Abstract
Climate change increases the occurrence of droughts, decreasing the production of tropical forages through the induction of physiological stress. Si is expected to broaden the limit from physiological stress of forages grown under water restriction, which may come from an improvement in the stoichiometric homeostasis of Si with N and C, favoring physiological aspects. This study assessed whether Si supply via fertigation improves physiological aspects and the water content in the plant by means of an antioxidant defense system and changes in the C:N:Si stoichiometry during the regrowth of two cultivars of Panicum maximum grown under two soil water regimes (70 and 40% of the soil’s water retention capacity). The forages studied are sensitive to water deficit without silicon supply. The application of Si via fertigation attenuated the water deficit, favoring plant growth by stabilizing the stoichiometric homeostasis C:N and C:Si, which are responsible for increasing the plant capacity of converting accumulated C in dry mass, favoring the water content of the plant tissue and the photosynthetic efficiency. This study highlights the importance of the physiological function of Si, and effects on the stoichiometry of C and N, which are neglected in most research on forages grown under water restriction.
Highlights
Climate change increases the occurrence of droughts, decreasing the production of tropical forages through the induction of physiological stress
Our study indicates that the line of research on the relationship between water deficit and Si in elementary stoichiometry is promising and should advance towards a better understanding of the multiple effects of this beneficial element on the plant
Panicum maximum cultivars Massai and BRS Zuri are sensitive to water deficit without silicon supply, which causes disturbance in stoichiometric homeostasis and in physiological aspects of the crop
Summary
Climate change increases the occurrence of droughts, decreasing the production of tropical forages through the induction of physiological stress. Most studies on stoichiometric homeostasis focus mainly on N and P, studies on the Si are incipient[28,29] These aspects are important because plants under water deficit have energy requirements for their metabolism, with a limitation in C O2 assimilation rate accompanied by an increase in the activity of another sink of absorbed energy, for example, photorespiration[30]. In this scenario, nutrient uptake is affected, impairing plant metabolism and disturbing the stoichiometric homeostasis of C, N, and Si in plant tissues under water deficit[31]. For example, to hemicellulose components via Si–OC bonds, forming an organosilicate compound[34]
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