Determination of Si critical level for two rice varities (Hashemi and Khazar) in a pot experiment
2005
Kavousi, Masoud | Shahdi Koumaleh, Abbas | Peykan, Maryam | Ali Nia, Mohammad Hassan | Rajabi, Mohammad
In order to determine soil Si critical level for Hashemi and Khazar rice varities an pot experiment was conducted in Rice Research Institute of Iran during 2003-2004. Surface soil samples (0-30 cm) were collected from different rice fields of Guilan province and available soil Si were measured in collected samples. 26 rice fields in first year and 18 rice fields in second year, were selected with lower available Si compared to other places. 9 kg of air dried soils of selected rice fields were transferred into the plastic pots. Application of 300 or 0 mg SiO2 kg-1 of soil were compared together in 26 soils in first (Hashemi variety) and 18 soils in second year (Khazar variety) in 3 replications. Nitrogen (as urea fertilizer) and phosphorous (as triple superphosphate fertilizer) were added to all plots in equal quantities. At the end of ripening stage rice plant was harvested from the first node above the soil and grain yield calculated based on the 14% moisture content. The results have shown that effects of Si application were significant at 1% level on straw and Si concentration of rice straw and at 5% level on grain yield, but not significant on the other measured parameters in first year. Si critical level for Hashemi variety was determined as 32 mg kg-1. Based on this critical level, 58% of investigated rice fields were deficit in the view of soil available Si. Critical concentration of Si in rice straw of Hashemi variety was determined 8%. The results have also shown that effects of Si application on grain yield, straw yield and Si concentration in Khazar variety were significant at 1% level. Application of Si have averagely increased Khazar grain yield as much as 21%. Si critical levels in soil and khazar straw were determined 91 mg kg-1 soil and 6.2%, respectively.
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