Quinoa stands out as an excellent crop in the Cerrado region for cultivation in the off-season or irrigated winter season. Here, we tested the effects of different water regimes on the agronomic characteristics, physiology, and grain quality of different elite quinoa genotypes under field conditions. The experiment was conducted under field conditions at Embrapa Cerrados (Planaltina, DF, Brazil). The experimental design was in randomized blocks, in a split-plot scheme, with four replications. The plots were composed of 18 quinoa genotypes and modified BRS Piabiru (the currently used genotype), and the split-plots were divided into 4 different water regimes. The following variables were evaluated: productivity and productivity per unit of applied water (PUAA), plant height, flavonoids, anthocyanins, gas exchange, chlorophyll, leaf proline, and relative water content. Our results showed that water regimes between 309 and 389 mm can be recommended for quinoa in the Cerrado region. CPAC6 and CPAC13 presented the highest yield and PUAA under high and intermediate WRs, and hence were the most suitable for winter growth under irrigation. CPAC17 is most suitable for off-season growth under rainfed conditions, as it presented the highest PUAA under the low WRs (247 and 150). CPAC9 stood out in terms of accumulation of flavonoids and anthocyanins in all WRs. Physiological analyses revealed different responses of the genotypes to water restriction, together with symptoms of stress under lower water regimes. Our study reinforces the importance of detailed analyses of the relationship between productivity, physiology, and water use when choosing genotypes for planting and harvest in different seasons.

Soil management systems exert different effects on soil attributes, especially on the organic matter content, and, consequently, the soil aggregation. The aim of this study was to evaluate the impact of different land uses practiced by quilombola family farmers on water stable aggregates, glomalin and organic carbon in soil aggregates. Soil samples were collected at depths of 0-10 and 10-20 cm from areas cultivated under the following management systems: 1) conventional corn plantation (MA), 2) cultivation of citrus trees intercropped with annual crops (AC) (a conservationist approach), 3) pasture of Brachiaria (Urochloa spp.) (PA), and, as reference, an area of the Cerrado (CR) free of any anthropogenic interference. The studied areas were evaluated in a completely randomized design, with five replications, in a subplot scheme. The plots were the management systems and the subplots the depths. Soil macro-aggregates were predominant at both depths and the aggregate stability indices were higher than 90 % for all management systems. Total organic carbon in the two aggregate classes (micro and macro-aggregates) correlated with the MWD (mean weight-diameter), but not with the easily extractable glomalin (EEG) related soil protein. Soil micro and macro-aggregates, EEG and MWD discriminated management systems and are important soil quality indicators. The carbon content in both micro-aggregates (C-MIC) and macro-aggregates (C-MAC) of the intercropped system (AC) was higher than in the CR. The soil attributes that best separated the areas were C-MIC, MWD and EEG in macro-aggregates for the depth of 0-10 cm, and EEG in micro-aggregates, together with MWD and C-MAC for the depth of 10-20 cm.

The Bacillus thuringiensis bacterium has demonstrated an effective potential in the control of several agricultural pests, among them nematodes. This study aimed to standardize and establish a methodology of bioassays of B. thuringiensis and Meloidogyne incognita with the use of resorcinol, select B. thuringiensis strains toxic to M. incognita in vitro and molecularly identify the presence of the cry6 gene in B. thuringiensis strains. Second-stage juveniles were subjected to resorcinol doses, verifying that the concentration of 0.2 % did not cause mortality and provided the Cry6A toxin ingestion. Thereafter, 16 B. thuringiensis strains were tested in the presence or absence of resorcinol, resulting in mortality rates of 4-36 %. Among the B. thuringiensis strains analyzed for the presence of the cry6 gene, only one was detected (S1617).

The replacement of native vegetation with nonnative vegetation for different land uses, which is a consequence of the intensification and expansion of agricultural production, significantly alters the dynamics of soil organic fractions. The aim of this study was to evaluate the changes in carbon and nitrogen contents and stocks, as well as the chemical fractions of organic matter, caused by different land uses in Cerrado areas. The selected areas were conventional tillage (CTS), no-tillage (NTS), eucalyptus cultivation (EC) and native Cerrado vegetation (NC) in the regions of Barreiras and Luís Eduardo Magalhães, Bahia State, Brazil. The highest carbon contents and stocks were found under NTS up to 10 cm, and these values, as well as those of EC, were equal to those found under NC below 10 cm. The same phenomenon was not verified for the nitrogen contents and stocks in the soil up to 20 cm deep. The values of carbon in the fulvic acid fraction (C-FAF) under NTS and EC were equal to those of NC up to 10 cm deep, but only EC was equal to NC below this layer. At the 10–20 cm depth, the C-FAF increased by 1.23 g kg-1 and 0.95 g kg-1 under NTS compared with those under EC and NC, respectively. With respect to the correlations between carbon fractionation and total organic carbon, the nonextractable humic fraction (C-HUM) had the strongest correlation with the TOC content, with r2 = 96 (p < 0.001). Over time, the input of residues in the NTS and EC areas contributed to increasing soil carbon stocks and organic matter quality, with a recovery of up to 84% of the carbon in humin.