Influence of Growth Retardants on Growth, Nutrient Content, and Yield of Tomato Plants Grown at Various Fertility Levels1

Abstract

Abstract Tomato transplants were grown at different fertility levels in mixtures of peat moss-turface and peat moss-perlite. Growth retardants, Cycocel and Alar, were applied to young plants when they attained the 3 true leaf stage. Cycocel was more effective in reducing growth than was Alar, regardless of the fertility level. Alar was effective in reducing growth of plants in both growing media. Cycocel treated plants were more drought resistant than were the Alar-treated plants. Plants treated with either Cycocel or Alar were more drought resistant and darker green in color than control plants. Chlorophyll content was measured on Alar-treated and control plants. Alar-treated plants contained more chlorophyll, and their leaves had more palisade cells than plants of the control. Cycocel-treated plants contained more N, P, Ca, and Mg, but less K than the control plants. Alar-treated plants contained more N and P than did the control plants and more K than control plants when grown in peat moss-perlite. In only 1 of 3 experiments did Alar-treated plants contain less Ca than control plants, but the chemical had no effect on the Mg content of the plants’ stems and leaves. A single spray of Alar at 2500 ppm increased yields of early fruits in 1 of 3 experiments. In this experiment, both early fruit number and weight were increased, but the fruits were smaller than those from Cycocel treated and control plants. Growth retardants and fertility rates used in these studies had no effect on total yields, although interactions existed between growth retardants and nutrient rates in their effect on nutrient uptake.