Plants populations and nitrogen doses on Macaquinho taro rhizomes yield

The experimental work was carried out in Dourados-MS, between August 30(th), 2001, and April 26(th), 2002, in a Dystrorthox Soil, clay texture. The objective was to evaluate the effects of plants populations and nitrogen doses upon yield of aerial part and rhizome fresh masses of Macaquinho taro clone. The treatments were arranged as 3 (80,000; 100,000 and 120,000 plants ha(-1)) x 3 (0; 45 and 90 k ha(-1) of nitrogen - N, utilized in urea form) factorial scheme, in a experimental randomized blocks design, with four replications. Harvest was done at 208 days after planting when total yield of leave, corm and cormel fresh masses, including classification in big (bigger than 40 g), medium (25 a 40 g) and small (smaller than 25 g) classes, besides of income calculation. Yields of leave, corm (RM) and cormel (RF) were not influenced by populations and N doses interaction. Yields of RM and total of RF were influenced by populations, and the highest yields occurred under populations of 120,000 plants ha(-1) (10.39 t ha(-1) of RM and 53.56 t ha(-1) of RF) and the smallest yields under 80,000 plants ha(-1) (7.58 t ha(-1) of RM and 38.00 t ha(-1) of RF). In yields of RF from different classes were detected significative influences of populations for big and medium RF and N doses for small RF. To consider yield of commercial rhizomes (RF of big and medium classes) and cutting costs, populations of 120,000 plants ha(-1) could have increased net income in 12.77% and 42.00% in relation to populations of 100,000 and 80,000 plants ha(-1), respectively. It was concluded that the highest yield of commercial rhizomes and the greatest income of Macaquinho taro was with 120,000 plants ha(-1), independent nitrogen dose studied.