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RESUMOObjetivou-se avaliar os efeitos de doses de gesso e de biofertilizante nos atributos químicos de um solo salino-sódico e no crescimento inicial de plantas de girassol. O experimento foi conduzido em casa de vegetação do Centro de Ciências Humanas e Agrárias da Universidade Estadual da Paraíba (CCHA-UEPB), Campus IV Catolé do Rocha-PB. Os tratamentos compreenderam um esquema fatorial 4x2 com quatro doses de gesso agrícola (25; 50; 75; 100% da necessidade de gesso -NG) na ausência e na presença de biofertilizante bovino (0 e 10% v/v), com três repetições. Após a aplicação dos tratamentos, incubação do solo e posterior lavagem, cultivaram-se plantas de girassol cultivar CF/01 ADVANTA durante 30 dias. A aplicação do gesso reduziu a salinidade e a sodicidade do solo, sendo que a dose de 100% da NG proporcionou as maiores reduções obtendo valores de RAS e PST mantendo-os inferiores a 12 (mmolc L -1 ) -0,5 e 15%, respectivamente. O melhor desenvolvimento das plantas de girassol ocorreu no solo com a presença de biofertilizante. A associação gesso e biofertilizante favoreceu a correção do solo salino-sódicos e cultivo do girassol. Palavras-chave: salinidade; sodicidade; Helianthusannuus L.; matéria orgânica SÁ, F.V.S.; MESQUITA, E.F.; BERTINO, A.M.P.; COSTA, J.D.; ARAÚJO, J.L. INFLUENCE OF PLASTER AND BIOFERTILIZER ON CHEMICAL ATTRIBUTES OF A SALINE SODIC SOIL AND ON INITIAL GROWTH OF SUNFLOWER ABSTRACTThe objective of this study was to evaluate the effects of plaster and biofertilizer levels on the chemical attributes of a saline sodic soil and on initial growth of sunflower. The experiment Sá, et. al 47 Irriga, Botucatu, v. 20, n. 1, p. 46-59, janeiro-março, 2015was conducted in a greenhouse of the Center of Humanities and Agricultural Sciences, Paraíba State University (CCHA-UEPB), Campus IV Catolé Rocha-PB, Brazil. Treatments were applied using a 4 x 2 factorial design with four levels of gypsum (25; 50; 75; 100% of the plaster need) in the absence and presence of bovine biofertilizer (0 and 10% v/v) and three replicates. After treatment application, soil incubation and subsequent washing, the sunflower plants cv CF/01 ADVANTA were grown for 30 days. Gypsum application reduced soil salinity and sodicity. Plaster need of 100% led to the greatest reductions in sodium adsorption ratio (SAR) and exchangeable sodium percentage (ESP), with values lower than 12 (mmolc L -1 ) -0.5 and 15%, respectively. Optimal sunflower plant development was observed in the presence of soil biofertilizer. The gypsum and biofertilizer association favored the correction of saline sodic soil and cultivation of sunflower plants.

The scarcity of good quality water is a limiting factor for irrigated agriculture, especially in arid and semiarid regions, where water sources generally contain high concentrations of ions. In such conditions, it is essential to cultivate genotypes with economic potential and tolerance to salinity. Considering the importance of citrus and the need to identify genetic materials that adapt to saline stress, this study evaluates the salinity tolerance of 10 genotypes with rootstock potential. For the irrigation water, five levels of electrical conductivity (ECw: 0.8, 1.6, 2.4, 3.2 and 4.0 dS/m at 25 °C) were used in a randomized block design with three replications, and seed germination and growth variables, as well as physiological plant parameters, were evaluated. The germination rate of the hybrid TSKC × CTARG – 019 was the best under salt conditions, as it was the genotype with the highest tolerance to salinity in the germination stage. Salinity reduced the growth of the citrus genotypes, with the possibility of using water with EC of up to 1.6 dS/m in the rootstock formation stage. Salt stress affected the photosynthetic rate of the genotypes ‘San Diego’ citrandarin and TSKC × CTSW – 018 by reducing the stomatal conductance, restricting the diffusion of CO2 into the substomatal camera. The genotypes TSKC × CTARG – 019, TSKC × CTTR – 012 and TSKC × TRBK – 007 have the greatest potential for growth and photosynthetic apparatus efficiency when subjected to salinity.

Salvia hispanica cultivation is recent in Brazil and occurs in the off-season, when there is lower water availability in the soil. Water deficit is one of the abiotic factors that most limit germination for compromising the sequence of metabolic events that culminate with seedling emergence. Several attenuating substances have been used to mitigate the effects resulting from this stress and give higher tolerance to the species. Thus, the objective of this study was to evaluate the action of different agents as water stress attenuators in the germination and accumulation of organic compounds in S. hispanica seedlings. The treatments consisted of pre-soaking the seeds for 4 hours in salicylic acid (1 mM.L-1), gibberellic acid (0.4 mM.L-1), distilled water and control treatment (without soaking). The seeds were germinated at osmotic potentials of 0.0, -0.1, -0.2, -0.3 and -0.4 MPa, using PEG 6000 as an osmotic agent. The variables germination percentage, germination speed index, shoot and primary root lengths, total dry mass, proline, total soluble sugars and total free amino acids were analyzed. Salicylic acid and gibberellic acid led to the best results among the attenuators tested, increasing germination, length, dry mass and biochemical components of S. hispanica seedlings under water deficit. Therefore, salicylic and gibberellic acids are efficient in mitigating water stress in S. hispanica seeds up to the potential of -0.4 MPa.

This research was carried out aiming at evaluating the effects of nitrate and ammonium ions on nutrient accumulation, biochemical components and yield of Italian zucchini (cv. Caserta) grown in a hydroponic system under salt stress conditions. The experiment was carried out in a greenhouse utilizing an experimental design in randomized blocks, arranged in a 2 x 5 factorial scheme, with 4 replications. The treatments consisted of two forms of nitrogen (nitrate - NO3- and ammonium - NH4+) and 5 electrical conductivity levels of irrigation water (ECw) (0.5, 2.0, 3.5, 5.0 and 6.5 dS m-1). The analysis of the results indicated that supply of N exclusively in NH4+ form promotes greater damage to the leaf membrane and reduction in accumulation of macronutrients and higher Na+/K+, Na+/Ca++ and Na+/Mg++ ratios in the shoots of zucchini plants. Electrical conductivity of irrigation water above 2.0 dS m-1 reduces the accumulation of nutrients in shoot and yield of Italian zucchini plant. The toxicity of NH4+ under Italian zucchini plants overlap the toxicity of the salinity, since its fertilization exclusively with this form of nitrogen inhibits its production, being the NO3- form the most suitable for the cultivation of the species.