Ensaio comparativo com duas soluções cáusticas minerais alternativas aos herbicidas agrotóxicos na dessecação da cultura do feijão (Phaseolus vulgaris L.)

Abstract

The use of desiccants has become common in the management of annual crops such as beans (Phaseolus vulgaris L.) in order to facilitate harvesting by eliminating green plant material and anticipating the drilling of another crop, such as wheat, soybean or maize. The present work evaluated potential alternative methods for desiccation using Lime Sulphur and Bleach Sulphur sprays, in comparison with the herbicide Glufosinate-Ammonium (Finale®) and a water control. The work was carried out from February 7 to 13, 2023 at Mr. Dalmir Baú’s family farm, located in the Tortelli Line Community, Municipality of Coronel Vivida – PR. The preparation of the sulphur mixtures and the application of the treatments in 24 plots of 50 m2 in a Complete randomized design was carried out on 07/02/2023 between 14 and 15 hours to take advantage of the drier and sunnier period. The follow-up with photos of the results of the desiccation was done until 02/10/2023, besides evaluating grain yields, as well as Destructive Growth Analyses of samples in the laboratory to determine moisture and dry matter content of bean plants and weeds. Although both sulphur sprays did not have a significant desiccant effect in relation to the control, they significantly increased grain yield in relation to the water control and the positive control with Glufosinate Ammonium, with Bleach Sulphur significantly surpassing Lime Sulphur in bean yields – which can be attributed to a late leaf nutritional effect on bean physiology that was confirmed by the apparent vegetative recovery of the plants, even at the end of their growth cycle. Glufosinate-Ammonium had the best desiccant effect, reflected in the significantly higher dry matter contents (equivalent to the lowest moisture contents) of the bean and weed plants in relation to the other treatments. The Lime Sulphur resulted in significantly higher dry matter contents of the aerial part of the bean trees in relation to the Bleach Sulphur and control sprays. The observed effects of sulphur based sprays on productivity, vegetative recovery and dry matter content of the aerial part of the bean plants deserve experimentation and more detailed studies for their confirmation and explanation in terms of plant physiology.