Deficiência hídrica: estudo de agentes osmóticos e tamanho de sementes

Abstract

The germination decreasing as a water deficit function is a wide spread occurrence in agricultural systems. This assay was divided in two steps. Firstly, the actions of different osmotic in the simulation of water deficit during germination were tested determining what is the most efficient. The second part was done using mannitol to determine the effect of water deficit in soybean of different sizes. In the first navy bean seeds cv 'IAC-Carioca-80-SH' were germinated at different water deficit potentials (zero; -0.6; -1.2 and 1.8 MPa) of mannitol, CaCl2, KCl and NaCl. In the second soybean seeds cv 'IAC-18' classified in sizes 12 and 13 and 'IAC-22' in 12, 13 and 14 were germinated in mannitol solutions with the same potentials used in the first. Experiment were carried out as completely random with four repetitions per treatment. The treatment evaluation was done by germination, first germination counting , vigour classification, hypocotil and shoot length and by shoot and root dry weight. The results showed that KCl and NaCl solutions had also the toxicity effect on the seeds, and they were not recommended as water deficit simulators. In relation to seed size, in higher water deficits the germination was bigger in larger seeds. Germination was less affected in both experiments then the seedling development in the different water potentials.