Plant spacing and variety affect pumpkin yield and fruit size, but supplemental nitrogen does not

Field studies were conducted at two locations in 1995 to determine the effect of spacing, nitrogen application, and variety on pumpkin (Cucurbita pepo L.) marketable yield. Pumpkin yield was unaffected by three rates of applied N (67, 112, or 157 kg N.ha(-1)). Marketable fruit number per hectare increased with both 'Howden' and 'Wizard' pumpkins as in-row plant spacing decreased from 1.2 to 0.3 m. Average fruit size significantly decreased at the closer spacing, but the decline in mass was much greater in nonirrigated as compared to irrigated plots. This resulted in a significantly greater yield in the irrigated plots at the closer spacing, while there was no significant increase in yield without irrigation. The results demonstrate that growers may increase the number of fruit per unit area with closer spacing but optimal soil moisture may be a prerequisite for the increase.