Folha viva, como critério de desfolha, para a produção de sementes de azevém anual, com elevado vigor

Abstract

The annual ryegrass (Lolium multiflorum L.) of paramount forage importance in temperate climate areas. Its expressive distribution has a relative contribution to the performance of areas of the crop-livestock integration system. The objective of this study, was to evaluate the effects generated by the interval and momently of defoliation on the production and quality of annual ryegrass seeds – BRS Estações. The maintenance of levels 0, 25 and 50% of the initial height of the plant at the time of defoliation characterized the intensity, while the intervals between defoliations were 2, that is, the necessary for the complete expansion of two and tree sheets. The results showed that higher intensities and shorter intervals between defoliations, allowed higher forage harvests, close to (4.0 ton.ha-1 ) of forage dry mass. Intense and infrequent defoliation resulted in high seed production (1.7 ton.ha-1 ). However, when performed with high frequency, it significantly reduced the weight of a thousand seeds (P<0.001) and disfavored the physiological quality, since higher starch and protein contents (P>0.05) were verified in seeds from plants maintained with 50% of your height after defoliation. When there was lower defoliation intensity, the proportion of leaves in the residue increased by more than twice. The highest levels of starch and protein showed a high correlation with the residue of live leaves and with germination, which demonstrates the marked effect of management on seed performance. The accelerated aging test of seeds was important to distinguish quality levels. In this evaluation, seeds from plants maintained with higher residue after defoliation showed a 26% lower lipid peroxidation rate compared to the higher intensity treatment, followed by greater activity and expression of the antioxidant enzymes SOD, CAT and APX (P< 0.05). Seedlings with superior performance after conducting this vigor test were verified in seeds originating from plants subjected to lower intensity and greater defoliation interval. In general, the adoption of defoliation that favored the maintenance of leaves in the residue allowed obtaining higher quality annual ryegrass seeds. The antioxidant activity after the accelerated aging test showed high potential to determine the quality of annual ryegrass seeds.