Photosynthesis of newly matured leaves during the ontogeny of barley grown at different nutrient levels

1975 ◽  
Vol 53 (21) ◽  
pp. 2389-2398 ◽  
Author(s):  
P. Ma ◽  
L. A. Hunt
Keyword(s):  
Nutrient Solution ◽  
Stem Elongation ◽  
Specific Weight ◽  
Leaf Length ◽  
Day Length ◽  
Silica Sand ◽  
Hordeum Vulgare L ◽  
Before And After ◽  
Length And Area ◽  
Hoagland Nutrient Solution

Various growth characteristics were measured throughout ontogeny for barley plants (Hordeum vulgare L. cv. Brant) grown in silica sand and irrigated daily with one-eighth (0.125 N), one-fourth (0.25 N), and one-half (0.5 N) dilutions of a modified Hoagland nutrient solution, at day–night temperatures of 25–20 °C, an irradiance of 53 nE cm−2 s−1 (400–700 nm), and a day length of 15.5 h.The net CO2 exchange rate (NCE) of newly matured leaf laminae did not differ between measurements made at the same irradiance before and after noon. By contrast, NCE was greater at all stages except stem elongation for plants supplied with 0.5 N nutrient solution than for those receiving 0.25 N and 0.125 N solutions. The nutrient effect was apparent even for the first leaf produced. A distinct ontogenetic pattern of change in leaf NCE was apparent under all nutrient treatments: NCE increased from leaf 1 to leaf 3, remained constant between leaf 3 and leaf 5, declined between leaf 6 and leaf 9, and then increased markedly from leaf 10 onwards. The changes in leaf NCE appeared to be associated with major events in ontogeny.Rate of leaf appearance was constant through ontogeny and was not affected by nutrient supply. Final leaf number was greater for the 0.5 N nutrient solution. Leaf length, width, area, and specific weight increased throughout the early stages of ontogeny, and decreased later. The decrease in leaf length and area was less for plants supplied with more nutrients.

Stem and leaf growth of alpine sun and prairie shade ecotypes of Stellaria longipes under different photoperiods: role of ethylene

2006 ◽  
Vol 84 (9) ◽  
pp. 1496-1502 ◽  
Author(s):  
Linda J. Walton ◽  
Leonid V. Kurepin ◽  
David M. Reid ◽  
C.C. Chinnappa
Keyword(s):  
Leaf Growth ◽  
Stem Elongation ◽  
Leaf Length ◽  
Leaf Expansion ◽  
Alpine Plants ◽  
Growth Responses ◽  
Stellaria Longipes ◽  
Length And Area ◽  
Radiation Conditions

Plant ecotypes of Stellaria longipes Goldie from competitive, shade-adapted prairie habitat and less competitive, nonshaded alpine habitat were subjected to shortened or extended photoperiod conditions. Increasing daylength was positively correlated to increased stem elongation in both ecotypes. Leaf length and area for shade (prairie) plants was significantly altered with increased photoperiods, whereas sun (alpine) plants exhibited minimal leaf expansion in response to increased photoperiod. Increased ethylene evolution in the alpine genotype during rapid stem elongation and extended photoperiods suggests that ethylene plays a growth regulatory role in this sun-adapted genotype. The prairie genotype evolved less ethylene during these same periods, indicating either a diminished requirement for elevated ethylene to effect elongation and leaf expansion responses or possibly increased ethylene sensitivity because of interactions with other hormones, such as gibberellin or auxin. The sun genotype consistently produced more ethylene than the shade genotype under all photoperiod treatments. We conclude that photoperiod alters stem elongation and leaf expansion responses; similar trends were observed for extended photoperiods as were observed for shaded conditions, specifically low light intensity (photosynthetically active radiation) conditions. Further, ethylene levels altered during these responses, especially in sun-adapted alpine plants, which suggests that ethylene is involved in these growth responses.

scholarly journals Effects of Day Length and Light Intensity on Growth of Barley IV. Genetically Controlled Variation in Response to Photoperiod

1966 ◽  
Vol 19 (4) ◽  
pp. 517 ◽  
Author(s):  
D Aspinall
Keyword(s):  
Floral Development ◽  
Stem Elongation ◽  
Dry Weight ◽  
Day Length ◽  
Common Mechanism ◽  
Hordeum Vulgare L ◽  
Floral Organogenesis ◽  
Shoot Dry Weight ◽  
Long Day ◽  
Wide Range

Apical growth, floral development, stem elongation, tillering, and dry weight at ear emergence were compared for 10 varieties of barley (Hordeum vulgare L.) growing in a range of photoperiods. All the varieties could be described as quanti. tative long. day plants but there was a wide range of response to the photoperiod. In all the varieties and over all photoperiods, apical primordium production was linked with floral organogenesis, suggesting a common mechanism of photoperiodic influence on the two proce~es. The control of internode elongation, however, varied between different varieties, commencing at a much earlier stage of floral organogenesis in some varieties than in others. Tillering appeared to be controlled more by the amount of energy available for photosynthesis than by any photoperiodic process, and this was also an important factor in shoot dry weight at ear emergence.

Day-length influence on reproductive development and tillering in ‘Fergus’ barley

1975 ◽  
Vol 53 (23) ◽  
pp. 2770-2775 ◽  
Author(s):  
D. T. Fairey ◽  
L. A. Hunt ◽  
N. C. Stoskopf
Keyword(s):  
Hordeum Vulgare ◽  
Reproductive Development ◽  
Tiller Number ◽  
Day Length ◽  
Floral Initiation ◽  
Internode Elongation ◽  
Spikelet Number ◽  
Hordeum Vulgare L ◽  
Initial Formation ◽  
Double Ridge

Effects of variation in day length on spikelet and tiller development were studied in a two-rowed barley, Hordeum vulgare L. cultivar ‘Fergus.’ Spikelet number and the length of the spikelet-forming phase increased with progressive reductions in day length from 24 to 12 h. However, increases in spikelet number were offset by abortion of spikelet primordia during spikelet differentiation and elongation of the stem internodes. Floral initiation occurred at all day lengths, but intemode elongation and heading were markedly delayed at 12 h. The cessation of spikelet initial formation and the beginning of internode elongation did not occur simultaneously in any day length. The latter began just before or at double ridge formation.Tiller numbers were highest at 12 h and progressively decreased in longer day lengths. Each plant produced four primary tillers at all day lengths, and differences in tiller number were accounted for by secondary and tertiary tiller production.

INFLUENCE OF PHOTOPERIOD ON THYROTROPIN RELEASING HORMONE-INDUCED PROLACTIN RELEASE IN EWES

1983 ◽  
Vol 63 (1) ◽  
pp. 67-73 ◽  
Author(s):  
B. E. HOWLAND ◽  
D. SONYA ◽  
L. M. SANFORD ◽  
W. M. PALMER
Keyword(s):  
Thyrotropin Releasing Hormone ◽  
Day Length ◽  
Constant Light ◽  
Serum Prolactin ◽  
Prolactin Release ◽  
Blood Samples ◽  
Releasing Hormone ◽  
Before And After ◽  
Release Curve ◽  
Short Days

The influence of photoperiod on serum prolactin levels and prolactin release induced by thyrotropin releasing hormone (TRH) was determined in ewes maintained under the following lighting regimes: Room 1, lighting mimicked natural changes in photoperiod; Room 2, annual photoperiod changes condensed into 6 mo with short days in June; Room 3, same as Room 2 except photoperiod changed abruptly from 16.5 to 8.0 h on 21 Mar. and back to 16.5 h on 21 June; Room 4, constant light. Weekly blood samples were obtained from February to August. Additionally, blood samples were collected before and after treatment with 10 μg TRH on 19 May, 13 June, 27 June and 19 July. Prolactin levels were elevated in ewes exposed to long days or constant light. The mean of all pre-TRH samples was significantly correlated with stress-induced elevations in prolactin (highest pre-TRH value) (r = 0.72) and area under the TRH-induced release curve (r = 0.56). The prolactin release in response to TRH was greatest in ewes exposed to long days or constant light. Abrupt increase of day length elevated pretreatment prolactin levels (P < 0.01) and increased area under the response curve (P < 0.05). Key words: Photoperiod, TRH, prolactin, ewes

Effects of Nitric Oxide Application on Antioxidant Enzyme Activities of Pepper Plants under Drought Stress

2021 ◽  
Vol 5 (4) ◽  
pp. 846-853
Author(s):  
Fikret YAŞAR ◽  
Özlem ÜZAL
Keyword(s):  
Nitric Oxide ◽  
Drought Stress ◽  
Plant Growth ◽  
Nutrient Solution ◽  
Enzyme Activities ◽  
Growth Parameters ◽  
Antioxidative Enzyme ◽  
High Dose ◽  
Antioxidant Enzyme Activities ◽  
Hoagland Nutrient Solution

The purpose of the study was to determine the relationship between the messenger molecule Nitric oxide (NO) and antioxidative enzyme (SOD: Superoxide Dismutase; CAT: Catalase; APX: Ascorbate Peroxidase) activities in some metabolic changes that occur under the effect of drought stress in plants, to determine the possible roles of Nitric Oxide and to obtain complementary information. The experiment conducted in a controlled environment, and plant were cultured in containers containing Hoagland nutrient solution. For drought stress application, 10% Polyethylene Glycol (PEG 6000) was added to the nutrient solution, which is equivalent to -0.40 MPa osmotic potential. Before the drought stress is applied, pepper seedlings of Demre cv were pre-treated with different doses of Sodium Nitroprusside (SNP) and Carboxy-PTIO (potassium salt) (cPTIO) (SNP 0.01, SNP 1, SNP 100 and SNP 0.01 + cPTIO, SNP + cPTIO, SNP 100+ cPTIO). On the 10th day of the drought application, the growth parameters of the plants; the plant fresh weights and their Antioxidative Enzyme Activities (SOD, CAT, APX) were determined. In terms of plant growth parameters, both plant growth and antioxidant anzyme activities of plants pretreated with 0.01 and 1 doses of SNP were lower than the high dose of SNP and the PEG application without pretreatment. The reason for the low enzyme activities in these applications can be attributed to factors such as the excess accumulation of organic acids such as proline in the cells of the plants and the decrease in H2O2 and O-2 levels in the presence of SNP.

scholarly journals Plant growth regulators to manipulate oat stands

2008 ◽  
Vol 13 (1-2) ◽  
pp. 186 ◽  
Author(s):  
A. RAJALA
Keyword(s):  
Plant Growth ◽  
Plant Growth Regulators ◽  
Growth Regulators ◽  
Stand Structure ◽  
Stem Elongation ◽  
Triticum Aestivum L ◽  
Grain Weight ◽  
Biological Traits ◽  
Hordeum Vulgare L ◽  
Division Cell

Plant growth regulators (PGRs) are exogenously applied chemicals that alter plant metabolism, cell division, cell enlargement, growth and development by regulating plant hormones or other biological signals. For example, some PGRs regulate stem elongation by inhibiting biosynthesis of gibberellins or through releasing ethylene. PGR effects are widely studied and reported on barley (Hordeum vulgare L.) and wheat (Triticum aestivum L.), whereas there are only a few reports addressing oat (Avena sativa L.). This is likely to be a result of smaller acreage and lower intensity of oat management and production and hence a reduced need for stem shortening by PGRs. However, this is not the case for all cereal producing regions and there exists a need to understand the potential application of PGRs to oat production. This paper represents a review of the potential of PGRs to regulate stem elongation and other biological traits governing plant stand structure and yield components, with special emphasis on oat and its responses to PGRs. Yield improvement requires more heads per unit land area, more grains per head or heavier grains. Of these yield-determining parameters, the number of head bearing tillers and grain numbers per head, compared with grain weight, are more likely to be improved by PGR application. In the absence of lodging, PGR may reduce grain yield due to potential reduction in mean grain weight and/or grain number. Cultivation systems aiming at extensive yields with intensive use of inputs likely benefit from PGR applications more often compared with low or moderate input cultivation, for which cost effectiveness of PGRs is not frequently reached.;

Influence of Silica Sand Particles on Disc Brake Squeal Noise

2013 ◽  
Vol 471 ◽  
pp. 81-85 ◽  
Author(s):  
Ahmad Razimi Mat Lazim ◽  
Abd Rahim Abu Bakar ◽  
Mohd Kameil Abdul Hamid ◽  
Izzat Mohd Asri
Keyword(s):  
Surface Condition ◽  
Surface Characteristics ◽  
Silica Sand ◽  
Brake Pad ◽  
Brake Squeal ◽  
The Road ◽  
Film Distribution ◽  
Before And After ◽  
Sand Particles ◽  
On The Road

Researchers in recent years begin to explore on tribological behavior of automotive brake squeal phenomena which covers the morphology, chemical composition, friction and wear, phase composition and third body or friction film distribution. However less effort has been made to study the tribological on the influence of small particles on brake squeal. During braking condition, both rotor and pads are exposed to road environmental particle which may affect pads surface condition. In order to assess the influence of this particle on brake squeal a series of squeal tests were performed. Silica sand grit particles with a size range between 400 to 200 μm which most available on the road surface were used in this experiment. Brake pad and disc surface characteristics were analyzed before and after squealing condition using Scanning Electron Microscope (SEM) and Energy dispersive X-ray analysis (EDX). The result shows that the silica sand particles had influence the squeal and surface behavior of the brake pad.

Juvenile lodging in barley: a yield-depressing phenomenon

1975 ◽  
Vol 26 (2) ◽  
pp. 231 ◽  
Author(s):  
CJ Gardener ◽  
AJ Rathjen
Keyword(s):  
Yield Components ◽  
Stem Elongation ◽  
South Australia ◽  
Leaf Length ◽  
High Fertility ◽  
Nitrogen Application ◽  
Area Index ◽  
Wire Grid ◽  
Plant Densities ◽  
The Relationship

A field experiment was conducted in South Australia to examine the relationship between juvenile lodging (lodging prior to stem elongation) and ear production in barley. Two levels of nitrogen application and six treatments were used either to prevent or increase juvenile lodging in two cultivars. Applications of 2-chloroethyltrimethylammonium chloride (CCC) at the fourth and sixth leaf stages shortened both pseudostems and leaves, prevented juvenile lodging, and increased the number of ears and the grain yield. CCC did not reduce the mature plant height, but did increase the incidence of Rhynchosporium secalis in one cultivar. Ear numbers were marginally increased by supporting the crop with a wire grid or by defoliating the crop to 20 cm at the fifth leaf stage, but this advantage was nullified by a compensating decrease in the other yield components. Removing up to 4 units of leaf area index at this stage did not reduce the yield. Deliberately lodging the crop before stem elongation had little effect since most of the controls lodged naturally. All treatments became erect during stem elongation, and the plants did not lodge again before maturity. It is concluded that short pseudostems, a maximum leaf length under 30 cm, fewer leaves per culm and a shorter period prior to stem elongation are characters which will reduce the juvenile lodging in barley which occurs when the crop is sown early at high plant densities or is grown at high fertility levels.

scholarly journals Effects of postgrazing residue on morphogenetic and structural characteristics of Tifton 85 pastures

2016 ◽  
Vol 37 (4) ◽  
pp. 2043
Author(s):  
Wilton Ladeira Silva ◽  
Ana Cláudia Ruggieri ◽  
Ricardo Andrade Reis ◽  
Américo Garcia Silva Sobrinho ◽  
Euclides Braga Malheiros
Keyword(s):  
Structural Characteristics ◽  
Stem Elongation ◽  
Light Interception ◽  
Climatic Conditions ◽  
Leaf Length ◽  
Elongation Rate ◽  
Area Index ◽  
Structural Variables ◽  
Senescence Rate ◽  
Leaf Appearance

The ideal time to start grazing is when pastures reach 95% light interception. The use of residual leaf area index (rLAI) to time the interruption of grazing under intermittent grazing has recently been studied in forage species in different climatic conditions in Brazil. However, studies evaluating the formation and development of leaves and tillers through morphogenetic and structural variables in functional rLAI are still lacking for Tifton 85 pastures. Therefore, the objective of this study was to evaluate the effects of varying rLAI in successive grazing cycles on morphogenetic and structural characteristics of Tifton 85 pasture grazed intermittently by sheep. Morphogenetic and structural characteristics were evaluated in three grazing cycles under three rLAI conditions (0.8, 1.6, and 2.4). The regrowth interval (time taken to return to 95% light interception) of pastures increased from 21.33 to 29.66 days with decreasing rLAI. The leaf appearance rate increased at a rate of 0.02 leaves tiller-1 day-1 and the number of live leaves per tiller increased by 0.41 with decreasing rLAI. Phyllochron, leaf elongation rate, final leaf length, leaf senescence rate, and stem elongation rate decreased linearly with decreasing rLAI. The number of live leaves per tiller was lower (7.97) in the third grazing cycle, probably owing to the higher senescence rate observed that same cycle, while the other variables had higher values. The 2.4 rLAI condition promotes excessive stem elongation, reduced leaf appearance, lower number of live leaves per tiller, and increased senescence of leaves, while the 0.8 and 1.6 rLAI conditions promote desirable morphogenetic and structural characteristics, which correlate directly with forage quality. In order to avoid excessive forage losses, grazing must occur preferentially by the end of March, when climatic conditions still support the appropriate development of the plants.

scholarly journals Effects of irradiance and penetration resistance on root and shoot growth of rice

1970 ◽  
Vol 20 (1) ◽  
pp. 65-70
Author(s):  
AHMZ Ali
Keyword(s):  
Penetration Resistance ◽  
Leaf Length ◽  
High Irradiance ◽  
Day Length ◽  
Seminal Root ◽  
High Penetration ◽  
Constant Rate ◽  
Root And Shoot Growth ◽  
Rate Of Photosynthesis ◽  
Root Axis

Plants of BR-29 rice were grown at low (0.05 MPa) and high (0.9 MPa) penetration resistances under low (187 μmol/sec/m2) and high (375 μmol/sec/m2) ) irradiances for three and nine days. There was no significant effect of irradiance (p > 0.05) on seminal root axis lengths of rice at three days after transplanting. At nine days after transplanting, seminal root axis lengths were significantly greater in high than low irradiances (p < 0.05), but only in low penetration resistance. Significant effect (p < 0.05) was also found on number of laterals in both low and high penetration resistances. In case of shoot lengths no significant differences (P > 0.05) were found at three or nine days after transplanting between low and high irradiances. But increase in leaf length with time was higher at low irradiance (up to 120 hours) than at high irradiance (up to 96 hours). However, in the phytotron, plants were getting irradiance at a constant rate for the total day length (12 hours) with little mutual leaf shading. It was assumed that these conditions would be likely to give a rate of photosynthesis close to the maximum. Therefore, it may be concluded from this experiment that irradiance can have more prominent effect on root than shoot at different penetration resistances in soil.Key words: Irradiance; Penetration resistance; Growth; RiceDOI: http://dx.doi.org/10.3329/dujbs.v20i1.8839Dhaka Univ. J. Biol. Sci. 20(1): 65-70, 2011 (January)

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