The Effect of Arginine on some Biochemical Attributes Strawberry Fruit (Fragaria× ananassa cv. Albion) under Deficit Fertigation

 Strawberries with the scientific name Fragaria × ananassa Dutch. It belongs to the Rosaceae family. Strawberry is one of the fruits that has found many fans around the world due to its aroma, taste and nutritional value. The main characteristics of strawberry fruit quality are flavor (ratio of sugar to acid and volatile compounds) and color. Excellent plants need nitrogen in addition to carbon to meet their growth and food needs. The most vital compounds in plant living cells are proteins, which are made up of amino acid building blocks. Different amino acid sequences cause variation in the resulting proteins. Arginine is a multifunctional amino acid found in living cells and is an important storage and transport form for organic nitrogen in plants. In addition to its function as a major component of protein, it is an essential metabolite for many cellular and growth processes. Studies have shown that arginine increases the synthesis of flowering hormones related to flowering and fruiting. This amino acid is also involved in the activity of various plant enzymes. This amino acid binds to membrane nucleic acids and phospholipids and increases the activity of enzymes such as catalase. Due to the importance of producing organic products and also due to the fact that so far no study has been done on the effect of arginine on the growth and physiological characteristics of strawberry cultivar Albion. Therefore, in this study, the role of arginine on some quantitative and qualitative characteristics of albumin strawberry fruit in hydroponic conditions was investigated.
 The present study was conducted in the greenhouse of the Faculty of Agriculture, Urmia University, Iran. In this study, the effect of arginine with three levels (0, 100 and 200 mg / l) on the quantitative and qualitative characteristics of Albion strawberry fruit under deficit fertigation conditions with two levels (140 and 180 ml) in a completely randomized design with 4 replications. In this study, traits such as fruit flavor, titratable acidity, soluble solids, fruit firmness, vitamin C, total phenol, total flavonoids, total anthocyanins and total antioxidant capacity were investigated. XTPlus-TA tissue analysis device was used to measure the firmness of fruit texture. Vitamin C content of fruit extract was measured by ascorbic acid based on dye reduction of 2,6 dichlorophenol indophenol (DCPIP). The Titration method was used to measure titratable acidity (TA). ATAGO manual refractometer was used to measure the amount of soluble solids. Also for measuring the taste of fruit by Voca et al. used. The Absorption difference method at different pHs was used to measure total anthocyanin. Total antioxidant capacity was assessed using the DPPH (1,1-diphenyl-2-picrylhydrazyl) method. Folin-ciocalteau method was used to measure the total phenol content. Shin et al. Method was used to measure the total flavonoid content of fruit.
 The results obtained from the analysis of variance of the data showed that the measured indices were affected by different treatments of arginine and deficit fertigation. Based on the results, arginine treatment on fruit flavor, titratable acidity, soluble solids, fruit firmness, total anthocyanin, vitamin C, phenol, flavonoids and total antioxidant capacity showed a significant difference. The highest amount of soluble solids, fruit flavor and firmness of fruit texture were recorded in arginine treatment with a concentration of 100 mg / l under normal fertigation conditions (180 ml). Also, the highest amount of phenol and total flavonoids was observed at the same level of fertigation, albeit with arginine treatment at a concentration of 200 mg / l. Also, the highest amount of anthocyanin, vitamin C and total antioxidant capacity were recorded in arginine treatment with a concentration of 200 mg / l, in conditions of mild deficit fertigation (140 ml).
 
Excessive use of chemical fertilizers in agricultural production, especially in hydroponic cultivation in greenhouses, causes fertilizer wastage and as a result increases production costs as well as increases greenhouse drainage. Therefore, it has destructive effects on the environment, so reducing the amount of nutrient solution can be a management option to reduce the harmful effects on the environment and save water. Also, due to the importance of producing organic products and increasing demand, the use of healthy and organic compounds such as amino acids (arginine) to increase the quality and quality of the product, is very necessary. In the present study, arginine treatment increased the quality of strawberry fruit by affecting its photochemical content such as total antioxidant activity, vitamin C, total phenol, anthocyanin, etc. in low solubility conditions. Also, by increasing the firmness of the fruit texture, it improved the appearance quality of the fruit, which is important for attracting the consumer's attention. In general, the results showed that arginine spraying (200 mg / l) in normal solution and mild dissolution conditions can be effective in improving the quality of strawberries cultivated in hydroponic conditions.