RESUMO Physalis angulata é uma Solanaceae, que produz frutos de alto valor comercial. A interferência de plantas daninhas no cultivo dessa espécie é um dos principais fatores limitantes e não há herbicidas registrados. O objetivo deste estudo foi avaliar a seletividade de herbicidas e o uso de adjuvantes no cultivo de P. angulata. Foram conduzidos três experimentos: dois em vasos, avaliando a seletividade dos herbicidas fluazifop-p-butílico, metribuzim, fomesafem+fluazifop-p-butílico, trifluralina e cletodim; e um a campo, com os herbicidas mais seletivos dos ensaios anteriores. Em vaso, foram realizadas avaliações visuais de fitotoxicidade, além da altura das plantas, diâmetro do caule e teor de clorofila, a cada 7 dias, até os 42 dias após aplicação. Ao término dos três experimentos, além dessas características, foram avaliados a área foliar, número de frutos e massa seca de folhas, caule e frutos. Os herbicidas clethodim sem adjuvante e fluazifop-p-butil são seletivos para P. angulata. Em condições de campo, a aplicação de fluazifop-p-butil + fomesafen não afetou negativamente a produtividade e o crescimento da cultura, sendo seletivo a P. angulata. O metribuzin não demonstrou potencial para ser utilizado nesta cultura.

ABSTRACT Physalis angulata is a Solanaceae that produces fruits with a high commercial value. The interference of weeds in the cultivation of this species is one of the main factors limiting its growth. There are no herbicides registered for this crop in Brazil. Thus, the objective of this study was to evaluate the selectivity of herbicides and the use of adjuvants for the cultivation of P. angulata. We conducted three experiments: two in pots, evaluating the selectivity of the herbicides fluazifop-p-butyl, metribuzin, fomesafen + fluazifop-p-butyl, trifluralin and clethodim; and one in field conditions using the most selective herbicides from previous experiments. In the pots, we performed assessments of phytotoxicity, height, stem diameter, and total chlorophyll content every seven days up to 42 days after application. At the end of the three experiments, we evaluated leaf area, number of fruits, and dry matter of leaves, stems, and fruits. The herbicides clethodim without adjuvant and fluazifop-p-butyl are selective for P. angulata crop. Under field conditions, the application of fluazifop-p-butyl + fomesafen did not negatively affect crop production and growth, being selective to P. angulata. Metribuzin do not have the potential to be used for this crop.

Abstract Background Recent studies have demonstrated an increase in plant growth due to the application of low doses of glyphosate, which is part of the phenomenon known as hormesis . Objective The present study aimed to evaluate the effects of glyphosate doses on the physiological and morphological parameters of Panicum maximum cv. Mombaça. Methods The experiment was carried out in a greenhouse for 49 days after the application of glyphosate, in pots arranged in a completely randomized design, with four replications. The treatments consisted of ten doses of glyphosate (0; 3.78; 8.10; 16.64; 33.48; 67.7; 135; 270; 540 and 1,080 g a.e. ha-1). Evaluations of growth, gas exchange, leaf temperature and plants’ intoxication were carried out. The data were subjected to ANOVA and when significant, regression analysis was performed using the models for dose-response curves. Results The physiological parameters, as well as the growth, were positively affected by the subdoses of glyphosate, with higher values than the control. The leaf temperature increased progressively according to the increase in doses. Conclusion Subdoses of 3.78 to 270 g a.e. ha-1 of glyphosate promoted an increase in plant’s growth and physiological parameters.

Abstract The new technology of sugarcane planting, known as one-eye-set seedlings, offer a high standard of plant health and vegetative vigor. However, there are no reports in the literature that evaluate the weed competition with one-eye-set sugarcane seedlings, and the periods in which weed communities need to be controlled in this system. Two interference experiments were conducted in field conditions. The first experiment determined the periods of weed interference of an infesting community predominated by Ipomoea hederifolia and Merremia aegyptia in sugarcane. In the second experiment, these same species competed with plants of the same sugarcane cultivar. Productivity and qualitative aspects of production were evaluated. The critical period of interference prevention in one-eye-set sugarcane system was 103 days, with weed community interference starting at 35 days and lasting until 138 days after planting. Weed coexistence during the entire sugarcane cycle reduced productivity by 60% and affected qualitative characteristics such as the total reducing sugars. Both species affected the vegetative development of the crop, mainly the tillering. I. hederifolia plants developed ahead of the M. aegyptia plants but in late evaluations the interference caused by M. aegyptia (77%) was greater (P<0.01) than that caused by I. hederifolia (72%).