Glycine mitigates fertilizer requirements of agricultural crops: case study with cucumber as a high fertilizer demanding crop

Background: Different approaches have been used to improve mineral nutrient status of plants in absence of chemical fertilization and toward safer products and improved human health. Amino acids have been proposed with such roles in different recent studies. In this study, glycine was applied as foliar (250, 500 and 1000 ppm) or as soil (250 and 500 mg/plant) to cucumber plants compared to unfertilized control and NPK fertilization, under greenhouse conditions. Results: The results showed that all glycine treatments increased leaf area and the economic life of plants compared to control. Soil application of glycine at higher concentration of 500 mg/plant was able to produce the same or better records than NPK fertilization, particularly regarding leaf mineral concentration, plant economic life and total yield. Leaf macro- micro-nutrients were most increased under 500 mg soil-glycine application. Foliar spray of 500 ppm glycine resulted in better records than the other two levels, as spray of 1000 ppm glycine showed adverse and toxic effects including leaf necrosis. Fruit firmness was increased only by NPK and soil application of 500 mg glycine, whereas fruit vitamin C was increased by NPK fertilization, soil application of glycine at both levels (250, 500 mg) and foliar application of glycine at 500 ppm compared to control plants. Conclusion: The results indicate that soil application of 500 mg glycine/plant was able to improve leaf mineral and physiological characteristics towards higher yield and quality.