Perturbations of the normal UV-B radiation environment alter leaf growth rates in Phlomis fruticosa L. seedlings

1995 ◽  
Vol 35 (3) ◽  
pp. 371-377 ◽  
Author(s):  
Y Petropoulou
Keyword(s):  
Growth Rates ◽  
Leaf Growth ◽  
Radiation Environment

scholarly journals Seasonal Acclimation Modulates the Impacts of Simulated Warming and Light Reduction on Temperate Seagrass Productivity and Biochemical Composition

2021 ◽  
Vol 8 ◽  
Author(s):  
Pedro Beca-Carretero ◽  
Tomás Azcárate-García ◽  
Marc Julia-Miralles ◽  
Clara S. Stanschewski ◽  
Freddy Guihéneuf ◽  
...  
Keyword(s):  
Growth Rates ◽  
Zostera Marina ◽  
Leaf Growth ◽  
Seawater Temperature ◽  
Trophic Levels ◽  
Experimental Warming ◽  
Omega 3 ◽  
Growth Physiology ◽  
Light Reduction ◽  
Climate Change Effects

Increases in seawater temperature and reduction in light quality have emerged as some of the most important threats to marine coastal communities including seagrass ecosystems. Temperate seagrasses, including Zostera marina, typically have pronounced seasonal cycles which modulate seagrass growth, physiology and reproductive effort. These marked temporal patterns can affect experimental seagrass responses to climate change effects depending on the seasons of the year in which the experiments are conducted. This study aimed at evaluating how seasonal acclimatization modulates productivity and biochemical responses of Zostera marina to experimental warming and irradiance reduction. Seagrass shoots were exposed to different temperatures (6, 12, 16, 20, and 24°C), combined with high (180 μmol photons m–2 s–1) and low (60 μmol photons m–2 s–1) light conditions across four seasons (spring: April, summer: July, and autumn: November 2015, and winter: January 2016). Plants exhibited similar temperature growth rates between 16 and 20°C; at 24°C, a drastic reduction in growth was observed; this was more accentuated in colder months and under low irradiance conditions. Higher leaf growth rates occurred in winter while the largest rhizomes were reached in experiments conducted in spring and summer. Increases in temperature induced a significant reduction in polyunsaturated fatty acids (PUFA), particularly omega-3 (n-3 PUFA). Our results highlight that temperate seagrass populations currently living under temperature limitation will be favored by future increases in sea surface temperature in terms of leaf and rhizome productivity. Together with results from this study on Z. marina from a temperate region, a wider review of the reported impacts of experimental warming indicates the likely reduction in some compounds of nutritional importance for higher trophic levels in seagrass leaves. Our results further demonstrate that data derived from laboratory-based studies investigating environmental stress on seagrass growth and acclimation, and their subsequent interpretation, are strongly influenced by seasonality and in situ conditions that precede any experimental exposure.

scholarly journals Barley Leaf Area and Leaf Growth Rates Are Maximized during the Pre-Anthesis Phase

Agronomy ◽  
2015 ◽  
Vol 5 (2) ◽  
pp. 107-129 ◽  
Author(s):  
Ahmad Alqudah ◽  
Thorsten Schnurbusch
Keyword(s):  
Leaf Area ◽  
Growth Rates ◽  
Leaf Growth ◽  
Barley Leaf

scholarly journals Effect of mechanical impedance on root and shoot growth of rice at time intervals

1970 ◽  
Vol 19 (2) ◽  
pp. 119-128
Author(s):  
AHMZ Ali
Keyword(s):  
Root Growth ◽  
Growth Rates ◽  
Shoot Growth ◽  
Leaf Growth ◽  
Mechanical Impedance ◽  
Growth Time ◽  
Time Interval ◽  
Night Time ◽  
Time Intervals ◽  
Root And Shoot Growth

In a phytotron chamber the effect of mechanical impedance on root and shoot growth of BR?29 variety of rice at different time intervals reaveled that length of the seminal axis and length of the longest leaf extended linearly in both unimpeded and impeded treatments. Diameter of roots increased in impeded treatment. The number of first order laterals also increased linearly with time in both unimpeded and impeded treatments. Although there were always significantly more laterals on the unimpeded root axes, lateral spacing does not show any tendency to change with time. Root growth rate was nearly half in impeded than in unimpeded treatment. The pattern of root length in unimpeded (UI) did not differ from that of the pattern in impeded (I) treatment as the ratios (I/UI) were more or less constant with time. The time of leaf appearance was delayed by one ? two days and leaf growth period was shortened by one day in impeded than in unimpeded treatment. Leaf growth rates did not differ significantly between day and night time although night time growth rates were always slightly less than day time. Key words: Mechanical impedance; Pattern of root growth; Time interval; Shoot growth; Rice DOI: http://dx.doi.org/10.3329/dujbs.v19i2.8953 DUJBS 2010; 19(2): 119-128

Effect of Temperature on Growth of Five Subtropical Grasses. I. Effect of Day and Night Temperature on Growth and Morphological Development

1978 ◽  
Vol 5 (2) ◽  
pp. 131 ◽  
Author(s):  
DA Ivory ◽  
PC Whiteman
Keyword(s):  
Growth Rate ◽  
Diurnal Variation ◽  
Constant Temperature ◽  
Growth Rates ◽  
Leaf Growth ◽  
Maximum Growth ◽  
Effect Of Temperature ◽  
Panicum Maximum ◽  
Morphological Development ◽  
Night Temperature

Cenchrus ciliaris, Chloris gayana, Panicum maximum var, trichoglume, Panicum coloratum var. makarikariense and Pennisetum clandestinum were grown in two experiments in controlled environments, each experiment having all possible day/night temperature combinations of (1) 10, 20, 30, and 40°C and (2) 15,25, 30 and 35°C. Both day and night temperatures significantly affected growth in all species. Growth was greatly restricted by constant temperatures of 10 and 15°, while maximum growth rates occurred at 29-35°C day temperatures with 26-30°C night temperatures. At optimum or supra-optimum temperatures a diurnal variation in temperature gave higher growth rates than a constant temperature for the same daily mean. By contrast, at suboptimum temperatures a constant temperature gave the highest growth rates and growth rate was decreased as the diurnal variation about a given daily mean temperature was increased. Mathematical functions relating the growth of each species to day and night temperature and maximum growth rate at optimum temperatures were developed. The effect of temperature on relative growth rate (Rw) was mediated through its effect on net assimilation rate (EA). Night temperature was found to affect Rw and EA independently of day temperature and therefore a prehistory effect of night temperature on photosynthesis in the subsequent day was indicated. Temperature had significant effects on tillering in P. maximum and P. clandestinum but had little effect in C. gayana, C. ciliaris and P. coloratum. The optimum temperatures for leaf growth and leaf area development in C. ciliaris and C. gayana were higher than the optimum temperatures for growth of the whole plant, while optimum temperatures for stem growth were lower. In P. maximum, P. coloratum and P. clandestinum, optimum temperatures for all growth components were similar. Differences between temperate and tropical grasses in morphological reaction to temperature are discussed.

Studies of grain production in Sorghum bicolor (L. Moench). V.* Effect of planting density on growth and yield

1975 ◽  
Vol 26 (1) ◽  
pp. 31 ◽  
Author(s):  
KS Fischer ◽  
GL Wilson
Keyword(s):  
Growth Rate ◽  
Grain Yield ◽  
Leaf Area ◽  
Growth Rates ◽  
Dry Matter ◽  
Leaf Growth ◽  
Crop Growth ◽  
Area Index ◽  
Crop Growth Rate ◽  
Net Assimilation

Growth analysis was applied to grain sorghum (cv. RS610) grown at low, medium and high population densities, i.e. 14,352, 143,520 and 645,836 plants ha-1 respectively. The medium densities had two arrangements of plants, square (S) and rectangular (R). Crop growth rates, inflorescence growth rates, leaf area indices, net assimilation rates and leaf growth rates were calculated from growth functions of plant dry matter and leaf area over time. Differences in crop growth rate between populations in the early stages were attributed to leaf area development—specifically to the initial leaf area (dependent on seedling number) and not to differences in leaf growth rates. Peak crop growth rates were 15.0, 27.5, 26.0 and 45.8 g m-2 day-1 for the low, medium (S), medium (R) and high populations respectively.The large difference between the growth rates of the medium (S) and the high populations was not explained by differences in the amount of radiation intercepted. Although leaf area indices were 4.6 and 10.2 respectively for the two populations, both canopies intercepted almost all of the noon radiation. Light extinction coefficients were 0.45 and 0.29 respectively. The relationship between net assimilation rate and leaf area index was such that for comparable leaf area indices above 2, plants at higher densities showed greater improvement in yield per unit increment in leaf area index. A maximum grain yield of 14,250 kg ha-1 was obtained at the high population density as a result of higher dry matter production, but a similar harvest index to that of the crops grown at the other densities. Inflorescence growth rate (g m-2 day-l) slightly exceeded crop growth rate in the latter part of grain filling, which indicated that there was some retranslocation to the grain of previously assimilated material. The maximum grain yield represents an efficiency of utilization of short-wave solar radiation during crop life of 2.5 x 10-6g cal-1. *Part IV, Aust. J. Agric. Res., 26: 25 (1975).

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