Initial Development of Sunflower (Helianthus annuus L.) under Weed Competition with Different Species of Grasses

Abstract

Introduction: All cultivated plants are subject to intra and interspecific grass competition, once this competition may gradually increase within the crop cycle. Objective: In view of the above, this work aims to evaluate the initial development of sunflower, when submitted to competition with different species of grasses. Material and Methods: A randomized block design was installed in a 2x4 factorial scheme, with two grass species, Urochloa decumbens cv. Basilisk and Panicum maximum cv. Mombasa, with four densities of competition with grasses, plus a control group (absence of grass) and four replications, total of 36 plots. Results and Discussion: During the sowing of the grasses, the following densities were considered: low; average; high and very high density of competition. While there was an increase in density of competition, sunflower development was impaired. Conclusion: The initial development of sunflower was impaired, with a yield of 49.06 cm2 for each weed and Panicum maximum species caused greater damage to the crop. The aerial part and the sunflower stomata were compromised.