LAUSR

Productivity of non-heading Chinese cabbage (Brassica rapa L. subsp. chinensis) was evaluated at Roodeplaat over two winter seasons (2012 and 2013). Agronomic factors considered were plant density, nitrogen level, irrigation frequency and planting date. Irrigating thrice or once a week with 50 kg N ha−1 at 50 000 plants ha−1 produced tall plants with large leaf area (p < 0.05). Irrigating once a week combined with 100 kg N ha−1 increased leaf chlorophyll content. Application of 50 and 100 kg N ha−1 significantly (p < 0.05) increased leaf number, plant height, chlorophyll fluorescence and yield for early and late planting dates. Irrigating three times a week led to significant (p < 0.05) increase in plant height and yield for late and early planting. Higher leaf quality parameters (chlorophyll content index and leaf area index) suggested that non-heading Chinese cabbage could be grown at densities of 50 000 plants ha−1. However, plant density of 133 333 plants ha−1 resulted in significantly (p < 0.05) higher yield in terms of leaf number and fresh mass for late planting in both seasons. Early planting, application of 50 kg N ha−1, irrigating three times a week and a plant population of 50 000 plants ha−1 is recommended for non-heading Chinese cabbage.