Morpho-physiological and biochemical responses in wheat foliar sprayed with zinc-chitosan-salicylic acid nanoparticles during drought stress

The Role of Stress Modifier Biostimulants on Adaptive Strategy of Oregano Plant for Increasing Productivity under Water Shortage

“…These biostimulants, play a crucial role in cell division and growth, plant nutritional cycle, electron transport system, stomatal conductance, and transpiration rates [ 22 , 23 ]. They are rich in plant growth regulators such as gibberellins, auxins, and cytokinins, which stimulate the activation of enzymes involved in photosynthesis and pigment production [ 32 , 33 , 34 , 35 ]. Biostimulants are also reported to influence the chloroplast size [ 22 , 23 ], and the number of chloroplasts within the cells, which in turn promote the synthesis of more chlorophylls [ 24 ].…”

“…The principal source of TSS is the hydrolysis of carbon reserves [ 34 ]. Since both photosynthesis and growth are affected by drought stress, the accumulation of TSS is influenced by their balance [ 33 ]. Considering that growth is affected before photosynthesis may be impaired by water shortage, the accumulation of photosynthesis products can be expected [ 11 ].…”

“…Therefore, they help plants retain more water inside cells and maintain turgor under drought stress, increasing plant resistance to cope with water deprivation conditions [ 38 , 39 ]. Higher levels of soluble sugars were observed in plants treated with stress modulators, as the foliar application of CHN, AMA, SEW, ASA, and SAA, probably enhanced vegetative growth and led to a greater concentration of carbohydrates [ 26 , 33 ]. The increase in TSS may also depend on the up-regulation of different genes involved in sugar transport and metabolism [ 30 ].…”

“…By reducing soil moisture content, CAT, SOD, and APX activities increased in oregano plants treated with the foliar application of the stress modifiers, according to previous findings, evidencing the increasing plant tolerance to water deficit after receiving biostimulant treatments [ 7 , 34 , 35 ]. The mechanism by which CHN neutralizes free radicals may be related to its structure, which consists of a large number of accessible amine and hydroxyl groups that can react with free radicals [ 33 , 45 ]. These results suggest that stress modifiers may help mitigate oxidative stress by maintaining steady-state intercellular ROS levels, and, consequently, protecting cell membranes from damage caused by a severe water deficit [ 23 , 33 , 43 , 45 ].…”

“…The mechanism by which CHN neutralizes free radicals may be related to its structure, which consists of a large number of accessible amine and hydroxyl groups that can react with free radicals [ 33 , 45 ]. These results suggest that stress modifiers may help mitigate oxidative stress by maintaining steady-state intercellular ROS levels, and, consequently, protecting cell membranes from damage caused by a severe water deficit [ 23 , 33 , 43 , 45 ]. Stress modifiers can also influence the resistance to water deficit and adverse environmental factors by affecting the expression of specific plant genes involved in the defense mechanisms against stressful conditions [ 7 ].…”