Inocencio Junior de Oliveira

Mungbean (Vigna radiata L.) is a Fabaceae species cultivated in several regions in Brazil. In Tocantins state, however, the few cultivars available are not indicated for the region, making it essential to select and subsequently recommend new cultivars. This study aimed to assess the agronomic potential and genetic divergence of mungbean lines to support the development of cultivars adapted to tropical floodplain conditions in Tocantins. Two trials were conducted in a randomized block design with four replications under tropical floodplain conditions, in the municipalities of Lagoa da Confusão and Formoso do Araguaia, Tocantins, Brazil. A total of 18 mungbean lines and two cultivars were studied. Were evaluated pod weight, pod length, number of grains per pod, 100-grain weight, grain yield, and grain index. Lines BRA-O84883 and BRA-O84654-1, with grain yields of 1,415.4 and 1,408.8 kg ha^–¹, respectively, exhibited high productivity, good results for the number of grains per pod and grain index, and were quite similar. Grain yield contributed most to genetic dissimilarity between the lines, with BRA-084638 and BRA-084794 the most divergent. To generate high genetic variability in segregating populations for future selection, it is recommended that crosses between lines BRA-084654-1 and BRA-O84883 and the cultivars BRS Esperança and BRS MG Camaleão, which combine genetic divergence and high grain yield, be part of mungbean breeding for cultivation in tropical floodplains in Tocantins, Brazil.

In this study, the effect of nitrogen fertilization and seeding density on the Area Under Disease Progress Curve (AUDPC) of rice blast disease was evaluated in irrigated areas with varying levels of organic matter. The experiment was conducted in two regions of Tocantins, Brazil (2022-2023), using a randomized block design (RBD) in a factorial arrangement of 5 nitrogen doses (DN) (Urea 45%, applied topically at rates of 0 (control), 19, 59, 100, 150 kg N ha-1) × 4 seed densities (DS) (50, 75, 100, 125 kg ha-1) × 2 cultivars (BRS A704 and BRS A706 CL), with 4 replications. Additionally, 230 kg ha-1 of 05-25-15 NPK fertilizer was applied at seeding. In the field, disease progress on leaves and panicles was monitored, while in the laboratory, panicle count and rice yield were recorded. The AUDPC results from the experimental areas revealed that in Formoso do Araguaia (FMA), nitrogen doses above 100 kg N ha-1 and in Lagoa da Confusão (LdaC), starting from 59 kg N ha-1, along with seed densities above 75 kg ha-1, significantly influenced the progression of rice blast disease. It is concluded that nitrogen excess, coupled with local climatic conditions, played a crucial role in disease intensity in rice.

Cassava is grown on the floodplains of the Solimões river and guarantees food security and income for farmers. However, negative interference of weeds can result in a significant yield loss in the crop. Therefore, the aim of this study was to evaluate the selectivity of herbicides and efficiency of chemical weed control in the cassava ‘Aipim-manteiga’ cultivar, in the floodplain of the Solimões river, in Iranduba, Amazonas. The experimental design was in randomized blocks with four replications. The herbicides evaluated were clomazone (1080 g ha-1), diuron (1750 and 2500 g ha-1) and oxadiazon (400 and 800 g ha-1), applied alone or with hoeing 90 days after planting (DAP). Two control treatments were included: weeding (hoeing) at 30, 60, 90 and 120 DAP and with no weed control. Clomazone caused mild toxicity in the plants, while with diuron and oxadiazon toxicity was moderate; all three were considered safe for the crop. The plant population of the crop was not affected by the herbicides. Clomazone afforded effective weed control up to 45 DAP only, and weeding was necessary at 90 DAP to eliminate negative interference by the weeds on crop yield. Diuron and oxadiazon were effective in controlling weeds throughout the crop cycle of the cassava. Weed interference during the crop life cicle reduced yield by 83.8%.

The objective of this work was to evaluate corn cultivars grown in the state of Amazonas, Brazil, which simultaneously show high grain yield, adaptability, and stability. The trials were carried out in seven environments in the state of Amazonas, in a randomized complete block design, with two replicates. The grain yield of 30 corn cultivars was evaluated in four growing seasons, from 2011/2012 to 2014/2015. The genetic parameters were estimated by the REML/Blup methodology. The selection for adaptability and stability was based on the predicted genetic value and on the harmonic mean of the relative performance of the genetic values. Despite the existence of genotype x environment interaction, cultivars with high adaptability and stability were identified. Iranduba - lowland, in 2011/2012 and 2014/2015 - and Rio Preto da Eva - upland, in 2012/2013 - stood out as favorable environments, while Iranduba - upland, in 2011/2012 and 2012/2013 - and Manaus - upland, in 2012/2013 and 2013/2014 - were classified as unfavorable environments. The single-cross hybrid BRS 1055 showed productive superiority and high stability in this region. The Sint 10771, Sint 10781, and Sint 10699 synthetic varieties showed high adaptability. BRS Caimbé shows specific adaptability to cropping in upland environments of the state of Amazonas, Brazil.

O feijão-caupi é cultivado principalmente por agricultores familiares, com adoção de baixo nível tecnológico, onde o manejo de plantas daninhas é realizado com capinas, sendo cansativa e com baixo rendimento operacional. O objetivo deste trabalho foi avaliar a seletividade de herbicidas e a eficácia de controle de plantas daninhas na cultura do feijão-caupi, variedade BRS Guariba. O experimento foi conduzido à campo com aplicação dos herbicidas (g i.a. ha^-1) sulfentrazone (500) e oxadiazon (600), em pré-emergência, e bentazon (600), bentazon + paraquat (39 + 62), fomesafen (225), fluazifop-p-butyl (250) e fomesafen + fluazifop-p-butyl (125 + 125), em pós-emegência, um tratamento com capina aos 20 e 34 dias após a emergência da cultura, e uma testemunha sem capina durante todo o ciclo da cultura. A aplicação do bentazon + paraquat provocou elevada fitotoxicidade no feijão-caupi, e o oxadiazon, sulfentrazone, bentazon e fluazifop-p-butyl garantiram de bom a excelente o controle das plantas daninhas, com produtividades semelhantes à obtida quando o controle foi realizado com duas capinas. O fomesafen associado ou não ao fluazifop-p-butyl provocou fitointoxicação moderada, atrasos no florescimento e colheita e redução de produtividade da cultura. A interferência de plantas daninhas durante todo o ciclo da cultura reduziu a produtividade de grãos em 42%.