不同供钾水平对玉露香梨幼苗光合特性和氮素吸收的影响OA

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-year-old'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.