Review of Negative Impact of Extreme Temperature Elevations on Plant Growth, Development and Crop Yield using Mathematical Equations

Paul O. Jaiyeola, Funmilola A. Oluwafemi, Abdullahi Ayegba, Irene E. Benibo

Temperature, Transpiration, Stomatal Conductance, Rubisco Activity

This study reviewed the negative impact of extreme temperature elevations on plant growth, development and crop yield using some mathematical equations that relates temperature either directly or indirectly with some agricultural parameters. The agricultural parameters employed are Temperature, Vapor Pressure Deficit (VPD), Transpiration, Leaf Water Potential, Stomatal Conductance, Photosynthesis, Carbon Dioxide (CO₂) Concentration, Substrate, Rubisco Activase/Activity, Electron Transportation and Cuticle Resistance. Ideally increasing temperature enhances transpiration and photosynthesis, but transpiration enhancement leads to leaf water loss and consequently to impaired Leaf Water Potential due to leaf water stress as transpiration increases with temperature. The decreased Leaf Water Potential results in a reduced stomata opening and Stomatal Conductance. Increasing VPD as temperature increases also reduce Stomatal Conductance. This stomatal closure or reduced Stomatal Conductance enhances CO₂ concentration on the leaf surface and intercellular system of the leaf which further causes reduction in Stomatal Conductance. The enhancement of CO₂ concentration on/in the leaf promotes greenhouse gases effect leading to leaf temperature enhancement. The increase in the CO₂ concentration accumulated on the leaf leads to impairment of Rubisco activity due to decrease in CO₂ assimilation, because the transpiration rate is not matching with the incoming CO₂ or the photosynthetic rate due to the leaf water stress, as transpiration increases with temperature. The excess CO₂ found accumulating on and inside the leaf further reduce Stomatal Conductance, enhance leaf temperature and low-down the electron transportation to reduce the Rubisco activase/activity that determine photosynthetic rate as temperature increases. It was discovered that increasing VPD as well as increasing CO₂ decreased Stomatal Conductance, having direct negative effect on Stomatal Conductance than temperature elevations. Increasing CO₂ concentration accumulated on the leaf with decrease in electron transportation decreases Rubisco activity that is meant to enhance photosynthesis as temperature increases. Increase in VPD and increase in CO₂ concentration on and inside the leaf, with the decrease in Leaf Water Potential can be seen as the direct and best factors that majorly influence Stomatal Conductance rather than increasing temperature that has indirect influence. The increase in Stomatal Resistance, decrease in Stomatal Conductance, decrease in electron transportation and increased CO₂ will in turn impair transpiration and photosynthetic rate (or Rubisco activity) which consequently leads to poor plant growth, development and most especially crop yield.

https://dx.doi.org/10.31873/IJEAS.8.4.05