Leaf photosynthetic characteristics in eight shaded Malaysian filmy ferns

Resumen. Las características fotosintéticas de ocho Malasia Hymenophyllaceae helechos membranosos de hábitats sombreados fueron investigados en este estudio. El contenido de clorofila fue mayor en Trichomanes meifolium, seguido por Cephalomanes obscurum, Hymenophyllum serrulatum, H. denticulatum, H. javanicum, H. acanthoides, H. y H. exsertum blandum con valores que van desde 3,3 hasta 8,6 mg/g peso fresco. El contenido de proteína soluble fue notablemente alta en H. serrulatum, con valores de 53 ± 3,50 mg/g, seguido por H. denticulatum, H. acanthoides, T. meifolium y las otras especies. La relación proteína:clorofila en los helechos fue baja como se esperaba, excepto en H. serrulatum, H. acanthoides y H. denticulatum. Número y tamaño de cloroplasto oscilaron entre las 34 y 138 por perfil de célula y entre 4,8 a 6,5 μm de diámetro, en el Hymenophyllaceae. Mediciones de la eficiencia cuántica de cuatro Hymenophyllaceae spp. mostraron valores de Fv / Fm que oscilan entre 0,73 a 0,81. El Hymenophyllaceae spp. también mostró baja en las tasas de asimilación de CO 2 in vivo y los puntos de saturación, que oscila entre 5 a 15 μmol CO 2 /m 2 /s y por debajo de 150 μmol/m 2 /s, respectivamente. Los hallazgos se añaden a nuestra comprensión de cómo los helechos membranosos se adaptan y prosperan en sus hábitats húmedos y sombríos. Palabras clave: Ciencia de las plantas; Fotosíntesis; Helechos vaporosos; Hymenophyllaceae; Hábitats sombreados. Abstract. The photosynthetic characteristics of eight Malaysian Hymenophyllaceae filmy ferns from shady habitats were investigated in this study. Chlorophyll content was highest in Trichomanes meifolium, followed by Cephalomanes obscurum, Hymenophyllum serrulatum, H. denticulatum, H. javanicum, H. acanthoides, H. exsertum and H. blandum, with values ranging from 3.3 to 8.6 mg/g fresh weight. Soluble protein content was remarkably high in H. serrulatum, with values of 53 ± 3.50 mg/g, followed by H. denticulatum, H. acanthoides, T. meifolium and the other species. Protein to chlorophyll ratios in the filmy ferns were low as expected, except for in H. serrulatum, H. acanthoides and H. denticulatum. Chloroplast number and size ranged between 34 to 138 per cell profile, and between 4.8 to 6.5 μm in diameter, in the Hymenophyllaceae. Quantum efficiency measurements in four Hymenophyllaceae spp. exhibited Fv/Fm values ranging between 0.73 to 0.81. The Hymenophyllaceae spp. also showed low in vivo CO 2 assimilatory rates and light saturation points, ranging between 5 to 15 μmol CO 2 /m 2 /s and below 150 μmol/m 2 /s, respectively. The findings add further to our understanding on how the filmy ferns adapt and thrive in their humid and shady habitats

Photonic multilayer structure of Begonia chloroplasts enhances photosynthetic efficiency

Enhanced light harvesting is an area of interest for optimizing both natural photosynthesis and artificial solar energy capture1,2. Iridescence has been shown to exist widely and in diverse forms in plants and other photosynthetic organisms and symbioses3,4, but there has yet to be any direct link demonstrated between iridescence and photosynthesis. Here we show that epidermal chloroplasts, also known as iridoplasts, in shade-dwelling species of Begonia5, notable for their brilliant blue iridescence, have a photonic crystal structure formed from a periodic arrangement of the light-absorbing thylakoid tissue itself. This structure enhances photosynthesis in two ways: by increasing light capture at the predominantly green wavelengths available in shade conditions, and by directly enhancing quantum yield by 5-10% under low-light conditions. These findings together imply that the iridoplast is a highly modified chloroplast structure adapted to make best use of the extremely low-light conditions in the tropical forest understorey in which it is found5,6. A phylogenetically diverse range of shade-dwelling plant species has been found to produce similarly structured chloroplasts7-9, suggesting that the ability to produce chloroplasts whose membranes are organized as a multilayer with photonic properties may be widespread. In fact, given the well-established diversity and plasticity of chloroplasts10,11, our results imply that photonic effects may be important even in plants that do not show any obvious signs of iridescence to the naked eye but where a highly ordered chloroplast structure may present a clear blue reflectance at the microscale. Chloroplasts are generally thought of as purely photochemical; we suggest that one should also think of them as a photonic structure with a complex interplay between control of light propagation, light capture and photochemistry

Influence of interstock grafting as a dwarfing component on peach trees development and fruit quality

A field experiment was conducted to investigate the interstock grafting effect as a dwarfing component on peach tree development and fruit quality. The study was made at the Ehime University Experimental Farm located in south-eastern Japan during the period 2001-2005. The results of the field experiment indicated that pruned branches weight and flowers number were lower in interstock than in control trees. However, percent fruit set was a little higher in interstock treated than in control trees. Fruit yield and fruit weight were lower in interstock treated than control trees. Soluble solids content and maturity index were higher in interstock treated trees than control, with an increasing trend in the period from 2001 to 2005, while titratable acidity showed an opposite trend. The results of this study showed that the interstock grafting is a useful dwarfing component for controlling the size of peach trees and improvement of fruit quality

Development of elephant apple fruit quality as affected by postharvest ethanol application and temperature

Experiments were conducted to study the effects of temperature and ethanol application on the development and quality of the elephant apple fruit. Various treatments were carried out, viz., at room temperature (RT, 28°C), in exposed sunlight (ES,35°C), in 70 ethanol (ET, 28°C), under plastic covering (PC, 28°C), under plastic covering plus 70 ethanol (PCET, 28°C), at low temperatures (LT, 12°C) and at freezing temperature (FT, -1°C). The longest preservation time was observed in fruits preserved in FT (-1°C) and shortest in fruits preserved in ES (35°C) whilst the maturity index was highest in ES (35°C) treatments and lowest in FT (-1 °C) compared to the other treatments at the end of the experiments. However, fruits kept at FT (-1 °)exhibited chilling injury symptoms. Total Soluble Solids (TSS) was highest in ES (35°C) and PCET (28°) from the 1st to the 7th harvest compared to other treatments. A similar increasing trend in TSS was observed in all the treatments. On the contrary, Titratable Acidity (TA) was highest in FT (-1°C) and LT (12°C) from the 1st till the 7th harvest Similarly a declining trend of TA was found in all the other treatments. TSS was found to be higher in pulp than in peel in the ethanol treatment at 6, 12, 24, 48 and 72 h. However, TA was higher in peel than pulp. The results showed that low temperatures (LT and FT) and plastic covering with 70 ethanol (PCET) delayed ripening in elephant apple fruits and were the best preservation techniques. © 2009 Asian Network for Scientific Information

Water deficit-induced changes on growth parameters and radiation use efficiency of promising durum wheat genotypes

The present study was carried out to study the performance of durum and bread wheat genotypes in relation to accumulation of dry matter, growth parameters, photosynthetically active radiation interception and radiation use efficiency under different irrigation regimes. The experiment was laid out in a split plot based on a complete randomized block design. Irrigation regime was considered as the main plots and included four levels. Sub-plots were assigned to four durum-promising lines and a bread wheat cultivar. It was observed that water limitation significantly decreased the accumulation of dry matter, growth parameter values, photosynthetically active radiation interception and radiation use efficiency compared to optimum irrigation in the different growth and developmental stages. Water limitation during the post anthesis period decreased the cumulative dry matter by 16 compared to optimum irrigation at the soft dough and physiological maturity stages. It appears that a severe decline in net assimilation rate (NAR) during the reproductive and grain filling phases was related to the high reduction in leaf area index (LAI) and crop growth rate (CGR) at post-anthesis, which consequently caused a severe reduction in the relative growth rate RGR and total dry matter in the same phase. The negative effect of early season water deficit on decreasing leaf area index and dry matter extended until terminal maturity. The application of water deficit from anthesis onwards until late grain filling resulted in a remarkable decline in the photosynthetically active radiation interception at the soft dough and physiological maturity stages. From anthesis to grain filling, the results showed that G2 durum wheat genotype (RASCON3/BEJAH7) and Chamran bread wheat cultivar exhibited the highest values for the photosynthetically active radiation interception. However, the radiation use efficiency was stabilized under water deficit condition due to a simultaneous reduction in the photosynthetically active radiation interception and dry matter accumulation

Physiological changes following pollination of Dendrobium Pompadour flowers

One of the most astounding phenomena in many flower species is pollination-induced senescence, where longevity of long-lived flowers is reduced and the functional life of the flowers are terminated. Ethylene which has long been implicated as the precursor of this phenomenon signals for other accompanying physiological changes such as perianth closure, discolouration, petal thinning, loss in flower weight and water uptake. Dendrobium Pompadour is one such orchid that undergoes pollination-induced senescence. In this study, it was found that the longevity of Dendrobium Pompadour flowers was significantly reduced by pollination. Furthermore, the quality of pollinated flowers was also significantly reduced when compared to unpollinated Dendrobium Pompadour