Ecophysiolgy of Yield and Quality As Influenced by Management, Inputs and Agro-Climatological Factors In Processing Carrots

Carrots are an important horticultural crop for individually quick frozen (IQF) processing in Nova Scotia. Adopting improved and sustainable management practices involves understanding the link between agro-climatological factors and crop yield and quality.  The objective of studies reported here was to understand carrot bulking physiology, yield and quality as influenced by agronomic, and agro-climatological factors. Three year field trials were conducted in Nova Scotia to look at interactive effects of seeding date, seeding rate and harvest date, as well as, nitrogen applications on marketable yield and quality. Two varieties of each processing carrot product, sliced (Maverick, Top Cut), diced (RCC, Cupar) and cut and peel (Top Cut, Sugarsnax) were used. Fertility experiments used nitrogen (34-0-0 NPK) at 0, 50, 100, 150, 200, 300 and 400 kg N/ha, which were broadcast in a split (60% pre-emergence and 40% 8 weeks after emergence) application.  Cut and Peel carrots were sown at 40, 50, and 60 seeds/30 cm^-1, Slicer carrots were sown at 25, 35, 45 seeds 30 cm^-1, and dicer carrots were sown at 9, 12, 16 seeds 30 cm^-1. Three seeding and harvest dates (early, mid and late) that were done two weeks apart. Yield, quality and weather data was collected. No significant interactive effect of nitrogen and variety in terms of marketable yield was observed. Overall, cut and peel variety Sugarsnax yielded 17.6% more than TopCut, slicer variety Maverick (61.7 t/ha) yielded 13.3% more than TopCut, and here were no differences between dicer varieties. Nitrogen rate of 150 kg N ha^-1 resulted in the best yields as higher rates did not yield much more. All carrots products showed a significant seeding date by harvest date interaction. Yields were significantly increased with an early seeding date and late harvest date. Harvest decision models showed that high and low temperature had the greatest influence on marketable and total yield of cut and peel carrots. Slicer and dicer marketable and total yield carrots were influenced by degree days and high temperature. From these results harvest decision models determined that these agroclimatological factors have an influence on harvest dates. Lower degree days are more desirable for marketable yields for cut and peel carrots compared to higher degree days for marketable yields for slicers and dicers. Overall, it would seem to indicate that an early seeding is best to obtain the highest marketable yields.