The chemical composition of foliage as an index of nutritional status in red pine (Pinus resinosa Ait)

Abstract

Near terminal foliage was sampled from 26 young, open-grown trees in each of three red pine plots on a potassium deficient site. The plots were respectively control, trees fertilized with potassium in the nursery and trees fertilized with potassium in the field. Multiple regressions relating tree height and leader length to foliar concentrations of sodium, potassium, calcium, magnesium, manganese, phosphorus, nitrogen, and silica were calculated to test Leyton's hypothesis that only deficient nutrients would be significantly related to growth in such equation. The hypothesis was supported by the pooled data and by the data from the trees fertilized in the nursery but not from the other two plots. The different elements were interrelated in the leaves so that results of multiple regression analyses were strongly influenced both by the combination of regressor variables used as well as by which one of a number of interrelated growth measurements was used as dependent variable. The closeness of correlation between variables and the chances of incorrect predictions appear to increase with severity of deficiency. However it was possible to relate leader length to foliar potassium in all three plots by one second-order polynomial regression which accounted for 66 per cent of the observed variation in leader length. The data confirmed the conclusion of Stoneet al. that excellent growth of red pine is possible when there is 450 mg/100 g of potassium in current-year red pine needles. Variations of some other factor which may be either external (site) or internal (genetic) is believed to be contributing to the variations in leader growth on this site.