The metabolic switch from C3-photosynthesis to crassulacean acid metabolism (CAM),and the antioxidative response of Mesembryanthemum crystallinum L. plants cultured under severe salt stress and high light intensities, and a combination of both stress conditions, were studied. High light conditions led to a more rapid CAM induction than salinity. The induction time was still shortened when both stress factors were combined. A main pattern observed in CAM plants was a decrease in mitochondrial Mn–superoxide dismutase (SOD) activity during the day. The activities of the chloroplastic Fe–SOD and cytosolic CuZn–SOD were increased due to salt treatment after a lag phase, while catalase activity was decreased. Combination of salt and light stress did not lead to a higher SOD activity as found after application of one stress factor alone, indicating that there is a threshold level of the oxidative stress response. The fact that salt-stressed plants grown under high light conditions showed permanent photoinhibition and lost the ability for nocturnal malate storage after 9 d of treatment indicate serious malfunction of metabolism, leading to accelerated senescence. Comparison of CuZn–SOD activity with CuZn–SOD protein amount, which was determined immunologically, indicates that the activity of the enzyme is at least partially post-translationally regulated.

Root-supplied Si is thought to play a role in alleviating the effects of water-deficit stress in several crops. However, little information is known about the contribution of Si, especially foliar application, in the biochemical and physiological mechanisms of potato (Solanum tuberosum L.) under water-deficit stress. The objective of this study was to evaluate the effects of soil-and foliar-applied soluble Si on Si accumulation, osmotic adjustment, antioxidant defense responses, pigments concentrations, and tuber yield of potato plants grown under water deficit. A greenhouse experiment was conducted using pots containing 35 dm 3 of a Typic Acrortox soil. Treatments included a control (no water-deficit stress or Si application), water-deficit stress (-0.060 MPa soil matric potential) without Si application, water-deficit stress with soil-applied soluble Si (50 mg dm -3 Si), and water-deficit stress with foliar-applied soluble Si (five sprays of 1.425 mM Si water solution). Soil-applied Si increased concentration and accumulation of Si in all parts of water-stressed potato plants while foliar-applied Si increased the Si concentration only in the tuber + roots, compared to the control and water-deficit treatment. Both soil-and foliar-applied Si increased proline, activity of catalase (CAT), and tuber dry weight and decreased hydrogen peroxide (H 2 O 2 ) concentration in water-stressed plants. The activity of superoxide dismutase (SOD) was increased only by the foliar application of Si. Water-stressed plants that received either soil-or foliar-applied Si maintained relative water content, concentrations of chlorophyll a and carotenoids, chlorophyll a/b ratio, and tuber yield similar to well-watered potato plants.

No abstract

Pistacia lentiscus is a wild species that grows widely in the Mediterranean area. However, despite it appearing to be particularly resistant to some stressful conditions, drought and salinity may alter its physiological and morphological behavior. While the responses of P. lentiscus to both stresses have been partially studied, its avoidance and tolerant mechanisms are poorly understood. In particular, changes in leaf tissue cell wall and the photosynthetic activity during a prolonged water deficit and salinity are unknown. Nursery grown plants were subjected to four irrigation treatments lasting eleven months: control (1 dS m-1 , 100% water holding capacity), two deficit treatments (moderate and severe water deficit, corresponding to 60 and 40% of control) and saline treatment (4 dS m-1 , same amount of water supplied as control). Biomass accumulation was affected more by deficit irrigation than by salinity. Salt tolerance in P. lentiscus was associated with the restricted uptake of Cland its storage in roots. However, the cumulative effect of irrigating with saline water involved an over-accumulation of Na + and Clin leaves, which probably contributed to the pronounced decrease in photosynthesis, confirming the importance of the length of exposure of the plants to salt stress. Plants under saline or severe deficit irrigation exhibited slight dehydration throughout the experiment, as indicated by the lower leaf water potential and relative water content, due to the low availability of substrate water (osmotic effect). The response of plants to severe water stress, which resulted in stomatal closure and a decrease in net photosynthesis rate, involved a marked decrease in plant height and growth, especially in the first months of the experiment, after which a slight acclimation may have occurred in these plants. Under moderate water stress, most of these responses were mitigated. Salinity induced active osmotic adjustment and decreased leaf tissue elasticity. Due to its tolerance of water stress and salinity, P. lentiscus is a suitable ornamental species for gardening in arid and saline area.

We tested the hypothesis that Eucalyptus globulus Labill. genotypes that are more resistant to dry environments might also exhibit higher cold tolerances than drought-sensitive plants. The effect of low temperatures was evaluated in acclimated and unacclimated ramets of a drought-resistant clone (CN5) and a drought-sensitive clone (ST51) of E. globulus. We studied the plants' response via leaf gas exchanges, leaf water and osmotic potentials, concentrations of soluble sugars, several antioxidant enzymes and leaf electrolyte leakage. Progressively lowering air temperatures (from 24/16 to 10/-2 degrees C, day/night) led to acclimation of both clones. Acclimated ramets exhibited higher photosynthetic rates, stomatal conductances and lower membrane relative injuries when compared to unacclimated ramets. Moreover, low temperatures led to significant increases of soluble sugars and antioxidant enzymes activity (glutathione reductase, ascorbate peroxidase and superoxide dismutases) of both clones in comparison to plants grown at control temperature (24/16 degrees C). On the other hand, none of the clones, either acclimated or not, exhibited signs of photoinhibition under low temperatures and moderate light. The main differences in the responses to low temperatures between the two clones resulted mainly from differences in carbon metabolism, including a higher accumulation of soluble sugars in the drought-resistant clone CN5 as well as a higher capacity for osmotic regulation, as compared to the drought-sensitive clone ST51. Although membrane injury data suggested that both clones had the same inherent freezing tolerance before and after cold acclimation, the results also support the hypothesis that the drought-resistant clone had a greater cold tolerance at intermediate levels of acclimation than the drought-sensitive clone. A higher capacity to acclimate in a short period can allow a clone to maintain an undamaged leaf surface area along sudden frost events, increasing growth capacity. Moreover, it can enhance survival chances in frost-prone sites expanding the plantation range with more adaptive clones.

ResumoA utilização de bioestimulantes pode alterar o desenvolvimento e o crescimento vegetal, porém, a ação dos mesmos pode ser variável conforme o estádio de desenvolvimento da planta. Objetivou-se avaliar o efeito de formas e épocas de aplicação de um bioestimulante (citocinina, ácido indolbutírico e ácido giberélico) na nodulação, alguns aspectos bioquímicos, crescimento e produtividade do feijoeiro cultivar Pérola. Os tratamentos foram: Testemunha (sem aplicação); TS -250 mL ha -1 em tratamento de semente (TS); V 4 -250 mL ha -1 via pulverização foliar em V 4 ; R 5 -250 mL ha -1 via pulverização foliar em R 5 ; TS+V 4 -250 mL ha -1 em TS + 250 mL ha -1 em V 4 ; TS+R 5 -250 mL ha -1 em TS + 250 mL ha -1 em R 5 ; V 4 +R 5 -250 mL ha -1 em V 4 + 250 mL ha -1 em R 5 e TS+V 4 +R 5 -250 mL ha -1 em TS + 250 mL ha -1 em V 4 + 250 mL ha -1 em R 5 . A aplicação do bioestimulante via foliar na fase vegetativa (V 4 ) ou início da reprodutiva (R 5 ) proporciona incrementos na nodulação, no crescimento radicular, no conteúdo de açúcares solúveis e aminoácidos totais e na atividade da nitrato redutase, porém, não interfe no crescimento da parte aérea e na produtividade da cultura do feijão. Palavras-chave: Phaseolus vulgaris, regulador vegetal, nitrato redutase, crescimento radicular AbstractThe use of biostimulants can alter plant growth and development, but the action of they may be varied according to the stage of development of the plant. The aim was to evaluate the effects of forms and times of a biostimulant (cytokinin, indolebutyric acid, and gibberellic acid) application on nodulation, some biochemical aspects, growth and yield of common bean cultivar Pérola. The treatments were: Control (without application); TS -250 mL ha -1 seed treatment; V 4 -250 mL ha -1 foliar spray in V 4 stage; R 5 -250 mL ha -1 foliar spray in R 5 stage; TS+V 4 -250 mL ha -1 in TS + 250 mL ha -1 in V 4 ; TS+R 5 -250 mL ha -1 in TS + 250 mL ha -1 in R 5 ; V 4 +R 5 -250 mL ha -1 in V 4 + 250 mL ha -1 in R 5 , and TS+V 4 +R 5 -250 mL ha -1 in TS + 250 mL ha -1 in V 4 + 250 mL ha -1 in R 5 .The foliar biostimulant application in the vegetative (V 4 ) or early reproductive phase (R 5 ) increases nodulation, root growth, content of soluble sugars, content of total amino acid and nitrate reductase activity, however, does not interfere with shoot growth and grain yield of common bean.

PRODUÇÃO DE FRUTOS DE PIMENTÃO EM DIFERENTES CONCENTRAÇÕES SALINAS.  Marcelo Leonardo1; Fernando Broetto2; Roberto Lyra Villas Bôas3; Rafael Simões Almeida2; José Abramo Marchese4.1Departamento de Engenharia Rural, Faculdade de Ciências Agronômicas, Universidade Estadual Paulista, Botucatu, SP,  marceloleonardo@fca.unesp.br2Departamento de Química e Bioquímica, Instituto de Biociências de Botucatu, Universidade Estadual Paulista, Botucatu, SP3UNESP-FCA, Departamento de Recursos Naturais / Ciência do Solo, Faculdade de Ciências Agronômicas, Universidade Estadual Paulista, Botucatu, SP4Laboratório Bioquímica e Fisiologia Vegetal CEFET-PR  1 RESUMO Utilizou-se a técnica de fertirrigação para conduzir experimento com pimentão (Capsicum annuum L.) híbrido Elisa. O trabalho teve como objetivo estudar impactos quantitativos na produção de frutos, em função do aumento da concentração salina no solo. Desta forma as concentrações de sais foram alteradas a partir da variação do fornecimento de KCl e Ca2NO3. Com esta variação, obtiveram-se valores elevados de condutividade elétrica no solo (CE), tomando-se a CE observada na fertirrigação tradicional, como controle (1,5 dS m-1). Além disso, verificou-se a possibilidade de atenuação do estresse salino com a aplicação de matéria orgânica no solo. Observou-se que os níveis de CE mantidos na cultura correlacionaram-se inversamente ao índice de pegamento e peso médio de frutos, sendo que para o tratamento mais severo aplicado (6,0 dS m-1) os frutos apresentaram redução de até 58% em peso médio e 55% em número de frutos por planta, comparado ao tratamento controle. Baseado nesses resultados demonstrou-se que a variação da CE na solução do solo interferiu drasticamente nos parâmetros de produção avaliados. UNITERMOS: Capsicum annuum L., fertirrigação, condutividade elétrica do solo, cultivo protegido.  LEONARDO, M.; BROETTO, F.; VILLAS BOAS, R.L.; ALMEIDA, R.S.; MARCHESE, J.A. PRODUCTION OF FRUITS OF BELL PEPPER IN DIFFERENT SALINE CONCENTRATIONS.  2 ABSTRACT An experiment with an Elisa hybrid sweet pepper (Capsicum annuum L.) crop using fertirrigation system was carried out in greenhouse. The aim of this study was to evaluate the quantitative effects of an increasing soil saline concentration on the production. The saline concentration was changed  by the variation of the KCl and Ca2NO3 concentration  in order to obtain high soil electrical conductivity (EC) values. Standard fertigation system (1.5 dS m-1) values were used as control parameters. Besides that, the possibility of saline stress attenuation by applying organic material into the soil was  studied. It was observed that the EC levels used in the crop were inversely correlated to the fructification index and the fruit mean weight. Under the most severe treatment (6.0 dS m-1) the fruit mean weight was reduced up to 58 % and the mean produced fruit number per plant was also reduced up to 55 %, when compared to the obtained results under controlled conditions. These results demonstrated that the EC variation in the soil solution had strong interference on the production parameters selected for the studies. KEYWORDS: Capsicum annuum L., fertirrigation, soil electrical conductivity; protected cultivation

RESUMO:A biomassa resultante do processamento da cana-de-açúcar como o bagaço, tem sido considerada como fonte de celulose com potencial para a produção de biocombustíveis. Este material lignoceluló-sico pode ser transformado em etanol desde que sua estrutura seja hidrolisada por processos químicos (ácidos) ou biotecnológicos (enzimas) gerando açúcares fermentescíveis. Este trabalho teve como objetivo a utilização de processos de pré-tratamento físico e químico para a pré-hidrólise do bagaço de cana-deaçúcar. Para o delineamento experimental foi utilizado tratamento ajustado em fatorial 4 X 2, pela combinação do tempo de pré-hidrólise (15, 30, 45 e 60 minutos) e concentração do ácido sulfúrico (7,0 e 9,0 %) sendo que a incubação foi à temperatura de 121°C em autoclave. Os dados foram submetidos à análise de variância e as médias dos tratamentos foram comparadas pelo teste de Tukey, a 5% de probabilidade. Os resultados obtidos mostraram que através do pré-tratamento ácido aplicado no material lignocelulósico houve quebra significativa das fibras do substrato, como celulose, hemicelulose e lignina. Palavras-chaves:Biomassa, tratamento ácido, celulose. PRE-ACID HYDROLYSIS OF SUGARCANE BAGASSE AND ITS PHYSICOCHEMICAL CHARACTERISTICS SUMMARY: The biomass resulting from processing sugarcane bagasse has been considered a source of cellulose with the potential production of bio-fuels. This lignocellulose can be processed into ethanol since is hydrolyzed by chemical processes (acids) or biotechnology (enzymes) which generate sugars suit forfermentation. This study had the objective to utilize physical and chemical pre-treatment processes for prehydrolysis of sugarcane bagasse. The experimental treatment was adjusted at a factor of 4 X 2, by the combination of pre-hydrolysis timing (15, 30, 45 and 60 minutes) and sulfuric acid concentrations (7.0% and 9.0%) which was incubated at a temperature of 121° C in an autoclave. The treatment data was sub-1 Parte da dissertação de mestrado 1° autor intitulada: "Estudo do pré-tratamento do bagaço de cana-de-açúcar e caracterização físico-química". 2 Aluna do Curso de Pós-Graduação -Energia na Agricultura -FCA/UNESP -Botucatu/SP -Brasil.