Germinação, emergência da plântula, produtividade e qualidade da fibra de Gossypium hirsutum L. CV. DP 660 sob ação de bioestimulante

Abstract

Cotton is the most important vegetable fiber for man who uses it as a raw material in the production of tissues which has intrinsic qualities unequaled to in other fibers. For this reason, the viability of the seed has been receiving special attention, since its quality is demonstrated in the subsequent cultures, in terms of uniformity, greater performance of plants and, consequently, greater productivity. The objective of this work was to quantify the effects and establish the appropriate concentrations of the Stimulate® bio-stimulant applied to seed or leaf, in the agronomic characteristics of field and laboratory and in the fiber properties cv. DP 660. The maternal effect was also evaluated in seeds deriving from parent plants which were cultivated under the effect of the same bio-stimulant. The field experiment was carried out on the experimental farm of the D&PL Brasil Ltda. in Uberlândia-MG, from January to July of 2007. The experimental design used was a completely randomized, with five treatments and four replications, including control (1); 15 (2) and 20 mL kg-1 in seed treatment (3); 15 mL kg-1 in seed treatment and 300 mL ha-1 in leaf spraying (4); 20 mL kg-1 in seed treatment and 300 mL ha-1 in leaf spraying (5). The germination experiments were carried out at the Ecophysiology Plant Laboratory of the Universidade Federal de Uberlândia, being installed in germination chamber between 25.5 and 26.0 ºC. The emergence experiments were installed in greenhouse covered with 50% light reducing screen, between 17.9 and 29.3 ºC. Data were collected every 24 hours; the protrusion of the embryo being observed for the experiments set up in the laboratory and the emergency of any part of the seedling above the substratum for the experiments maintained in greenhouse. The germination and emergence experiments were divided into two groups, the first being carried out with seeds originating from parent plants treated with biostimulant and the second group made with seeds treated directly with bio-stimulant. The seeds treated directly with the bio-stimulant were maintained in control (1) and with Stimulate® at doses of 15 (2), 20 (3), 25 (4) and 30 mL kg-1 seed (5). The bio-stimulant as seed treatment and leaf application did not alter the agronomic characteristics of field, nor did it alter the fiber properties significantly. The seeds produced by parent plant treated with bio-stimulant presented higher emergency percentage (96.87 ≤ E ≤ 100%), in relation to control treatment (94.53%), indicating that bio-stimulant application can benefit seed production fields. For the other characteristics evaluated significant differences were not detected among treatments.