Effect of Planting Date and Plant Densities on Yield and Yield Components of Sweet Corn (Zea mays L. var saccharata)

An experiment was carried out to investigate the effect of planting date and plant densities on yield and yield components of sweet corn at agricultural and resources research center of Razavi Khorasan, Iran during 2009 growing season. A split plot experiment, based on randomized complete block design with four replications performed using SC 403 cultivar. The main plots belonged to three planting dates (D1: May 15, D2: July 4, D3: July 25) while subplots belonged to different plant densities (P1: 66600, P2: 83300 and P3: 111000 plants ha-1). There was significant different between planting dates in respect of plant height, ear height, leaves number, leaves number above ear, stalk diameter, de-husked ear yield, conservable grain yield, ear number per plant, grain rows per ear, ear length and diameter, grain depth, 1000- grains weight and harvest index. The highest (18.27 t ha-1) and lowest (0.93 t ha-1) conservable grain yield produced at D1 and D3 respectively. Delay cropping resulted in lower grain yield due to lower growth duration, lower temperatures and solar radiation at late season. There was significant difference between different plant densities in respect of ear yield, de-husked ear yield and fresh forage yield. The highest (8.86 t ha-1) and lowest (7.69 t ha-1) grain yield observed for P3 and P1 respectively. Harvests invest affected by interaction between planting date and plat density. The highest conservable grain yield produced at May 15 at the highest plant density level (111000 plants ha-1).