Presowing Bioregulator Seed Treatments Increase the Seedling Growth and Yield of Tomato (Solanum lycopersicon)

The bioregulators indole acetic acid (IAA), indole butyric acid (IBA), and naphthalene acetic acid (NAA) were investigated for their effects on seedling growth and yield of tomato (Solanum lycopersicon). Seeds of tomato genotypes NHLy11, NHLy12, NHLy13, NHLy15 and NHLy16 were subjected to presowing treatments in 25-, 50-, 75-, 100-, 125-, and 150-mg/l concentrations of each of the bioregulators and control replicated three times in a completely randomized design. Results revealed that IAA and IBA significantly retard (P < 0.05) the growth of radicles and hypocotyls of all test genotypes relative to controls, especially at the high concentrations of 125- and 150-mg/l solutions of the bioregulators. NAA treatments enhanced seedling growth moderately at concentrations up to 100 mg/l. At 125- and 150-mg/l concentrations, the seedlings showed reduced radicle and hypocotyl lengths compared with those of controls. All treated genotypes had higher average fruit weight and mean fruit yield than controls at the 100-mg/l concentration of the bioregulators. IAA had the highest yield of 25,900 kg fw ha(-1) in the NHLy12 genotype, whereas the lowest yield of 3,760 kg fw ha(-1) was obtained in the IBA-treated NHLy16 genotype. This study showed that presowing seed treatments with IAA, IBA, and NAA were effective in enhancing seedling growth and yield in tomato, especially at the 100-mg/l concentration.