ABSTRACT The use of salt stress attenuators is considered an important tool to minimize the deleterious effects of salts. However, its application to chives (Allium schoenoprasum L.) has not been studied. This study aimed to evaluate the induction of salt stress tolerance in chives plants in relation to growth and enzymatic reactions, when subjected to different salinity levels of the nutrient solution, after acclimation of seeds with hydrogen peroxide (H2O2) for 24 h. The experiment was conducted in a greenhouse, where chives seeds were acclimated by H2O2 at concentrations of 0.0, 0.15, 0.30, 0.45 and 0.60 mmol. After germination, the plants were cultivated in hydroponic system with electrical conductivities of 1.0, 2.0, 3.0, 4.0 and 5.0 dS m-1. Plant height, length and number of leaves, H2O2 content, malondialdehyde and catalase (CAT) activity were evaluated in chives plants. The increase in the salinity of the nutrient solution up to 5 dS m-1 reduced by 5.88%, 17% and 9.63% plant height, leaf length and number of leaves, respectively. It was observed that the acclimation of chives seeds with H2O2 at 0.45 mmol g-1 fresh mass in plants that were cultivated in nutrient solution of 3.73 dS m-1 led to maximum CAT activity, minimizing the deleterious effects of nutrient solution salinity on plant growth.

RESUMO A microirrigação associada à fertilização nitrogenada visa suprir a demanda hídrica e nutricional da palma forrageira. Objetivou-se, com este estudo, avaliar o crescimento e a produtividade da palma forrageira irrigada por microirrigação e fertilizada com nitrogênio. O experimento foi conduzido a campo, na fazenda Poço Redondo, Santa Luzia, PB, Brasil (6° 52’ 27’’ S e 36º 56’ 0’’ W e altitude de 299 m), entre abril e dezembro de 2017. O delineamento experimental foi em blocos casualizados no esquema fatorial 5 x 2, sendo cinco frequências de irrigação (7, 14, 21, 28 e 35 dias) e dois tipos de fertilização (solo fertilizado com nitrogênio e não fertilizado), na cultivar Orelha de Elefante Mexicana, com três repetições. Diferentes frequências de irrigação promovem decréscimo na produtividade de biomassa verde e acréscimo na produtividade econômica da água quando se utiliza o cladódio para semente na palma forrageira cv. Orelha de Elefante Mexicana. A fertilização nitrogenada aumentou o crescimento e as produtividades de biomassa verde, da água e econômica. O maior retorno econômico é obtido com a produção de cladódios comercializados para material propagativo. A redução da frequência de irrigação proporciona maior economia de água, aumentando a área irrigada e a produção, ao utilizar menor volume de água com alta frequência.

ABSTRACT Microirrigation associated with nitrogen (N) fertilization aims to meet the water and nutritional demands of cactus pear. The objective of this study was to evaluate the growth and yield of cactus pear (Opuntia ficus-indica) irrigated by microirrigation and fertilized with N. The experiment was conducted in the field at the Poço Redondo farm, Santa Luzia, PB, Brazil (6° 52’ 27’’ S and 36º 56’ 0’’ W and altitude of 299 m), between April and December 2017. The experimental design was in randomized blocks in a 5 x 2 factorial scheme, with five irrigation frequencies (7, 14, 21, 28 and 35 days) and two types of fertilization (soil fertilized with N and not fertilized) in the cultivar ‘Orelha de Elefante Mexicana’, with three replicates. Different irrigation frequencies promote reduction in green biomass yield and increase in the economic water productivity when using of the cladode for propagative material. Nitrogen fertilization increased growth, green biomass yield, water productivity and economic water productivity. The greatest economic return is obtained by producing cladodes marketed for propagative material. Reducing the frequency of irrigation promotes greater water saving, increasing the irrigated area and production by using less water at high frequency.

RESUMO Objetivou-se com este estudo avaliar a produtividade do colmo, do açúcar e a qualidade tecnológica de duas variedades de cana-de-açúcar sob diferentes lâminas de irrigação e doses de nitrogênio. O experimento foi conduzido em dois anos consecutivos (2015 e 2016) na Fazenda Olho D’Água, em Itambé, Pernambuco. O delineamento experimental foi em blocos casualizados no esquema de faixas subsubdivididas, com quatro repetições. Os tratamentos foram constituídos de quatro lâminas de irrigação (L1 = 12, L2 = 45, L3 = 100 e L4 = 125% da evapotranspiração da cultura - ETc, cana planta) e (L1 = 10, L2 = 40, L3 = 100 e L4 = 125% de ETc, cana soca), quatro doses de nitrogênio (N1 = 0, N2 = 50, N3 = 100 e N4 = 200 kg ha-1 de N) e duas variedades de cana-de-açúcar (RB92579 e RB002754). A cana-de-açúcar irrigada com as maiores lâminas de 1.324,06 e 1.242,3 mm na cana planta e na cana soca produziu, respectivamente, 38,40 e 49,14 t de colmo ha-1 e 0,48 e 1,82 t de açúcar ha-1 a mais em comparação à irrigada com as menores lâminas de 124,06 e 99,4 mm. A maior produtividade de colmo foi obtida na combinação de 120,7 kg ha-1 de N e 1266,6 mm de lâmina de irrigação. A qualidade tecnológica da cana-de-açúcar possui relação positiva com o aumento da lâmina de irrigação na cana planta e na cana soca e, tem relação negativa com o nitrogênio.

ABSTRACT The objective of this study was to evaluate the stalk yield, sugar yield and technological quality of two varieties of sugarcane under different irrigation depths and nitrogen doses. The experiment was conducted in two consecutive years (2015 and 2016) at Olho D’Água Farm, in Itambé, Pernambuco, Brazil. The experimental design was randomized blocks in the split-split-strip-plot scheme, with four replicates. Treatments consisted of four irrigation depths (L1 = 12, L2 = 45, L3 = 100 and L4 = 125% of the crop evapotranspiration - ETc, plant cane) and (L1 = 10, L2 = 40, L3 = 100 and L4 = 125% ETc, ratoon cane), four doses of nitrogen (N1 = 0, N2 = 50, N3 = 100 and N4 = 200 kg ha-1 of N) and two varieties of sugarcane (RB92579 and RB002754). Sugarcane plants irrigated with the highest depths of 1,324.06 and 1,242.3 mm in the plant cane and ratoon cane cycles respectively produced 38.40 and 49.14 t of stalks ha-1 and 0.48 and 1.82 t of sugar ha-1 more, compared to those irrigated with the lowest depths of 124.06 and 99.4 mm. The highest stalk yield was obtained with the combination of 120.7 kg ha-1 of N and 1266.6 mm of irrigation depth. Sugarcane technological quality is positively correlated with the increase of the irrigation depth in the plant cane and ratoon cane cycles and negatively correlated with nitrogen.

ABSTRACT The use of tools such as process capability index for irrigation aims to observe how this irrigation is adequate in terms of quality. The aim of the study was analyzing the Christiansen uniformity coefficient and the flow of a drip irrigation system with self-compensating emitters under water different salt concentrations, using the process capability index. The research was conducted in a greenhouse at the Federal University of Campina Grande (UFCG). The experimental design was a randomized block in a factorial 5 x 2 with three replications, the factors consisted of five levels of irrigation water salinity (CEw) (0.6, 1.5, 2.5, 3.5 and 4.5 dS m−1 at 25°C) and two running times (0 and 350 hours of operation). The Christiansen uniformity coefficient (CUC) for new and used emitters was greater than 90%, in different salt concentrations studied. The flow of emitters is maintained within the statistical quality control, since management and maintenance operations are made after 350 hours of operation. The potential process capability index for the Christiansen uniformity coefficient was higher than recommended for new and used emitters, being the process within the required specifications.

Avaliou-se o efeito da aplicação em excesso de fertilizantes via irrigação em solos com diferentes níveis de salinidade, sobre as variáveis produtivas do tomateiro em ambiente protegido localizado no Departamento de Engenharia de Biossistemas da ESALQ/USP, Piracicaba-SP. O delineamento estatístico foi o em blocos casualizados em esquema fatorial 6x2 com quatro repetições, em que os fatores consistiram em seis níveis iniciais de salinidade do solo (S1 = 1,62; S2 = 2,40; S3 = 2,98; S4 = 3,48; S5 = 4,63 e S6 = 5,82 dS m-1) e em dois manejos da fertirrigação (M1 - Adubos aplicados em fertirrigação obedecendo à curva de absorção de nutrientes da cultura e M2 - Cultivo sem aplicação de fertilizantes via água de irrigação). As variáveis fitomassa fresca de frutos e número de frutos foram afetadas estatisticamente, tanto pelo manejo quanto pela salinidade do solo com reduções de 38,82 e 27,31 % para o manejo M1. A interação entre (salinidade x manejo) e a salinidade isolada influenciou significativamente os componentes estudados, exceto para fitomassa seca do caule e raiz na interação. O manejo M1 foi superior em todos os componentes de produção estudados quando comparado ao manejo M2. O limiar para a cultivar foi superior ao encontrado na literatura.

The effect of application of fertilizers in excess through irrigation in soils with different levels of salinity was evaluated on variables of tomato production, in a greenhouse located in Department of Biosystems Engineering of ESALQ/USP, in Piracicaba, Brazil. The experimental design was randomized blocks, in a factorial scheme 6 x 2 with four replications, the factors consisted in six levels of initial soil salinity (S1 = 1.62, S2 = 2.40, S3 = 2.98, S4 = 3.48, S5 = 4.63 and S6 = 5.82 dS m-1) and two fertigation managements (M1 - Fertilizer applied in fertigation obeying the nutrient absorption curve of crop, and M2 - Cultivation without application of fertilizers through irrigation water). The variables fresh biomass of fruit and number of fruits were statistically affected by both factors-types of management and salinity levels with reductions of 38.82 and 27.31% for the M1 management. The interaction between salinity x management and salinity isolated significantly influenced components studied, except dry biomass of stem and root for interaction. The management M1 performed better for all yield components studied when compared to M2 management. The threshold for the cultivar was higher than that found in the literature.