Coloration, anthocyanin concentration, and growth of croton (Codiaeum variegatum L.) as affected by cotton gin trash compost use in the potting medium

Abstract

Compost from cotton gin trash was evaluated as a peat substitute in Codiaeum variegatum L. production. Rooted cuttings were grown for 8 months in media containing cotton gin trash compost, sphagnum peatmoss, and perlite in 1:3:4, 1:1:2, and 3:1:4 ratios respectively, and their growth was compared with a control medium of 1 peat:1 perlite (by volume). Even when 75% of peat in the control medium was replaced by cotton gin trash compost, plant height, leaf number, and leaf size were unaffected, whereas root dry weight was increased in the medium with 25% peat replacement. Although replacement of peat by cotton gin trash compost did not affect quantitative characteristics of croton foliage growth, it affected the foliage color, as plants in media with cotton gin trash compost had more areas colored red in their leaves. The increase of red coloration was proportional to the increase of cotton gin trash compost in the medium. The phenomenon was more intense in the lower leaves than the apical ones. Anthocyanin concentration measurements showed that the gradual increase of cotton gin trash compost level in the growth medium caused a gradual increase of the anthocyanin concentration in the leaves. This effect is discussed in relation to chemical properties of the media, as electrical conductivity, pH, and nutrient concentrations. The gradual increase of cotton gin trash compost level caused an analogous increase of N, P, and K concentrations in the medium. Also, media with cotton gin trash compost had high electrical conductivity at the beginning of the culture period, related to the cotton gin trash compost level, which was reduced to values similar to that in the control medium after 50 days of culture. Na concentration in the media ranged similarly to electrical conductivity. The pH was positively related to cotton gin trash compost level, and media with a high cotton gin trash compost level had increased pH during the culture period compared with the control.