Under salt stress conditions, plant growth is reduced due to osmotic, nutritional and oxidative imbalance. However, salicylic acid acts in the mitigation of this abiotic stress by promoting an increase in growth, photosynthesis, nitrogen metabolism, synthesis of osmoregulators and antioxidant enzymes. In this context, the objective was to evaluate the effect of salicylic acid doses on the growth and physiological changes of eggplant seedlings under salt stress. The experiment was conducted in a greenhouse, where the treatments were distributed in randomized blocks using a central composite matrix Box with five levels of electrical conductivity of irrigation water (CEw) (0.50; 1.08; 2.50; 3.92 and 4.50 dS m-1), associated with five doses of salicylic acid (SA) (0.00; 0.22; 0.75; 1.28 and 1.50 mM), with four repetitions and each plot composed of three plants. At 40 days after sowing, plant height, stem diameter, number of leaves, leaf area, electrolyte leakage, relative water content, and total dry mass were determined. ECw and SA application influenced the growth and physiological changes of eggplant seedlings. Increasing the ECw reduced growth in the absence of SA. Membrane damage with the use of SA remained stable up to 3.9 dS m-1 of ECw. The relative water content independent of the CEw increased with 1.0 mM of SA. The use of SA at the concentration of 1.0 mM mitigated the deleterious effect of salinity on seedling growth up to 2.50 dS m-1 of ECw.

Sweet potatoes are an important staple food for human consumption. This study evaluated sweet potato yield in response to potassium fertilization using different sources and splitting. It was conducted at the Universidade Federal da Paraíba, Areia-PB. A complete randomized block experimental design was used in a 7 × 2 factorial arrangement. The fertilization was split into seven treatments (100% after planting; 100% at 30 days after planting (DAP); 100% at 60 DAP; 50% after planting and 50% at 30 DAP; 50% after planting and 50% at 60 DAP; 50% at 30 DAP and 50% 60 at DAP; 33% after planting, 33% at 30 DAP, and 33% at 60 DAP). Two fertilization sources were used, namely potassium chloride and potassium sulfate, with three replicates. Plant fresh mass, mass of marketable roots, production of marketable roots per plant, leaf K concentration, total and marketable root yields were evaluated. Chloride and sulfate potassium efficiently increased the fresh mass of the plant and the mass of marketable roots, respectively. The marketable yield of the roots (25.16 and 22.28 Mg ha-1) was higher than the national average (14.07 Mg ha-1) when K2O was supplied in the sulfate and potassium chloride sources, respectively. The leaf K concentration remained within the standard levels for the crops under chloride and potassium sulfate fertilization. Potassium sulfate application results in higher sweet potato yields. When supplied in a single application, chloride and sulfate potassium increase the total and commercial yield only when the plants are at 60 DAP.

Agricultural production in semi-arid areas of the globe is dependent on species adapted to conditions of low availability of resources, such as water. Cowpea (Vigna unguiculata L. Walp.) is a vegetable widely grown in regions with water restrictions, however, even with its good adaptability, it is vulnerable to the effects of prolonged droughts. In this sense, this research aimed to analyze the influence of rainfall patterns on the production dynamics of cowpea during the period of fifteen years (2002-2016) in the municipality of Conceição, Paraíba, Brazil. A correlation matrix was used to analyze the influence of precipitation on the production variables of the cowpea crop, as well as the relationship between these variables. Subsequently, the Principal Component Analysis (PCA) was carried out. The results showed a strong reduction in the production variables of cowpea from the year 2012, which is due to the reduction of rainfall in this period and was proven through the correction matrix, which showed a positive correlation of rainfall mainly with the planted and harvested area. The PCA recorded 91.02% of explanation in the first two axes, and demonstrated that for production and productivity, other factors in addition to good rainfall levels are necessary to increase the productive results of cowpea in the municipality.

Sugarcane is a crop of worldwide economic value used in sugar, electricity, and alcohol production. This review demonstrates the importance of the main micronutrients and their respective effects on the development and yield of sugarcane. Micronutrient deficiency is one of the limiting factors in sugarcane productivity in producing regions. This deficit is related to several aspects, such as fertilizer use with low micronutrient levels, increased agricultural productivity, and decreased productivity levels of soil organic matter. Thus, proper fertilization management can circumvent the limiting factors such as the foliar application of boron and soil fertilization of zinc, both resulting in greater stem production. Molybdenum increases biological nitrogen fixation in sugarcane and contributes to the accumulation of N in the plant. Iron and manganese are involved in chlorophyll content and dry matter accumulation in sugarcane. In this review, we show the contributions of fertilization with microelements to the development of the sugarcane sector. In this perspective, more research is needed on micronutrient fertilization to increase sugarcane productivity in different soil and climate conditions.

Adequate mineral fertilization and staking are necessary to obtain good productivity in yam cultivation. The objective of this study was to determine the increase in yield and quality of yams subjected to nitrogen doses and staking methods. This study was carried out under field conditions using a randomized block design in a 5 × 3 factorial scheme, with five nitrogen doses (0, 50, 100, 150 and 200 kg ha-1) and three staking methods (wire trellises, single staking, and without staking) with four replicates. Nitrogen doses were applied in topdressing, and split into equal parts at 60 and 90 days after seed tuber planting. Tuber length and weight, starch and leaf nitrogen concentrations, and total and marketable yields were determined. Staking promoted higher total yield, mass, length, and leaf nitrogen concentration, but no changes were observed in starch concentration among the staking methods. Commercial productivity was higher with single staking. Planting yam with staking and a nitrogen dose of 120.70 kg ha-1 is recommended to promote maximum productivity.