Uncle Ben
Well-Known Member
Some of you guys need to do less posting in cannabis forums and more research about botany.
The rates of photosynthesis and respiration are influenced by many factors, e.g. light, temperature, carbon dioxide, relative humidity, etc. Therefore, temperature cannot be considered in isolation and any statement about an optimum temperature for growth of a given crop cannot be made.
The interaction of factors affecting plant growth is explained based on Blackman’s Principle of Limiting Factors: the rate of a process influenced by many separate factors is limited by the pace of the slowest factor.
In the greenhouse, specific day/ night temperatures are maintained for each flower crop to obtain profitable growth and market quality. Night temperatures have traditionally been stressed in recommendations because plants grow more at night than during the day.
The growth of many plants can occur over a wide range of temperatures. This range may be defined at three basic levels: 1) a minimum temperature below which no growth occurs, 2) an optimum temperature at which the greatest growth occurs, and 3) a maximum temperature above which no growth occurs. Growth rate increases above the minimum temperature until an optimum is reached, then declines until the maximum temperature is reached. The minimum, optimum, and maximum temperatures varies widely among plant species.
Most plants do not respond in the same way to temperature at all stages of growth. Generally, seed germination and early seedling growth occurs most rapidly at warmer temperatures. These same warm temperatures may be detrimental to growth as the plant matures. Young plants have a large leaf area (photosynthetic tissues) compared to stem and root area (respiration tissues). High relative photosynthetic area and warm temperatures favors carbohydrate production and utilization for growth. However, when plants get older, there is more stem and root area (respiration tissues) to leaf area so cooler temperature favor growth by reducing respiration. Plants in a vegetative stage of growth generally have a warmer temperature optimum than those in a reproductive stage. Different parts of the same plant may also have different optimum temperatures for growth. Thus, root growth may show a different response from shoot growth.
http://www.ag.auburn.edu/hort/landscape/temperature.html
The rates of photosynthesis and respiration are influenced by many factors, e.g. light, temperature, carbon dioxide, relative humidity, etc. Therefore, temperature cannot be considered in isolation and any statement about an optimum temperature for growth of a given crop cannot be made.
The interaction of factors affecting plant growth is explained based on Blackman’s Principle of Limiting Factors: the rate of a process influenced by many separate factors is limited by the pace of the slowest factor.
In the greenhouse, specific day/ night temperatures are maintained for each flower crop to obtain profitable growth and market quality. Night temperatures have traditionally been stressed in recommendations because plants grow more at night than during the day.
The growth of many plants can occur over a wide range of temperatures. This range may be defined at three basic levels: 1) a minimum temperature below which no growth occurs, 2) an optimum temperature at which the greatest growth occurs, and 3) a maximum temperature above which no growth occurs. Growth rate increases above the minimum temperature until an optimum is reached, then declines until the maximum temperature is reached. The minimum, optimum, and maximum temperatures varies widely among plant species.
Most plants do not respond in the same way to temperature at all stages of growth. Generally, seed germination and early seedling growth occurs most rapidly at warmer temperatures. These same warm temperatures may be detrimental to growth as the plant matures. Young plants have a large leaf area (photosynthetic tissues) compared to stem and root area (respiration tissues). High relative photosynthetic area and warm temperatures favors carbohydrate production and utilization for growth. However, when plants get older, there is more stem and root area (respiration tissues) to leaf area so cooler temperature favor growth by reducing respiration. Plants in a vegetative stage of growth generally have a warmer temperature optimum than those in a reproductive stage. Different parts of the same plant may also have different optimum temperatures for growth. Thus, root growth may show a different response from shoot growth.
http://www.ag.auburn.edu/hort/landscape/temperature.html
In my tweeks, I recommend a happy medium of about a 10 - 20F DIF and gave the reason for my madness which is backed up by scientific data (see my previous post). 
