Document Type : Research Article
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Abstract
The present study was aimed to determine the effect of drip irrigation methods and nitrogen levels and their interaction on corn root development and study of the root movement model. For this purpose, a split plot field experiment based on randomized complete block with irrigation method in two levels (surface and subsurface drip) as main treatment and Nitrogen fertilization in two levels (50 and 100% of fertilizer requirement) as sub main treatment at 3 replications was conducted at Agricultural Engineering Research Institute, Karaj, Iran using corn variety 370 double-cross. Monitoring of root depth was performed by digging trenches and observation of soil profile. The samples were collected during the growing season with 10 day intervals (8 times totally) and root weight in different soil layers was measured by harvesting of soil monoliths and washing in plastic filters under water pressure. Results showed that the depth of root development up to 20 days after planting was significantly more in surface irrigation method compare to subsurface drip irrigation method; but it was not significant in 30 to 80 days after planting at 5% level. The depth of root development was not significantly different in different nitrogen levels in fertigation method at 5% level. Interaction of irrigation methods and nitrogen levels also didn’t show significant effect on depth of root development at different corn stages growth at 5% level. Root width development was not significantly different in all treatments. The most root distribution observed at 20 to 40 cm and 0 to 20 cm of soil layer in subsurface drip irrigation and subsurface drip irrigation methods, respectively. The lowest root density was observed at 40 to 60 cm soil layer in both studied irrigation methods. Also the roots were more uniformly distributed in soil in subsurface drip irrigation method compare to surface drip irrigation method. The most accurate root depth estimation was achieved by the linear, Borg & Grims and Cropwat models, respectively.
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