Genótipos de algodoeiro herbáceo (Gossypium hirsutum L. r. latifolium H.) submetidos a estresse hídrico na fase de germinação.

Abstract

With the objective to study the effect of the six levels of the osmotic pressure (0.0; -0.2; -0.4; -0.6; -0.8 and -1.0 MPa), induced by polyethylene glycol 6000, on the germination of the seeds and seedlings' growth often cultivars and lineages of upland cotton (Gossypium hirsutum L. race latifolnim H), was carried out a trial, under controlled conditions laboratory, making use of the Germitest paper as a substract, in a experimental design completely randomized, in a 1 0 x 6 factorial scheme, with four replications, each consisting of 50 seeds for germination and 10 seeds for vigour test. There was effect of water stress, simulated by PEG-6000, on the seeds' germination and on seedlings' vigour. The effect of water stress over the germination and seedlings' vigour, was severe at -0.8 MPa. The cultivars CNPA Précoce 2 and CNPA Précoce 1 were found to be less sensitive on reduced osmotic potentials (-0.6 and -0.8 MPa). both in terms of germination (first, second and "third" counting) and vigour (first counting and rate velocity index of germination test), while LG ROGERS e CNPA 7H were classified as more or less sensitive ones In the seedlings' vigour test, the cultivar CNPA Précoce 2 was found to be the most vigourous under reduced osmotic potentials (-0.4 and -0.8 MPa), in terms of lenght of aenal portion (epycotyl + hypocotyl) and of radicle, well as radicle/aerial portion quocient and free material weight, while the cultivars LG ROGERS. CNPA 7H and CNPA Précoce 1 were more or less sensitive. The lineage CNPA 86-1 ]°5-l was found to be the most sensitive, m the germination and vigour tests. The percentage of detenored seeds declined, but the percentage of seeds not swelled was increased in the major PEG-6000 concentration levels In water stress conditions, radicles tended to be longer than the aerial portion, in the initial phase of the germination of the seeds.