The stimulatory effects of 2,4-D as hormetic on maize seedling's growth

Abstract

The 2,4-D was applied as hormetic, to increase germination ability and growth of seedlings originated from 19 maize inbred lines seeds (germination between 2 and 97%). The seeds were soaked in solution of 2,4-D, diluted to hormetic concentration. After germination capacity was determined, normal seedlings were fractionated into: root, shoot and seed rest, in order to establish fresh and dry weights and volume of free water in them. Sum of hydrolysis, biosynthesis and free energy were calculated. Increased germination percentage, by 2,4-D was not linear for all germination values, meaning that germination was more than doubled in seeds with initial germination below 10%. On the other hand, germination increase was only 2% in seeds with initial germination over 90%. Additionally, fresh weight of root and shoot increased up to 90 and 49%, respectively as consequence of promoted hydrolysis and biosynthesis. The high values of free energy (> +7 KJ) in control seedlings indicated that potential energy was spent, thus lowering growth and biosynthesis levels. The 2,4-D treated seedlings, with potential energy about +/- 0.1 KJ point out that processes in seedling are spontaneous, i.e. are oscillating about equilibrium, enabling more efficient utilization of seed substance, affirmed by elevated biosynthesis and growth.