Wetland areas in Indonesia cover more than 33,3 million hectares, and slightly less than 40 % is inland swamp. During the rainy season, for up to 9 months annually, the wetlands are flooded, and no conventional agricultural activities can be done by local farmers. However, this condition can be seen as an opportunity to employ floating culture system. The objective of this research was to evaluate responses of leaf celery to floating culture system with different depths of water-substrate interface and NPK-fertilizer application. The results of this study indicated that the depth of water-substrate interface (WSI) should be maintained between 1 to 3 cm. At less than 1 cm, continuous contact between the water surface and the bottom part of the substrate cannot be ensured; meanwhile, aerobic substrate volume was reduced and caused significant effects on growth and yield in celery plants if WSI was deeper than 3 cm. Moreover, the effectiveness of NPK-fertilizer application was weakened if the depth of WSI was at 6 cm. Fresh leaf yield in celery plants harvested at 45 days after transplanting (DAT) can be predicted as early as 3 weeks earlier using the midrib length of the largest leaf or plant height as a predictor measured at 26 DAT.
HIGHLIGHTS
Depth of water-substrate interface (WSI) should be maintained between 1 to 3 cm for better growth and higher yield in floating culture system
Effects of NPK fertilizer application diminished if WSI deeper than 3 cm
Yield of celery harvested at 45 days after transplanting can be predicted as earlier as 3 weeks using midrib length of the largest leaf or plant height as predictor
GRAPHICAL ABSTRACT
Plant production and water purification efficiency by rice and umbrella plants grown in a floating culture system under various water environmental conditions
