In order to study the effect of sowing date and plant density on ear of sweet corn an experiment was conducted in Gorgan Reaserch station since June 2001 during 3 years. In this experiment five sowing date (24th June, 9th July, 24th July, 18th Agust and 23th Agust) and four plant density (45000, 55000, 65000 and 75000 plant per hectar) were evaluated in form of factorial experiment (5×4) within randomized comelet block design. Results indicated that ear length, plant hight, can seed weight, grain/ear ratio and harvest index was under the influence of year and maximum ear weight obtained amount 12810 kg/ha in theirty year. With delay sowing date until 9th July amount of ear weight was fixed but amount of it in July was smaller than June. Although with delay sowing date in July ear weight was fixed and maximum ear weight achived amount 13690kg/ha in 24th June.Stistically there wasn’t any different between plant density for ear weight and can seed weight but with increase plant density ear length and grain/ear ratio decreased. So for obtain maximum yield and marktable 45000-55000 plant/ha for sweet corn in summer sowing can be recommended.
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