The objective was to evaluate the growth and yield of sugarcane irrigated with brackish water and leaching fractions. A completely randomized experimental design was used, in a 5 x 2 factorial scheme, with four replicates. The treatments consisted of five irrigation water salinity levels (0.5, 2.0, 3.5, 5.0 and 6.5 dS m-1) and two leaching fractions (0 and 0.17), corresponding to 100 and 120% of the crop evapotranspiration. The irrigation management was performed daily. Irrigation water salinity levels were obtained by adding NaCl and CaCl2 to the public-supply water, in order to obtain a molar ratio between Na:Ca of 1:1. The following measurements were taken: height and stem diameter; number of tillers; number of leaves and leaf area with monthly frequency between 60 and 300 days after planting (DAP). It was concluded that irrigation water salinity negatively influenced the variables of growth and yield in the sugarcane, and the leaching fraction of 0.17 was capable of reducing the deleterious effects of the salts on the plants.

A Caatinga é um bioma marcado por intensos processos de degradação carecendo de estratégias mitigadoras para compensação como o cultivo de mudas. Este estudo teve como objetivo avaliar o processo de produção e aprofundar as discussões acerca da importância da produção de mudas nativas da caatinga para o semiárido do Nordeste brasileiro. O estudo foi realizado no Centro de Educação Ambiental do Semiárido de Pernambuco – CEASAPE, em Ibimirim - PE. Para obtenção dos resultados alcançados foram realizadas pesquisas bibliográficas sobre a problemática e análise documental do histórico da ONG, visitas técnicas para tomada de informações acerca das metodologias adotada na atividade desenvolvida pela sua equipe multiprofissional administrada pela ASSUVAM. Diante do exposto pode-se averiguar que o CEASAPE aproveita de maneira aceitável os mecanismos e utensílios para a atividade de produção de mudas, dentre eles a matéria-prima com foco na recuperação de áreas degradadas e paisagismo urbano para o município de Ibimirim e semiárido de Pernambuco. Com isso, conclui-se que a produção de mudas nativas é uma alternativa para recomposição das áreas antropizadas da caatinga e desenvolvimento sustentável do semiárido.

A B S T R A C TSalt-tolerant plants are important to cope with salinity and/or sodicity problems in semiarid regions. The dwarf coconut palm (Cocos nucifera L.) has emerged as a salt-tolerant crop once established. However, little is known about the mechanisms that contribute to the survival of coconut seedlings under salinity stress. This study aimed to evaluate the effect of saline water on morpho-physiological and biochemical responses of dwarf coconut seedlings. Treatments were composed of five levels of water salinity, expressed by its electrical conductivity (ECw), as follows: 0.9 (control); 5.2; 10.1; 15.3 and 19.3 dS m -1 in a completely randomized design with four replications. The high levels of organic solutes (carbohydrates and soluble amino-N) and Na + in roots, that contribute to the low values of Na + /K + ratio in the leaves, suggest that roots play an important role in the mechanism of salt tolerance of coconut seedlings. The use of brackish water with ECw of 5.2 dS m -1 allows seedling production, with no loss of quality. Based on total dry matter accumulation, seedlings were classified as moderately tolerant to the salinity of 10.1 dS m -1 .Alterações fisiológicas e iônicas em mudas de coqueiro anão irrigado com águas salinas R E S U M O A utilização de plantas tolerantes ao estresse salino é necessária para remediar o problema da salinidade e/ou sodicidade em regiões semiáridas. Deste modo, o coqueiro anão (Cocos nucifera L.) vem se destacando como uma cultura tolerante ao estresse salino, porém pouco se sabe sobre os mecanismos que contribuem para a tolerância dessa espécie. Neste contexto, objetivou-se com este trabalho avaliar as respostas fisiológicas e iônicas de mudas de coqueiro anão em função do estresse salino. Os tratamentos compreenderam cinco níveis de salinidade da água de irrigação -CEa: 0,9 (tratamento controle); 5,2; 10,1; 15,3 e 19,3 dS m -1 em delineamento inteiramente ao acaso com quatro repetições. Os elevados teores de solutos orgânicos (carboidratos e N-aminossolúveis) e a retenção de Na + nas raízes, o que favoreceu a manutenção de baixos valores da relação Na + /K + nas folhas, indicam que o sistema radicular desempenha papel importante no mecanismo de tolerância das mudas de coqueiro à salinidade. O uso de água salobra com CEa de 5,2 dS m -1 permite a produção de mudas, sem perda de qualidade na fase de viveiro. As mudas foram classificadas como moderadamente tolerantes à salinidade de 10,1 dS m -1 baseado na massa seca total da planta.

The use of treated domestic wastewater in agriculture is promising because it contains essential nutrients for crops, especially for cotton plants. Information on leaf gas exchanges helps to understand the responses of plants to different water and nutrient managements, since they directly affect physiological processes. Thus, the objective of this study was to evaluate the effect of potassium fertilization and irrigation with treated wastewater on the gas exchange of naturally colored cotton plants grown in the semi-arid region of the state of Pernambuco, Brazil, providing a reference for evaluations of responses of cotton plants to abiotic factors. The experiment was conducted in a randomized block design, in a 5 × 5 factorial arrangement, with four replications. The treatments consisted of five potassium rates (0, 50, 100, 150, and 200% of the recommended rate for the crop) and five irrigation depths (50, 75, 100, 125, and 150% of the evapotranspiration of the crop). The highest stomatal conductance, transpiration, net assimilation rate, intercellular CO2 concentration, and carboxylation efficiency were found in irrigated plants with 110, 99, 117, 150, and 113% of ETc, combined with the potassium rates of 96, 113, 97, 100, and 100% of the recommendation rate for the crop, respectively. The increase in irrigation depths increased the diffusion of CO2 of the plants. The highest instantaneous water-use efficiency was found with the irrigation of 150% of ETc without potassium fertilization. According to the interaction between irrigation depths and potassium rates, the most efficient potassium rate for naturally colored cotton depends on the irrigation depth applied.

The objective of this study was to evaluate the effect of light availability and salt stress on the growth and quality of hazel sterculia seedlings. The experiment was conducted with two light conditions-full sun (L1), and 50% shading (L2)-and five salinity levels in the irrigation water-1.0 (S1), 2.2 (S2), 3.2 (S3), 4.2 (S4), and 5.1 (S5) dS m-1. The environment with 50% shading was the most suitable to produce hazel sterculia seedlings, even under high salinity (5.1 dS m-1). Increasing salinity negatively affects the growth and quality of hazel sterculia seedlings. Therefore, controlling sunlight availability and irrigation water saline conditions increases rooting potential and seedling survival in the field.

This study evaluated the contribution of potassium (K) nutrition and application of wastewater depths to the agronomic performance of colored cotton. Treatments consisted of five irrigation depths (50, 75, 100, 125 and 150% of crop evapotranspiration -ETC) and five K doses (0, 50, 100, 150 and 200% of the recommendation for the crop) and an absolute control irrigated with 100% ETCwater depth and fertilized with 100% N-P-K recommendation. Each treatment and the control had four replicates. Plant height, stem diameter, leaf area and shoot dry matter accumulation of cotton were evaluated at 130 days after emergence (DAE), whereas seed cotton weight was evaluated at 135 DAE. Our findings indicate that the use of treated domestic sewage for 100% ETCreplacement promotes greater gains of weight and growth in colored cotton without the need for K fertilization, evidencing the potential of wastewater for colored cotton for sustainable agriculture.

The objective of this study was to evaluate, through multivariate data analysis, which tree legume residues have the best fertilizer potential for agricultural crops in the semi-arid region of northeastern Brazil. The experiment was conducted in pots, in a randomized block design, with seven treatments and four replicates. Treatments consisted of residues of Sabiá, Jurema Preta and Gliricidia, besides two parts of the plant: leaves and leaves + branches. The pots were filled with 8.0 dm 3 of soil and the residues were added in the form of green mass, corresponding to 73.0 g of dry mass per pot. Maize seeds were sown and, at 65 days after addition of the residues, soil chemical attributes, growth and nutrient contents in the plants were evaluated. The data were studied through principal component analysis, clustering analysis, canonical discriminant function analysis and means comparison test from canonical variable 1. Gliricidia residues positively influenced soil K and Mg contents, as well as height, stem diameter, number of leaves and leaf contents of P, N and Mg in maize plants. These residues showed greater dissimilarity and separation compared to the control treatment and led to statistically higher means compared to the other treatments. Jurema Preta leaves positively influenced soil Ca, N and TOC, as well as leaf contents of K and Ca and total dry mass of maize. Multivariate statistical analysis made it possible to identify distinct potentials among legume residues for use as fertilizer in maize crop, and Gliricidia is the species with highest potential.

Treated domestic sewage (TDS) can contribute to plant nutrition and improve crop production. However, there are no data for its use in coloured cotton under a deficit or excess irrigation in combination with potassium fertilization rates (KRs), mainly under semiarid tropical conditions. The research was conducted using a randomized complete block design in a factorial scheme (5 × 5, irrigation regimes vs. potassium rates), plus an additional treatment as the control ((5 × 5) + 1). The treatments consisted of five TDS irrigation regimes (50, 75, 100, 125, and 150% of crop evapotranspiration—ETC) and five KRs (0, 50, 100, 150, and 200% of the local crop recommendation), plus a control—CT— (irrigated with fresh water at 100% ETC and fertilized according to the local crop recommendation) and four replications. The optimal crop yield, water use efficiency, and potassium use efficiency were obtained when TDS was applied as a deficit irrigation treatment of 75% of ETc or as full irrigation (100% of ETC) and when associated with moderate increases in K fertilization. These treatments also resulted in a better fibre quality when compared to the CT, meeting or exceeding the requirements of the textile industry. Therefore, moderate deficit irrigation with TDS is indicated as an important strategy to save fresh water and to reduce the use of fertilizers, while having the potential to increase profit margins for cotton production in tropical semiarid regions.