Effect of the Cultivation Systems and Split Fertilizer Applications on the Growth and Yields of Tatsoi (Brassica rapa subsp. narinosa)

Tatsoi [Brassica rapa subsp. narinosa (L.H.Bailey) Hanelt] is a leafy vegetable with potential for cultivation in a riparian wetland ecosystem. The floating culture system has the advantage of ensuring a sufficient water supply in the growing substrate due to the continuous upward water movement caused by capillarity force. This study evaluated the responses of the tatsoi plant to split fertilizer applications under conventional cultivation and floating culture systems. The fertilizer treatments consisted of control (F0), single (F1), split into 2 (F2), split into 3 (F3) or split into 4 applications (F4). The results showed that early growth of tatsoi was better using floating culture than the conventional system. However, tatsoi adapted well to conventional and floating culture systems as long as sufficient nutrients were available. A single application of 6 g NPK fertilizer (16:16:16 v/v/v) at transplanting provided sufficient nutrients, as indicated by the number of leaves, total leaf area, canopy area, stem dry weight, and leaf dry weight at harvest. The leaf SPAD values in the tatsoi plants were higher in the floating culture system than in the conventional system at 14 and 20 DAT fertilized with a 4-split application. Transplanting occurred 14 days after seed planting (DAP), and harvest occurred 49 days later. A quadratic regression model using leaf length (L), leaf width (W), or L×W as predictors was reliable for non-destructive leaf area estimation in the tatsoi plant. It is recommended for farmers to apply a single NPK fertilizer at the rate of 6 g/plant to achieve an optimum yield in tatsoi cultivated using a conventional or floating culture system. HIGHLIGHTS Tatsoi plant grew well under conventional and floating culture systems as long as sufficient nutrients were available Splitting fertilizer into several times of application did not significantly better than single application of NPK fertilizer at time of transplanting SPAD values in the tatsoi leaves were higher in the floating culture than in the conventional system Length and width of leaves were reliable predictors for non-destructive accurate leaf area estimation in the tatsoi plant GRAPHICAL ABSTRACT