Densidade de semeadura e desempenho produtivo de cultivares de arroz na fronteira oeste - RS

Abstract

Rice is one of the most economically important crops for the western border of Rio Grande do Sul, with rice farmers who adopt advanced technologies and that they are high grain yields. However, some cultural practices developed at present are not yet implemented by the fear on the part of technicians and rice farmers. Among the various practices that can be changed is the traditional planting density, for smaller quantities. Depending on the development of modern cultivars do not have the need to sow seeds of high densities to obtain productive plantations and uniform stand. It is known that populations in high intra-specific competition occurs and thereby reduce the yield. The research objective is to work, to study the performance of rice varieties in West Border of Rio Grande do Sul under different plant densities. The experiment was conducted in a randomized block design with four replications, the treatments being represented by the varieties of rice IRGA 409, and OLIMAR PUIT INTA - CL seeding density and the same with 40, 60, 80 and 100 kg ha-¹. The variables were numbers: tiller, panicle, grains per panicle, grain sterile, filled grains per panicle and yield. Each cultivar behaved similarly over the variables, except that the IRGA 409 was influenced negatively by reducing the seeding rate. Cultivar PuitaInta-CL had a higher number of filled grains per panicle, total grains per panicle, panicle number per area and yield, regardless of seeding rate tested. The increase of planting density negatively affected all variables studied, except for grain yield shows that a quadratic, where the maximum point was reached with 75 kg ha-¹ seed for the cultivars and OlimarPuita INTA-CL. Among the tested cultivars IRGA 409 was the most affected by the reduction of plant density, sowing is not recommending the same in density of less than 100 kg ha-¹. Lower seeding rates can be recommended for the West Border of Rio Grande do Sul, but for some rice cultivars and where there are favorable growing conditions.