Modulation of growth and biochemical responses in spinach (Spinacia oleracea L.) through foliar application of some amino acids under drought conditions

Abstract

As part of human nutrition, organic fertilizer decreases chemical fertilizers exposure and increases plant nutritional value, which is a major concern nowadays. This study highlights the current state of knowledge on the effect of drought stress and amino acid application to avert drought damage to two spinach (Spinacia oleracea L.) varieties at the developmental and maturation stages. Two varieties of spinach, namely Desi and VRI-2019, were exposed to different amino acid treatments such as methionine (Meth), tyrosine (Tyr), phenylalanine (Phe), proline (Pro) and mixture at 250 mg/L at 50% (drought) and 100% (control). The results showed that drought stress deteriorated spinach's growth and yield attributes and hindered the nutrient uptake of essential nutrients. However, the amino acid application improved the quantity and quality composition of secondary metabolites (flavonoids and phenolics) and enhanced the growth (root length, fresh and dry weight, shoot length, fresh and dry weight), yield attributes (number of leaves, the weight of leaf, yield per plant and leaf area), nutrient uptake (calcium and potassium) and antioxidant machinery (catalase and peroxidase), which differed depending on the spinach varieties; therefore, the use of Desi variety should be recommended under drought-prone areas with the addition of mixed emulsion of amino acids or/and separate doses according to the amino acid availability.