Effects of substrates and nutrient solutions on the growth and development of hydroponic purple lettuce (Lollo Rossa)

This study evaluates the effects of substrates and nutrient solutions on the growth and development of hydroponic purple lettuce (Lollo Rossa) to determine optimal cultivation conditions. The experiment was designed as a two-factor randomized complete block design, including three substrates (rice husk ash, coconut fiber, and a mixture of both) and three nutrient solutions (Knops, Hoagland, and Johnson), resulting in nine treatments. The results show that the Johnson solution produces the best growth performance in terms of leaf number, plant height, and root length. Notably, the combination of the Johnson solution and the mixed substrate (coconut fiber + rice husk ash at a 1:1 ratio) yields the highest fresh weight, dry weight, and actual yield. No significant effect was observed on Brix values.