The Effects of Nitrogen Fertilization and Stage of Fruit Maturity at Harvest on Yield and Nutritional Value of Scallop Squash

Abstract

The aim of the field study was to evaluate the response of scallop squash crop to nitrogen fertilization in the case of cultivation for receiving the fruits with 3-6 cm, 6.1-12 cm or >12 cm in diameter. 'Sunny Delight F 1 ' was grown from seeds and supplied with 60, 120, 180, 120 + 60, 240 or 120 + 60 + 60 kg N•ha -1 . Harvest, which started at the end of June or in early July was conducted with frequency of 2 days, 3-4 days or one week intervals, respectively for small, medium, and large size fruits. Results of the study showed that irrespective of the size of harvested fruits, the maximum mean yield of scallop squash for 3 years was assured by application of 240 kg N•ha -1 , and similar effect was provided by 120 + 60 kg N•ha -1 . Heavy N fertilization was beneficial for the number of fruits setting and early fruit yield, with no change the nutritional value of the crop. Harvest conduced in more advanced stages of fruit maturity increased yields but caused substantial reduction of fruit number from the unit area. Small size fruits with diameter 3-6 cm had the highest nutritional value expressed by the amounts of vitamin C, carotenoids and total polyphenols. Fruits of later stages of maturity contained higher level of total sugar.