Seedling sweetgum (Liquidambar styraciflua L.) half-sib family response to N and P fertilization: growth, leaf area, net photosynthesis and nutrient uptake
2003
Chang, Scott X.
Information concerning sweetgum (Liquidambar styraciflua L.) genotypic variation and response to fertilization is needed for developing site-specific silvicultural techniques for plantation establishment. A pot experiment was conducted to investigate the effect of N and P application, and family on sweetgum growth and nutrient uptake. Two rates of N (0 vs. 100 kg N/ha equivalent) and P (0 vs. 50 kg P/ha equivalent), and two half-sib families (F10022 and F10023) were used in a split-plot experiment. Two months after the treatments were applied, N application increased height growth and total leaf area (LA) by 209 (P=0.002) and 138% (P=0.019), respectively, over the no N treatments, and P application increased basal diameter (BD) growth and total LA by 24 (P=0.002) and 23% (P=0.006), respectively, over the no P treatments. Genotypic effects were significant on BD growth and LA development and differences between the half-sib families in diameter growth response can be explained by differences in LA expansion. Both N and P additions increased foliar P, K, Ca and Mg content and the total uptake of these nutrients by the seedlings. The combined effect of N and P application was much greater than either N or P application alone in growth, LA and nutrient uptake responses, indicating that the proper balance of N and P nutrition is important for optimal sweetgum seedling growth. Seedling biomass production was significantly related to specific leaf area (SLA), total LA and foliar N concentration or content, and LA changes explained 90% of the growth responses.
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