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• Drought stress reduced yield and nutritional content. • Drought stress reduced photosynthesis and secondary metabolites in two spinach varieties. • Amino acid application improved the osmolytes and antioxidant activities of spinach under drought stress. • Nutrient acquisition and translocation were improved by foliar spray of amino acids. 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. [ABSTRACT FROM AUTHOR]

Salinity is affecting more than 6 million hectares of cultivated area in Pakistan. The use of amino acids offers a pragmatic solution for minimizing the adverse effects of salinity on Spinacia oleracea L. (spinach). The present study evaluated the possible potential of amino acids in enhancing the salinity tolerance in spinach and identified the probable underlying mechanisms. The experiment comprised of two factors viz. amino acids with total of seven treatments; control, salinity (sal) 100 mM, Methionine + sal, Phenylalanine + sal, Proline + sal, Tyrosine + sal, Combined amino acids + sal, and two spinach cultivars (Desi Palak and VRI-2019). Salinity stress decreased the morpho-physiological attributes of both spinach cultivars, nevertheless, the application of combined amino acids effectively improved the tolerance against salinity stress. Compared with control, all applications of amino acids increased the root and shoot length, fresh and dry weight, number of leaves, and plant yield per plant of both spinach cultivars. However, the maximum was noted by the application of combined amino acids. Combined amino acids triggered the activities of antioxidants (catalase, superoxide dismutase, peroxidase), increased the contents of free proline, phenolics, flavonoids, chlorophyll a, b, carotenoids, calcium, and potassium in root and shoot while decreasing the reactive oxygen species (hydrogen peroxide) and sodium contents in both spinach cultivars under saline conditions. Overall, the VRI-2019 performed better than Desi Palak. The vigorous growth along with higher salinity tolerance because of amino acid treatments was linked to better chlorophyll contents, higher accumulation of osmolytes, maintenance of ionic balance, and an improved antioxidant defense system in Spinacia oleracea. [ABSTRACT FROM AUTHOR]

Cucumber is one of the important vegetables for nourishing human being due to the presence of nutrients and vitamins throughout the world. However, its production is decreasing due to several environmental stresses. Amongst the abiotic stresses, salinity is the foremost problems for agricultural crops which cause a great loss in crop production in the world. A number of management approaches have been executed to cope with salinity problem. However, the foliar application of amino acids to enhance plant tolerance under salt stress is a cost-effective technology being utilized in all over the world. For this purpose, the experiments were conducted to evaluate the foliar application of two amino acids i.e., phenylalanine (75 and 100 ppm) and methionine (25 and 50 ppm) separately and in combinations on four cucumber genotypes (HC-999, Valley, NSCCM1 and Akbar). Results showed that 25 ppm methionine showed better behavior towards the enhancement of biomass production as compared to 50 ppm methionine and 75 and 100 ppm phenylalanine separately under saline and non-saline conditions. However in combinations, the 25 ppm methionine with 100 ppm phenylalanine showed better performance in nonsaline and saline conditions in biomass production as compared to all other treatments of both amino acids separately and also in combined foliar sprays. The foliar application of 100 ppm phenylalanine showed better results in nutrients uptake as compared to other treatments of both amino acids separately under saline and non-saline conditions. Therefore the application of 25 ppm methionine with 100 ppm phenylalanine may be used to improve the quantity and quality of cucumber to grow in saline soils. [ABSTRACT FROM AUTHOR]