Stimulation Effects of Foliar Applied Glycine and Glutamine Amino Acids on Lettuce Growth

Abstract

Amino acids have various roles in plant metabolism, and exogenous application of amino acids may have benefits and stimulation effects on plant growth and quality. In this study, the growth and nutrient uptake of Romain lettuce (Lactuca sativa subvar Sahara) were evaluated under spray of glycine or glutamine at different concentrations of 0 (as control), 250, 500 and 1000 mg.L-1, as well as a treatment of 250 mg.L-1 glycine+250 mg.L-1 glutamine. The results showed that there was significant increase in leaf total chlorophyll content under Gly250+Glu250, Gly250 and Glu1000 mg.L-1treatments, and in leaf carotenoids content under 250 mg.L-1 glutamine spray compared with the control plants. Shoot fresh and dry weights were highest under 500 mg.L-1 glycine, whereas root fresh weight was highest under 250 mg.L-1 glycine spray. Foliar application of glycine and glutamine had no significant increase in leaf mineral concentrations except for iron, in which 1000 mg.L-1Gly spray resulted in significantly higher leaf Fe concentration compared with the control plants. Leaf vitamin C was increased at 250 and particularly 500 mg.L-1 spray of glycine and glutamine compared with the control. Nevertheless, different amino acid treatments had no significant effect on plant height, leaf SPAD value, root dry weight, and leaf concentrations of N, K, Ca, Mg and Zn. The results indicate that foliar application of glycine and glutamine amino acids can have beneficial effects on lettuce growth, as higher fresh yield, leaf chlorophyll content and vitamin C were obtained by low to moderate concentrations of glycine and/or glutamine amino acids.

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

“…The biostimulation of amino acids on plant vegetative growth traits including leaf SPAD value and leaf area has been also reported in other studies [21,41]. In a study with foliar application of glycine or glutamine in concentrations of 250, 500 and 1000 ppm, it was shown that only glycine at 250 ppm and glutamine at 1000 ppm significantly increased leaf chlorophyll compared to control plants; however, amino acids had no effect on lettuce plant height [2]. Foliar treatment of glycine at 1000 ppm adversely influenced many growth traits of cucumber.…”

“…The enhancement in leaf mineral nutrients due to application of glycine [20,21,41] or even other amino acids [3,9,14,17] has been reported. In a study with lettuce plants only leaf Zn, but not other minerals, was increased by foliar application of 500 ppm glycine [2]. Plant genotype, growth conditions and soil fertility levels are important factors in this regard.…”

“…Plant height, leaf area and leaf SPAD value are among the most important morphological traits of plant growth that are influenced by many factors including mineral fertilization [2,18]. These traits, in cucumber as a high resource demanding crop, are more critically influenced by fertilization than other crops [34].…”

“…Different compounds and agronomic techniques have been proposed and used extensively to enhance mineral nutrition of plants under optimum or stress conditions [23,28,37]. The biostimulation effect of amino acids on plant growth and nutrient uptake enhancement has been frequently reported [2,9,46]. Due to their nature, low application rates and higher efficiency, amino acids are fully friendly to soil, environment and human health [32].…”

Differential Response of Cotton Growth, Yield and Fiber Quality to Foliar Application of Spirulina platensis and Urea Fertilizer

“…In addition, methionine, which also appeared in the chemical analysis of the Spirulina platensis cells used in this study (Table 1), was found by Chen, et al and El-Awadi, et al [34,35] to involve in synthesis of growth regulation substances, encompassed cytokines, leading to increases in NPK contents and dry weight of plant shoots, while tryptophan and phenylalanine increased leaf surface area [36,37] and cysteine expressed important roles in development of cytosol and mitochondria in plant cells, improving hairy plant roots with active nutrients uptake by specific mechanisms described in [38]. Recently, glycine and glutamine were also found in foliar spray cyanobacterial stimulators [39], and also found here in this study as two of the amino acids constituents of the preparation (Table 1). They also found by Mohammadipour and Souri, [40,41] to increase N, Ca, K, P, Fe, Mg, Zn uptake, plant height, shoot and root weights, soluble solids, and vitamin C of the known antioxidant activities.…”