遮阴和氮素梯度处理对芒萁光合生理的影响.

We studied the effects of light intensity and nitrogen concentration on photosynthetic physiological parameters in clonal ramets of Dicranopteris dichotoma. Different levels of light intensity(light shading, L1; medium shading, L2; and heavy shading, L3) and nitrogen concentrations(control, N0; low nitrogen, N1; moderate nitrogen, N2; and high nitrogen, N3) were used, and differences in the photoresponse process, photosynthetic pigment content, and chlorophyll fluorescence induction kinetic parameters of potted D. dichotoma were analyzed. Under L1 treatment, photoinhibition was observed. Nitrogen application improved the net photosynthetic rate(Pn), stomatal conductance(Gs), transpiration rate(Tr), and fluorescence intensity(F) of D. dichotoma. The ramets under the N2 treatment had the largest light ecological amplitude, with a 37.9% higher Pn than that under N0 treatment. Under L2 treatment, the dark respiration rate(Rd) of the ramets was lower than that under L1 treatment. Nitrogen application enhanced the light utilization capacity of D. dichotoma. The performance index was the highest under L2 N2 treatment, reaching 1.78. Under L3 condition, the Pn, F, and specific activity parameters of D. dichotoma decreased with nitrogen concentration. Light intensity had a significant effect on photosynthetic pigment content(P<0.05), and nitrogen application promoted the content of chlorophyll a and total chlorophyll. It was concluded that D. dichotoma under L1 N2 treatment had the highest photosynthetic potential. The L2 N2 treatment was the most suitable for D. dichotoma to accumulate photosynthate, with the highest activity of photosynthetic system II. Under L3 condition, nitrogen application was not conducive to the growth of D. dichotoma. [ABSTRACT FROM AUTHOR]