Document Type : Original Article
Authors
1 Department of Field Crops Sciences, College of Agricultural Engineering Sciences, University of Baghdad, Baghdad, Iraq
2 Department of Soil Sciences and Water Resources, College of Agricultural Engineering Sciences, University of Baghdad, Baghdad, Iraq
3 Dept of Field Crop Sc, Coll. of Agric.l, University of Anbar, Iraq
Abstract
Maintaining hormonal balance in plants is a significant challenge, and it becomes even more critical under environmental stress conditions, which lead to plant stress, whether biotic or abiotic. This is because plant hormones, in conjunction with other molecular signals, determine the direction of growth (increase or decrease), its extent (cell number and size), its nature (vegetative or reproductive), and the plant's response to the surrounding environmental conditions. This makes hormonal imbalance a critical existential challenge for plants. The increase in CO2 has multiple effects on hormonal balance and, consequently, on plant growth and productivity. It boosts hormones that promote vegetative growth while reducing inhibitors, stimulating important processes such as chlorophyll production and preservation from degradation, enhancing photosynthesis efficiency, improving nutrient absorption from the soil, maintaining water balance, and increasing the efficiency of transport processes within the plant. This results in an increase in the biomass produced per unit area, which is beneficial. However, it could also lead to excessive vegetative growth, shading of lower leaves, and a delay in reaching the reproductive growth stage, potentially reducing the harvest index despite an increase in total dry matter. Although increased CO2 enhances the plant’s tolerance to heat stress, elevated temperatures do not only represent heat stress but also water stress due to rapid evaporation. This can lead to soil salinization because salt accumulation causes ionic and oxidative stress. This imbalance in hormonal, nutritional, and oxidative systems is difficult to predict with precision, but it generally represents a disruption in the system that hinders the plant's healthy growth. Additionally, it increases the plant's susceptibility to serious fungal diseases. Therefore, addressing the increase in CO2 using all available means is a necessity, not a luxury. Permanent changes in the climate may occur that cannot be reversed, such as large floods, hurricanes, wildfires, droughts, dust storms, and the resulting famines and compounded disasters.
Keywords
)
