Physiological Action of Ethylene in Crop Plants : IV. Effect of ethylene application to roots on the growth of tomato and soybean plants

Abstract

This investigation was carried out to determine the effect of ethylene in soil on growth of tomato and soybean plants. These plants were grown by fog culture system and the roots were exposed to 1 to 10 ppm of ethylene for a week. The results obtained are summarized as follows: 1. When roots were exposed to ethylene, the root elongation was greatly inhibited but the dry weight of roots increased in both tomato and soybean plants. 2. Shoot growth in tomato plants was inhibited when roots were exposed to ethylene. In soybean the dry weight of shoots increased with 1 to 10 ppm ethylene application to roots and stem elongation was promoted when roots were exposed to 1 ppm of ethylene. 3. Ethylene application caused a brownish discoloration of the roots. The root apices were swollen and curled. Ethylene also stimulated development of root hairs in tomato and secondary branched roots in soybean. 4. When roots were exposed to ethylene, the oxidizing activity of α-naphthylamine by roots decreased significantly in tomato, but showed a marked increase in soybean. 5. These results suggest that the low concentration of ethylene in the soil atmosphere affected the development and growth of roots as well as the growth of shoots in field.