Growth and Quality of Screenhouse-Grown Radish in Various Compost Amendments

Radish (Raphanus sativus L.) is widely consumed and an important crop in Asia. Present cultivation, however, utilizes synthetic pesticides and fertilizers, which are discouraged in organic agriculture. The objectives of this study were to evaluate the physico-chemical properties of potting mixes with various nutrient amendments, and to determine their effects on growth and development of screenhouse-grown potted R. sativus cv. Everest. Synthetic amendment was phosphorus (diammonium phosphate), whereas compost amendments were each at 10% or 20% w/w of the following: a) Department of Agriculture (DA) vermicompost, b) Tacunan (Tacunan) vermicompost, and c) Dr. Bo's Biofertilizer (DBB) high-temperature compost. Before cultivation, physico-chemical properties from treatments with compost showed higher values than with phosphorus or pure potting mix. After cultivation, pH remained slightly acidic to near-neutral, with highest organic matter resulting from 20% DBB, and with the highest moisture content and water-holding capacity from 20% DA. Germination was 100% for 10% Tacunan and 20% DA. Longest (40 cm) and dark green (4 rating) leaves were from plants grown in 20% DBB. DBB significantly increased fresh weight, moisture content, and biomass in shoots. Taproots were longest (13.66 cm) and heaviest (113 g) in 20% DA, whereas Class I taproots were from 20% DA or from 20% Tacunan. Potting mix alone consistently gave the poorest shoot length (8.15 cm), root length (9.66 cm), and root diameter (4.08 cm). Petiole quality was comparable for all treatments, but highest freshness score (4.44) was recorded in plants amended with 10% Tacunan. For taproot marketability, 20% DA is recommended for the cultivation of potted radish in screenhouses.