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Growing degrees (GDs) is defined as the number of temperature degrees above a certain threshold base temperature, which varies among crop species. The base temperature is that temperature below which plant growth is zero. GDs are calculated each day as maximum temperature plus the minimum temperature divided by 2, minus the base temperature.
In 2-week-old white spruce seedlings that were then grown for 6 weeks in soil at temperatures of 15 °C, 19 °C, 23 °C, 27 °C, and 31 °C; shoot height, shoot dry weight, stem diameter, root penetration, root volume, and root dry weight all reached maxima at 19 °C. [100]
The Utah model assigns different weight to different temperature bands; a full unit per hour is assigned only to temperatures between 3 °C (37 °F) and 9 °C (48 °F). Maximum effect is achieved at 7 °C (45 °F). [4] Temperatures between 13 °C (55 °F) and 16 °C (60 °F) (the threshold between chilling and warm weather) have zero weight ...
Plots of pressure vs temperature for three different gas samples extrapolated to absolute zero. The ideal gas law is based on observed empirical relationships between pressure (p), volume (V), and temperature (T), and was recognized long before the kinetic theory of gases was developed (see Boyle's and Charles's laws). The ideal gas law states ...
Specific leaf area is a ratio indicating how much leaf area a plant builds with a given amount of leaf biomass: = where A is the area of a given leaf or all leaves of a plant, and M L is the dry mass of those leaves. Typical units are m 2 /kg or mm 2 /mg.
Temperature has a multiplicity of effects on plants depending on a variety of factors, including the size and condition of the plant and the temperature and duration of exposure. The smaller and more succulent the plant, the greater the susceptibility to damage or death from temperatures that are too high or too low. Temperature affects the ...
Although the increase in plant size is more or less proportional to plant mass already present, plants do not grow strictly exponentially. [11] In a period of several days, plant growth rate will vary because of diurnal changes in light intensity, and day-to-day differences in the daily light integral. At night, plants will respire and even ...
Biomass partitioning is the process by which plants divide their energy among their leaves, stems, roots, and reproductive parts.These four main components of the plant have important morphological roles: leaves take in CO 2 and energy from the sun to create carbon compounds, stems grow above competitors to reach sunlight, roots absorb water and mineral nutrients from the soil while anchoring ...