Nondestructive and rapid estimation of hardwood foliar nitrogen status using the SPAD-502 chlorophyll meter

摘要: The utility of a portable chlorophyll meter (SPAD-502, Minolta Camera Co. Ltd., Japan) for rapidly and nondestructively assessing foliar N status hardwood species was evaluated in two experiments. In experiment one (established near Raleigh, North Carolina), 0, 56, 168, or 336 kg N/ha (ammonium nitrate) applied June 1998 to sycamore (Platanus occidentalis L.), sweetgum (Liquidambar styraciflua green ash (Fraxinus pennsylvanica Marsh.), swamp cottonwood (Populus heterophylla L.) obtain samples with range concentrations. Significant regression equations were established between concentration (obtained through chemical analysis) SPAD value all four studied August 1998. two, the further tested 1999 on eastern NC examine whether crown position date measurement affect relationship readings slopes lines similar but intercepts variable among dates positions. best correlations concentrations obtained upper early growing season lower late season. demonstrated be useful tool status, particularly relative comparison purposes, may have efficient application field assessments decision-making operational nutrient management programs species. Accurate prediction % by difficult giving generally medium correlation coefficients.