Effect of Planting Date on Grain Yield and Its Components and Reaction to Important Maize Viruses in Fars Province in Some Exotic and Iranian Maize Hybrids

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Abstract

Spring planting of KSC704 maize hybrid in temperate areas of Fars province in Iran is usually infected with maize rough dwarf and Iranian maize mosaic viruses. Cold temperatures also affect summer sown maize cv. KSC704 hybrid late in autumn befor harvest. To evaluate effects of planting dates on exotic medium maturity hybrids with European origin and reaction of Chinese hybrids to important maize viruses in Fars province two separate experiments was carried out. These experiments were conducted using randomized complete block designs (split plot arrangement in the first trial) with four replications in Zarghan field station, Shiraz, Iran, in two growing seasons (2006-2007). Results, in first trial, showed that growing season effect on grain yield was not significant. Planting date had significant effect on grain yield and yield components. One month delay in planting date decreased the viral infection in all hybrids. OSSK602 hybrid had the highest grain yield with 10.2 t/ha. However, this hybrid in first planting date had high viral infection, and grain yield of about 6 ton/ha. In second trial, Chinese maize hybrids showed tolerance to either viruses . Although they showed high viral infection symptoms, but produced reasonable grain yield. Therefore, it was concluded that Chinese maize hybrids have sources of resistance or tolerance to these viruses and could be used in the national maize breeding programs for development of resistant/tolerant maize hybrids.

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