Effect of the ground-water regime and nitrogen fertilizer on the yield and quality of apples.

Abstract

Results are summarized of a 12-year experiment with Cox's Orange Pippin and Golden Delicious on M9 rootstock. A 5-ha field of calcareous clay soil recently reclaimed from the sea was laid out to give 2 replicates of each of 11 drainage/subirrigation regimes. Three levels of N application were superimposed. The results are discussed in terms of changes in soil physical properties (structure, subsidence and compaction), root and shoot growth, and fruit yields and quality. Maximum vegetative growth occurred at groundwater levels of 70 to 130 cm in combination with adequate N application (75-150 kg N ha^-1 year^-1). The adverse effects of high groundwater levels on vegetative growth increased at higher N levels. Differences in fruit yields due to groundwater level were <= 10% in fertilized plots. Yields were highest at the deepest groundwater level (130 cm). N application adversely affected skin colour and increased russeting and bitter pit. Bitter pit was also high in trees subjected to high winter water tables and low summer water tables. The amount of first-class fruit remained virtually unchanged above average leaf N levels of 2.2-2.3% in Cox's Orange Pippin and 2.1-2.2% in Golden Delicious. [See also Horticultural Abstracts 55, 4126.] (Abstract retrieved from CAB Abstracts by CABI’s permission)