Cultivares diploides e tetraploides de azevém anual em terras baixas da fronteira oeste do RS

Abstract

The annual ryegrass is one of the grasses that stands out most in the southern region of the country, due to its characteristics of high forage production and nutritional quality. The objective of this study was to evaluate the total dry matter yield and nutritional quality of diploid and tetraploid annual ryegrass cultivars on the western border of RS. The experiment was conducted between May and November 2016, in the experimental area of the Federal University of the Pampa, Itaqui - RS Campus. The climate of the region is subtropical without dry season defined according to the climatic classification of Koppen and the soil of the place of study is classified as Plintossolo Háplico. The genotypes evaluated were three diploid cultivars (Le 284, BRS Ponteio and Camaro) and five tetraploids (Winter Star, Scorpio, Barjumbo, Bar HQ and Foal). The experimental design was a randomized block design, with four replications, using 4.25 m² plots with five central lines. The evaluations consisted of cuts made when the plants reached 20 cm in height, leaving a residue of 10 cm. (%). The studied variables were dry matter concentration (%), crude protein (%), mineral matter (%), neutral detergent fiber (FDN, %) and acid detergent fiber (FDA, %). Data were submitted to analysis of variance and comparison of means by Tukey test at 5% of error probability. There was a difference (P <0.05) between the tested materials and the total dry matter yield, with the Potro cultivar presenting the highest average. The variables of leaves, dry matter content and crude protein presented significance for the interactions between cultivars and number of cuts; already for mineral matter there was a significant effect among the cultivars and cuts, and for NDF there was a significant effect for the number of cuts. The foal cultivar was superior in total dry matter yield, however, the Barjumbo ryegrass stood out presenting a higher proportion of leaves and crude protein, evidencing its better nutritional quality. In general, the tetraploid cultivars were superior to the diploid cultivars.