GROWTH ANALYSIS AND GRAIN YIELD BY SOYBEAN CANOPY STRATUM IN RESPONSE TO PLANT ARRANGEMENT

Abstract

Plant arrangement that allow better plant distribuition in the area improve plant growth, resulting in larger grain yield. The experiment was performed at the Agronomic Experimental Station of the Universidade Federal do Rio Grande do Sul, in Eldorado do Sul, Rio Grande do Sul, Brazil, in the 2000/01 growing season. The objectives were to evaluate the soybean growth by canopy stratum in response to plant arrangemnt and the effect in grain yield. The cultivar tested was 'BRS 137', in no-till planting. The treatments were arranged in a split-splitplot randomized complete-block design, with four replications. Water availability (with and without irrigation), row spacing (20 and 40 cm) and population leveis (20, 30 and 40 plants/m 2) were tested. Growth atributes (leaf area index and dry matter), grain yield, by soybean canopy stratum, were determined in samples of ten plants, in sequence in the row, in each sub-subplot. Grain yield was incresead by irrigation and was detected interaction between row spacing and plant population. The plant arrangement of 20 cm row spacing and population of 20 plants/m 2 resulted in greater grain yield. There was a linear decrease in grain yield with the increase in population, with row spacing (20 cm) reduction. The same was also noticed at the medium and botom canopy stratum. These results were consequence of the higher leaf area index and dry matter obtained in the soybean vegetative period, mainly in the medium and botom canopy stratum.