Adequate management of saline water irrigation and nitrogen (N) fertilizer application in agriculture can contribute substantially to expanding guava cultivation in the semi-arid region of Northeast Brazil. This study aimed to evaluate gas exchange and production of ‘Paluma’ guava cultivated with different levels of water salinity and N. The experiment was carried out in drainage lysimeters under field conditions in an experimental area of the Federal University of Campina Grande (UFCG), Campus of Pombal, PB, Brazil. The experimental design was randomized blocks, in a 5 × 4 factorial scheme, with five levels of water salinity – ECw (0.3, 1.1, 1.9, 2.7 and 3.5 dS m-1) and four doses of N (70, 100, 130 and 160% of the recommendation) with three replicates. The dose relative to 100% corresponded to 541.1 mg of N dm-3 of soil. The following production components were evaluated: number of fruits, mean fruit weight, polar and equatorial diameter of fruits, and polar diameter/equatorial diameter ratio. In addition, the following physiological variables were evaluated at 180 days after fruit pruning: stomatal conductance, CO2 assimilation rate, internal CO2 concentration and transpiration rate. CO2 assimilation and transpiration rate were used to calculate instantaneous water use efficiency. The interaction between water salinity and N doses did not cause significant effects on any variable studied. Irrigation water salinity above 0.3 dS m-1 hampered gas exchange at 180 days after fruit pruning and negatively affected production components.

Quantitative and qualitative limitations of water resources in Northeast Brazil, besides the excessive use of fertilizers without criteria related to soil analysis and crop needs, has called the attention for studies on techniques that allow saline waters to be used in agriculture. This study aimed to evaluate physiological and growth responses of grafted guava plants, cv. Paluma, as a function of irrigation with saline water and foliar applications of proline. The experiment was carried out in protected environment in Pombal – PB, Brazil, in a randomized block design in 4 x 4 factorial scheme, with three replicates, and treatments consisted of four levels of irrigation water electrical conductivity – ECw (0.3; 1.0; 1.7 and 2.4 dS m-1) associated with four doses of proline (0, 5, 10 and 15 mmol L-1). Grafted plants of guava cv. Paluma can be grown using water with ECw of 1.1 dS m-¹ since it led to acceptable mean reduction of 10% in growth and physiological activity. Mean proline dose of 8 mmol L-1 leads to increase in the number of leaves and dry matter accumulation. The interaction between proline doses and water salinity levels did not affect either growth or physiology of grafted plants of guava cv. Paluma, at 101 days after transplanting.

The objective of this study is to characterize six forage grass cultivars used for hay production. The morphological and morphometric characteristics of these cultivars were determined using a completely randomized block design, and the rates of loss of dry matter and crude protein (CP) were evaluated using a completely randomized design with a 6 x 5 factorial scheme (six cultivars vs. five drying periods [0, 1, 2, 3 and 4 hours]) and three repetitions. Morphological and morphometric characteristics and the chemical composition of the cultivars were analyzed using the Scott-Knott test, and the drying time was assessed using linear regression analysis at a level of significance of 5%. There was a significant effect (p < 0.05) of morphological and morphometric characteristics, except for stem thickness (p=0.1) and the live-to-dead biomass ratio (p=0.27). The Massai cultivar presented a higher leaf to stem ratio (1.23 ± 0.60). There was an increased linear response (p < 0.05) for the rate of water loss in the six evaluated cultivars. The Massai cultivar had a safe storage moisture content (80% dry matter) after 3 hours and 11 minutes of sun exposure, and the drying rate was 10.34% per hour of sun exposure. The cultivars Paredão and Marandú showed a decreasing linear effect of CP content across the harvest period, corresponding to 22.07% and 21.38 ± 0.55% in fresh plants, respectively, and 20.13% and 18.11 ± 0.55% after 4 hours of sun exposure, respectively. The Massai cultivar had the most efficient rate of water loss, reaching a safe storage moisture content in 3 hours and 6 minutes, with a CP content of 18.63%.

Resumo: Objetivou-se avaliar a concentração de potássio, sódio e a produção na mamoneira cv. BRS Energia, em função da irrigação com águas salinizadas e adubação nitrogenada nas diferentes fases fenológicas, em experimento conduzido em lisímetros de drenagem sob condições de campo no Centro de Ciências e Tecnologias Agroalimentar da Universidade Federal de Campina Grande. O delineamento experimental utilizado foi o de blocos casualizados, arranjados em esquema fatorial 5x2x2, constituídos pela combinação de cinco níveis de condutividade elétrica da água de irrigação -CEa (0,3; 1,2; 2,1; 3,0 e 3,9 dS m -1 ), duas doses de nitrogênio-DN (100 e 160 mg kg -1 de solo) e duas fases fenológicas (vegetativa e formação da produção -floração e frutificação). A concentração de potássio e sódio nas folhas, caule e raízes da cv. BRS Energia foram mensuradas aos 120 dias após o semeio. O aumento dos níveis de salinidade da água elevou a concentração de sódio nas folhas, caule e raízes, sendo o efeito variável de acordo com os estádios de desenvolvimento. A maior concentração de K + nas folhas, caule e raízes foi obtida quando se irrigou com água de CEa de 0,3; 1,8 e 0,3 dS m -1 respectivamente. Os diferentes níveis de CEa afeta de forma negativa a produção, independente da fase de desenvolvimento. Doses crescentes de N e a interação entre os fatores estudados não interferiram sobre a concentração de K + e Na + em nenhuma parte avaliada. Palavras-chave: Ricinus communis L., qualidade de água, nutrição mineralAbstract: Thus, the aim of this study was to evaluate the concentration of potassium and sodium in the castor bean cv. BRS Energia as a function of irrigation water salinity and nitrogen fertilization in different phenological phases in an experiment conducted in drainage lysimeters under field conditions, at the Centro de Ciências e Tecnologias Agroalimentar da Universidade Federal de Campina Grande. The experimental design was in a randomized block with 20 treatments arranged in a factorial 5 x 2 x 2, constituted by the combination of five levels of electrical conductivity of irrigation water -ECw (0.3, 1.2, 2, 1, 3.0 and 3.9 dS m -1 ), two nitrogen doses-DN (100 and 160 mg kg -1 of soil) and two phenological stages (vegetative and formation of productionflowering and fruiting). The concentration of sodium and potassium in the leaves, stem and roots of cv. Energia BRS were measured at 120 days after sowing. The increased levels of salinity increased the sodium concentration in the leaves, stems and roots, and the effect varied according to the developmental stages. The highest concentration of K + in the leaves, stem and roots was obtained when irrigated with water of ECw of 0.3, 1.8 and 0.3 dS m -1 respectively. The different levels of ECw negatively affect the production, independent of the development phase; Increasing doses of N and the interaction between the factors studied did not interfere in the concentration of K + and Na + in any part.

Forage sorghum is a crop that can be planted in semiarid regions, due to its greater adaptability to dry climate environments, and can replace maize in these regions, which are often unsuitable for its production. Thus, the objective of the study was to evaluate the structural, morphological and nutritional characteristics of 23 sorghum hybrids forage cultivated in rainfed conditions, planted in different climate conditions, comparing the hybrids, in order to determine what produces the best in the climatic conditions of the explored region, and also to indicate whether this crop can be planted as a replacement for maize in environments not suitable for planting it. The research was conducted in climate BSh in the Municipality of Alvorada do Gurgueia, and climate Aw in the Municipality of Bom Jesus, both in the state of Piauí from 2014 to 2015. Each trial consisted of 20 experimental forage sorghum hybrids [Sorghum bicolor (L.) Moench], and three commercial hybrids. A randomized block design was used, with three replications in a factorial scheme (2 × 23). The growth characteristics determined were hybrid × climate interaction for the variables plant height, lodging and leaf/stem ratio. For the variable number of tillers, there was a significant difference only between hybrids. There was no difference between hybrids only for the lodging variable of climate Aw. The other variables showed a difference in all hybrids evaluated. There was an interaction for production of dead matter and total dry forage mass between the different environments and hybrids evaluated. For leaf production, there was an effect only for the different environments. For the chemical characteristics, there was an interaction for all variables analyzed between the different environments and hybrids evaluated. The semi-arid region of the State of Piauí, climate BSh which presents a high climatic risk for maize cultivation, proved to be favorable for forage sorghum production. The forage sorghum also presented agronomic characteristics similar to those found in semi humid climate Aw, a favorable region for maize cultivation. In addition, the tested hybrids showed good chemical characteristics, so the BSh climate has great exploratory potential for the cultivation of forage sorghum.

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This study aimed to evaluate the quality of Tanzania grass (Panicum maximum) haylage with varying contents of dry matter (DM) and stored for 90 days. The quality of this grass was evaluated through the lens of a variety of physiochemical properties (e.g., chemical composition, aerobic stability, pH, microbial profile, etc.). A completely randomized design was used with four treatments (in natura, 400, 500, and 600 g kg-1 DM) and five replicates. Treatment with 600 g kg-1 DM yielded the highest DM haylage (p < 0.01) and soluble carbohydrate content (p < 0.01). Treatment in natura resulted in the highest O2concentration inside the bales (p < 0.01), whereas treatments with 500 and 600 g kg-1 DM resulted in the highest CO2 values. The highest acetic acid concentrations of 36.4 ± 1.6, 38.2±1.6, and 48.9 ± 1.6 g kg-1 DM (p < 0.01) were observed post the in natura, 500 g kg-1 DM, and 600 g kg-1 DM treatments, respectively. Treatment with 600 g kg-1 DM yielded the highest pH value at hour zero (p < 0.01). Tanzania grass with 500 and 600 g kg-1 DM produced the highest quality haylage. Highlights: Haylage can be defined as stored pre-dried forage with a dry matter (DM) content of approximately 400 to 800 g/kg. Aerobic stability was affected by the interaction between the different plant DM contents and hours of exposure of the Tanzania grass haylage to air after opening the bales. Haylage surface temperature has a linear relationship with the length of time the materials are exposed to air. Higher plant DM yields Tanzania grass haylage of high quality. Tanzania grass with 500 and 600 g kg-1 DM for haylage production is indicated.

RESUMO:As regiões semiáridas apresentam elevadas temperaturas e irregularidades pluviométricas originando problemas quantitativos quanto qualitativos, o que proporciona déficit e acumulo de sais nas fontes hídricas. Diante da problemática, estudou-se o efeito da irrigação com águas de distintos níveis salinos e adubação nitrogenada no crescimento de portaenxerto da aceroleira CMI 102, em experimento conduzido em ambiente protegido do Centro de substrato favorece o maior crescimento de porta-enxerto de aceroleira.