Desenvolvimento e produtividade de batata-doce cultivada sobre diferentes coberturas de solo e intensidades de capinas

Abstract

The sweet potato crop (Ipomoea batatas) which belongs to the Convolvulacae family presents an elevated relevancy to the family agriculture, because in this context, it is used to feed animals and humans. One of the factors that limit the production of the sweet potatoes crop is the competition held by the weeds, manly if considered the fact that sweet potato crops present a low competitive ability, which results in the necessity of an intensive control of such species. With that in mind, a test was conducted with the objective of measuring the effect of the competition between the weeds and the sweet potatoes crop in different tillage systems. A field work was conducted, during the agricultural years of 2017/18. The experimental design used was Random Blocks with four repetitions of the experiment. The crops were allocated in a factorial scheme of 5 x 4. The first factor was composed of different managements of soil coverage: conventional tilling; minimum cultivation with grey Mucuna (Mucuna pruriens), sudan grass (Sorghum sudanese); intercrops (grey mucuna + sudan grass) and fallow. The second factor was constituted by different intervals in the weeds control, in this case, it was: control after 20 days after the planting of the branches (DAP); control at 15, 30 and 45 DAP; including a reference without weeding in which the crops remained in competition during the whole cycle and one reference without the weed competition. The variables quantified in the period of growth were: length and the number of branches and cover crops. During the 135 DAP harvest, the following criteria was evaluated: lenght and number of branches, dry mass of the vines; harvest index; plant population; number of roots, commercial and noncommercial, number of roots per plant (total, commercial and non-commercial), productivity of the all the roots, commercial and non-commercial. The data was submitted to a homoscedasticity test and when the results were significant enough they were transformed with the x+a equation, posteriorly the data was submited to a variance analysis and, when meaningful enough, they were compared using the Turkey test at a 5% probability rate. The longer the sweet potatoes crop remained in competition with the weeds, the bigger were the damages caused to the crop, with a decrease in every variable studied. When three weedings were effected or the crops remained weed free, a good and healthy growth was observed. Regarding the different planting systems, it was noted that the minimum cropping system with grey mucuna coverage and the conventional tilling show similar results in the variables studied, revealing that when in comparison with the other systems these ones were more efficient, and if less weedings were made, the results were better. Regarding the commercial productivity, the minimum cropping system with grey mucuna coverage presented more roots. When the sweet potato crop remains in competition with the weed for long periods of time, its growth and productivity end up compromised. When the sweet potato crop is cultivated with conventional tilling or minimum cropping after the coverage with grey mucuna has been done, and when weedings are done, there is a raise in growth and productivity of the sweet potato crop