Effect of reusing coir-based substrates with municipal compost and biochar on growth and phytochemical accumulation in lettuce

Abstract

The aim of this research was to evaluate the influence of reusing, coir-based substrates with municipal organic compost or biochar on growth and phytochemical accumulation in lettuce. The experiment included five substrates: coir (new) and four mixtures: coir: biochar: perlite, coir: compost: perlite, coir: biochar: pine bark, and coir: compost: pine bark. All of the mixtures had already been used to grow transplanted spinach and had the same ratio among components (78:12:10%, v/v). Lettuce (Lactuca sativa L. cv. Godzilla) seedlings were transplanted into Styrofoam plant boxes. The planting boxes wer irrigated daily by drip with a complete nutrient solution. Shoot dry weight and head fresh yield in reused mixes were similar to those obtained in coir. Lettuce head fresh yield ranged from 4.6 to 4.9 kg m-2. Leaf total phenols of the plants grown in reused mixes was higher or equal to those plants grown in coir. Leaf total phenols of the plants grown in reused mixes were higher or equal to those grown in coir. Leaf anthocyanin and flavonoid contents were unaffected by substrates. These results indicate that coir-based growing media can be reutilized to grow lettuce without decrease the yield or phytochemical accumulation.