Effects of different methods of urea application and harvesting time on the physical properties of maize (Zea mays L.) hybrids

A field experiment was conducted to study the physical properties of maize grain in response to different urea fertilization methods (urea foliar spraying and soil application)، three harvest times (grain moisture content of 20، 30 and 40 pecent) in four maize hybrids (three foreign hybrids e. g. NS640، Jeta600، Konsur580 and one common hybrid، SC704 as control) at Khorram Abad Agricultural Research Station in 2010. The experimental design was a strip split plot based on a complete block design with four replications. The fertilization method was considered as horizontal factor and the vertical factors were hybrid and grain moisture content (harvest time) in a split plot arrangement. Analysis of variance showed that there were significant differences among grain moiusture at harvest time treatments in terms of length، bulk density، real density and specific grain area. The 20% grain moiusture at harvest time was the best based on the physical properties. Also the effect of fertilization methods was significant for grain width and 1000-grain weight. Results showed that the highest grain width (7. 81mm) and thousand kernel weight (257. 38g) was achieved at urea soil application.. According to the results، Jeta Hybrid showed better physical properties compared to the other hybrids. Because، this hybrid had the highest real density (1. 71 g/cm3)، porosity (54. 23%) and thousand kernel weight (266. 57g)، indicating higher grain quality.