Purple nuts edge (Cyperus rotundus L.) is responsible for great losses in crop production areas. Purple nuts edge tubers possess substances with allelopathic effects on certain crops. The aim of this study was to evaluate the physiological quality of lettuce and rocket salad seeds grown on different substrates in the presence of purple nuts edge extract. A completely randomized experimental design was used with a 3×5 factorial scheme (three substrates × five doses of purple nuts edge extract) and four replicates of 50 seeds. The extract was diluted to four different concentrations (25, 50, 75 and 100%), and distilled water was used as a control treatment (0%). Seeds were sown in three different substrates: Germitest paper, sand or soil. The first and second germination count, the total germination and the germination speed index were evaluated. Lettuce germination was affected by the application of purple nuts edge extract to the tested substrates. Lower germination percentages were observed for sand than for the remaining tested substrates. The application of purple nuts edge extract did not affect the evaluated germination parameters for rocket salad seeds. The germination of lettuce and rocket salad seeds was higher with soil as substrate.
Além da dinâmica do N, o SPD também interfere na atividade dos microrganismos do solo, pois os resíduos orgânicos ou palhada são fontes de energia (carbono) e nutrientes para a maioria das populações microbianas do solo, aumentando a atividade biológica e melhorando as relações ecológicas. Este trabalho avaliou a atividade microbiana do solo com diferentes palhadas e épocas de aplicação de nitrogênio. Os tratamentos consistiram em dois tipos de palhadas, Urochloa ruziziensis e Pueraria phaseoloides L. (kudzu), Plantio direto ou incorporado, diferentes épocas de aplicação do adubo nitrogenado, 35% aplicados em pré-semeadura da cultura (crambe) ou 35% aplicado em cobertura e a testemunha sem utilização da palhada, totalizando dez tratamentos. Aos 35 dias após emergência das plantas coletou-se uma amostra de solo de cada vaso, na profundidade de 0-10 cm, para avaliação do Carbono da Biomassa Microbiana do Solo (C-BM), da Respiração Basal do Solo (RBS) e do Quociente metabólico (qCO2). A incorporação de Pueraria phaseoloides e a adubação nitrogenada em cobertura favorecem a atividade microbiana no solo.
Oxyfluorfen is a pre-emergent herbicide applied via soil; however, the soil attributes have not been considered to predict the herbicide doses. This study aimed to evaluate the bioavailability of the oxyfluorfen herbicide in Brazilian Savanna soils with contrasting attributes. The experiment was carried out in a 6 x 8 factorial scheme, with 6 replications. The evaluated factors were soil types [Gleissolo Melânico distrófico - GMd (Typic Humaquept); Latossolo Vermelho ácrico - LVw (Rhodic Acrustox); Latossolo Vermelho distrófico - LVd (Rhodic Haplustox); Neossolo Quartzarênico órtico - RQo (Typic Quartzpsamment); Neossolo Flúvico Tb distrófico - RYbd (Fluventic Dystrustept); and washed sand] and oxyfluorfen doses (0; 360; 480; 720; 1,440; 2,880; 4,320; and 5,760 g a.i. ha-1). The herbicide bioavailability was determined according to the bioassay methodology. The dose that provided 80 % of Cucumis sativum control (C80%) ranged from 9.9 (LVw) to 1,884.4 g a.i. ha-1 (GMd), what can be attributed to the high sorption of the herbicide in the GMd, as observed by the adsorptive rate. The soil texture did not show correlation with the oxyfluorfen bioavailability. In the LVd, which is from the same order and with texture similar to that of the LVw, the C80% was 76 times higher (754.28 g a.i. ha-1). Furthermore, for the RYbd, which is a sandy soil, the C80% was even high (1,256.9 g a.i. ha-1). The cation exchange capacity (CEC) (-0.83**) was the only soil attribute able to predict the herbicide bioavailability. The oxyfluorfen bioavailability is highly dependent on the soil attributes, and, in Brazilian Savanna soils, it can be predicted using the CEC.
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