Influence of calcium on vegetative and reproductive development of Pelargonium

Abstract

Cloned stem cuttings of geranium (Pelargonium peltatum) were maintained in control and mineral deficient solutions for five weeks. Hydroponic solutions were formulated to be deficient in a single mineral; e.g., ‐Ca, ‐Fe, ‐Mg, ‐N, and ‐P. Positive control solutions contained all macro and micronutrients, while negative controls consisted of double distilled water. Weights and numbers of all organs of the shoot were determined, as was an analysis of adventitious roots. Plants grown in ‐Ca solutions characteristically manifested reduced organ weights and numbers as compared to plants grown in other mineral deficiencies and both controls. Examples of reduced values recorded in ‐Ca plants, as compared to the negative control plants, were: (i) a 60% decrease in overall plant weight, (ii) a 40% reduction in the total weight of leaves per plant, (iii) a 50% reduction in stem weight, (iv) a 60% drop in the weight of the stem base and associated adventitious roots, (v) a 30% decline in inflorescence weight, (vi) a 20% reduction in the number of leaves produced per plant, and (vii) a 20% decrease in the weight of individual leaves. Perhaps the most striking developmental distinction was the absence of adventitious roots in ‐Ca plants. Cuttings in distilled water produced an average of nearly 30 roots near the stem base. Anatomical examination of stem bases from plants grown in Ca‐deficient nutrient solutions revealed a few initiated roots in only one instance, but all roots were poorly developed and few in number. Most stem bases in ‐Ca did not have any initiated root primordia. It is believed that Ca has the capability of ameliorating mineral toxicity induced by other elements in the nutrient solution.