ABSTRACT
The objective of this work was to study the effect of six levels of osmotic potential (0, -0.2, -0.4, -0.6, -0.8 and -1MPa), induced by polyetilene glycol 6000 (PEG-6000), on the vigour of seed germination of ten bean cultivars (Phaseolus vulgaris, L.). The experiment was conducted in laboratory under controlled conditions of temperature and humidity, using paper towels as a substract. The experimental design was completely randomized in a 10 x 6 factorial scheme with four replications each consisting of 10 seeds. The growth of radicle and hypocotyl as well as the radicle/hypocotyl relation were evaluated. The measurement of seedlings was made in all cultivars, for each level of PEG-6000, when one of ten cultivars reached the 80% germination or after 20 days elapsed from the beginning of the test, with seedling showing the hypocotyl and the radicle well differentiated, with a minimum length of 0.5cm. The results obtained have shown that there was influence of PEG-6000 on the seedlings' vigour. 'Diamante Negro' was found to be the most vigourous cultivar under reduced osmotic potential (-0.4MPa and -0.6 MPa), while 'Safira' was the most sensitive one. In water stress conditions radicles tended to be longer than the hypocotyl, and the less tolerant genotypes developed higher radicle/hypocotyl relations.
Key words:
PEG-6000; osmotic potential; radicle/hypocotyl relation; seed