Document Type : Research Paper
Authors
1
Department of Plant Production and Genetics Engineering, Faculty of Agricultural Sciences, University of Guilan, Rasht, Iran
2
Associate Professor, Rice Research Institute of Iran, Agricultural Research, Education and Extension Organization (AREEO), Rasht, Iran
3
DProfessor, Department of Computer Engineering, Faculty of Engineering, University of Guilan, Rasht, Iran
10.22124/cr.2024.25854.1831
Abstract
Introduction
Optimizing nitrogen fertilizer use is crucial for increasing efficiency and reducing its adverse environmental impacts in rice paddies. However, accurately predicting the timing of nitrogen requirements and effectively managing it in rice cultivation is challenging. Due to low nitrogen use efficiency and the difficulty in precisely forecasting plant needs, only 30-50% of the applied nitrogen is typically absorbed by the crop. Utilizing digital imagery to estimate the nitrogen content in rice leaves can aid farmers in managing fertilization by providing a relatively accurate assessment of the plant's nitrogen status. This approach requires establishing a relationship between the amount of applied nitrogen, the plant's nitrogen content, and the parameters of digital images. Therefore, given the importance of rice cultivation in Guilan and the necessity of optimizing nitrogen use, this study was designed and conducted to investigate the effect of varying nitrogen application rates on nitrogen content, leaf area, and biomass of Hashemi rice in Rasht.
Materials and methods
This experiment was conducted during the 2016-2017 growing season as a randomized complete block design with three replications at the research farm of the Faculty of Agricultural Sciences, University of Guilan, on Hashemi rice. Seven nitrogen levels (0, 30, 45, 60, 75, 90, and 105 kg N/ha from urea) were applied as the experimental treatments. Transplanting occurred on April 30, with three seedlings per hill, spaced 20×20 cm apart, in plots measuring 3×2 meters. Samples were collected at various growth stages to measure plant nitrogen content, leaf area, and dry biomass. The data were analyzed using ANOVA, followed by Duncan's multiple range test for mean comparisons.
Research findings
The analysis of variance revealed that increasing nitrogen application up to 45 kg/ha did not significantly affect plant nitrogen content compared to the control, while 60 kg/ha resulted in a significant difference compared to both 30 kg/ha and the control. Further increases beyond 60 kg/ha had no significant effect on tissue nitrogen content. The findings also indicated that the highest nitrogen content occurred at the tillering and booting stages, while the lowest was observed at the transplanting time. Nitrogen application also had a significant impact on leaf area, with the largest leaf areas recorded at 90 and 105 kg N/ha, and the smallest in the control, which showed no significant difference from the 30 and 45 kg N/ha treatments. The significant interaction effect of nitrogen application and sampling time on biomass indicated that the highest biomass was observed at 105 kg N/ha during the booting stage. Increasing nitrogen not only increased biomass but also altered the proportion of biomass accumulated at different growth stages relative to total biomass.
Conclusion
Overall, the findings of this study suggest that the optimal nitrogen rate for enhancing nitrogen content in rice tissues ranges between 45 and 60 kg N/ha. To achieve at least 95% of the maximum tissue nitrogen content, a minimum of 57.64 kg N/ha is required. This level of nitrogen application not only boosts nitrogen content and plant biomass but also plays a crucial role in improving efficiency and reducing nitrogen losses in rice paddies.
Keywords
Main Subjects
)