Light Leaf Research Articles

Light Leaf: Observations of Leaves in Light

Light Leaf: Observations of Leaves in Light

Sward structure, morphological components and forage yield of massai grass in response to residual effect of swine biofertilizer

The present study aimed to evaluate the residual effects of the application of biofertilizer and mineral fertilizer on sward structure and morphological components of Panicum maximum cv. Massai. The experimental design comprised randomized blocks with six treatments consisting of increasing doses of swine biofertilizer (0, 10, 20, 30 and 40 Mg ha-1) and mineral fertilization (150 kg N ha-1, 33 kg P ha-1), with four replicates. The variables analyzed were pasture height, light interception, leaf area index, forage mass and morphological components. Plant height responded linearly and positively to biofertilizer levels in the three evaluations. The highest averages for light interception (51.63%) and leaf area index (1.64) were observed for the 240 days (40 Mg ha-1). Dry leaf mass was influenced by the increase in biofertilizer dose, with increments of 39.68%, 25.07% and 44.66% for the 240, 300 and 360 days, respectively, when compared to the control treatment. Mineral fertilization promoted lower mass of dead material and lower leaf area index but did not differ from biofertilizer for the other variables. The residual effect of swine biofertilizer was greater than that of mineral fertilization, with a minimum use of 20 Mg ha-1 a practical agronomic recommendation.

Light and Water Conditions Co-Regulated Stomata and Leaf Relative Uptake Rate (LRU) during Photosynthesis and COS Assimilation: A Meta-Analysis

As a trace gas involved in hydration during plant photosynthesis, carbonyl sulfide (COS) and its leaf relative uptake rate (LRU) is used to reduce the uncertainties in simulations of gross primary productivity (GPP). In this study, 101 independent observations were collected from 22 studies. We extracted the LRU, stomatal conductance (gs), canopy COS and carbon dioxide (CO2) fluxes, and relevant environmental conditions (i.e., light, temperature, and humidity), as well as the atmospheric COS and CO2 concentrations (Ca,COS and Ca,CO2). Although no evidence was found showing that gs regulates LRU, they responded in opposite ways to diurnal variations of environmental conditions in both mixed forests (LRU: Hedges’d = −0.901, LnRR = −0.189; gs: Hedges’d = 0.785, LnRR = 0.739) and croplands dominated by C3 plants (Hedges’d = −0.491, LnRR = −0.371; gs: Hedges’d = 1.066, LnRR = 0.322). In this process, the stomata play an important role in COS assimilation (R2 = 0.340, p = 0.020) and further influence the interrelationship of COS and CO2 fluxes (R2 = 0.650, p = 0.000). Slight increases in light intensity (R2 = 1, p = 0.002) and atmospheric drought (R2 = 0.885, p = 0.005) also decreased the LRU. The LRU saturation points of Ca,COS and Ca,CO2 were observed when ΔCa,COS ≈ 13 ppt (R2 = 0.580, p = 0.050) or ΔCa,CO2 ≈ −18 ppm (R2 = 0.970, p = 0.003). This study concluded that during plant photosynthesis and COS assimilation, light and water conditions co-regulated the stomata and LRU.

Effect of Square Planting and Nitrogen Scheduling on Yield and Micrometeorological Parameters in Maize

<p class="1">Altering plant spatial distribution induces changes in micro-meteorology of crop canopy and have cumulative effect on yield. Creation of suitable plant spatial distribution is indispensable to explore the beneficial effects of spatial pattern and it could be possible only through altering rectangular spatial distribution, which is commonly practiced in maize. Most of the nitrogen (N) scheduling approaches are growth stages based without considering crop demand and soil fertility status which may not yield better, warrants need based N management for better production in maize. The present study has investigated effects of spatial pattern and nitrogen scheduling on intercepted photosynthetically active radiation (IPAR), light extinction co-efficient (‘k’), leaf temperature (LT) and productivity of maize. The experiments were conducted during 2011 and 2012 at Tamil Nadu Agricultural University, Coimbatore. Treatments were laid out in split-plot design and replicated thrice. Treatments were: six levels of spatial pattern (60 × 25, 30 × 30, 35 × 35, 40 × 40, 45 × 45 and 50 × 50 cm). Growth stage based and need based approach of leaf color chart based (LCC) nitrogen scheduling were imposed. Field experimental results indicated that maize canopy under 30 × 30 and 35 × 35 cm spatial pattern intercepted 10 to 15% more light compared to rectangular pattern (60 × 25 cm). The ‘k’ value and leaf temperature were reduced under this pattern. Higher maize grain yield (GY) was recorded at 35 × 35 cm spatial distribution. The LCC based N scheduling recorded higher values of IPAR, LT and lower ‘k’ values. Square planting favored canopy micro-meterological parameters and which in turn enhanced grain yield of maize.</p>

Development of a SCAR Marker for Rapid Identification of New Kentucky Bluegrass Breeding Lines

As a commonly used turfgrass, Kentucky bluegrass (Poa pratensis L.) (KBG) has many commercially available cultivars for production. After several years of screening, two new lines were obtained (‘KBG03’ and ‘KBG04’), which have high tolerance to summer. The study showed that the two lines revealed similar morphological characteristics, with light green leaf color, narrow leaf blade, high plant height and light 1,000-grain weight. A total of 400 random amplified polymorphic DNA (RAPD) primers and 256 sequence-related amplified polymorphism (SRAP) primer combinations were screened among the two lines and other 4 imported commercial cultivars. The percentages of polymorphic sites were 65.5% (RAPD) and 22.6% (SRAP) respectively. By cluster analysis of RAPD and SRAP data, the dendrogram at a similarity of 0.29 gave two main clusters, of which one group had 4 commercial cultivars, and the other had the two new breeding lines. Furthermore, one specific band of ‘KBG04’ was successfully converted into a dominant sequence characterized amplified region marker (SCAR196). Then the SCAR marker was verified by 39 KBG DNA samples, including imported varieties, domestic varieties and self-breeding lines of our laboratory, and it exhibited high consistency with the original RAPD polymorphic amplification. The results showed that the SCAR marker can be used to distinguish the new line ‘KBG04’ from numerous KBG germplasms, which would be useful for cultivar identification and property rights protection in the future.

Optimization of the rounded leaf offset table in modeling the multileaf collimator leaf edge in a commercial treatment planning system.

An editable rounded leaf offset (RLO) table is provided in the Pinnacle3 treatment planning software. Default tables are provided for major linear accelerator manufacturers, but it is not clear how the default table values should be adjusted by the user to optimize agreement between the calculated leaf tip value and the actual measured value. Since we wish for the calculated MLC‐defined field edge to closely match the actual delivered field edge, optimal RLO table values are crucial. This is especially true for IMRT fields containing a large number of segments, since any errors would add together. A method based on the calculated MLC‐defined field edge was developed for optimizing and modifying the default RLO table values. Modified RLO tables were developed and evaluated for both dosimetric and light field‐based MLC leaf calibrations. It was shown, using a Picket Fence type test, that the optimized RLO table better modeled the calculated leaf tip than the Pinnacle3 default table. This was demonstrated for both an Elekta Synergy 80‐leaf and a Varian 120‐leaf MLC.PACS numbers: 87.55.D‐, 87.55.de, 87.55.Qr

Static Analysis and Fatigue Life prediction of Composite Leaf Spring for a Light Commercial Vehicle (TATA ACE)

In this research work an attempt has been made to check the suitability of composite materials like E- Glass/Epoxy, Graphite/Epoxy, Boron/Aluminum, Carbon/Epoxy and Kevlar/Epoxy for light commercial vehicle leaf spring. First the static analysis is carried out for steel and different composite leaf spring using FE solver ANSYS V10. The obtained results are compared with theoretical values and observed that they have good agreement with each other. The fatigue life of various composite leaf springs is calculated using Hwang and Han relation. From the results it can be concluded that Boron/Aluminum and Graphite/Epoxy are best suitable composite material for leaf spring.

Field assessment of photosynthetic characteristics in micropropagated and grafted wych elm (Ulmus glabra Huds.) trees

A field test of wych elm (Ulmus glabra Huds.) trees micropropagated in tissue culture was established to compare their photosynthetic characteristics with those from control grafted scions. Measurements were made at the sixth growing season after planting. The results showed similarities between the two stock types in terms of height, diameter at breast height, and leaf morphology. Grafted trees, which were markedly less rejuvenated than micropropagated trees, performed better in many of the light absorption and leaf gas exchange attributes including maximum CO2 assimilation rate at saturating photosynthetic photon flux density (Pmax), apparent quantum yield of photosynthesis (α), transpiration rate (E), and stomatal conductance (gs). In the grafts, the direct effect of photosynthesis could be clearly identified by a significantly lower specific leaf area and a higher content of leaf dry mass. Chlorophyll a fluorescence parameters showed non-stressed growth patterns in both stock types. Rates of the maximal photochemical efficiency of photosystem II (Fv/Fm), potential electron capacity (‘area’), and variable-to-initial fluorescence ratio (Fv/F0) were higher in micropropagated elms. Findings from this study indicate that micropropagated elm stock is ready for testing on a larger scale.

The role of photosynthesis in the recruitment of juvenile Quercus gambelii into mature Q. gambelii communities

Abstract Previous work with Quercus gambelii (Gambel's oak), a widespread oak species from the mountains of the western United States and northern Mexico, showed high juvenile density (< 3 cm in DBH [diameter at breast height] or less than 150 cm in height), but few or no small (3–5 cm in DBH) tree sized plants, suggesting a recruitment bottleneck. We postulate that there could be several factors preventing the recruitment of juveniles into the adult population, including reduced light levels, herbivory, competition for soil resources, or a combination of these factors. In this study, we evaluated the response of leaves of Q. gambelii to various light levels. Surface light levels and leaf gas exchange rates were measured for sun (open) and shade (understory) Q. gambelii seedlings in Q. gambelii communities in the Lincoln National Forest, New Mexico, USA. Mean daily photosynthetic flux densities (PFD) in the understory during the monsoon period (wet season) were 40 ± 46 µmol m−2 sec−1, or 6% of the open co...

Low light and low leaf calcium and boron concentrations are associated with fruit pitting, a new disorder in mango (Mangifera indica L.) in India

SummaryA study was conducted to investigate factors associated with fruit pitting, a new physiological disorder in mango (Mangifera indica L.). The incidence of pitting, along with intercepted light (photosynthetic photon flux density; PPFD) and net CO2 assimilation (A) were measured over 2 years at the top of the tree, and 1.0 m and 0.5 m above the crotch (i.e., the main branch-point) in the SE, NE, NW, and SW directions of the tree canopy in the mango cultivars ‘Alphonso’, ‘Amrapali’, ‘Bangalora’, ‘Bombay Green’, ‘Chausa’, ‘Dashehari’, ‘Langra’, ‘Neelum’, ‘Sensation’ and ‘Tommy Atkins’. Leaf nutrient concentrations were also determined in branches bearing normal and pitted fruit. The incidence of pitting was lowest (6.3%) in fruit at the top of the tree, followed by fruit 1.0 m (13.6%) or 0.5 m (20.0%) above the crotch. Similarly, the incidence of pitting was lowest (4.9%) in fruit from the SE of the canopy, followed by those from the NE (8.3%), SW(13.6%), and NW (20.0%). The incidence of pitting in different parts of the canopy reflected the PPFD and A values (A = 0.03 PPFD – 5.736; R2 = 0.91; Pitting (%) = 0.002 – 0.05 PPFD2 – 0.56 PPFD + 37.79; R2 = 0.894). ‘Dashehari’ mango had the highest incidence of fruit pitting (21.8%), and ‘Tommy Atkins’ had the lowest incidence (9.1%). The concentrations of leaf calcium (Ca) [1.17% (w/v) vs. 2.08% (w/v)], and boron (B) (28 µg g–1 vs. 45 µg g–1) were lower in branches bearing pitted fruit than in those bearing normal fruit, respectively. There were inverse quadratic relationships between the mean incidence of pitting and mean leaf Ca levels (Pitting (%) = 11.40 Ca2 – 48.84 Ca + 61.95; R2 = 0.48), and mean leaf B levels (Pitting (%) = 0.040 B2 – 3.67 B + 90.26; R2 = 0.97), and a linear relationship between leaf B and Ca concentrations (B = 20.93 Ca + 0.156; R2 = 0.76). These results suggest that pitting is related to low light levels, and to low concentrations of Ca and B. Experiments are in progress to resolve this problem using foliar or soil applications of Ca and B, and pruning of trees.

Tobacco cultivar and type mediated effects on the population of aphid parasitoid, Aphidius sp. (Hymenoptera: Aphidiinae) and predator, Cheilomenes sexmaculata (Fabricius) (Coleoptera: Coccinellidae).

During 1998-2002, three experiments Were conducted under net housc house conditions to determine the tritrphie interactions involving certain tobacco varieties, aphid, Myzus nicotianae and the aphidophagous species, Aphidius sp. and Cheilomens sexmaculata . The results revealed that C. Sexmaculata population on tobacco cultivars, CM-12 with dark cast leaf character and VT-1158 with open typc leaf character, was higher than in Gouthami with semi-erect and light cast leaf character and Jayasri (erect type). Among the tobacco types, Lanka special (cheroot) followed by Kumkumadri (beedi) were more attractive to the beetle than Badami local ( rustica ) and Samsun (Aromatic). Highest amount of leaf surface waxes detrimental to movement of coccinellids was observed in rustica tobacco (225μg/cm<SUP2) and the lowest in Lanka special (42μg/cm<SUP2). It was also observed that nutritional status of aphids fed on Lanka tobacco was superior to those fed on least preferred varieties. In the casc of Aphidius sp. parasitization involving different tobacco types, significant differences were not observed at top lear position. In Ihe middle leaf position, highest percent parasitization (80.40) was noticed in variety Kanchan followed by Samsun (70.00) and DR-I Lanka (69.54). Except in varieties GT-4 and Kumkumadri (beedi), higher parasitization on bottom leaves was recorded in the rest. The opportunities for utilizing genetic diversity in crop plants for enhancing natural enemy activity are elucilhlted.

Genotypic Differences in Antioxidative Stress and Salt Tolerance of Three Poplars Under Salt Stress

To evaluate genotypic difference in antioxidative ability and salt tolerance in poplars, the authors investigated the effects of increasing content of soil NaCl on salt concentration in leaves, superoxide dismutase (SOD) and peroxidase (POD) activities, malondialdehyde (MDA) content, and membrane permeability (MP) in Populus euphratica Oliv., P. popularis “35–44,” and P. × euramericana cv. I-214 (hereafter abbreviated as P. cv. I-214). Na+ and Cl− concentrations in leaves of P. popularis increased markedly over the increase of the duration of exposure to salinity, and culminated after 28 days of salt stress. SOD and POD activities declined correspondingly, followed by significant increases of MDA and MP, and leaf injury was finally observed. Compared with P. popularis, leaf Na+ and Cl− in P. cv. I-214 exhibited a trend similar to P. popularis, but a lower salt-induced increase of MDA and permeability was observed and lighter leaf necrosis occurred. In contrast to P. popularis and P. cv. I-214, SOD and POD activities in P. euphratica leaves increased rapidly at the beginning of salt stress with a light soil NaCl concentration of 58.5 mmol/L. Furthermore, salt ion concentration, MDA content, and MP in P. euphratica leaves did not increase significantly during 28 days of increasing salt stress. Therefore, the increase in MP in P. popularis and P. cv. I-214 had a close relationship with a salt buildup in leaves under increasing salt stress. Salt-induced declines of SOD and POD activities might accelerate lipid peroxide and consequently resulted in ion leakage. P. euphratica rapidly activated antioxidant enzymes after the onset of salt stress, which might reduce the accumulation of reactive oxygen species and the subsequent acceleration of lipid peroxide. P. euphratica leaves exhibited a higher capacity to exclude salt in a longer period of increasing salinity, thus limited salt-induced lipid peroxide and MP, which contributed to membrane integrity maintenance and salt tolerance of P. euphratica.

Japanese Barberry (Berberis thunbergii) in Forest Understory: Leaf and Whole Plant Responses to Nitrogen Availability

We investigated whether Japanese barberry in forest understory responded to N availability through physiological adjustments at the leaf level or growth components at the plant level. Barberry increased foliar N, photosynthesis at ambient and saturating light and specific leaf area in proportion to N availability. Barberry relative production rate increased with foliar N, leaf biomass, specific leaf area and total canopy N mass. Increases in production and N uptake were proportional and, thus, neither photosynthetic nitrogen-use efficiency nor production per unit of total canopy N differed with treatment or across the range of N status.

Comparison of Upper Leaf and Lower Leaf of Rice Plants in Response to Supplemental Nitrogen Levels

A field study was conducted to study effects of four nitrogen (N) supplemental levels on biomass, protein‐N, non‐protein‐N, and starch of an upper and a lower leaf in rice (Oryza sativa L.). The ranges of leaf protein‐N, non‐protein‐N, total N, and starch concentrations were from 1.18% to 3.66%, from 0.13% to 0.67%, from 1.32% to 4.14%, and from 38.4 mg g−1 to 108.6 mg g−1, respectively. The upper leaf appeared to be more sensitive than the lower leaf in response to N levels on biomass, but larger differences of protein‐N, total N, and starch contents were observed among nitrogen level treatments in the lower leaf than in the upper leaf. Protein‐N may be the best indicative of N status in rice. The lower leaf had a considerably higher ratio of protein‐N to non‐protein‐N at panicle formation and heading growth stage. The lower leaf had higher starch contents, which decreased with increasing N level. The response differences between the upper leaf and the lower leaf with relation to light conditions, developmental extent and leaf function were discussed. The results suggested that the lower leaf could be more suitable as a test sample for N status diagnosis by leaf chemical analysis, especially during the reproductive growth stage.

A COUPLED PHOTOSYNTHESIS AND STOMATAL CONDUCTANCE MODEL FOR MANGO LEAVES

The first step of the modelling approach consisted in designing a model of leaf diffusive conductance (gs) adapted from Ball, Woodrow and Berry (1987), expressing gs mainly as a function of Anet. The widely accepted biochemical model of C3 leaf photosynthesis of Farquhar, von Caemmerer and Berry (1980) was parameterized for well-lit, young, mature mango leaves using response curves of net photosynthesis to intercellular CO2 concentration (A-Ci curves). To obtain an analytical solution for leaf photosynthesis, we used the following additional conductance relation : Ci = Ca - Anet / gb - Anet / gs, where Ca stands for the ambient CO2 concentration and gb for the conductance across the laminar boundary layer. The resulting model of leaf photosynthesis was tested against three sets of data from gas exchange measurements obtained with a portable infrared gas analyser on leaves of 12 year old mango trees, cv. Lirfa, at two periods of the year : August, just before flowering, and from November to December, during the fruiting stage. The need to take into account the influence of light availability, leaf age and sink activity on photosynthetic capacity to upgrade the model is discussed.

THE ANALYSIS OF LIGHT INTERCEPTION AND LEAF AREA INDEX (LAI) IN CENTRAL LEADER 'FUJI/M26' AND 'JONAGOLD/M26' APPLE ORCHARDS PRODUCING HIGH YIELDS AND QUALITY FRUIT

THE ANALYSIS OF LIGHT INTERCEPTION AND LEAF AREA INDEX (LAI) IN CENTRAL LEADER 'FUJI/M26' AND 'JONAGOLD/M26' APPLE ORCHARDS PRODUCING HIGH YIELDS AND QUALITY FRUIT

Seasonal variation of leaf colour in Syrian barley and its association with photosynthetic electron transport rate

Leaves, formed at later developmental stage, in barley genotypes native to Syria are lighter green than those adapted to wetter areas. In the present study, six barley genotypes were objectively assessed for leaf colour throughout a cropping season. Leaf colour was measured by using a chroma meter. The L* a* and b* axes provide a three-dimentional coordinate space of colour that relates to human perception. L* measures psychrometric lightness. The a* axis transects the red and green hues, while the b* axis transects the blue and yellow hues. Syrian landraces showed considerably higher L* indicating that they have a lighter leaf colour. They had higher a* and lower b* values than those of dark-green group until February, and then turned to lower a* and higher b* values thereafter. This indicated ťhe leaves of Syrian landraces had lesser green and yellow hue in winter than in spring. The relationship between leaf-colour variables and the photosynthetic electron transport rates were also explored both in winter and in spring. It is considered that low chlorophyll content and/or higher chlorophyll a/b reduces the risk of damage from photoinhibition.

INFLUENCE OF LIGHT AND REGULATORS ON SENESCENCE RELATED CHANGES IN DETACHED SOYBEAN LEAVES Glycine max

The rate of senescence and the soluble protein profile from the detached soybean leaf senescing either in darkness or light was analysed and compared to those of leaves in which senescence was delayed by application of cytokinin, IAA or enhanced through the action of abscisic acid. Senescence of detached leaf in light differed significantly from senescence in darkpess Ther!!!! chlorophyll and protein were lost at a higher rate in darkness than light. Changes observed during incubation in light or darkness appeared to be related to the condition rather than the role or progress, of senescence. Incubation with IAA delayed senescence only moderately as compared to BA. Cytokinins delayed and ABA accelerated the changes in soluble protein profile compared to water.

Linkage of Physiological Processes and Ecosystem Processes by Integrating Gas Exchange Chamber and Eco-Physiological Computer Simulation Model

For analyzing and interpreting forest dynamics at community and ecosystem levels, this paper introduces the eco-physiological model and gas exchange chamber. The model considered spatial distributions of light intensity and leaf area of different leaf layers within the tree crown on an individual tree basis. Diurnal and seasonal fluctuations of the transpiration rate from May to October 1989 in a standing Fagus crenatatree were measured at intervals of two weeks. The equation variables were defined by multiplying the VPD by the square root of photon-flux density. Estimation of transpiration of a tree was done by multiplying the transpiration rate per unit area by the leaf area at different leaf layers and the light attenuation rate at the same layer. Total stand transpiration was estimated by summing up the transpiration of the trees. The total annual amount of stand transpiration was 3.200 t HiOlhz.The maximum value of mean diurnal transpiration was 2.5 mm in August; and those of May and October were only 1.5 mm. The use of the combinations of the model and gas exchange chamber interrelations helps clarify the unknown functions, productive structures, and relationships among the items within a forest community and its environment.

Wirkung von 5-Azadihydrouracil auf den Gehalt und die Retention des Chlorophylls bei gesunden and virusinfizierten Tabakpflanzen

Summary The effect of the antiphytoviral compound 5-ADHU upon chlorophyll retention in leaf discs of healthy and PVX-infected tobacco plants (Nicotiana tabacum L. “Samsun”) was investigated. Incubation with 10-4 mol · 1-1 5-ADHU retarded the degradation of chlorophyll in leaf discs of infected plants. Pretreatment with 5-ADHU (5 · 10-3 mol · 1-1) retarded the chlorophyll degradation in leaf discs of infected plants significantly after 72 h dark incubation. In intact TMV-infected plants (“White Burley”) spray-application of 5-ADHU (0.9 ´ 10-3 mol · 1-1) stabilized the chlorophyll content in leaves of all insertions. Leaves of infected plants always contained significantly less chlorophyll than healthy untreated or healthy treated plants. The differences in chlorophyll content between healthy and diseased plants correspond to 4... 5 leaf insertions in healthy plants. The chlorophyll contents of light green and dark green leaf areas of TMV-infected tobacco plants revealed differences similar to those between healthy and virus-infected plants. The relationships are discussed that may exist between virus infection, senescence and stress on the one hand and chlorophyll content on the other.