Resumo -O uso de água salina, na irrigação, tem sido um desafio para os pesquisadores e produtores rurais, sendo constantemente desenvolvidos estudos que possibilitem o uso de água, de qualidade inferior, sem afetar o rendimento e qualidade dos produtos agrícolas. Este trabalho foi realizado com o objetivo de avaliar o efeito de diferentes níveis de salinidade da água de irrigação e doses de fósforo na cultura do rabanete. O delineamento experimental adotado foi inteiramente ao acaso, arranjados em esquema fatorial 4 x 4 com três repetições. Os tratamentos resultaram da combinação de quatro níveis de salinidade da água de irrigação (S 1 -0,5; S 2 -2,0; S 3 -3,5 e S 4 -5,0 dS m -1 ) com quatro doses de fósforo (0; 100; 200 e 300 mg dm -3 ). As variáveis avaliadas foram: número de folhas, área foliar, massa fresca e seca das raízes. A cultura do rabanete respondeu significativamente a interação entre salinidade e fósforo para área foliar, massa fresca e seca das raízes; e de forma isolada para número de folhas. Doses crescentes de fósforo reduziram à sensibilidade da cultura do rabanete à salinidade de até 3,5 dS m -1 . O manejo da adubação fosfatada é uma alternativa para amenizar o efeito da salinidade no desenvolvimento da cultura do rabanete. Palavras-chave -Raphanus sativus L.. Salinização. Plantas-efeito do fósforo.Abstract -The use of saline water for irrigation has been a challenge for the researchers and farmers, studies continually being developed to enable the use of lower quality water without interfering with the yield and quality of products. This work was conducted to evaluate the effect of different salinity levels water irrigation and phosphorus doses in radish. It was used an entirely statistical randomized design, in factorial scheme 4 x 4, with three replications. The treatments resulted from the combination of four salinity levels of irrigation water (S 1 -0.5; S 2 -2.0; S 3 -3.5 and S 4 -5.0 dS m -1 ) with four phosphorus levels (0; 100; 200 and 300 mg dm -3 ). The variables evaluated were: number of leaves, leaf area, root fresh and dry weight of roots. The radish responded significantly the interaction between salinity and phosphorus for leaf area, fresh and dry weight of roots, and isolated the factors for number of leaves. Increasing doses of phosphorus reduced the sensitivity of radish culture to salinity up to 3,5 dS m -1 . The management of phosphorus is an alternative to alleviate the effect of salinity in the development of radish.

Objetivou-se com o presente trabalho avaliar o efeito de diferentes substratos na emergência e desenvolvimento inicial de plântulas de sabiá (Mimosa caesalpiniifolia Benth.). Para isso, foi instalado um experimento em casa de vegetação do Departamento de Ciências Vegetais da Universidade Federal Rural do Semi-árido (UFERSA), Mossoró-RN. O delineamento estatístico utilizado foi inteiramente casualizado (DIC) e os tratamentos foram compostos por nove substratos (T1: vermiculita; T2: fibra de coco; T3: comercial hortimix®; T4: vermiculita, fibra de coco e composto orgânico (1:1:1); T5: fibra de coco e composto orgânico (1:1); T6: fibra de coco e composto orgânico (1:2); T7: vermiculita e composto orgânico (1:1); T8: vermiculita e composto orgânico (1:2) e T9: composto orgânico), com quatro repetições de 25 sementes. As variáveis avaliadas foram: porcentagem de emergência; índice de velocidade de emergência; comprimento de parte aérea e de raiz; diâmetro do colo; matéria seca de folhas, caule, raiz e total; área foliar; área foliar especifica e razão de peso foliar. Os substratos fibra de coco, comercial hortimix® e vermiculita mostraram-se superiores, tendo estes substratos promovido boa emergência e desenvolvimento inicial de plântulas de sabiá. As misturas de vermiculita, fibra de coco e composto orgânico (1:1:1); fibra de coco e composto orgânico (1:1); fibra de coco e composto orgânico (1:2) e vermiculita e composto orgânico (1:1) não mostraram-se adequadas para emergência e desenvolvimento inicial de plântulas de sabiá. Não houve emergência no composto orgânico puro e na mistura de composto orgânico e vermiculita (1:2).

Information about the response of onion to different potassium doses may contribute to optimizing the use of fertilizers and, consequently, make the activity more profitable and environmentally sustainable. In this context, the aim of this study was to evaluate the effects of doses of potassium on onion yields. Two field experiments were carried out in the periods of September to December 2012 and April to July 2013. The experimental design used was completely randomized blocks with four replications. The treatments corresponded to the potassium doses (0, 36, 72, 108, 144 and 180 kg ha-1 of K2O). Potassium fertilization promoted an increase in the content of K in the leaf, commercial and total yield, with the maximum obtained in the dose of 180 kg ha-1 of K2O. The maximum overall and commercial yields were respectively 54.69 and 54.12 t ha-1 in the experiment of September to December 2012 and 47.39 and 46.39 t ha-1 in that of April to July 2013.

The objective of this study was to evaluate the performance of onion cultivars as a function of the spacing between plants. The experimental design was a complete randomized block in a 3 x 4 factorial scheme, with four replicates. The treatments were composed of the combination between three onion cultivars (Vale Ouro IPA 11, Serena and Rio das Antas) and four plant spacings (3, 6, 8 and 10 cm). The evaluated characteristics were total, marketable and unmarketable yield of bulbs, percentages of bulbs in classes 1, 2, 3 and 4, bulb mean weight, bulb dry weight. In onion cultivation, the cultivars Rio das Antas and Serena are the most indicated, with the highest marketable yields at 6 and 3 cm spacings between plants, respectively. The cultivar Vale Ouro IPA 11 presented higher marketable yield for the spacing of 5 cm between plants.

The lack of phosphorus in soil affects the development and productivity of plants; however, in order for them to express the full potential, it is necessary to supply this nutrient. The objective of this study was to define adequate doses of phosphorus, which maximize the productivity and quality of four beet cultivars, and to identify among them the most efficient use of phosphorus. The experiment was carried out at the Rafael Fernandes Experimental Farm, of the Federal Rural Semi-Arid University, Mossoró, RN state, Brazil, from July to October 2016. The experimental design was a randomized block in a 4 x 4 factorial scheme with four repetitions, corresponding to four beet cultivars (Early Wonder, Fortuna, Kestrel and Cabernet) and four doses of phosphorus (0, 90, 180 and 270 kg ha-1 of P2O5). The dose that maximized commercial productivity was 186 kg ha-1 of P2O5 for the cultivars Early Wonder (21.71 t ha-1) and Kestrel (22.59 t ha-1), 180 kg ha-1 of P2O5 for Carbenet (25.82 t ha-1) and 183 kg ha-1 of P2O5 for Fortuna (25.40 t ha-1). The Cabernet and Fortuna cultivars were classified as not efficient but responsive, whereas Early Wonder and Kestrel were efficient but not responsive. Phosphorus did not influence content of soluble solids and percentage of white rings at the root.