Desempenho forrageiro de cultivares de azevém diploides e tetraploides na região da fronteira oeste do Rio Grande do Sul

Abstract

Italian ryegrass is one of the most used winter forages in the southern Brazil, due to its high performance of forage production and nutritional quality. The objective of this study was to evaluate the total dry matter yield and morphological composition of annual ryegrass diploid and tetraploid cultivars in the RS region. The experiment was conducted in the experimental area of the Federal University of Pampa, Campus Itaqui - RS, between April and December 2017. The climate of the region is Cfa, subtropical without dry season defined according to Koppen climate classification and the soil classified as Plintossolo Háplico.. The experimental design was a randomized block design with four replications, using 4.25 m² plots with five rows. The genotypes observed were three diploid cultivars (Le 284, BRS Ponteio and Camaro) and five tetraploids (Winter Star, Escorpio, Barjumbo, Bar HQ and Potro). The evaluations consisted of cuts of the three central lines, realized when the canopy of the plant reached 20 cm of height, leaving a residue of 10 cm. The variables studied were total dry matter yield (kg DM ha-¹), dry matter production by cuttings (kg DM ha-¹), leaf (%), stem (%), inflorescence participation, and dead material participation (%). 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 materials tested for total dry matter production, with the cultivar BRS Ponteio presenting the highest average. The variables of leaves, stem and inflorescence, presented significance for the interactions between cultivars; already for dead matter there was no significant effect among the cultivars and cuts. The cultivar BRS Ponteio was superior in total dry matter yield, however, the Bar HQ stood out presenting a higher proportion of leafs, evidencing its better nutritional quality. In general, the diploid genotypes were superior to the tetraploids in relation to the production, but not superior in nutritional quality.