Supplemental exogenous NPK application alters biochemical processes to improve yield and drought tolerance in wheat (Triticum aestivum L.).

The recent food security issues, combined with the threats from climate change, demand future farming systems to be more precise and accurate to fulfill the ever increasing global food requirements. The role of nutrients such as nitrogen (N), phosphorous (P), and potassium (K) in stimulating plant growth and development is well established; however, little is known about their function, if applied in combination, in improving crop yields under environmental stresses like drought. The aim of this study was to evaluate the effects of combined foliar spray of supplemental NPK (NPKc) on physiological and biochemical mechanisms that enhance the drought tolerance potential of wheat for improved yield. Foliar NPKc markedly influenced the accumulation of osmoprotectants and activity of both nitrogen assimilation and antioxidant enzymes. It significantly improved the concentration of proline (66 %), total soluble sugars (37 %), and total soluble proteins (10 %) and enhanced the activity of nitrate reductase, nitrite reductase, catalase, and peroxidase by 47, 45, 19, and 8 %, respectively, with respect to no spray under water-deficit conditions which, in turn, improve the yield and yield components. The accumulation of osmolytes and activity of antioxidant machinery were more pronounced in drought tolerant (Bhakkar-02) than sensitive genotype (Shafaq-06).

Supplemental selenium improves wheat grain yield and quality through alterations in biochemical processes under normal and water deficit conditions.

The paper mainly reported the effects of exogenous selenium (Se) supply (Se seed priming, Se fertigation and Se foliar spray) on physiological and antioxidant system of wheat aiming to clarify its effect on yield and nutritional quality of wheat under both normal and water deficit conditions. Water stress markedly decreased the grain Se, iron (Fe), phosphorous (P), zinc (Zn) and magnesium (Mg) contents. Supplemental Se (Na2SeO4) improved the yield and quality of water stressed plants due to enhancement in the production of osmoprotectants and increased activity of antioxidant enzymes. The foliar spray of Se was more effective than Se fertigation and Se seed treatment. To the best of our knowledge, this is the first elaborate study that involved various Se application methods to evaluate the efficiency of Se supply to plants that would be crucial to develop better understanding of Se translocation and accumulation within crop plants under drought stress.

Effect of selenium foliar spray on physiological and biochemical processes and chemical constituents of wheat under drought stress.

Selenium (Se) is considered an essential micronutrient for humans, animals and plants due to its physiological and antioxidative properties. The positive role of Se in attenuation of drastic effects of various environmental stresses in plants is, however, still unclear and need to be explored. The present study aimed at investigating the physiological and biochemical changes induced by Se foliar spray to improve the drought tolerance potential of wheat. Additionally, we also examined the effect of supplemental Se on uptake of nutrients using detection by ICP-OES. Foliar Se application significantly lowered osmotic potential (13%) that markedly improved turgor by 63%, enhanced transpiration rate (60%), improved accumulation of total soluble sugars (33%) and free amino acids (118%) and activity of antioxidant system which ultimately increased the grain yield by 24%. Supplemental Se also significantly increased Se contents (5.77µgg(-1)DW) and improved Fe (91%) and Na (16%) uptake, whereas it reduced Zn accumulation by 54% and did not affect Ca contents. The results supported our hypothesis that supplemental Se influences nutrients uptake and wheat yield through maintenance of turgor and gas exchange characteristics and enhancement in antioxidant system activity.