In regions with high temperatures, carrot cultivation is impracticable, as high temperatures tend to reduce yield and quality of the product. However, with the advent of summer cultivars, carrot cultivation in these regions has become viable. The aim of this work was to evaluate the performance of ten carrot cultivars in different planting seasons. The experiments were carried out at the Rafael Fernandes Experimental Farm of the Federal Rural Semiarid University (UFERSA). The experiments were carried out in May, June, July and August of 2017. The experimental design was a randomized block with ten treatments and four repetitions. The characteristics that were evaluated were the root classification (long, average and short roots); commercial, non-commercial and total yield; dry plant weight and root fresh weight. Both the planting season and the cultivar played important roles in agronomic performance throughout the experimental period. In May and June, the highest average yields and plant growth were obtained (43 and 45 t ha-1 yield, respectively). Hybrid cultivars showed better performance than open-pollinated cultivars in terms of yield. The Brasília, BRS Planalto, and Kuronan varieties showed poor performance in all the evaluated characteristics.

The objective of this study was to evaluate the efficiency of the use of phosphorus by maize cultivars for the production of green ears. Two experiments were carried out, one in the rainy season (March to June) and the other in the dry period (August to December), both at the Rafael Fernandes Experimental Farm, in the community of Alagoinha, belonging to the Universidade Federal Rural do Semiárido, in the municipality of Mossoró, RN, Brazil. The treatments consisted of a combination of three levels of phosphorus (low, medium and high) and eight corn cultivars (Dona Josélia, Carrapateira, Pontinha, Cruzeta, Potiguar, BRS 2022, Status and AG 1051). A randomized block design was used in a 3 × 8 factorial scheme, with four repetitions. The evaluated characteristics were: number and total mass of green ears, number and mass of tradable, stuffed and depleted green ears, agronomic and physiological efficiency of production of recovery and use of phosphorus. The cultivars showed better productive performance when fertilized with phosphorus. The cultivars Cruzeta, Potiguar, BRS 2022, Status, AG 1051 and Carrapateira were the most efficient in the use of phosphorus to produce green maize.

The cultivation of onion in the Brazilian Northeast region has been gaining prominence due to the favorable edaphoclimatic conditions and the use of technology. However, the increase in production costs, price fluctuations and the suppression of sulfur in fertilizer formulations constitute a risk for the farmers. Thus, the aim of this study was to evaluate the productive and economic aspects of onion production as a response to sulfur fertilization. Two experiments were carried out from June to November 2018 and 2019, at the Rafael Fernandes Experimental Farm, belonging to the Universidade Federal Rural do Semi-árido, in the municipality of Mossoró, Rio Grande do Norte, Brazil, in an Ultisol. The experimental design was randomized complete blocks with 14 treatments and four replicates, corresponding to the combination of two onion cultivars and seven doses of sulfur. The following characteristics were evaluated: sulfur content in the diagnostic leaf, bulb yield, total operating costs, gross revenue, net revenue, rate of return and yield index. Regardless of the cultivar, input costs add up to higher expenses, reaching approximate values of 60.6 and 48.4% of the total operating cost for the Rio das Antas and IPA 11 cultivars, respectively. Rio das Antas was more sulfur efficient, achieving greater bulb yield and net revenue. The 34 kg ha-1 sulfur dose promoted maximum yield and net revenue for Rio das Antas. The application of sulfur did not influence the yield of the IPA 11 cultivar.

Effect of planting date on postharvest quality of roots of different carrot cultivars grown in the Brazilian semiarid regionIn regions with high temperatures, carrot cultivation is difficult because high temperatures tend to reduce the size and pigmentation of the root and, consequently, the yield and quality of the product. However, with the advent of summer cultivars, the cultivation of quality carrots under high temperatures has been viable. The aim of this work was to evaluate the postharvest quality of ten carrot cultivars as a function of different planting dates. The experiments were carried out on the Rafael Fernandes Experimental Farm of the Universidade Federal Rural do Semi-Árido (UFERSA). Four experiments were carried out in May, June, July and August 2017. The experimental design was a randomized block with ten treatments and four replications. The following was evaluated: white halo percentage, soluble solids content, total soluble sugars, total titratable acidity, soluble solids/titratable acidity ratio and beta-carotene content. The interaction between the carrot cultivars and planting date had a significant influence on the postharvest quality of carrot roots. The hybrid cultivars had an overall better post-harvest quality. The carrots sown in July had better quality traits; however, they were more affected by the "white halo" disorder.

Fertilization plays an important role on carrot's yield, root quality, storage, plant growth and on the environment. It was aimed to evaluate the plant growth and macronutrients accumulation of carrot cultivars as a function of two planting dates, under high temperatures in the Brazilian semi-arid. The experiments were carried out in randomized blocks design, with ten treatments and four repetitions. Treatments consisted of ten carrot cultivars sowed in two Planting dates. The characteristics that were evaluated were: plant growth (plant height, number of leaves, plant dry matter accumulation, mean fresh mass of the root) and macronutrient accumulation (N, P, K, Ca and Mg) in plant, leaves and root. Plant's mean height ranged from 42.53 cm (Melinda) to 49.25 cm (Nativa); the highest plant dry matter was obtained by BRS Planalto (12.36 g) and Kuronan (12.18 g); the mean number of leaves was the lowest in Melinda and Nativa: 8.64 and 7.64 leaves plant -1 . The root's fresh weight had a significant decrease among the planting dates for the Brasília, Francine and Suprema cultivars. The nutrient accumulation varied accordingly to the planting date and cultivar.