Document Type : Original Article
Authors
1
Associate professor, Department of Horticulture Science, University of Mohaghegh Ardabili. Ardabil, Iran.
2
PhD. Student of Department of Horticulture Science, University of Mohaghegh Ardabili. Ardabil, Iran.
3
Graduate of Department of Horticulture Science, University of Mohaghegh Ardabili. Ardabil, Iran.
10.30466/rip.2021.53381.1164
Abstract
This study was conducted during the 2014–2015 growing season at the Campus of Agriculture and Natural Resources, University of Mohaghegh Ardabili, to evaluate the effects of humic acid concentrations, application methods, and nitrogen levels on biochemical traits of strawberry (Fragaria × ananassa cv. Paros). The experiment was arranged as a split–split plot design based on a randomized complete block with three replications. Nitrogen levels (50, 100, and 150 kg/ha) were assigned to the main plots, humic acid application methods (foliar and soil) to the subplots, and humic acid concentrations (0, 2, 4, and 6 kg/ha) to the sub-subplots. Measured traits included fruit yield, proline content, total phenol, soluble sugars, starch content, total nitrogen, total protein, and leaf chlorophyll. The results indicated that the triple interaction among nitrogen level, application method, and humic acid concentration was statistically significant for all measured traits at the 5% probability level. The optimal treatment combinations varied among traits: For nitrogen and proline content, foliar application was most effective. For starch content, soil application of 2 kg/ha humic acid combined with 150 kg/ha nitrogen was optimal. For soluble sugars and total phenol, 2 kg/ha humic acid was most effective. For fruit yield and total chlorophyll, 4 kg/ha humic acid with 100 kg/ha nitrogen produced the best results. These effects may be attributed to enhanced nitrogen uptake, increased nitrogen metabolism, and improved protein synthesis induced by humic acid. Additionally, humic acid delayed chlorophyll degradation, positively affecting carbohydrate synthesis, enzyme activity, and yield. Application of humic acid in combination with nitrogen fertilizer improved nitrogen uptake and use efficiency in strawberry, with 100 kg/ha nitrogen producing better results than higher or lower rates. Overall, foliar application of humic acid proved more effective than soil application, and the combination of 2 kg/ha humic acid with 100 kg/ha nitrogen was identified as the most suitable treatment for strawberry cultivation.
Keywords
)