Photosynthetic parameters and growth in seedlings of Bertholletia excelsa and Carapa guianensis in response to pre-acclimation to full sunlight and mild water stress / Parâmetros fotossintéticos e crescimento em mudas de bertholletia excelsa e carapa guianensis em resposta a pré-aclimatação a pleno sol e estresse hídrico moderado

Light and water are important factors that may limit the growth and development of higher plants. The aim of this study was to evaluate photosynthetic parameters and growth in seedlings of Bertholletia excelsa and Carapa guianensis in response to pre-acclimation to full sunlight and mild water stress. I used six independent pre-acclimation treatments (0, 90 (11h15-12h45), 180 (10h30-13h30), 360 (09h00-15h00), 540 (07h30-16h30) and 720 min (06h00-18h00)) varying the time of exposure to full sunlight (PFS) during 30 days, followed by whole-day outdoor exposure for 120 days. Before PFS, the plants were kept in a greenhouse at low light levels (0.8 mol m-2 day-1). The PFS of 0 min corresponded to plants constantly kept under greenhouse conditions. From the beginning to the end of the experiment, each PFS treatment was submitted to two water regimes: moderate water stress (MWS, pre-dawn leaf water potential (L) of -500 to -700 kPa) and without water stress (WWS, L of -300 kPa, soil kept at field capacity). Plants under MWS received only a fraction of the amount of water applied to the well-watered ones. At the end of the 120-day-period under outdoor conditions, I evaluated light saturated photosynthesis (Amax), stomatal conductance (g s), transpiration (E) and plant growth. Both Amax and g s were higher for all plants under the PFS treatment. Stem diameter growth rate and Amax were higher for C. guianensis subjected to MWS than in well-watered plants. The contrary was true for B. excelsa. The growth of seedlings was enhanced by exposure to full sunlight for 180 minutes in both species. However, plants of B. excelsa were sensitive to moderate water stress. The higher photosynthetic rates and faster growth of C. guianensis under full sun and moderate water stress make this species a promissory candidate to be tested in reforestation programs.

A luz e a água são importantes fatores que limitam o crescimento e o desenvolvimento das plantas. O objetivo deste estudo foi avaliar os paâmetros fotossintéticos e o crescimento em mudas de Bertholletia excelsa e Carapa guianensis em resposta a pré-aclimatação à luz solar plena e estresse hídrico moderado. Foram usados seis independentes tratamentos de pré-aclimatação a pleno sol (PFS), sendo estes de (0, 90 (11h15-12h45), 180 (10h30-13h30), 360 (09h00-15h00), 540 (07h30-16h30) e 720 min (06h00-18h00)) durante 30 dias seguidos por um período de exposição a pleno sol de 120 dias durante o dia todo. Antes da PFS, as plantas foram mantidas em casa de vegetação a baixos níveis de luz (0,8 mol m-2 dia-1). O PFS de 0 min correspondeu às plantas mantidas constatemente na casa de vegetação. Cada tratamento de PFS foi submetido desde o início até o final do experimento a dois regimes hídricos, denominado de estresse hídrico moderado (MWS, potencial hidrico da folha medido antes do amanhecer (ΨL) de -500 a -700 kPa) e sem estresse hídrico (WWS , ΨL de -300 kPa, solo mantido na capacidade de campo). As plantas do tratamento MWS receberam apenas uma fração do volume de água fornecido para aquelas do tratamento WWS. No final do período de 120 dias foi avaliada a fotossíntese saturada por luz (Amax), a condutância estomática (gs), transpiração (E) e o crescimento. Amax e gs foram maiores em todas as plantas sob o tratamento de PFS. A taxa de crescimento em diâmetro e Amax foram maiores em plantas de C. guianensis submetidas à MWS. O contrário foi observado em B. excelsa. O crescimento das mudas foi maior nas plantas expostas à luz solar em 180 minutos em ambas as espécies. Entretanto, as plantas de B. excelsa foram mais sensíveis ao estresse hídrico moderado. C. guianensis foi à especie que teve melhor desempenho fotossintético e crescimento sob estresse hídrico moderado e luz solar plena...

Measurement of [226]Ra, [228]Ra, [137]Cs and [40]K in edible parts of two types of leafy vegetables cultivated in Tehran province-Iran and resultant annual ingestion radiation dose

The sources of radioactivity in the environment have natural, terrestrial and extraterrestrial, and anthropogenic origins. Plants may get radioactive nuclides in two ways: [i] by the deposition of radioactive fallout, [ii] by absorption from the soil. The concentrations of the natural radionuclides [[226]Ra, [228]Ra, [40]K] and the artificial radionuclide [[137]Cs] in leek and parsley in Tehran province-Iran were determined using HPGe. Also the effective dose due to the ingestion of such vegetables by the population of Tehran province was studied. The average value of radionuclide concentrations in parsley samples were measured 177.69 +/- 12.47 mBq kg[-1] fresh for [226]Ra; 349.62 +/- 28.42 mBq kg[-1] fresh for [228]Ra; 187364.6 mBq kg[-1] fresh for [40]K. The average value of radionuclide concentrations in leek samples were measured 94.31 +/- 6.46 mBq kg[-1] fresh for [226]Ra; 207.47 +/- 19.46 mBq kg[-1] fresh for [228]Ra; 174555 +/- 1704.21 mBq kg[-1] fresh for [40]K. The concentrations of [137]Cs in most of Parsley and Leek samples were below the minimum detectable activity [MDA]. The Average [226]Ra and [228]Ra activities in 29 leek and parsley samples were about 2.63 and 6.78 times the reference values, respectively. The annual effective dose resulting from the studied radionuclides for the adult population in Tehran province were found to be safe in comparison with normal background areas

Activity concentration of radionuclides in plants in the environment of Western Ghats

A field study on the transfer of primordial radionuclides 238U, 232Th, 40K and fallout radionuclides 210Po in different plant species in tropical forest of western Ghats environment is presented. The top storey, Second storey, Shrubs and epiphytic plant species were chosen and concentration of these radionuclides in plant and soil were measured by employing gamma ray spectrometer and alpha counter. The concentration ratio shows the variation in different species while a wild plant Elaeocarpus oblongus and epiphytic plants indicated preferential uptake of these radionuclides. The dust trapped in the root system of epiphytic plants could be used as bioindicator to monitor fallout radionuclides in the Western Ghats. The concentration of 232Th and 40K in leaves depends on the age of the leaves

Efeitos da radiação gama na microbiota e no teor de vitamina C de agrião (Nasturtium officinale) orgânico minimamente processado: aceitação e intenção de compra do produto irradiado / Effects of gamma irradiation in microbiota and of vitamin C of organic watercress (Nasturtium officinale) minimally processed: acceptance an intention of irradiated produce

O aumento do consumo de vegetais frescos e a globalização do mercado de hortaliças e frutas frescas provocaram um aumento na preocupação com as enfermidades transmitidas por alimentos (ETA) associadas a esses produtos. No Brasil, a produção de hortaliças orgânicas vem crescendo, aproximadamente 40 ’POR CENTO’ ao ano. Considerando o exposto, foram analisadas 108 amostras de agrião orgânico minimamente processado e irradiado coletadas, aleatoriamente, em produtores da região de São Roque, São Paulo, no período de novembro de 2005 a março de 2007, para avaliar a ecologia microbiana e a concentração de vitamina C ao longo da cadeia produtiva. As amostras de agrião orgânico coletadas no campo e as de minimamente processado apresentaram populações superiores a 3,0 log UFC/g para aeróbios mesófilos, aeróbios psicrotróficos, Pseudomonas spp, coliformes termotolerantes e E. coli. Salmonella spp, E. coli 0157:H7 e L. monocytogenes não foram detectadas ao longo da cadeia produtiva...

Effect of gamma irradiation and sulphur fertilizer on growth and chemical composition of hibiscus sabdariffa L

Field experiments were carried out during two successive seasons to investigate the effect of gamma irradiation and sulphur fertilization on growth and chemical composition of Hibiscus sabdariffa L. The results showed that sulphur application stimulated plant height, branches number as well as yield components. The maximum values of these characters were obtained as a result of 250 kg S/fed. On the other hand, sulphur treatments increased fixed oil content, anthocyanin content and flavones yield. Concerning the effect of irradiation treatments, it could be concluded that these treatments increased both plant height and branches number. Also, exposed seeds to 1 krad enhanced fruits fresh weight. Generally, most of irradiation treatments increased chemical constituents content of sepals, except pH and TSS%, which had no clear trend. Interaction treatments between irradiation and sulphur application gave in most cases a pronounced effect on vegetative growth and chemical constituents of roselle plants

Effect of microwave treatment on khalal stage of hayani dates

Microwave treatment was applied to dates of Hayani variety at khalal stage followed by drying in an oven at 50 degree. Microwaving for varying times from 0.5 to 10 min and subsequent analyses revealed that the best treatment time was 2 min which led to high contents of reducing and total sugars, acceptable taste [low astringency] and good color. The dried treated dates showed a better taste and lower astringency compared to fresh dates