Effects of sowing date and plant density on morphological triats, yield and yield components of sweet corn (Zea mays L.)

In order to evaluate the effect of sowing date and plant density on the morphological triats, yield and yield components of sweet corn (Zea mays L. var SC. 403) an experiment was conducted at the Khorasan Razavi Agricultural Research and Natural Resources Center, Mashhad, Iran during 2008. This experiment was carried out as split plot based on RCBD with four replications. The sowing date (14th June, 3th July and 24th July) and plant densities (66600, 83300 and 111000 plants.ha-1) were arranged in main and sub plots, respectively. The results showed significant differences between different sowing dates for plant height, ear height, and no. of leaves/plant, no. of leaves above ear, stem diameter, dehusked ear yield, can grains yield, no. of grain rows/ear, ear length, ear diameter, kernel depth, no. of ear.plant-1, 1000 kernel weight, ear harvest index and plant harvest index. The highest and the lowest can grains yield with 18.27 and 0.930 ton ha-1 was belonged to 14th June and 24th July sowing date, respectively. Although, delay in sowing date, led to decrease of growth period and also decrease of temperature can lead to improper transfer of photosynthetic materials and cause to grains yield decrease. The plant density had significant effects on husked ear yield, dehusked ear yield and forage yield. The highest can grains yield was harvested from the highest plant density (8.862 t.ha-1) and the lowest can grains yield derived from the lowest plant density (66600 plants.ha-1) with 7.692 t.ha-1). Finally, the interaction of sowing date and plant density was significant only for harvest index. Therefore, the sowing date 14th June and the highest plant density (111000 plants.ha-1), is recommended for summer sowing date of sweet corn in Mashhad with maximum and better can grains production.