Weed management in watermelon crop in no-tillage and conventional systems

We evaluated strategies for weed management on the production of watermelon in no-tillage and conventional systems, in successive cultivation to the melon crop. The research was carried out in split plots, distributed in the experimental design of randomized blocks. Two cropping systems were evaluated in the plots (no-tillage and conventional tillage) and in the sub-plots were evaluated nine strategies of weed management [covered with polyethylene film, with weeding at 14 days after transplanting (DAT); 14 and 28 DAT, 14 and 42 DAT; 14, 28 and 42 DAT; 28 DAT, 28 and 42 DAT; 42 DAT and control without weeding]. Before the implantation of the experiment, the area was cultivated with melon in the respective cropping systems, the straw mulch being used again in the treatments with no-tillage system, as well as polyethylene film in the treatments with use of this material in two cropping systems. At 14, 28 and 42 DAT and at harvest of watermelon (80 DAT), were assessed the density and dry mass of weeds. The weeds were cut at ground level, separated by species, counted and put into oven with forced air at 65 C until constant weight to determine dry mass. From the watermelon crop were evaluated the number of marketable fruits, total number of fruits, average mass of marketable fruits per plant and average fruit mass (total) per plant and marketable and total yield. The no-tillage system reduced the density and dry mass of weeds, requiring only one weeding between 14 and 42 DAT, whereas in the conventional tillage system two weedings were needed, at 14 and 28 DAT. When the crop was maintained without weeding throughout the cycle, there was a reduction of 100 and 35.7% in marketable fruit yields in conventional and no-tillage systems, respectively. The no-tillage and polyethylene film in conventional tillage system enabled the cultivation of watermelon in succession to the melon crop, reducing weed interference and providing satisfactory productivity.