Off and away. Cleaned, scrubbed, and reworked a few things in the tent. @1400ppm, The increased CO2 allows plants to thrive at higher temperatures, which in turn necessitates higher humidity to maintain the ideal VPD for healthy growth and transpiration. 80F -5F = 75F LST with 70% RH = 0.72 kPa. Higher temperatures and humidity promote rapid growth, nutrient uptake, and photosynthesis while maintaining a lower stress level. Temperature influences the rate of enzymatic reactions involved in aerobic respiration. Enzymes, such as those involved in glycolysis, the Krebs cycle, and the electron transport chain, work most efficiently at an optimal temperature range. In low temperatures, enzymatic activity will slow down, thus reducing the rate of aerobic respiration. In high temperatures, enzymes can become denatured, thus impairing their function and stopping the process of aerobic respiration. Glucose is the primary fuel for aerobic respiration. The rate of aerobic respiration increases with the availability of glucose, as it is the starting point for glycolysis. If glucose levels are low, cells may rely on alternative energy sources such as fatty acids or amino acids , but these processes may yield less ATP or be less efficient. To determine this effect, carbon dioxide volume was measured (as carbon dioxide is an output of aerobic respiration) 18/6 with the 6 being IR instead of darkness, keeping temps overnight a neat 77F-80F. Think of my tent as a lung. What goes in must come out. When the rate of air going out exceeds the amount of air coming in, it creates a negative pressure. Tent concaves (bends in). If set up correctly, your RH will begin to drop slowly to the desired level you set, and the extraction turns off when it reaches 50% RH. The plant, as it performs cellular respiration, will always be releasing more water into the air, so the RH% of the tent overnight will always increase, so long as oxidative phosphorylation is occurring. As soon as the RH% creeps back up to 55%, the extraction turns back on, over and over, this creates a strong pressure differential which will work wonders on your grow. replicating high and low pressure fronts in nature, critical for oxygen diffusion, but more importantly, full control of your RH%. Moisture will not transfer from a saturated atmosphere to another if that air is already at or above its saturation point, meaning the air can't hold any more water vapor. Once I understood that water is produced as a by product during cellular respiration, specifically at the very end of the electron transport chain (ETC) where electrons are finally transferred to molecular oxygen., higher the RH of the air the more resistance there is for more moisture to be added to that environment, and effects the ease with which it does so. But none of that water comes from the pot; it's pulled from the air. If you run high daytime RH, your medium/pot is 100% reliant on transpirational root pull to move water. ZERO evaporation happens across the atmosphere if the tent air has high RH%, the medium cannot release its water through evaporation. Once a canopy develops, light no longer slowly wicks and evaporates from the topsoil. The Soil-Plant-Atmosphere Continuum (SPAC) describes the continuous pathway and process of water movement, driven by a gradient in water potential, from the soil, through the plant's roots, stem, and leaves, and finally evaporating into the atmosphere through transpiration. There is evaporation, there is transpiration, then there is evapotranspiration; Evapotranspiration (ET) is the combined total of two processes: evaporation (water lost directly from soil and surface water into the atmosphere) and transpiration (water released from plants to the atmosphere through their leaves). Evapotranspiration represents the total amount of water that moves from the medium into the air. There is no such thing as a medium with too much water, only a medium that retains too much for too long. The water must always flow efficiently from one atmosphere(Medium) to another(Air) in a timely manner. Moisture is a critical factor for bacterial growth and decay. Dictating how long it's allowed to sit in any one location for any given period is a key preferred control. To ensure a net reduction in a bacterial population, the rate of removal (ET) must exceed the rate of bacterial growth (decay rate), which is often modeled as a growth rate for the specific bacterium under the given conditions. By optimizing daytime VPD, we also optimize conditions for bacterial growth to explode exponentially above 77°F.. If water is allowed to sit in a medium without an escape within a timeframe, nothing good will happen. IF High RH is maintained overnight as well as during the day, placing 100% of water movement at the behest of daytime transpiration, roots can only pull where they can reach, and if soil is compressed above a certain point, moisture will become trapped in a medium with no way of moving day or night. This will begin the countdown for decay to take hold. When water stagnates in a medium, it loses oxygen, creating anaerobic conditions that foster the growth of harmful microorganisms like bacteria and fungi, which can produce toxins and disease vectors. Thigmomorphogenesis, the process by which plants respond to mechanical stimuli like touch by altering their growth and development, resulting in significant morphological changes to improve survival against mechanical perturbations. This complex response involves sensing touch and initiating physiological and genetic responses, leading to changes in form and structure over days or weeks. The process is triggered by physical forces such as wind, rain, or touch. Plants adapt to these stimuli by changing their shape and structure, which may include slower growth, thickened stems, or altered leaf development. Plants possess sophisticated mechanisms to detect even subtle mechanical stimuli and initiate responses. A variety of molecules, including calcium ions, jasmonates, ethylene, and nitric oxide, are involved in signaling these mechanical inputs. Touch can induce the expression of genes that encode proteins for calcium sensing, cell wall modification, and defense mechanisms. A plant exposed to constant wind may become shorter and sturdier. A plant that is touched frequently might grow slower to conserve energy and develop thicker cell walls. These changes increase a plant's resilience and ability to survive in harsh environments.