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.

Nitrogen exerts a marked influence on the yield and quality of the onion. The present work was developed from June to October 2016, aiming to evaluate the yield and quality of two cultivars of onion under a system densified as a function of nitrogen doses in Mossoró, RN, Brazil. A randomized block design was used in a 2 x 7 factorial scheme, with four repetitions, corresponding to two cultivars (IPA 11 and Rio das Antas) and seven nitrogen doses (0, 45, 90, 135, 180, 225 and 270 kg ha-1 of N), provided by fertigation, with four repetitions. The dose of 92 kg ha-1 of N provides the highest total and marketable yields of bulbs. Nitrogen fertilization increases the concentrations of N, chlorophyll a, b and total in the leaves of the onion, as well as the percentage of bulbs of classes 3 and 4 and the pungency, reducing the percentage of bulbs of class 2 and non-commercial. The doses of 108 and 82 kg ha-1 of N provide the highest rates of return for ‘IPA 11’ (R$ 2.07) and ‘Rio das Antas’ (R$ 2.41), respectively.

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.

The italian zucchini is a vegetable of national importance, much appreciated, which requires techniques that aim to increase production in less space. Plant spacing can influence the development of plants and the fruit production. The objective of this study was to evaluate the performance of Italian zucchini cultivars as a function of plant spacing. The experimental design was a randomized blocks in a 2 x 4 factorial scheme with four repetitions. The treatments consisted of a combination of two cultivars of zucchini (Alícia and Caserta) and four spacings between plants (0.4, 0.5, 0.6 and 0.7 m). The evaluated characteristics were: total number of fruits plant-1, number of commercial fruits plant-1, total productivity, commercial and non commercial, fresh mass of commercial fruits and dry mass of the plant. The cultivars responded differently to spacings between plants. The Alicia hybrid showed higher commercial yield, 28,490.5 kg ha-1 at spacing of 0.64 m between plants and Caserta cultivar, 26,398.8 kg ha-1 at spacing of 0.4 m.

The increase in plant density, combined with the use of hybrids in onion cultivation, has provided significant gains in yield, with a direct impact on the amount of absorbed macronutrients. The present work aimed to evaluate the yield and quality of two onion cultivars under a densified system as a function of potassium doses supplied via fertirrigation. A randomized complete block design was used in a 2 x 7 factorial scheme with four replications. The treatments consisted of two cultivars (IPA 11 and Rio das Antas) and seven potassium doses (0, 70, 140, 210, 280, 350 and 420 kg ha-1 K2O), provided by fertigation. The potassium doses that provided maximum total and commercial yields were 215 and 216 kg ha-1 of K2O, respectively. The soluble solids and the percentage of bulbs of classes 2, 3 and 4 were not influenced by potassium fertilization. There was a reduction in the percentage of non-commercial bulbs with the increase of potassium doses. The dose with maximum economical efficiency was 210.6 kg ha-1 of K2O, responsible for a commercial yield of 61.8 t ha-1.