Abstract
We investigated the effects of nitrogen fertilization rate and the timing of fertilization on the growth, fruit yield and fruit quality of the short-internode squash cultivar Cucurbita maxima Duchesne ‘TC2A’ based on experiments performed in an Andosol upland field converted from a paddy rice field in Hokkaido, Japan. Rice (Oryza satuva L.) was planted in the previous year and cattle manure composted with wheat straw at a rate of 1 t/10a was applied before ‘TC2A’ seedlings were transplanted in the experimental field. The treatment factor included in this experiment was the amount of nitrogen fertilization : 0, 4, 8 and 12 kg N/10a. Increasing the nitrogen application rate resulted in increases in both fruit yield and quality, but a rate of 12 kg N/10a failed to provide any further improvement over a rate of 8 kg N/10a. Basal fertilization plus topdressing, as compared with basal fertilization alone, enhanced foliage persistence and alleviated the decrease in quality caused by sunburn on the fruit surface and subsequent rotting. These results suggest that 4 kg N/10a basal fertilization plus 4 kg N/10a topdressing would be effective for ‘TC2A’ cultivation in upland fields converted from paddy fields in Hokkaido.
