The phytohormones likely to be envolved in growth and protein reserve accumulation in soybean seeds were studied by artificial cultivation of fruits. Explants from soybean fruits with pericarp fully expanded and seeds with 100 mg of fresh mass were cultivated in vitro with naphthalene acetic acid (NAA), gibberelic acid (GA3), benzylad enine (BA) and abscisic acid (ABA) initially alone at 10-7, 10-6, 10-5 and 10(4) mol.L-1 rates. Phytoregulators combinations were determined as a function of greater increments in seeds dry weight. On the basis of previous observations of. GA3 and BA promoted seed development only in high concentrations, while NAA was ineffective and ABA inhibited seed growth. When applied concurrently with GA3 or BA, the NAA stimulated seed growth, suggesting that interactions may occur among them. NAA and BA alone or combined induced increase in seed protein content but ABA inhibited the protein accumulation. The artificial cultivation system employed in this assay has been shown to be suitable for studies of growth and protein accumulation in soybean seeds.
explants; gibberelic acid; phytoregulators
