Joint action of particulate fall-out nickel and rooting medium nickel on soybean plants

A factorial experiment in a controlled environment with four levels of particulate nickel and four levels of rooting medium nickel was used to obtain response surfaces describing the effects of these sources of nickel on growth and on stem nickel content of soybean plants. Covariate measurements were used to increase precision. The response surfaces were displayed as contour plots to aid in the interpretation of joint action of the two sources. Both particulate and rooting medium nickel decreased plant growth and there was generally additive joint action when the sources were combined. Growth response patterns differed among leaves, stems and roots and the two sources differed in their effect on specific leaf weights and shoot/root weight ratios. Tissue dry matter concentration was altered in both stems and roots. Stem tissue accumulation of nickel was mainly affected by the particulate concentration.