Under saline soil conditions or soil irrigated with saline water (when comparing with non-saline condition), what are the possible reasons for the crop/canopy/organ temperature difference?
Under water stress plants trend to close stomata, reducing photosynthesis and transpiration. Reductions in traspirations directly increase the foliar-canopy temperature avoiding the evaporation of the water inside the leaves and this energy termic dissipation process.
The two answers given above are true because plants find it difficult to take in saline water because its water potential is much lower (more negative) than the water potential in the leaf or the whole plant in that matter. Thus unless the plant is adapted to the saline conditions it will experience increased respiration to generate energy for its life maintenance, and hence producing heat which can be sensed as differential temperature.
Under stress conditions abscisic acid content in the leaves increases thus resulting in stmatal closure,resulting in inhibition in metabolic activities and transpiration.
Reduction in transpiration is directly related to increase in canopy temperature.
Akwilin the heat produced by respiration can be considered really lower if you compare with the stomata closure.
The main reason is for sure the reduced transpiration rate caused by the closure of stomata in response to the lower water potential of the salt treated soil. However, other responses could be considered: some can compensate as changes in leaf angle or development of smaller leaves that dissipate heat more efficiently; others may add up as an increased rate of heat dissipation from the photosystems. I searched before without success if someone has ever quantified this heat dissipation in terms of the leaf energy budget. Basically when conductance is reduced a smaller part of the PAR can be used for photosynthesis and this excess light is dissipated as heat to prevent damages to the photosystems.
Best luck with your research
I think water is one of the most important material for crop or plant growth and has a relation with temperature due to physiological characteristic. Therefore with increasing the water scarcity in agroecosystem, temperature of plant increase and show the level of crop or plant water stress.
All nutrients like N, P, K, and other micronutrients like Fe, Cu, B, Mn, etc are available in salt form. But proper ionic condition or form required for plant uptake. If soil or irrigated water contain more salt then EC will be disturb and available nutrient will be converted in non uptaketable form. So proper EC will be will be required for proper plant growth
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