Foliar Application of Ornithine on Morphological Traits, Mineral Elements Content, and Antioxidant Enzymes Activity of Pistacia vera L. ‘Ahmad Aghaei’

Document Type : Full Paper

Authors

• Mahmood Delfani
• Mesbah Babalar
• Mojtaba Delshad

Department of Horticultural Sciences, Faculty of Agriculture, College of Agriculture, College of Agriculture & Natural Resources, University of Tehran, Karaj, Iran

Abstract

Keywords

• Amino acid
• Enzyme activity
• Foliar spraying
• Productivity
• Sustainable agriculture

Main Subjects

• Fruit Science

Extended Abstract

Introduction

Pistachio is one of the most important horticultural products of Iran, which has long been considered a strategic non-oil export commodity. Pistachio yields are often negatively affected by some physiological problems, such as the abscission of inflorescence buds and fruits, deformed or blank nuts, and non-split shells. In addition, the meager organic matter amount and the lack of balance in the soil's nutrients in pistachio farming areas have caused the performance of this strategic product to be lower. Therefore, foliar spraying will significantly help the growth and development of pistachio trees. Amino acids are involved in growth, respiration, and photosynthesis and are precursors in plant hormones and growth substances synthesis. Ornithine, as an alkaline amino acid, has several roles in the growth and development of plants. Ornithine not only directly plays a significant role in the production of proline and polyamines as two non-enzymatic antioxidants, but it can also lead to the production of the arginine amino acid, another precursor for the production of polyamines.

Considering the decrease in yield and quality of pistachio trees due to physiological and soil problems and the effect of using biological stimulants on improving the vegetative and reproductive growth of horticultural crops, this study was carried out to determine the effect of external application of the ornithine amino acid on the quantitative and qualitative characteristics of pistachio cv. Ahmad Aghaei.

Materials and methods

This research was conducted in Rasfijan pistachio orchard in 2020-2021, located in Zawiya city of Zarandieh, Markazi province, on 18-year-old pistachio trees of the Ahmed Aghaei cultivar grafted on Badamie-Zarand rootstock. The experiment was conducted over two years as randomized complete blocks with 4 levels of ornithine amino acid (0, 2.5, 5, and 7.5 mM) with 6 replications. Foliar sprays of ornithine were applied at four times 1) buds swelling time; 2) leaf area reaches 50%; 3) leaf area reaches 75%; and 4) concurrent with the initial start of kernels filling.

Results and Discussion

The results showed that the highest fresh fruits weight (13217 and 6165 g per tree), dry fruit weight (4691.2 and 2124.67 g per tree), current year shoot length (21.12 and 21.2 cm), leaf area (3435.66 and 3634.5 cm² in the current year's branch), split nuts (79.9% and 80.58%) and the lowest blank nuts (1.16% and 1.02%) in the first and second years of the experiment, respectively, were obtained at 7.5 mM ornithine. Ornithine foliar application affected the macro- and micro-elements content in pistachio leaves and fruits, and the highest nitrogen, phosphorus, calcium, iron, and zinc content in pistachio leaves and fruits were obtained at 7.5 mM ornithine. The ornithine also significantly improved the antioxidant capacity and activity of treated trees, and the highest enzymes activity of ascorbate peroxidase (APX), catalase (CAT), and superoxide dismutase (SOD) was obtained at 7.5 mM ornithine.

Conclusion

In general, according to the results, spray application of ornithine, as an essential natural compound from a scientific and economic viewpoint, can be an excellent alternative to avoid the application of chemical fertilizers, and be an essential step towards food safety and agricultural sustainability.