Fungicidas foliares : influência sobre a qualidade de grãos de soja intacta

Abstract

In the light of the climatic conditions (tropical and sub-tropical) has been registered in Brazil, each season, high indexes of diseases caused by microrganisms. Of these, the fungal are the most limiting for the productive system of soybean. The chemical control is the measure of control more used, however the insertion of new materials, these being more resistant, facilitates and provides the obtaining of better quality grain. The present study had the objective to evaluate qualitative aspects of soybeans (Intact), of different cultivars, in function of the application of fungicides. The experiment was conducted in the northern region of Mato Grosso, municipality of Sinop in the harvest of 2014/2015. The experimental design was in randomized blocks, with three repetitions and factorial scheme 5 x 8, being 5 systems of fungicides and 8 soybean cultivars intact (IPRO). Were Used 5 (five) systems of chemical products: T1 (Protioconazol + Trifloxystrobin); T2 (Azoxystrobin + Benzovindiflupir); T3 (Picoxystrobin + Cyproconazole); T4 (Fluxapiroxade + Pyraclostrobin); T5 (Azoxystrobin + Cyproconazole). The post-harvest parameters evaluated were: specific mass apparent, mass of 1.000 grains, and incidence of fungi, besides properties related to the size and shape of the grain. The data were submitted to analysis of variance and the F test (p<0.05). When observed effect of treatments, the averages were compared by the Tukey test at 5% probability. The results of bulk density, true density, and mass of thousand grains presented values higher than those found in the region, indicating that the crop was propitious for grain production of good quality. The variety M7739 presented the highest values for those properties. The treatments that stood out, with consequent better physical quality of the grains were T1, T4 and T5, in this order. For the characteristics related to size and form of the grain, there were no statistical differences for the majority of varieties. Soybean plants subjected to T5 presented better results in size and shape of the grains. The fungi identified were Fusarium, Aspergillus, Penicillium, Rhizopus, Colletotrichum, Phomopsis and Macrophomina. The results for Phomopsis e Macrophomina were irrelevant when compared to others. The incidence of Fusarium presented higher values to 80% in almost all samples. The treatments that inhibited the incidence of most fungi were the T1 (Protioconazol + Trifloxystrobin) and T3 (Picoxystrobin + Cyproconazole).