Abstract This study evaluate growth, gas exchange, solute accumulation and activity of antioxidant enzymes in dwarf cashew clones subjected to salinity. Shoot dry mass reduced 26.8% (CCP06) and 41.2% (BRS189) at 16 dS m-1, concerning control. For net photosynthesis, CCP06 and BRS189 presented 69.8% and 34.7% of reduction, respectively. Na+ and Cl- contents increased in leaves and roots, in both clones, although CCP06 leaves presented Na+ concentrations lower than those of BRS189, the first one was the clone that the most accumulated such toxic ion, whereas K+ content remained almost unchanged for both clones. Soluble N-amino was the organic solute that more varied with salinity in cashew seedlings. Salt stress increased the activity of superoxide dismutase in both clones, mainly 16 dS m-1 treatment. Additionally, salinity promoted increases in ascorbate and guaiacol peroxidase activities, and the last enzyme was the main involved in H2O2 removal. Despite the reductions in growth and gas exchange, dwarf cashew seedlings of both clones presented an osmotic adjustment mechanism, and an efficient enzymatic antioxidant system that were able to attenuate the salt and oxidative stress, respectively. Our research suggested that BRS189 clone is more tolerant to salt stress than CCP06.

ABSTRACT. Plants are often exposed to abiotic stresses such as salinity, which represents a barrier to the cultivation of agricultural species mainly in arid and semi-arid regions. This study evaluated the development of four saccharine sorghum genotypes for tolerance to different salinity levels under greenhouse conditions. The experimental design was a randomized complete block arranged in a 5 × 4 factorial scheme, which corresponded to five levels of irrigation water salinity [electrical conductivities of 0.5 (control), 2.5, 5.0, 7.5, and 10.0 dS m-1] and four saccharine sorghum genotypes (CSF 11, CSF 15, P 76 and P 298), with five replicates. The plants were evaluated for dry mass production, leaf area, height, stalk diameter, leaf gas exchange and relative chlorophyll content. The growth and leaf gas exchange measurements of the saccharine sorghum plants were significantly affected by salinity stress. Among the genotypes, CSF 11 and CSF 15 exhibited smaller reductions in growth, whereas P 298 showed the greatest reduction. These findings show that genotype CSF 11 can be classified as the most tolerant to salt stress, and genotype P 298 is the most sensitive.

RESUMO Objetivou-se, com este trabalho, investigar os mecanismos bioquímicos associados às ações isoladas e/ou simultâneas do déficit hídrico e da salinidade do solo, em plantas jovens de coqueiro através da mensuração do acúmulo de solutos orgânicos (carboidratos solúveis, N - aminossolúveis e prolina livre) em folhas e em raízes. No experimento conduzido em casa de vegetação, em Fortaleza, CE, avaliaram-se, sob delineamento estatístico de blocos casualizados, no arranjo de parcelas subdivididas, os efeitos de diferentes níveis de deficiência hídrica (parcelas) mediante a imposição de distintos percentuais de reposição das perdas de água por evapotranspiração potencial da cultura - ETpc (20; 40; 60; 80 e 100%), associados às subparcelas, constituídas pelos níveis de salinidade do solo no extrato de saturação (1,72; 6,25; 25,80 e 40,70 dS m-1), proporcionados pelos solos coletados no Perímetro Irrigado Morada Nova. A salinidade não alterou os teores dos solutos orgânicos; todavia, verificaram-se incrementos nos teores foliares e radiculares de prolina livre em resposta à deficiência hídrica. Este fato corrobora com uma possível contribuição à osmorregulação e/ou osmosproteção da espécie em condições adversas de suprimento hídrico.

ABSTRACT The objective of this study was to investigate the biochemical mechanisms associated with isolated and/or concurrent actions of drought and soil salinity in seedlings of coconut tree, through the accumulation of organic solutes (soluble carbohydrates, soluble amino N and free proline) in leaves and roots. The experiment, conducted in a protected environment, in Fortaleza, Brazil, in a randomized block design, in a split-plot arrangement, evaluated the effects of different levels of water stress (plots) by imposing distinct percentages of replacement of water losses through crop potential evapotranspiration - ETpc (20, 40, 60, 80 and 100%), associated with subplots consisting of increasing levels of soil salinity in saturation extract (1.72, 6.25, 25.80 and 40.70 dS m-1) provided by the soils collected in the Irrigated Perimeter of Morada Nova. Salinity did not change the concentration of organic solutes; however, there were increases in leaf and root levels of free proline in response to water stress, which contributes to the osmoregulation and/or osmoprotection of the species under adverse conditions of water supply.

O objetivo foi avaliar as propriedades e a expressão gênica de isoformas de β-galactosidase isoladas de caules de plântulas de feijão-de-corda cv Pitiúba em diferentes estádios de desenvolvimento semeadas na ausência e presença de NaCl. As sementes foram semeadas em folhas de papel filtro embebidas em água destilada (controle) e em solução de NaCl 100 mM. As plântulas foram coletadas nos estádios de desenvolvimento III (ED III) e VIII (ED VIII). As isoformas da enzima, β-gal I, II e III, apresentaram massas moleculares de 89; 146 e 124 kDa, respectivamente, e o mesmo pH (4,0) e temperatura ótima de ensaio (55 °C), em todas as condições estudadas. As três isoformas mostraram-se estáveis até a temperatura de 50 °C. As curvas de termoinativação em função do tempo para as enzimas mostraram que, na temperatura de 60 °C, as curvas foram bifásicas. As análises da expressão gênica de β-galactosidases foram feitas usando primers degenerados e RNA total de caules de plântulas semeadas em condições controle e com tratamento salino, nos ED III e ED VIII. Os resultados revelaram maior nível de transcritos no ED VIII, com redução dos níveis de transcritos de β-galactosidases quando submetidos ao tratamento salino. Os resultados mostraram que as β-gal I, II e III não sofrem modificações ao longo dos estádios iniciais de desenvolvimento. Há algumas diferenças entre as propriedades das três isoformas. A salinidade afetou a expressão gênica das enzimas. As enzimas foram expressas diferentemente nos ED III e ED VIII.

The aim of this work was to evaluate the properties and gene expression of isoforms of β-galactosidase, isolated from the stems of seedlings of the cowpea cv. Pitiuba, at different stages of development and sown in the absence and presence of NaCl. Seeds were sown onto sheets of filter paper soaked in distilled water (control) and a 100 mM NaCl solution. The plants were collected at the III (ED III) and VIII (ED VIII) stages of development. Isoforms of the enzyme β-gal I, II and III presented molecular weights of 89, 146 and 124 kDa respectively, and the same pH (4.0) and optimum test temperature (55 °C) under all the conditions studied. The three isoforms were stable up to 50 °C. The thermal inactivation curves of the enzymes as a function of time were biphasic at a temperature of 60 °C. Analysis of the gene expression of β-galactosidase was carried out using degenerate primers and total RNA from the stems of seedlings at ED III and ED VIII, sown both as control and under saline treatments. The results showed higher transcript levels at ED VIII, with reduced levels of β-galactosidase transcripts under saline treatment, and that β-gal I, II and III do not undergo changes during the early stages of development. There are a few differences in the properties of the three isoforms. Salinity affected the gene expression of enzymes. The enzymes were expressed differently for ED III and ED VIII.

RESUMO O objetivo deste estudo foi verificar se a substituição de nitrato (NO3-) por amônio (NH4+), no meio de crescimento, previne os danos na eficiência do fotossistema II (PSII) e a degradação de pigmentos fotossintéticos causados pela salinidade em plantas de sorgo. As plantas foram cultivadas em soluções nutritivas com diferentes relações dos íons NO3- e NH4+ (100:0, 75:25, 50:50, 25:75 e 0:100) a 5,0 mM. O estresse salino foi imposto pela adição de 75 mM de NaCl no meio de crescimento e as análises foram realizadas após dez dias de estresse. Os efeitos mais marcantes da nutrição com nitrogênio foram observados em plantas nutridas na relação 50:50. Sob condições de estresse salino, plantas nutridas nessa relação apresentaram aumentos na eficiência máxima do fotossistema II (Fv/Fm), os quais foram associados com menores coeficientes de extinção não-fotoquímica (NPQ). Adicionalmente, plantas estressadas nutridas na relação 50:50 apresentaram maior rendimento quântico efetivo do PSII (ΦPSII) e altas taxas de transporte de elétrons (ETR), bem como aumentos nos teores de clorofila b e de antocianinas. A análise em conjunto dos resultados sugere que a nutrição nitrogenada com quantidades iguais dos íons nitrato e amônio previne a degradação de pigmentos fotossintéticos e permite maior eficiência do PSII em plantas de sorgo sob estresse salino

ABSTRACT This study was carried out to evaluate if replacement of nitrate (NO3-) by ammonium (NH4+) in the growth medium prevents the damage in the photosystem II (PSII) efficiency and degradation of photosynthetic pigments caused by saline stress in sorghum plants. Sorghum bicolor plants were cultivated in nutrient solutions containing different NO3-:NH4+ ratios (100:0, 75:25, 50:50, 25:75 and 0:100) at a final concentration of 5.0 mM. Salinity was imposed by adding NaCl at 75 mM in the growth medium; and the analysis were performed after ten days of salt stress. The most striking effects of nitrogen regime were observed in plants supplied with equal amounts of NO3-: NH4+ (50:50). Under salt stress, 50:50-grown plants displayed an increase in the photosystem II maximum efficiency (Fv/Fm), which was associated with a lower non-photochemical quenching (NPQ). The superior performance of salt-stressed plants grown in 50:50 ratio was indicated by a higher effective quantum yield of PSII (ΦPSII) and electron transport rate (ETR), as well as increased chlorophyll b and anthocyanins. In conclusion, nitrogen nutrition with same amounts of nitrate and ammonium avoids the degradation of photosynthetic pigments and allows higher PSII efficiency in salt-stressed sorghum plants.

Hydrogen peroxide (H2O2) is an essential signaling molecule that mediates plant responses against several biotic and abiotic stresses. H2O2 pretreatment has emerged as a signaling way, inducing salt stress acclimation in plants. Here, we analyzed the effects of H2O2 leaf pretreatment on the non-enzymatic defense system (ascorbate and glutathione), plant growth, relative water content (RWC), relative chlorophyll content, H2O2 content, and gas exchange in maize plants under NaCl stress. The results showed that salinity reduced the leaf area and shoot and root dry mass as compared to control, and the leaf spraying with H2O2 significantly improved the growth of salt stressed plants. Photosynthesis and transpiration, stomatal conductance and intercellular CO2 concentration were strongly decreased by salinity after 7 and 14 days of salt exposure; however, the decrease was lower in plants sprayed with H2O2. The improved gas exchange in H2O2-sprayed stressed plants correlated positively with higher RWC and relative chlorophyll content and lower leaf H2O2 accumulation under NaCl stress conditions. Ascorbate and glutathione did not play any obvious effects as non-enzymatic antioxidants in the ROS scavenging. In conclusion, the salt tolerance induced by H2O2 leaf pretreatment is attributed to a reduction in the H2O2 content and maintenance of RWC and chlorophyll in maize leaves. These characteristics allow maize plants to maintain high rates of photosynthesis under salt stress and improve the growth.

O objetivo deste trabalho foi estudar o efeito do nitrato (NO3-) no crescimento e no acúmulo de solutos inorgânicos e orgânicos em plantas de milho submetidas à salinidade. O delineamento experimental foi o inteiramente casualizado, com cinco repetições, sob esquema fatorial 2×4, constando de oito tratamentos: dois níveis de salinidade (NaCl a 0 e 75 mM) e quatro concentrações de NO3- (0,5; 2,5; 5,0 e 7,5 mM) em sistema hidropônico. A massa seca da parte aérea e das raízes foi reduzida pela salinidade, porém isso foi menos evidente quando as plantas foram submetidas a concentrações de NO3- abaixo de 2,5 mM. O melhor crescimento das plantas foi observado na concentração aproximada de NO3- a 5,0 mM. Os teores de Na+ e Cl- aumentaram com a salinidade em todos os órgãos estudados, havendo maior acúmulo desses íons nas raízes. De modo geral, os teores de K+ foram pouco afetados por esse estresse. Com o aumento da concentração de NO3- no meio, houve melhora na absorção desse íon, levando à redução da absorção de Cl- e ao acúmulo de prolina e N-aminossolúveis. O estresse nutricional é mais limitante ao crescimento das plantas de milho que o estresse salino, cujos efeitos prejudiciais são minimizados por uma nutrição de NO3- adequada.

This work aimed to study the effect of nitrate (NO3-) on growth and accumulation of inorganic and organic solutes in maize plants subjected to salinity. The experiment was carried out in a completely randomized design, with five replications, and a 2×4 factorial scheme, consisting of eight treatments: two salinity levels (NaCl at 0 or 75 mM) and four different concentrations of NO3- (0.5, 2.5, 5.0 or 7.5 mM) in nutrient solution. The dry mass of shoots and roots was reduced by salinity, however, this was less evident when plants were exposed to concentrations of NO3- below 2.5 mM. The best growth was observed in the approximate concentration of 5.0 mM NO3-. The Na+ and Cl- contents increased with salinity in all organs studied, and the highest accumulation of these ions was observed in the roots. In general, the K+ content was not severely affected by this stress. With the increase of NO3- concentration in the medium, there was an improvement in the absorption of this ion, leading to reduced uptake of Cl- and the accumulation of proline and soluble amino acids. Nutritional stress is more limiting to plant growth of maize than the salt stress, with harmful effects being alleviated by an adequate nutrition of NO3-.

An adequate mineral nutrition is essential for the development and productivity of pineapple. However, little is known about the nutritional and metabolic changes that occur in this crop in response to micronutrient deficiency or excess, particularly on tropical conditions. Thus, the objective of this study was to evaluate the application effects of micronutrients in soil and in leaf on biochemical responses of leaves during the development cycle of the pineapple crop. Samples were collected at 3, 6, 9, 12, and 17 months after transplantation. Leaf soluble carbohydrates and N-aminosoluble compounds were determined, as well as variations in the titratable acidity and pH. The soil and leaf micronutrient application increased the concentrations of carbohydrates and N-aminosoluble and reduced the leaf pH, and the changes were more significant in the last sampling (17 months after transplantation). Reductions in concentrations of carbohydrates and increase in the titratable acidity of the pineapple leaves collected at the end of the night were also observed, a fact that reflects the metabolism of Crassulacean acid metabolism species. The strategy of micronutrient application contributes positively to alter the metabolism of plants of pineapple cv. Victoria, especially during flowering and fruit development.

Cereus jamacaru, uma cactácea encontrada comumente no nordeste brasileiro, é amplamente usada como planta forrageira e como ornamental e medicinal. No entanto, existem poucas informações sobre os aspectos fisiológicos e bioquímicos relacionados à sua germinação. O objetivo desse estudo foi avaliar a mobilização de reservas durante a germinação e o crescimento inicial de plântulas de C. jamacaru. Para isso, as sementes foram germinadas em câmaras de germinação e coletadas aos 0, 2, 4, 5, 6, 8 e 12 dias após a germinação para as análises fisiológicas e bioquímicas. As sementes quiescentes apresentaram tegumento espesso e rugoso e embriões curvados. Os lipídios foram as reservas mais abundantes, correspondendo aproximadamente a 55% e 65% da massa seca dos cotilédones e eixo hipocótilo-radícula, respectivamente. Os açúcares solúveis e o amido foram as reservas menos abundantes, correspondendo aproximadamente a 2,2% da massa seca dos cotilédones, embora suas reservas tenham apresentado mudanças significativas durante a germinação. As proteínas solúveis corresponderam a 40% da massa seca dos cotilédones, que foi reduzida a 81% no período final de germinação comparado a sementes quiescentes. As sementes de C. jamacaru podem ser consideradas oleaginosas devido ao seu alto conteúdo de lipídios. Além disso, os lipídios foram as principais reservas mobilizadas durante a germinação porque seus níveis foram fortemente reduzidos durante esse período, enquanto que as proteínas foram a segunda reserva mais utilizada nesse processo.

Cereus jamacaru, a Cactaceae found throughout northeast Brazil, is widely used as cattle food and as an ornamental and medicinal plant. However, there has been little information about the physiological and biochemical aspects involved in its germination. The aim of this study was to investigate its reserve mobilization during germination and early seedling growth. For this, C. jamacaru seeds were germinated in a growth chamber and collected at 0, 2, 4, 5, 6, 8 and 12 days after imbibition for morphological and biochemical analyses. Dry seeds had wrinkled seed coats and large, curved embryos. Lipids were the most abundant reserve, comprising approximately 55% and 65% of the dry mass for cotyledons and the hypocotylradicle axis, respectively. Soluble sugars and starch were the minor reserves, corresponding to approximately 2.2% of the cotyledons' dry mass, although their levels showed significant changes during germination. Soluble proteins corresponded to 40% of the cotyledons' dry mass, which was reduced by 81% at the final period of germination compared to dry seeds. C. jamacaru seed can be classified as an oil seed due to its high lipid content. Moreover, lipids were the main reserve mobilized during germination because their levels were strongly reduced after seed germination, while proteins were the second most utilized reserve in this process.

Cereus jamacaru is a widespread Cactaceae of northeast Brazil, largely used as cattle food, and as ornamental and medicinal plant. Despite its distinguished importance, until now, there has been little information about the physiological aspects involved on its germination. The objective of this study was to evaluate the effect of light and temperature interaction on the seed germination and seedling establishment of this plant. The evaluated variables were germination percentage at 7 (% G7) and at 14 days after imbibition (% G14), germination average time index (GSI), germination average time (GAT), germination accumulated frequency (GAF), seedling dry mass and height. The highest % G14 and GSI were at 25 ºC in white light, whereas the highest GAT values were in darkness for all evaluated temperatures. On the other hand, % G14, GSI and GAF had the lowest values in darkness. Seeds germinated even in darkness, being however stimulated by the presence of light. The combination of white light and temperature of 25 or 30 °C is the most appropriate condition for seed germination tests.

The growth and nutrient assimilation was evaluated in CaCl2- and CaSO4-supplemented cowpea plants subjected to salt stress (75 mM NaCl). The salinity significantly reduced the cowpea vegetative growth. The addition of CaCl2 in the growth medium did not significantly affect plant growth, while for the CaSO4, the beneficial effects of Ca2+ were moderate. Salinity increased the Na+, K+, Cl-, N and P content in the plants, however it decreased the content of Ca2+ and Mg2+. Increases in Ca2+ concentration in the nutrient solution caused decreases in the Na+ and Mg2+ contents and increases in Ca2+, K+, P, and Cl- contents. The supplemental Ca2+ may alleviate the Na+ toxicity and may improve nutritional and ionic balance in cowpea, but it cannot overcome the osmotic effects associated with the increased total salt concentration.

Objetivou-se com este trabalho avaliar os efeitos da salinidade em três estádios de desenvolvimento (ED) da plântula de cajueiro anão-precoce, a saber, germinação, emergência e estabelecimento da plântula, tentando estabelecer uma relação entre o desenvolvimento e o acúmulo de íons nos tecidos da plântula. Para isso, castanhas do clone CCP-06 de cajueiro anão precoce foram semeadas em bandejas de plástico contendo vermiculita umedecida com água destilada (0,0 dS m-1) ou soluções de NaCl com condutividades elétricas variando entre 3,0 e 18,0 dS m-1 e mantidas em casa de vegetação. Determinaram-se a percentagem de plântulas que alcançaram os ED estudados e o tempo e a velocidade com que isso ocorreu, assim como a matéria seca dos cotilédones e eixo embrionário e os teores de Na+, K+ e Cl- do eixo embrionário. A salinidade retardou o desenvolvimento das plântulas nos ED correspondentes à emergência e estabelecimento, entretanto apenas neste último ED é que a percentagem final de plântulas foi reduzida, acompanhada pela inibição da depleção das reservas cotiledonares e decréscimo da massa seca do eixo embrionário. Em todos os ED, os teores de Na+ e Cl- aumentaram com a salinidade, mas isso foi mais pronunciado nas plântulas estabelecidas, nas quais houve redução dos teores de K+. Os resultados obtidos sugerem que as plântulas de cajueiro anão precoce são mais sensíveis à salinidade durante a etapa de estabelecimento e que os efeitos deletérios desse estresse são mediados, pelo menos em parte, pelo acúmulo excessivo de íons Na+ e Cl- na plântula.

We investigated the effects of salinity on (germination, emergence and establishment of dwarf-cashew seedling) trying to establish a link between development and ion accumulation in the seedling tissues. In a greenhouse, cashew nuts were sown in trays containing vermiculite moistened with distilled water (0.0 dS m-1) or with NaCl solutions with electrical conductivities ranging between 3.0 to 18.0 dS m-1. We determined the percentage of seedlings that reached the development stages studied and the time and speed at which this occurred, as well as cotyledon and embryonic axis dry mass and the Na+, K+ and Cl- contents of embryonic axis. Salinity delayed emergence and establishment seedling, however, only the final percentage of established seedlings was reduced, accompanied by inhibition of depletion of reserves and a decrease in embryonic axis dry mass. Na+ and Cl- contents increased with salinity, but this was more pronounced in established seedlings, in which there was a reduction in content of K+. Results suggest that dwarf cashew seedlings are more sensitive to salinity during the establishment stage and that deleterious effects of salt stress are mediated, at least in part, by excessive accumulation of Na+ and Cl- in the seedling tissues.

Although it has been known that the seed's physiological potential affects its response to osmoconditioning and abiotic stresses, researches involving seed aging and priming associated to abiotic stresses are scarce. The aim of this work was to evaluate the role of seed priming on salt tolerance in sorghum seedlings from seeds with two vigor levels (aged or non-aged) and to verify the organic and inorganic solute contributions as osmoregulators in NaCl-stressed seedlings from aged and primed seeds. The combinations of two seed vigor levels (aged or not), two seed types (primed or not) and two salinity levels (exposed to NaCl at 100 mM or not) were evaluated. In low physiological quality seeds (aged seeds), priming provided an attenuation of salinity's negative effects (0 or NaCl at 100 mM) on seedling growth. The accumulation of Na+ and Cl- ions in NaCl-stressed sorghum seedling shoot from primed seeds indicate a plant osmotic adjustment induced by seed priming, which was efficient in reducing the osmotic stress caused by salinity. Proline was the main organic solute that contributed to osmoregulation in NaCl-stressed sorghum seedling shoot and its levels increased due to seed priming. Changes in inorganic and organic solute contents, in both shoot and roots, could have been induced by seed priming and as a function of salt stress tolerance, although the changes in these organs were poorly related to each other.

Este trabalho teve como objetivo avaliar os efeitos da adubação de fundação e foliar com micronutrientes sobre aspectos físicos e qualitativos do abacaxi cv. Vitória, nas condições do Perímetro Irrigado Baixo Acaraú, norte do Estado do Ceará, sob duas coberturas do solo (bagana e plástico preto) arenoso e de baixa fertilidade. O delineamento experimental utilizado foi em blocos casualizados, em parcelas subdivididas, com quatro doses de adubação de fundação, e quatro níveis de adubação foliar, com cinco repetições. Para a adubação de fundação foi utilizado FTE-12 nas doses de 0; 60; 120 e 180 kg ha-1. Os quatro níveis de adubação foliar foram: AF0 (sem adubação); AF1 (15 adubações foliares, usando um total de 1.158,75 g ha-1 de Fe, 844,65 g ha-1de Mn, 391,5 g ha-1 de Zn, 322,65 g ha-1 de Cu e 216 g ha-1 de B); AF2 (15 adubações foliares, usando o dobro das quantidades do nível AF1), e AF3 (15 adubações foliares, usando o triplo das quantidades do nível AF1). Aos 13 meses após o plantio das mudas obtidas por micropropagação, foi realizado o tratamento de indução floral, e cinco meses mais tarde, a colheita, determinando-se as seguintes variáveis dos frutos: peso, diâmetro mediano, sólidos solúveis (SS) e acidez titulável (AT). O peso e o diâmetro mediano do fruto aumentaram com a elevação das doses de micronutrientes, aplicados no solo e via foliar, nas plantas cultivadas sob ambas as coberturas de solo. Por outro lado, a qualidade da polpa do fruto foi pouco afetada pelos tratamentos estudados. Foi observado pequeno aumento do teor de sólidos solúveis nos frutos das plantas cultivadas em solo, com cobertura de bagana, e pequena redução da acidez titulável no caso da cobertura com plástico preto, em ambos os casos, apenas para os micronutrientes aplicados via foliar.

The objective of this study was to evaluate the effects of foundation and leaf fertilization with micronutrients on fruit size and quality of pineapple cv. Vitória under the environmental conditions of the Baixo Acaraú irrigated perimeter in Northern Ceará State, Brazil, under two covers (bagana and black plastic) of the sandy soil of low fertility. The experimental design was a randomized split blocks one with four levels of soil dressing and four levels of foliar fertilization, with five replications. Micronutrient soil dressing was studied as FTE-12 at doses of 0, 60, 120 and 180 kg ha-1. The four levels of foliar fertilization were: LF0 (without fertilizer), LF 1 (15 leaf fertilization, using the amount of 1158.75 g Fe ha-1, 844.65 g Mn ha-1, 391.5 g ha-1 Zn, 322.65 g ha-1 Cu and 216 g ha-1 B), LF2 (15 leaf fertilization, using twice the quantities of level LF1) and LF3 (15 leaf fertilization, using three times the amount of level LF1). At 13 months after planting the micropropagated plantlets was carried out the floral induction treatment and five months later the fruit harvest determining the following variables: fruit weight and median diameter, soluble solids content (SS) and titratable acidity (TA). Both fruit weight and diameter increased with increasing doses of micronutrients applied to the soil and to the leaves, of plants grown both on bagana soil cover and plastic mulch. On the other hand fruit pulp quality was little affected by the treatments studied. There were a small increase of SS contents for plants grown on bagana soil cover and a small decrease of titratable acidity for those grown on plastic mulch, in both cases just in response to micronutrient foliar application.

A exploração do cajueiro sob condições de irrigação tem-se mostrado bastante promissora, especialmente no estado do Ceará, porém a resposta dessa cultura ao regime hídrico depende do genótipo. Objetivouse, com este trabalho, comparar respostas fisiológicas e bioquímicas (teores de solutos orgânicos e inorgânicos e trocas gasosas), tal como a produtividade de plantas de cajueiro anão precoce (Anacardium occidentale L.) sob dois regimes hídricos (sequeiro e irrigado). O experimento foi conduzido no Campo Experimental da Embrapa Agroindústria Tropical, em Pacajus CE, no período de agosto de 2006 a janeiro de 2007. As plantas foram submetidas a dois tratamentos: um sem irrigação e outro com água de poço com condutividade elétrica (CEa) de 0,5 dS m-1. As respostas fisiológicas foram avaliadas mensalmente e os dados de produção foram obtidos no período de novembro a janeiro. Os teores foliares de N-aminossolúveis e prolina foram mais elevados nas plantas cultivadas em condições de sequeiro do que naquelas irrigadas, porém não houve diferença significativa entre os tratamentos para as trocas gasosas, teores de carboidratos solúveis, K+, Na+ e Cl-. Entretanto, com exceção da fotossíntese, todas as variáveis estudadas apresentaram alterações com as épocas de coleta. Apesar das alterações em algumas variáveis ao longo do experimento, a produtividade das plantas não foi afetada pelo estresse hídrico.

The exploitation of cashew under irrigated conditions has been very promising, especially in the state of Ceará, however, the response of this crop to the water regime depends on the genotype. This work attempts to compare the physiological and biochemical responses (content of organic and inorganic solutes and gas exchange) and yield of precocious dwarf cashew (Anacardium occidentale L) plants under two water regimes (irrigated and rainfed). The experiment was conducted at the experimental field of Embrapa Agroindústria Tropical, in Pacajus, Ceará, from August 2006 to January 2007. The plants were subjected to two treatments: without irrigation and another irrigated with water with electrical conductivity of 0.5 dS m-1. The physiological responses were assessed monthly and the production data were obtained from November to January. The levels of N-aminosoluble and proline in the leaves of plants grown under dry farming conditions were higher than in irrigated, but no significant difference was found between treatments for gas exchange, soluble carbohydrates, K+, Na+ and Cl-. However, except for photosynthesis, all the variables showed changes in collection times. Despite changes in some variables during the experiment, the yield of plants was not affected by water stress.