Department of Plant Sciences

Broccoli (Brassica oleracea var. italica) is an important high-nutritional-value vegetable yet broccoli plant and nitrogen nutrition relations are not well understood. We conducted a study of broccoli plant response to nitrogen nutrient treatments in a commercial production field in Nova Scotia. The objectives were to quantify the effects of nitrogen nutrition on direct-seeded broccoli development and plant nitrogen uptake in different soils. The nitrogen treatments consisted of the rates of 0, 25, 50, 75 and 100 kg ha-1, arranged with four replicates in a split-block design with soil type as the main plot. The two soil types were the well-drained Kentville (Kt) loam and the imperfectly-drained Woodville (Wd) loam. The N treatments were applied to the 60-day cultivar ‘Everest’ at shoot-tip straightened stage. Results showed that the direct-seeded broccoli N uptake ability was significantly higher (6.2 g plant-1) in the Wd soil, where the soil was near neural (pH 6.2) and contained more water (12% soil water content, SWC), compared to the Kt soil where the soil was acidic (pH 5.2) and drier (8% SWC). Broccoli plants responded significantly up to the lower N rate (50 kg ha-1) in the Wd soil but to the higher rate (75 kg ha-1) in the Kt soil. There was a significant correlation between head yield and leaf-stem N reserves (R2 = 0.56, P < 0.01). It was suggested that increasing N uptake could stimulate broccoli heading. Soil pH (6.2) and SWC (12%) conditions could promote broccoli plant N assimilation. Further quantification of regulating N temporal reserves in leaves and stems could enhance N transfer to sinks (heads), which would be the mechanism of promoting broccoli plant floret development.