تأثير الرش بـ Tryptophan و Glycine والبوتاسيوم النانوي في بعض صفات النمو ومحتوى المواد الفعالة لنبات الستيفيا Stevia rebaudiana Bertoni

"Effect of spraying Tryptophan and Glycine and Nano -potassium on some growth characteristics and the active substance content of Stevia

Abstract
The experiment was conducted in the plastic house of the Department of Horticulture and Landscaping at the College of Agriculture, Karbala University, for the period from 15/1/2022 to 15/4/2022 in order to study the role of the two amino acids tryptophan and glycine , individually or in combination with of nano-potassium on the growth and production of the stevia plant and its content of medically active ingredients. The study was carried out as a factorial experiment within a randomized complete block design (RCBD) with three replications. The experiment included three factors, as the first factor represents the amino acid tryptophan, with three concentrations (0, 25, and 50) mg. L-1 and the second factor was the amino acid glycine with three concentrations (0, 500 and 1000) mg. L-1, while the third factor was potassium nano-fertilizer with two concentrations (0, 2) g. L-1. Three sprays per treatment,and the results were as shown below:
The treatment of spraying with the amino acid tryptophan at a concentration of 50 mg. L-1 had a significant superiority in all vegetative growth traits, including plant height, number of main branches, stem diameter, fresh and dry weight of leaves and branches, number of leaves, one leaf area, total leaf area and total chlorophyll content (77.24 cm, 8.72 main branch. Plant-1, 6.851 mm, 71.21 g. plant-1, 37.76 g. plant-1, 68.48 g. plant-1, 22.02 g. plant-1, 142.58 leaf. plant-1, 9.86 cm². leaf-1, 15.04 dsm2 .plant-1 ,9.667 mg.100 g-1 fresh weight respectively), as well as a significant increase in the percentages of nitrogen, phosphorus, potassium, protein and carbohydrates (3.102%, 0.355%, 7.594%, 19.38%, 57.134 mg. g-1 dry weight, respectively) and an increase in the content of the active substance for each of Stevioside and Rebaudioside, which reached (386.42, 210.73) μg. ml-1 respectively.
It was noted that the treatment of spraying with the amino acid glycine at a concentration of 1000 mg. L-1 was significantly superior in all vegetative growth characteristics, including plant height, number of main branches, stem diameter, fresh and dry weight of leaves and branches, number of leaves, single leaf area, total leaf area and total chlorophyll content (82.84 cm, 9.72 main branch. plant-1, 7.543 mm, 74.09 g. plant-1, 39.77 g. plant-1, 71.22 g. plant-1, 22.87 g. plant-1, 151.84 leaf. plant-1, 10.62 cm².leaf-1, 16.85dsm2. plant-1 , 10.071 mg.100 g-1 fresh weight respectively). Also, it was found that there was a significant increase in the percentages of nitrogen, phosphorus, potassium, protein and carbohydrates (3.234%, 0.379%, 7.836%, 20.21%, 56.695 mg. g-1 dry weight, respectively), and an increase in the content of the active substance of Stevioside and Rebaudioside A (404.32, 202.82) μg. ml-1 respectively.
The results showed the superiority of potassium nanoparticles at a concentration of 2 g. L-1 in all indicators of vegetative growth, especially plant height, stem diameter, fresh and dry weight of leaves and branches, number of leaves, leaf area, total leaf area and total chlorophyll content (72.31 cm, 6.146 mm, 62.31 g. plant-1, 33.88 g. plant-1, 59.04 plant-1, 20.53 g. plant-1, 128.41 leaves. plant-1, 8.66 cm2. leaf-1, 12.09dsm2. plant-1, 8.816 mg. 100 g-1 fresh weight, respectively), while it had no significant effect on the number of total branches in the plant. The same concentration caused a significant increase in the percentage of elemental phosphorus, potassium and carbohydrate content (0.297%, 6.981%, 49.465 mg. g-1 dry weight respectively) and an increase in the content of Rebaudioside A only and amounted to 165.08 μg. ml-1.
All the interactions between the study factors had a significant effect on all the studied traits, especially the interactions between the amino acids.
As for the triple interaction between the factors, the treatment (2 g. L-1 potassium + 50 mg. L-1 tryptophan + 1000 mg. L-1 glycine) gave the highest rates and excelled in all vegetative growth characteristics, including plant height and the number of main branches stem diameter, fresh and dry weight of leaves and branches, number of leaves, leaf area, total leaf area and total chlorophyll content (89.68 cm, 12.67 main branch. plant-1, 9.407 mm, 95.10 g. plant-1, 48.43 g. plant-1, 92.83 g. plant-1, 28.05 g. plant-1, 189.09 leaves. plant-1, 14.32 cm2. leaf-1, 27.08dsm2. plant-1, 12.609 mg.100 g-1 fresh weight, respectively) and it was found that there was a significant increase in the percentages of nitrogen, phosphorus, potassium, protein and carbohydrates (3.463%, 0.574%, 11.348%, 21.64%, 68.624 mg. g-1 dry weight, respectively), and an increase in the active substance content of Stevioside and Rebaudioside A amounted to (555.57, 284.81) μg. ml-1 respectivel