Effect of Fertilization Methods on Growth of Grand Rapids Lettuce in Floating Cultivation Systems

Lettuce is an important horticultural crop with high economic value and a short cultivation cycle. In areas with limited land availability, floating cultivation systems offer an innovative and sustainable solution for vegetable production. However, the restricted volume and nutrient-holding capacity of the growing media in such systems require an effective fertilization method to optimize nutrient uptake and plant growth. This study evaluated the effects of four fertilization methods—pouring, spraying, spot, and spreading—on the growth and yield of lettuce cultivated in floating media. Results indicated that fertilization methods had no significant effect on overall growth and yield; however, distinct trends were observed among treatments. Foliar spraying resulted in the highest chlorophyll content (SPAD value), number of leaves, and leaf weight, reflecting enhanced photosynthetic efficiency and vegetative development. In contrast, the spreading method produced slightly higher fresh weight but with lower nutrient-use efficiency. Overall, spraying method was identified as the most effective and efficient fertilization method under floating cultivation conditions, as it enables direct nutrient absorption through the leaves and minimizes nutrient losses. These findings provide valuable insights for improving nutrient management in space-limited systems and contribute to the advancement of sustainable horticultural production practices.