نوع مقاله : مقاله پژوهشی
نویسندگان
1 دانشجوی کارشناسی ارشد، گروه آگروتکنولوژی، دانشکده کشاورزی، دانشگاه تربیت مدرس، تهران، ایران
2 استاد، گروه آگروتکنولوژی، دانشکده کشاورزی، دانشگاه تربیت مدرس، تهران، ایران
3 دانش‌آموخته دکتری، گروه آگروتکنولوژی، دانشکده کشاورزی، دانشگاه تربیت مدرس، تهران، ایران
4 مربی، گروه آگروتکنولوژی، دانشکده کشاورزی، دانشگاه تربیت مدرس، تهران، ایران
چکیده
کلیدواژه‌ها
موضوعات
عنوان مقاله [English]
نویسندگان [English]
Introduction
Drought is one of the primary limiting factors in the production of crops, particularly sweet sorghum. Drought stress negatively impacts various aspects of sweet sorghum growth by causing morphological, physiological, and biochemical changes, preventing the plant from achieving optimal yield. Additionally, in arid and semi-arid regions, sweet sorghum yield declines due to the lack of soil organic matter and nitrogen. Therefore, the application of nitrogen fertilizers is essential to address this issue.
Materials and methods
To investigate the effect of different irrigation regimes and nitrogen levels on the yield and yield components of sweet sorghum (Sorghum bicolor L. cv. ‘Pegah’), an experiment was conducted as a split-plot design based on a randomized complete block design with three replications in Qom. The irrigation regimes included optimal irrigation, mild water deficit, moderate water deficit, and severe water deficit, applied respectively after the depletion of 30%, 45%, 60%, and 75% of the available soil water in the root zone, followed by irrigation up to field capacity. These irrigation levels were randomly assigned to the main plots. Nitrogen levels of 0 (control), 50, 100, 150, and 200 kg per hectare were randomly assigned to the subplots.
Research findings
Results showed that irrigation regimes and nitrogen levels had a significant effect on all evaluated traits, including relative water content (RWC) of leaves, anthocyanin, soluble sugars, chlorophyll a, and chlorophyll b, with these effects being significant at the 1% level. The interaction between irrigation and nitrogen was also significant for all traits except for RWC, crop growth rate (CGR) on the 30th day, and leaf area index (LAI). Reduced water and nitrogen levels led to a decrease in forage and grain yield, as well as yield components in sweet sorghum. Highest grain yield, thousand-seed weight, chlorophyll, and RWC were achieved with 150 kg.ha-1 of nitrogen and optimal irrigation, showing a significant difference compared to other nitrogen levels. The highest anthocyanin content was observed with 150 kg.ha-1 of nitrogen under moderate water stress, while the maximum soluble sugar content was recorded with 200 kg/ha of nitrogen under severe water stress. Severe water stress resulted in an 87.77% reduction in grain yield compared to optimal irrigation. However, the application of 150 kg.ha-1 of nitrogen under severe water stress increased grain yield by 80.74%. These changes were also effective under other irrigation regimes, showing a significant improvement in yield.
Conclusion
In conclusion, it can be stated that different irrigation regimes have varying effects on the evaluated traits, including yield and yield components of the Pegah variety of sweet sorghum. The results also indicated that the highest grain yield was obtained with the application of 150 kg.ha-1 urea under optimal irrigation, mild water stress, moderate water stress, and severe water stress, yielding 7390.93, 5698.40, 3782.94, and 938.23 kg.ha-1, respectively. Based on these findings, for improving the physiological and functional traits of the Pegah variety of sweet sorghum under stress or non-stress conditions, the application of 150 kg.ha-1 nitrogen is recommended.
کلیدواژه‌ها [English]
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