The Diagnosis and Recommendation Integrated System (DRIS) is a promising diagnostic method in the nutritional assessment of commercial crops. The aim of this work was to establish and compare specific DRIS nutritional standards for Tommy Atkins, Kent and Keitt mango tree, as well as for the group of cultivars in the sub-Middle São Francisco Valley, Brazil. The study was carried out in commercial orchards of Tommy Atkins, Kent and Keitt cultivars, in the Sub-Middle São Francisco Valley. To form the database, leaf samples were collected in the pre-flowering, where the nutritional contents were determined. DRIS norms were established and together with the data of productivity and nutritional contents of the subpopulations of high and low productivity were compared by the t test. The contents of S and micronutrients showed greater variability. The nutritional contents of the high-productivity subpopulation were less distorted. The nutrients P, K, Mg, S, Mn and Zn for Tommy, K for Kent, N for Keitt and P, K and S for the set of cultivars were higher in the high productivity subpopulation. The specific norms for each cultivar were more consistent and could serve as a reference for nutritional diagnostics of the mango tree in the region.

Many methods of nutritional diagnosis present discordant reports. It is necessary to study how these diagnoses relate to agricultural productivity and nutrient balance for a more efficient nutritional monitoring of the crops. This study had two objectives: (1) evaluate and compare Diagnosis and Recommendation Integrated System (DRIS) and Compositional Nutrient Diagnosis (CND) methods for nutritional diagnosis of sugarcane cultivated in the Northeast of Brazil; (2) establish standards, identify and hierarchize nutritional limitations. The database consisted of 183 samples, in which 31 were in areas with high productivity (³ 80 Mg ha-1) and 152 of areas with low productivity (< 80 Mg ha-1). Sugarcane leaves were collected and contents of N, P, K, Ca, Mg, S, Fe, Zn, Cu, Mn and B were determined. The DRIS indexes were calculated by methods DRIS-Beaufils, DRIS-Jones, DRIS-Elwali and Gascho, M-DRIS Beaufils, M-DRIS Jones, and the indexes CND too were calculated. The DRIS-Beaufils, DRIS-Jones, M-DRIS Beaufils and M-DRIS Jones methods tended to agree on the nutritional diagnosis of sugarcane. The nutritional diagnosis of the CND method interpreted by the Potencial Fertilization Response (PFR) was different from the DRIS methods for N and Mn nutrients. The M-DRIS Beaufils and M-DRIS Jones methods showed a higher correlation with nutrient contents. However, there was no significant correlation between agricultural productivity and nutrient balance index mean (NBIm), suggesting that other factors influenced sugarcane production more than nutritional factors. The nutritional diagnosis methods identified excessive fertilization with N and limitations of Ca, Mg, K, S, Mn, Cu, Zn and B in sugarcane in the Northeast of Brazil.

The São Francisco Valley region of Brazil is a leading exporter of mango fruits. Previous nutritional diagnosis can identify stresses, provide adjustments for nutritional limitations, and promote more efficient fertilization and nutrient management. This study aimed to compare the nutritional diagnosis of mango trees in the post-harvest and pre-flowering phases and to correlate them with productivity. Norms and indices of the Integrated System of Diagnosis and Recommendation (DRIS), as well as the Nutritional Balance Index and the Potential of Response to Fertilization were generated for each phenological phase of the mango trees. Optimal concentrations and ranges of nutrients were established, classified as deficient, balanced, or excessive, and subsequently compared to each other and to values recommended in the literature. The indices were correlated with the productivity of the orchards in each phenological phase of the mango trees. When comparing the DRIS norms of post-harvest and pre-flowering phenological phases, 55% of the averages differed. The sufficiency ranges of the post-harvest and pre-flowering phases were generally different from those referenced in the literature. Nutritional diagnoses for P, K, Ca, Mg, S, Zn, and Cl altered between phenological phases. The nutritional diagnosis performed in the post-harvest phase showed that nutritional imbalance affected productivity.

Deforestation of Caatinga and inadequate land use of these dry environments have impacted soil quality in Northeastern Brazil. The objectives of this study were: (a) to evaluate the effect of deforestation and different agricultural uses on the physical and chemical properties of soil, and humic fractions of soil organic matter in dry environments; and (b) to detect the soil properties that were most affected by anthropic actions. We evaluated four dry areas in Chapada do Araripe, NE Brazil: preserved native vegetation; degraded native vegetation; cassava conventional cultivation; and eucalyptus agro-energy cultivation. Soil fertility, total organic carbon and humic fractions of soil organic matter were lower in the degraded native vegetation area. The best indicators for soil quality evaluation were: macroporosity; bulk density; soil resistance penetration; sum of bases (mainly Ca2+); available P; and saturation by Al3+. Total organic carbon and humic acid fractions of soil organic matter were important in improving soil quality. These properties were influenced by deforestation and agricultural uses, suggesting that the deforestation of native vegetation in dry environments has high capacity to degrade the soil, preventing its regeneration.

Silicon has been associated with beneficial effects on plants such as tolerance to water deficit, salt stress and reduced transpiration. This work aimed to evaluate the effect of silicon application on the development and productivity of corn submitted to different periods of water deficit in the semi-arid region of Piauí. The experimental design used was a randomized block design, in a 4x2 factorial arrangement, formed by the combination of four silicon doses (0, 50, 100 and 200% of the recommended dose) and two water deficit conditions (moderate and severe), with four repetitions. The recommended dose was 1.0 L ha^-1 of silicate, according to the manufacturer. The variety used was the super early BRS Gorutuba. Each plot consisted of four 4.0 m rows spaced at 0.80 m from each other, with the central rows being considered as useful area and the outer rows as border. The data were submitted to variance analysis using the F test. To verify the optimal silicon dose, for each stress intensity, polynomial regression analysis was applied (P<0.05).There was a significant interaction effect for the variables aboveground fresh mass, aboveground dry mass, and yield. Doses of 0.84 and 0.55 L ha^-1 of silicon were the most indicated for moderate and severe deficit, respectively. Doses above 1L ha^-1 reduced the growth and productivity of corn.

The cultivation of fruit trees is influenced by abiotic factors such as nutritional management. However, fertilizers are used in large amounts in vineyards, resulting in excess nutrients that can cause stress and reduce fruit quality. Calcium (Ca) is one of the most used nutrients in vineyards due to its effects on fruit quality. However, excess of Ca interferes with the distribution of Ca compounds in fruits, being a form of abiotic stress. The aim of this study was to evaluate the influence of the nutritional balance of table grape orchards on calcium nutrition and fruit quality. Nineteen table grape orchards were selected in the Submédio São Francisco Valley in 2019 and 2020 crops. The nutritional diagnosis was performed using the integrated diagnosis and recommendation system (DRIS) and the average nutritional balance index (NBIm) was calculated. The concentration of Ca-pectate, Ca-total, berry firmness, soluble solids, titratable acidity, soluble solids/titratable acidity ratio and dry matter were determined in the fruits. The nutritional diagnosis identified excess Ca in the orchards. The correlation between Ca-pectate and the average NBIm was negative, indicating that the Ca-pectate concentration is higher in vines that are more nutritionally unbalanced. However, the Ca-total in the fruit was not correlated with Ca-pectate. Ca-total and Ca-pectate were not correlated with berry firmness. Calcium nutrition is complex and highlights the importance of associating the assessment of nutritional balance with Ca in fruit quality to optimize the nutritional management of the grapevine.