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We examined physiological and growth promotion traits in water-deprived pineapple explants inoculated with two endophytic diazotrophic bacteria. The following questions were addressed: (i) Is the root inoculation efficient to increase bacteria population associated to pineapple explants? (ii) Are nutrient concentrations improved in pineapple explants in response to endophytic bacteria inoculation? (iii) Can endophytic bacteria improve pineapple explants’ growth and photosynthesis? (iv) Is it possible to mitigate water deprivation negative effects and facilitate pineapple explants’ acclimatization using endophytic diazotrophic bacteria? Pineapple ‘Vitoria’ explants grown in vitro were inoculated with two different bacteria species. Therefore, 10 mL of bacteria suspension (108 cells mL−1) of either Burkholderia silvatlantica strain UENF 117111 or Herbaspirillum seropedicae strain HRC54 were applied in the substrate after transplantation. Uninoculated explants received 10 mL of autoclaved DYGS liquid medium (Control treatment). These treatments were subdivided in two water regimes, so that explants were either full-irrigated (FI) or non-irrigated (NI) for 24 days. Thereafter, NI explants were re-irrigated to saturation for two days. We found that: (i) The inoculation was efficient to increase bacteria associated to the plantlets; (ii) Nutrient concentrations were not improved in pineapple explants inoculated with both bacteria species; (iii) B. silvatlantica did not change both growth and photosynthetic capacity of the explants. Nonetheless, H. seropedicae inoculation caused negative effects on growth, whereas Anet was increased; (iv) The use of both bacteria delayed water deprivation effects and maintained the photosynthetic capacity through C3 metabolism intact for longer periods under water deprivation, as well as by recovering Anet after re-irrigation.

The Jacarepagua Lagoon (JPAL) is part of a lagoon complex, formed by others threelagoons, located in the west zone of Rio de Janeiro city, and has largest drainage area of the complex (103 Km2). JPAL constantly receives the clandestine release of domestic and industrial effluents, in addition to diffuse contributions from drainage waters from different sources, with a high pollution load. Ecological Risk Assessment (ERA) is an important tool with a more global view of the risks for the management of contaminated areas, including the identification of adverse effects of contaminants on the environment. This study aimed to develop an ERA for the JPAL, using two lines of evidence (LoE): Ecotoxicological LoE and Ecological LoE. The sediments samples were collected in four sampling points (SP) in the JPAL. The Ecotoxicological LoE was based on chronic ecotoxicity assays (Chlorella vulgaris and Ceriodaphnia dubia) to estimate the Ecotoxicological Risk. The Ecological LoE was based on the analysis of the richness and abundance of local algae species to estimate the Ecological Risk. The Environmental Risk was estimated by integrating the Risks of the two LoE. The Ecotoxicological Risk was 0.80±0.12, classified as very high (0.75-1.0). The highest Ecotoxicological Risk was estimated for the SP3, being 0.95. The Ecological Risk was 0.746±0.01, classified as high risk (0.50-0.75). The estimated Environmental Risk was 0.78±0.08, which was a very high risk. The highest Environmental Risk was estimated also for the SP3, being 0.88. In summary, JPAL had an advanced stage of contamination, with a high content of organic matter in the sediment, caused by irregular effluents released. JPAL's current environmental risk exposes the urgent need for more inspection actions to prevent the release of sewage before the total degradation of the local ecosystem.

RESUMO A utilização da técnica de enxertia em maracujazeiros tem sido uma estratégia promissora para o desenvolvimento de cultivares tradicionais de maracujazeiros que, por sua vez, apresentam raízes suscetíveis a vários patógenos do solo. Contudo, não se conhece o efeito desta técnica sobre as trocas gasosas, as relações hídricas e a eficiência fotoquímica em plantas desta espécie. O objetivo deste trabalho foi estudar a capacidade fotossintética, as relações hídricas e o crescimento de maracujazeiros propagados por semente (PPS) e propagados por enxertia (PPG), submetidos à limitação da disponibilidade de água no solo. O presente estudo foi realizado em casa de vegetação, utilizando mudas de Passiflora edulis f. flavicarpa e mudas enxertadas [Passiflora edulis f. flavicarpa (enxerto) e Passiflora mucronata (porta-enxerto)] cultivadas em potes de 3,5 dm3. Aos 37 dias após o transplantio (DAT), foi suspensa a irrigação em metade das plantas propagadas por sementes (PPSDS, plantas propagadas por sementes em condições de deficiência hídrica) e em metade das plantas propagadas por enxertia (PPGDS, plantas propagadas por enxertia em condições de deficiência hídrica). Em um outro grupo de plantas, o solo foi mantido na capacidade de campo. As trocas gasosas, a emissão da fluorescência da clorofila, a estimativa do teor de clorofilas e os potenciais hídricos foliar e do solo foram determinadas durante o experimento. Nas plantas PPSDS e PPGDS, a restrição hídrica reduziu os valores da condutância estomática, o rendimento quântico incidente (Φi) e a massa seca da raiz em relação aos respectivos controles mantidos irrigados (PPS e PPG). Tanto para as PPSDS e PPGDS, até os valores de -50 kPa de potencial hídrico do solo, houve redução da taxa fotossintética em 50%, sem haver redução do potencial hídrico foliar. Em relação às plantas enxertadas, as plantas propagadas por semente apresentaram maiores valores das medidas biométricas, tanto cultivadas na condição de capacidade de campo, como cultivadas na condição de limitação de água no substrato. A técnica de enxertia não comprometeu o estado hídrico, a emissão da fluorescência e as trocas gasosas. ABSTRACT Grafting has been used in passion fruit as a promising strategy for the improvement of traditional cultivars, which have roots susceptible to several soil pathogens. However, the effect of grafting on gas exchange, water relations, and photochemical efficiency in passion fruit is still not understood. The objective of this study was to evaluate the photosynthetic capacity, water relations, and the growth of seed-propagated (PPS) and grafted (PPG) passion fruit under drought stress. Ungrafted seedlings of Passiflora edulis f. flavicarpa and seedlings of Passiflora edulis f. flavicarpa (scion) grafted onto Passiflora mucronata (rootstock) were cultivated in a greenhouse in 3.5-dm3 pots. At 37 days after transplanting (DAT), one-half of the seed-propagated plants had the watering suspended (PPSDS, plant propagated by seed under drought stress) as well as one-half of the grafted plants (PPGDS, plant propagated by grafting under drought stress). Another group of plants was kept in soil at field capacity. Gas exchanges, chlorophyll fluorescence emission, chlorophyll content, and leaf and soil water potentials were determined during the experiment. Drought-stressed plants (PPSDS and PPGDS) reduced the stomatal conductance, incident quantum yield (Φi), and root dry mass in relation to the respective watered controls (PPS and PPG). Up to -50 kPa of soil water potential, both PPSDS and PPGDS reduced the photosynthetic rate by 50%, without reducing leaf water potential. The seed-propagated plants showed higher growth characteristics than the grafted plants in both conditions, at the field capacity and in the substrate with water limitation. Grafting showed no effect on water status, fluorescence emission, and gas exchange.

Papaya ( Carica papaya L.) nutrient requirements can be supplied through fertigation. However, this application method can increase solute concentrations, thereby increasing salinity and raising the electrical conductivity (EC) of the substrate when the nutrients are applied at supra-optimal levels. This can profoundly affect plant photosynthetic capacity and growth. We undertook an investigation to determine: (i) if reduced papaya growth due to salinity is caused by a possible decrease in osmotic potential, a nutrient imbalance, or both, (ii) the sensitivity of stomata of two papaya genotypes to increased EC, and (iii) if increased EC is detrimental to papaya photochemical capacity. Two different papaya genotypes (Sunrise Golden and Uenf-Caliman 01 hybrid) were fertilized with a nutrient solution with different EC: 1.0, 1.6, 2.2, 2.8 or 3.4 deciSiemens per meter (dS m −1 ). We found that (i) reduced growth was likely caused by a decrease in osmotic potential of the substrate. Nutrient imbalances were not present and did not account for growth reductions of either genotype under elevated EC, (ii) both genotypes are very sensitive to stomatal effects in response to increased EC, and (iii) an increase in EC up to 3.4 dS m −1 did not negatively affect the photochemical capacity of either genotype. However, there may have been non-stomatal effects at the Calvin cycle enzyme level. The results of this study show the importance of considering salinity as a relevant abiotic condition for papaya plantations and provide a basis for further field experiments to evaluate effects of high solute concentrations on yield and quality of papaya fruit.

Papaya canopy architecture enables all the leaves to receive sufficient amounts of sunlight to optimize leaf gas exchange due to the spiral phyllotaxis. Thus, there may be a close relationship between photosynthesis and transpiration measurements at single-leaf and whole-canopy levels. We tested this hypothesis by simultaneously measuring single leaf and whole canopy gas exchange of ‘Gran Golden’ papaya during two seasons. Whole-canopy gas exchange was measured on five plants during four days in July (winter) from 08:00 to 1700 h and three days in December (summer) from 06:00 to 1700 h in 2006. Single-leaf gas exchange measurements were performed using the fully exposed 12th and 13th leaf from the apex on five plants adjacent to those with whole canopy chambers at the same time of the day. Net photosynthetic rate (A) values on a single-leaf or whole-canopy basis in field-grown papaya were similar and highly correlated under clear sky conditions since the open canopy architecture of papaya plants allowed saturating light intensities for photosynthesis to reach all leaves. Conversely, whole-canopy transpiration (Ec), was approximately 50% of single-leaf transpiration (El) likely due to high air temperature and VPDleaf-air and increased leaf fan speed in the LI-6200 leaf chamber (single leaf) compared to the whole canopy chamber. Therefore, water use efficiency measured on a single-leaf basis seems to have reduced applicability in papaya water relations studies.

Pineapple (Ananas comosus L.) is a bromeliad with constitutive CAM metabolism. However, facultative C3/CAM metabolism in the first 2 months of growth is a characteristic of this species. Thus, young pineapple plants can exhibit C3 photosynthesis when the environmental conditions, such as the diurnal temperature range and water supply, are favorable to growth. However, high temperature diurnal amplitude, soil/air moisture alterations and changes in light intensity in association with air humidity have caused facultative C3/CAM metabolism. The objective of the study was to assess the physiology and growth of ex vitro ‘Vitoria’ and ‘IAC Fantastico’ pineapple genotypes during acclimatization from the in vitro environment. The research was carried out in a greenhouse using the split plot design used in the in vitro culture (Couto et al, Rev Bras Frutic 36(2):459–466, 2014). The explants were planted in trays with Vivatto® substrate. The net photosynthesis rate, growth and photochemical efficiency were measured at 60 and 75 days of acclimatization (DA). The greater growth (canopy diameter and height, shoot dry mass, total dry mass and leaf area) of ‘IAC Fantastico’ was associated with CAM metabolism. CAM metabolism was likely induced by the stressful environmental micrometeorological variables inside the greenhouse. In contrast, ‘Vitoria’ exhibited C3 metabolism and reduced growth at 60 and 75 DA. ‘Vitoria’ had greater photosynthate partitioning to the root system and high photochemical efficiency 75 DA. We conclude that the stress imposed by the environmental conditions induced CAM metabolism in ‘IAC Fantastico’ and increased growth gain characteristics at 60–70 DA.

Whole-canopy gas exchange measurement in papaya can provide a scientific basis to optimize irrigation and fruit yield and quality. The objectives of this study were to: (1) verify the relationship between xylem sap flow measured by the heat coefficient method, and whole canopy transpiration in ‘Gran Golden’ papaya (Carica papaya L.), (2) examine the relationship between xylem sap flow determined from calculations based on forcing water flow through a stem section, and whole canopy transpiration, and (3) verify the relationship between transpiration measured in a plant chamber and calculated reference evapotranspiration (ET0). The experiment was conducted in a commercial planting at the Caliman Agricola SA farm, Sooretama, ES, Brazil in summer and winter. Whole-canopy gas exchange was measured in custom-built, flow-through whole-canopy Mylar® chambers. There was a correlation (r2 = 0.65) between xylem sap flow measured with the heat coefficient (K) method and whole-canopy transpiration rate measured in the chambers. However, sap flow methodology could not convert this correlated response into an accurate estimate of papaya transpiration measured with whole canopy chambers. The sap flow methodologies were linearly correlated with whole canopy transpiration but each would require additional calibration to the crop. ET0 was correlated with whole canopy transpiration in winter but not in summer likely due to stomatal control of transpiration, as a result of the high leaf temperature and ET0 in summer. The concept of sap flow to measure transpiration has value in papaya production but supplementary studies will be necessary to improve the accuracy and estimation of the whole-canopy transpiration in the papaya plant.

Introduction. Papaya is one of the very few fruit crops multiplied by seed. Unfortunately, the use of seedlings hampers the preservation of favorable plant characteristics and delays the appearance of the first flowers. In addition, the polygamous nature of papaya imposes planting 3-4 seedlings per hole in order to be certain of obtaining the right sex type. These shortcomings can be circumvented by clonal multiplication. This work aimed to multiply selected papaya cultivars from cuttings using the rooting promoting auxin indole-3-butyric acid (IBA). Materials and methods. Two experiments were conducted; the first one followed a completely randomized factorial design, with cultivars ’Golden’ and ‘Uenf/Caliman 01’ as levels of the first factor, and 0, 500, 1,000, 1,500, and 2,000 ppm IBA as levels of the second factor. In this first trial, rooted cuttings of ‘Uenf/Caliman 01’ were taken to the field and compared to seedlings soon after planting and 4.5 months later. In the second experiment, IBA levels were increased aiming to enhance rooting percentage. Physiological assessments of rooted cuttings were also performed in this second experiment. Results and discussion. A concentration of 3,000 ppm IBA gave the best results for ‘Golden’, while lower concentration (1,500 ppm) seemed indicated for ‘Uenf/Caliman 01’. Rooting success in ‘Uenf/Caliman 01’ was improved by using cuttings obtained from beheaded mother plants. The analyses showed that a few roots were sufficient to maintain good water status and photosynthetic rate in new plantlets. Conclusion. Plants propagated from cuttings had early flowering and produced first fruits at a lower height than seedlings in the field.

This study assessed the ecophysiological aspects of the in vitro multiplication of ‘Golden’ papaya in response to different light qualities, ventilation systems and sucrose concentrations related to photosynthesis, chlorophyll fluorescence, water balance and growth. The treatments were performed in a complete, randomised split-plot design with four replicates. These treatments consisted of white and red light, closed and ventilated culture systems and four sucrose concentrations (10, 20, 30 and 40 g L−1) in the culture medium. The lowest plantlet water loss rate was obtained using the ventilated culture system. The photochemical damage was attributable to the reduced maximum PS II quantum yield and the efficiency of the oxygen-evolving complex (OEC). The increase in the production of papaya dry biomass was due to the exogenous carbon source, the sucrose that was added to the culture medium. In this study, there was no photosynthetic carbon assimilation (Aactual, actual photosynthetic rate) or oxygen evolution (Apot, potential photosynthetic rate) due to the damage caused by the presence of sucrose in the culture medium to the photochemical capacity of the oxygen-evolving complex (OEC) and PS II activity. Further studies are needed using a sucrose concentration below 10 g L−1 in association with the increased irradiance of the culture chamber (red lights) as well as carbon dioxide enrichment (over 400 μL L−1 of air). These conditions may stimulate the autotrophic metabolism of this species for in vitro cultivation and increase the rate of biomass production.

This study was carried out to verify the practical use of the portable chlorophyll meter-PCM502 (PCM) in two papaya cultivars with contrasting green coloring of the leaf blade (‘Golden’: yellowish-green; ‘Solo’: dark green). The relationship was studied between the photosynthetic process and leaf nitrogen concentration, chlorophyll concentration and SPAD readings. The Portable Chlorophyll Meter (or SPAD meter) is a simple, portable, accurate, fast and inexpensive tool. Two Carica papaya L cultivars were grown in a greenhouse with 30 % interception in the photosynthetic active radiation (PAR). At 90 and 100 days after sowing (DAS), two groups of leaves from each cultivar were used for experiments. One group was considered as “young” leaves (3rd or 4th leaf from the apex) and one group as “mature” leaves (6th or 7th leaf from the apex). In these experimental conditions the following parameters were measured: net photosynthesis, Fv/Fm (potential maximal quantum yield of PSII), total chlorophyll concentration and leaf organic nitrogen. At SPAD values lower than 20 for ‘Golden” and 30 for ‘Solo’, the Fv/Fm ratios were correlated with the increase in the ratio as determined by the PCM. There were cultivar differences related to N allocation in the leaf. ‘Golden’ partitioned significantly less N to chlorophyll synthesis than ‘Solo’ at equivalent leaf N concentrations. This explains in large part the yellowish green leaf coloring of ‘Golden’ papaya. These cultivar differences in chlorophyll concentration were measurable with PCM technology. In contrast, at SPAD values

The effects of successive brassinosteroid analogue (BR) applications (0.1 mg l −1 of brassinosteroid analogue BB-16) were evaluated on commercial yellow passion fruit ( Passiflora edulis f. flavicarpa ) orchards in the first year of production. The treatments applied were: control, BR-1 (1 BR application shortly after the first flowers appeared), BR-2, BR-3, BR-4 and BR-5 (BR application in two, three, four and five consecutive weeks after the appearance of the first flowers, respectively). The fruits were collected for seven consecutive weeks (105 fruits treatment −1 ) and fruit mass, length and diameter, soluble solid contents; pulp mass and peel thickness were evaluated in the laboratory. Multivariate analysis was performed in order to determine whether there were differences among the treatments taking into account all the measurements made. BR-3 was the most promising treatment because it produced the highest number of fruits plant −1 (81.5) compared to the control (53.5) and the soluble solid content was 1 °Brix greater than the control. The BR-3 treatment resulted in a 65% increase in the estimated yield of the passion fruit plants, corresponding to 20 t ha −1 compared to the control yield of 12 t ha −1 . The results showed that BB-16 sprayed during a period of reproductive development can increase the number of fruits per plant.

The chlorophyll meter (SPAD-502) is a simple, portable diagnostic tool that measures the greenness or relative content of leaves. Compared to the traditional destructive methods, the use of this equipment saves time, space and resources. The objective of this study was to establish a correlation between the photosynthetic pigments content extracted in DMSO, the total nitrogen content and the chlorophyll a fluorescence variables with the SPAD-502 readings in Coffea canephora Pierre leaves. The SPAD-502 has been shown to be a good tool to diagnose the integrity of the photosynthetic system in coffee leaves, and can thus help in the advanced interpretations of the photochemical process of these plants. The SPAD readings lower 40 show impairment in photosynthetic process. Thus, the portable chlorophyll SPAD-502 can be used to analyze the photosynthetic pigments, and total nitrogen can also help in interpretation of the photochemical process in coffee plants.

The techniques utilized to extract chlorophyll from plant materials are destructive and based on methods that use organic solvents. This study proposes the non-destructive quantification of chlorophyll and nitrogen concentration using a portable chlorophyll meter (SPAD-502). Further, was possible to establish relationships between chlorophyll fluorescence and SPAD-502 values. This methodology could save time, space and resources, and could be used for analysis of the photosynthetic processes. Papaya leaves (Solo and Formosa groups) of different ages were collected from 15-month-old plants cultivated in a commercial field in São Francisco de Itabapoana, Rio de Janeiro State (41(0):15W; 21(0):27S). Correlations were established between the chlorophyll content and carotenoids extracted in DMSO, nitrogen content, a chlorophyll a fluorescence (Fphi, Fmax, Fnu/Fmax, qN, qP, NPQ) with readings from SPAD-502 taken on papaya leaves of different ages. The results show that while the q p and the Fnu/Fmax increased with SPAD-502 readings of up to 40, the qN and NPQ variables decreased. The Fmax presented a direct linear correlation with the SPAD-502 values while the Fphi variable did not correlate with the SPAD-502 values. The portable chlorophyll meter was shown to be useful for nondestructive determination of photosynthetic pigments (chlorophyll and carotenoids) and can be used indirectly in advanced interpretation of the photochemical process in Carica papaya L. leaves. Os métodos utilizados para a extração de clorofila em materiais vegetais são destrutivas e baseiam-se em métodos que utilizam solventes orgânicos. Este trabalho propõe a quantificação não-destrutiva dos teores de clorofila e nitrogênio por meio do SPAD-502. Ainda, foi possível estabelecer uma relação entre a fluorescência e os valores obtidos pelo SPAD-502. Tal metodologia poderá proporcionar uma substancial economia de tempo, espaço e recursos contribuindo na melhoria das interpretações dos processos fotossintéticos. Para tanto, foram utilizadas folhas de mamoeiros (grupos 'Solo' e 'Formosa') de diferentes estádios de desenvolvimento, coletadas de plantas com 15 meses de idade, cultivadas em plantio comercial no município de São Francisco de Itabapoana/RJ. Foram estabelecidas correlações entre os teores de clorofila e carotenóides extraídos em DMSO, os teores de nitrogênio, a fluorescência da clorofila a (Ffi, Fmax, Fni/Fmax, qN, qP, NPQ) e as leituras pelo SPAD 502 em folhas da espécie em estudo, dos grupos 'Solo' e 'Formosa'. Os resultados mostraram que enquanto a variável qP e a relação Fni/Fmax foram crescentes, até leituras do SPAD-502 próximas a 40, as variáveis qN e NPQ se mostraram decrescentes. Foi verificado que a variável Fmax apresentou uma correlação linear, direta, em relação aos valores do SPAD-502, enquanto que a variável Ffi não apresentou nenhuma correlação com os valores do SPAD-502. De acordo com os resultados apresentados, concluiu-se que o determinador portátil de clorofila poderá ser utilizado na quantificação dos pigmentos fotossintéticos (clorofilas e carotenóides) e poderá indiretamente auxiliar nas interpretações avançadas do processo fotoquímico da fotossíntese em plantas da espécie Carica papaya L.

Submitted by Guilherme Lemeszenski (guilherme@nead.unesp.br) on 2013-08-22T18:44:15Z No. of bitstreams: 1 S1807-86722013000100007.pdf: 649420 bytes, checksum: 63e098f988f142e204077e3e7f270d8f (MD5) Made available in DSpace on 2013-08-22T18:44:15Z (GMT). No. of bitstreams: 1 S1807-86722013000100007.pdf: 649420 bytes, checksum: 63e098f988f142e204077e3e7f270d8f (MD5) Previous issue date: 2013-03-01 Made available in DSpace on 2013-09-30T19:32:17Z (GMT). No. of bitstreams: 2 S1807-86722013000100007.pdf: 649420 bytes, checksum: 63e098f988f142e204077e3e7f270d8f (MD5) S1807-86722013000100007.pdf.txt: 19834 bytes, checksum: d4cac23c5eeb39967aaa18f0eb302f94 (MD5) Previous issue date: 2013-03-01 Submitted by Vitor Silverio Rodrigues (vitorsrodrigues@reitoria.unesp.br) on 2014-05-20T15:08:48Z No. of bitstreams: 2 S1807-86722013000100007.pdf: 649420 bytes, checksum: 63e098f988f142e204077e3e7f270d8f (MD5) S1807-86722013000100007.pdf.txt: 19834 bytes, checksum: d4cac23c5eeb39967aaa18f0eb302f94 (MD5) Made available in DSpace on 2014-05-20T15:08:48Z (GMT). No. of bitstreams: 2 S1807-86722013000100007.pdf: 649420 bytes, checksum: 63e098f988f142e204077e3e7f270d8f (MD5) S1807-86722013000100007.pdf.txt: 19834 bytes, checksum: d4cac23c5eeb39967aaa18f0eb302f94 (MD5) Previous issue date: 2013-03-01 O objetivo deste ensaio foi determinar equações que indiretamente associem os valores obtidos no medidor de clorofila SPAD-502 aos teores de clorofila e carotenóides de genótipos de capim-elefante anão. Folhas de genótipos de capim-elefante anão foram utilizadas e, depois de coletadas, foram transportadas em caixas de isopor, protegidas da luz, até o laboratório de Fisiologia Vegetal da UENF. Posteriormente, os discos foliares de área conhecida foram extraídos. Com o auxílio do medidor portátil de clorofila (MPC) SPAD-502, foi obtida a média de 5 leituras/disco foliar e utilizaram-se 6 discos para cada intervalo, distribuídos de acordo com a seguinte escala de valores do MPC: 0-10; 10-20; 20-30; 30-40; 40-50; 50-60. O medidor de clorofila SPAD-502 possibilitou uma rápida e eficaz estimativa do conteúdo de clorofila total, clorofila-a e clorofila-b em genótipos de capim-elefante anão. Equations that indirectly associate the rates obtained by chlorophyll meter SPAD-502 to chlorophyll and carotenoids rates of dwarf elephant grass genotype are provided. Leaves of the genotype of dwarf elephant grass were employed. After being collected, they were transported in light-protected styrofoam boxes to the Plant Physiology Laboratory of UENF. Leaf discs of the known area were then extracted. An average of 5 readings/leaf disc were undertaken by portable chlorophyll meter SPAD-502, with 6 discs for each range and distributed according to the following scale: 0-10; 10-20; 20-30; 30-40; 40-50; 50-60. Chlorophyll meter SPAD-502 provides a quick and efficient estimate of total chlorophyll, chlorophyll-a and chlorophyll-b in genotypes of dwarf elephant grass. Universidade Federal dos Vales do Jequitinhonha e Mucuri Faculdade de Ciências Agrárias Departamento de Zootecnia Universidade Estadual do Norte Fluminense Darcy Ribeiro Laboratório de Zootecnia e Nutrição Animal Centro de Ciências e Tecnologias Agropecuárias Universidade Estadual do Norte Fluminense Darcy Ribeiro Laboratório de Melhoramento Genético Vegetal Centro de Ciências e Tecnologias Agropecuárias Universidade Federal do Espírito Santo (UFES) Departamento de Zootecnia Centro de Ciências Agrárias Universidade Estadual Paulista Júlio de Mesquita Filho Faculdade de Medicina Veterinária e Zootecnia de Botucatu Universidade Estadual Paulista Júlio de Mesquita Filho Faculdade de Medicina Veterinária e Zootecnia de Botucatu

Brassinosteroids (BS) application is associated with the increase of tolerance to some kinds of stresses, such as those induced by the infection of pathogens, temperature, salt and water deficiency. In this work, the influence of a spirostanic analogue of brassinosteroid (SAB) in the leaves of papaya Golden and UENF/CALIMAN 01 (UC 01) was tested to evaluate alterations in the content of chlorophyll in plants submitted to drought stress (DS). When plants were 70 d old, SAB was applied (0,1 mg L-1) for five consecutive days in half of the plants meant for the experiment. The treatments were: control irrigated (I), I with SAB (IB), DS and DS with SAB (DSB). The evaluated leaves were marked in accordance to the age: LEAF 1 (youngest expanded leaf), LEAF 2 (insertion immediately below LEAF 1) and LEAF 3 (insertion immediately below LEAF 2). The same leaves were used throughtout the experimental period. After the thirteenth day, the chlorophyll contents of DSB (Golden and UC 01) were always lesser than the treatment DS in LEAF 2. The irrigation was restarted in stressed plants on the fifteenth day, followed by new application of SAB (IB and DSB treatments). In Golden plants, DSB showed the lowest values of chlorophyll contents after re-watering, while in UC 01, differences in chlorophyll contents between treatments DS and DSB had not occurred. Alterations in Fv/Fm relation did not occur among the treatments during stress. In genotype UC 01, the irrigated plants showed minor values of Fv/Fm at the end of the experiment, whereas the plants submitted to DS presented increments in this relation in this same time. These results indicate that SAB might have contributed to accelerate the rate of leaf senescence of the oldest leaves of stressed plants, redistributing photoassimilates and other compounds for the youngest leaves.

The Portable Chlorophyll Meter (PCM) is used to estimate the total chlorophyll and leaf nitrogen content of various species. Since there is a relationship between the chlorophyll concentration and the photochemical efficiency, a relationship can also be established between the PCM readings and some fluorescence variables to provide information on photosystem II (PSII) structure and activity. Papaya (Carica papaya L.) plants ['Sunrise Solo' (leaves with intense green coloring) and 'Golden' cultivars (leaves with yellow-green coloring) were grown in a greenhouse with 30% interception of photosynthetically active photon flux density. The plants were cultivated in 15L plastics pots. Ninety to 100 days after planting the older leaves turned yellow and the chlorophyll fluorescence variables and PCM readings were measured. At low PCM values (less than 30 to 'Sunrise Solo' and less than 20 to 'Golden') the PSII structure and activity were damaged, which is likely related to a reduction in the numbers of active reaction centers (RC/CS0). At higher PCM values the chlorophyll a fluorescence variables (ABS/RC, DI0/RC, TR0/CS0 e ET0/CS0) that are related to PSII structure and activity PSII were not responsive. These results indicated that the effects of chlorophyll content measured by PCM on the photochemical phase of photosynthesis evaluated by chlorophyll fluorescence occur after the degradation of chlorophyll molecules is initiated. In papaya the Portable Chlorophyll Meter (SPAD-502) was shown to be suitable for diagnosis of PSII energy distribution under N stress and senescence.

Submitted by Vitor Silverio Rodrigues (vitorsrodrigues@reitoria.unesp.br) on 2014-05-27T11:24:40Z No. of bitstreams: 0Bitstream added on 2014-05-27T14:30:42Z : No. of bitstreams: 1 2-s2.0-77950835346.pdf: 150951 bytes, checksum: ae4c1afb39ddcaff022c77fc73dc7399 (MD5) Made available in DSpace on 2014-05-27T11:24:40Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-04-19 The experiment was carried out aiming to evaluate the gas exchange of dwarf elephant grass genotypes under different hydric conditions, in a randomized design with three replications. Genotypes of dwarf elephant grass (Mott, CNPGL 94-34-3 and CNPGL 92-198-7) were analyzed under two hydric conditions: irrigated (I) and non-irrigated (NI). Differences between treatments I and NI were observed for all genotypes for photosynthesis, stomatal conductance, transpiration and water vapor pressure deficit. Genotype CNPGL 94-34-3 presented highest tolerance to hydric stress, followed by Mott and CNPGL 92-198-7 genotypes. All genotypes presented high photosynthetic rate, under ideal conditions of soil humidity, thus characterizing the analyzed dwarf elephant grass genotypes as plants with high photosynthetic efficiency. Departamento de Zootecnia-Forragicultura e Pastagem Faculdade de Ciências Agrárias Universidade Federal Dos Vales Do Jequitinhonha e Mucuri, Rod. MGT 367, Km 583, 5000, 39100-000, Diamantina, Minas Gerais Laboratório de Zootecnia e Nutrição Animal Centro de Ciências e Tecnologias Agropecuárias Universidade Estadual Do Norte Fluminense Darcy Ribeiro, Campos dos Goytacazes, Rio de Janeiro Laboratório de Melhoramento Genético Vegetal-Fisiologia Vegetal Centro de Ciências e Tecnologias Agropecuárias Universidade Estadual Do Norte Fluminense Darcy Ribeiro, Campos dos Goytacazes, Rio de Janeiro Laboratório de Fitotecnia Centro de Ciências e Tecnologias Agropecuárias Universidade Estadual Do Norte Fluminense Darcy Ribeiro, Campos dos Goytacazes, Rio de Janeiro Faculdade de Medicina Veterinária e Zootecnia de Botucatu Universidade Estadual Paulista Júlio de Mesquita Filho Botucatu, São Paulo Faculdade de Medicina Veterinária e Zootecnia de Botucatu Universidade Estadual Paulista Júlio de Mesquita Filho Botucatu, São Paulo

Brazil is the largest world producer of papaya and the third largest exporter despite of only 1.5 to 2.0% of its production is exported. Such an underexplored exportation potential highlight the necessity for physiological studies on new cultivars and hybrids to verify their agronomic and commercial viability. Two Brazilian states, Bahia and Espirito Santo, are responsible for 80% of national production. Papaya can also be an agricultural alternative to north / northeast of Rio de Janeiro, because the region is close to consumer centers and have similar environmental conditions of the most productive regions. Nevertheless, it is worth to develop cultivars that can express the highest yield potential in this region. The aim of this work was to characterize physiologically two hybrids developed for the north/northeast of Rio de Janeiro (UENF/Caliman 01 and JS12) in comparison with three top commercial genotypes (Golden, Sunrise Solo 7212 and Tainung) of Caricapapaya L. The cv. Golden presented the lowest shoot and root growth, the lowest height, shrunk diameter, specific leaf weight, less efficiency in electrons transport per sample area and show the lowest ability to synthesized total chlorophylls in comparison with the others genotypes. At noon, this genotype showed higher stomatal conductance, related to the leaf-air vapor pressure deficit, which lead to higher transpiration rate and intrinsic water use efficiency. No differences were detected in the photosynthetic rates among the five genotypes suggesting that the UENF`s hybrids are endowed with similar photosynthetic capacity and morphological characteristics to the top commercial genotypes. The relevance of this characterization to drive future successful genetic improvement programs will be discussed.

The purpose of this study was to evaluate the nitrogen-use efficiency of 15 corn hybrids in different environments. The experiment was conducted at the research station Embrapa Milho e Sorgo, in environments with low (12 kg ha-1) and high (120 kg ha-1) nitrogen fertilization, in a randomized block design with three replications. The chlorophyll content, leaf nitrogen and nitrate reductase activity in the flag leaf were determined at flowering and the grain yield was evaluated at harvest. The chlorophyll content proved to be sensitive to nitrogen availability, although without discriminating genotypic differences efficiently. To use nitrate reductase for this purpose, further studies are needed on the reliability of this biochemical variable to diagnose genotypes efficient in N use precociously. The hybrid L2xL3 was considered promising for maize breeding programs aimed at gene introgression related to N-use efficiency.