jumpincactus
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Here is a snippet I found relating to optimal root zone temps. They claim more leaf and dry weight yields based on 20 deg C or 68 deg F
Of course the plant used in the study wasn't cannabis, so until legal restrictions on cannabis studies are loosened and more studies are performed using cannabis specifically, we can only play around to find the sweet spot for our beloved plant. As different species and geographical locations will differ with varying genotypes/phenotypes of plants.
For example strawberries had lower fruit yields at higher RZT and actually preferred temps lower than 20 deg C. So really the take away here is we can only experiment to find what works for each of our strains in our own studies,
The influence of supra-optimal root-zone temperatures on growth and stomatal conductance in Capsicum annuum L.
Dodd IC1, He J, Turnbull CG, Lee SK, Critchley C.
Abstract
Pepper (Capsicum annuum L.) plants were grown aeroponically in a Singapore greenhouse under natural diurnally fluctuating ambient shoot temperatures, but at two different root-zone temperatures (RZTs): a constant 20 +/- 2 degrees C RZT and a diurnally fluctuating ambient (A) (25-40 degrees C) RZT. Plants grown at 20-RZT had more leaves, greater leaf area and dry weight than A-RZT plants. Reciprocal transfer experiments were conducted between RZTs to investigate the effect on plant growth, stomatal conductance (gs) and water relations. Transfer of plants from A-RZT to 20-RZT increased plant dry weight, leaf area, number of leaves, shoot water potential (psi shoot), and gs; while transfer of plants from 20-RZT to A-RZT decreased these parameters. Root hydraulic conductivity was measured in the latter transfer and decreased by 80% after 23 d at A-RZT. Transfer of plants from 20-RZT to A-RZT had no effect on xylem ABA concentration or xylem nitrate concentration, but reduced xylem sap pH by 0.2 units. At both RZTs, gs measured in the youngest fully expanded leaves increased with plant development. In plants with the same number of leaves, A-RZT plants had a higher gs than 20-RZT plants, but only under high atmospheric vapour pressure deficit. The roles of chemical signals and hydraulic factors in controlling gs of aeroponically grown Capsicum plants at different RZTs are discussed.
https://www.ncbi.nlm.nih.gov/pubmed/10938830
Of course the plant used in the study wasn't cannabis, so until legal restrictions on cannabis studies are loosened and more studies are performed using cannabis specifically, we can only play around to find the sweet spot for our beloved plant. As different species and geographical locations will differ with varying genotypes/phenotypes of plants.
For example strawberries had lower fruit yields at higher RZT and actually preferred temps lower than 20 deg C. So really the take away here is we can only experiment to find what works for each of our strains in our own studies,
The influence of supra-optimal root-zone temperatures on growth and stomatal conductance in Capsicum annuum L.
Dodd IC1, He J, Turnbull CG, Lee SK, Critchley C.
Abstract
Pepper (Capsicum annuum L.) plants were grown aeroponically in a Singapore greenhouse under natural diurnally fluctuating ambient shoot temperatures, but at two different root-zone temperatures (RZTs): a constant 20 +/- 2 degrees C RZT and a diurnally fluctuating ambient (A) (25-40 degrees C) RZT. Plants grown at 20-RZT had more leaves, greater leaf area and dry weight than A-RZT plants. Reciprocal transfer experiments were conducted between RZTs to investigate the effect on plant growth, stomatal conductance (gs) and water relations. Transfer of plants from A-RZT to 20-RZT increased plant dry weight, leaf area, number of leaves, shoot water potential (psi shoot), and gs; while transfer of plants from 20-RZT to A-RZT decreased these parameters. Root hydraulic conductivity was measured in the latter transfer and decreased by 80% after 23 d at A-RZT. Transfer of plants from 20-RZT to A-RZT had no effect on xylem ABA concentration or xylem nitrate concentration, but reduced xylem sap pH by 0.2 units. At both RZTs, gs measured in the youngest fully expanded leaves increased with plant development. In plants with the same number of leaves, A-RZT plants had a higher gs than 20-RZT plants, but only under high atmospheric vapour pressure deficit. The roles of chemical signals and hydraulic factors in controlling gs of aeroponically grown Capsicum plants at different RZTs are discussed.
https://www.ncbi.nlm.nih.gov/pubmed/10938830