物生长和氮代谢起着关键作用，研究不同钾水平对玉露香梨幼苗生长和氮素吸收利用的影响，可为玉露香梨生产上科学施钾提供理论依据。以一年生玉露香梨幼苗为试材进行砂培试验，研究不同供钾水平（0、3、6、9、12 mmol/L，分别以K0、K1、K2、K3、K4表示）对幼苗生长、光合特性及氮素吸收利用的影响。结果表明，K2处理玉露香梨幼苗地下部生物量、根系长度、根系总表面积和根系活力均显著高于其他处理。叶片净光合速率、蒸腾速率、气孔导度和荧光特性指标随着钾浓度的升高，均呈现出先升高后降低的趋势，在K2处理达到最大值；而胞间CO₂浓度呈现出先降低后升高的趋势，在K2处理达到最小值。K2处理根、枝干、叶各器官对氮的征调能力分别是K0处理的1.65、1.27、1.38倍，¹⁵N吸收量和¹⁵N利用率分别是K0处理的1.83和2.19倍。综上所述，钾的亏损或过量均抑制根系生长和光合作用，生物量减少，降低对氮的吸收利用。适宜的供钾水平能够促进幼苗根系生长，同时促进氮素由地下部向地上部的转运，实现氮素的高效吸收利用，从而促进玉露香梨幼苗的生长。更多还原

【Abstract】 Potassium plays a crucial role in plant growth and nitrogen metabolism. Studying the effects of different potassium levels on the growth and nitrogen absorption/utilization of ‘Yuluxiang’ pear seedlings can provide a theoretical basis for scientific potassium fertilization in ‘Yuluxiang’ pear production. A sand culture experiment was conducted using one-yearold ‘Yuluxiang’ pear seedlings to investigate the effects of different potassium supply levels（0,3,6,9,and 12 mmol/L,denoted as K0,K1,K2,K3,and K4,respectively） on seedling growth,photosynthetic characteristics,and nitrogen absorption and utilization. The results showed that the K2 treatment significantly increased the belowground biomass,root length,total root surface area,and root activity of ‘Yuluxiang’ pear seedlings compared with other treatments. The net photosynthetic rate,transpiration rate,stomatal conductance,and chlorophyll fluorescence parameters of leaves initially increased and then decreased with rising potassium concentrations,peaking under the K2 treatment. In contrast,intercellular CO₂ concentration showed an opposite trend,reaching its lowest value at K2 treatment. The nitrogen mobilization capacity of roots,branches and stems,and leaves under K2 treatment was 1.65,1.27,and 1.38 times that of K0 treatment,respectively;the ¹⁵N uptake and ¹⁵N utilization rate were 1.83 and 2.19 times those of K0 treatment,respectively. In summary,both potassium deficiency and excess could inhibit root growth and photosynthesis,reduce biomass accumulation,and impair nitrogen uptake and utilization. Optimal potassium supply（6 mmol/L level） promoted seedling root development while enhancing nitrogen translocation from roots to shoots,thereby achieving high-efficiency nitrogen assimilation and ultimately improving the growth of ‘Yuluxiang’ pear seedlings.更多还原