MEASURING THE EFFECT OF AN ABIOTIC STRESS ON COMPETITION

Using recently developed solution culture techniques, the effect of a non-resource abiotic stress, nickel toxicity, was tested on intraspeci fic nutrient competition among wheat. The choice of an appropriate sta tistical model was of paramount importance in interpreting these effec ts. We argue that a multiplicative model is more appropriate for exper iments on interactions of competition and abiotic stress. By such an a nalysis, nickel had no relative effect on the ability of competition t o reduce plant size in two experiments, and caused a small reduction i n competition in another. These results are contrary to other reports of the effect of a non-resource abiotic stress on competition and appe ar to be due to an increased demand for nutrients in the presence of t oxic levels of nickel. The effects of an abiotic stress on competition may thus be specific to the stress and not generalized across all abi otic stresses.