Competitiveness of tomato (Lycopersicon esculentum Mill.) with weeds at various nitrogen doses and weed free periods

The research objectives were to determine the effect of nitrogen dose and weed-free period on the competitiveness of tomato plants with weeds. The research used 6 x 4 Factorial Randomized Group Design. The first factor was the weed-free period (P) which consisted of six levels, namely weeds during tomato growth (P 0 ), weed-free two weeks after planting (P 1 ), weed-free four weeks after planting. (P 2 ), weed-free six weeks after planting (P 3 ), weed-free eight weeks after planting (P 4 ), and weed free until harvest (P 5 ). The second factor was the dose of nitrogen (N) consisting of 4 levels, namely: without fertilization (N 0 ), fertilizing 50 kg N ha −1 (N 1 ), fertilizing 100 kg N ha −1 (N 2 ) and fertilizing 150 kg N ha −1 (N 3 ). The variable of observation was analyzed univariately using the F test and continued with the (Student-Newman-Keul) SNK test with a test level of 0.05. The plants growth rate weeds were analyzed by regression in the form of a curve as a function of time to see the dynamics of weed growth. The amount of competition between weeds and tomatoes were done through the competition index value approach. The results showed that the was a change in the value of competition between tomato plants with weeds at each level of nitrogen dose and weed-free period, this change decreased with increasing nitrogen dose. The highest yield was obtained when weed-free during tomato growth, namely 25.88 tons ha −1 with a fertilizer dose of 100 kg ha −1 .