This study aimed to verify the effect of co-inoculation, association between Azospirillum brasilense and Bradyrhizobium japonicum bacteria, on soybean plants subjected to water deficit at two sowing dates. Two field experiments were conducted at the Universidade Federal de Tocantins, campus of Palmas, Brazil, in 2016. The experimental design was randomized blocks in a split-split-plot arrangement with four repetitions, where the plots consisted of two irrigation depths (100 and 25% of crop evapotranspiration - ETc), the subplots was composed of two methods of inoculant application (inoculation with Bradyrhizobium japonicum and co-inoculation with Azospirillum brasilense + Bradyrhizobium japonicum) and the sub-subplots comprised two soybean cultivars (TMG 132 and ANTA 82). The cultivars responded differently to the sowing dates. Co-inoculation did not influence grain yield under full irrigation conditions (100% ETc), in neither cultivar evaluated. However, under the water deficit condition (25% ETc), the grain yield of the cultivar TMG 132 increased 77.20%, indicating that there are different responses of interaction between Azospirillum brasilense, plant genotype and sowing dates.

Anthracnose caused by Colletotrichum graminicola (Ces.) Wils is among the most aggressive maize diseases worldwide, considerably hindering crop productivity. To investigate the responses underlying the host-pathogen interaction involved in anthracnose infection, we conducted two field experiments in some of the main grain producing areas of the State of Tocantins, in Brazil. Four maize hybrids (with differential tolerance to C. graminicola) were sown in February and March, 2017. Chlorophyll fluorescence measures were performed according to the OJIP protocol; additionally, SPAD readings were conducted and productivity components were assessed. Inoculation with the fungus spore suspension affected the response curve of the chlorophyll fluorescence transient, SPAD index, and productivity components. Anthracnose stalk rot caused 20-25% reduction in grain weight, 6-8% reduction in maize ear size, and 20-23% reduction in ear weight. Furthermore, plants experiencing C. graminicola rot showed reduced SPAD index and a 24-34% reduction in the activity indicator of PSII (PI Total ). These changes in the photosynthetic apparatus were successfully observed via chlorophyll fluorescence measurements.

A soja (Glycine max (L.) Merrill) é o principal cultivo agrícola produzido na região do Matopiba. Entretanto, o sucesso ou quebra da produção de soja está relacionada ao déficit e/ou excesso hídrico. A pegada hídrica (PH) avalia a pressão das atividades humanas sobre os recursos hídricos. Assim, esse artigo tem por objetivo investigar a produtividade e pegada hídrica da soja, sob cenário atual e mudanças climáticas. A produtividade e pegada hídrica futura foram obtidas através do modelo de crescimento de cultura AquaCrop da FAO e do downscaling dos modelos de circulação geral da atmosfera HadGEM2-ES e MIROC5, para os cenários de RCP 4.5 e 8.5. Atualmente a produtividade da soja na região do Matopiba varia de 2,6 a 3,0 t ha-1 e a PHsoja de 2.036,6 a 2.584,12 m³ t-1. As projeções, geradas pelos modelos e RCP, sugerem aumento da produtividade da soja em até 2,0 t ha-1 e decréscimo na PHsoja de 700 m³ t-1. A avaliação da PHsoja futura, por suas componentes verde (água derivada da precipitação) e azul (de rios, subterrâneo), mostra que a demanda por água azul será maior que por água verde. A componente cinza (grau de poluição da água) da PHsoja diminui, mas esse componente deverá aumentar, uma vez que, considerou-se apenas fertilizantes nitrogenados e com valores praticamente constantes. Esses resultados ressaltam a importância de se criar estratégias de adequadas de manejo e cultivo, sob cenário de aumento produtividade de soja e da demanda por água azul, mantendo um uso aceitável dessa água.

The soybean chemical composition is strongly influenced by genetic factors, as well as their interaction with the environment and management practices. Among the environmental factors, water deficit and temperature are those that most contribute to modify the chemical composition of beans, especially oil and protein contents. The present study aimed to assess the effects of co-inoculation with Azospirillum brasilense on soybean oil and protein contents. Two field experiments were carried out on different sowing dates. The design consisted of randomized blocks, in a split-split-plot arrangement, with four replications, including two irrigation depths (25 % and 100 % of the ETc), two inoculation methods [Bradyrhizobium japonicum (strains Semia 5079 and Semia 5080) and Azospirillum brasilense (strains AbV5 and AbV6 + Bradyrhizobium japonicum)] and two cultivars (ANTA 82 and TMG 132). The co-inoculation did not affect the oil and protein contents of beans for any of the assessed management conditions. The water deficit in the reproductive stage, combined with the sowing dates, altered the oil and protein contents in both the assessed cultivars, showing, respectively, a higher average protein and oil content in the beans for the cultivars TMG 132 and ANTA 82.

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