Effects of mycorrhizal inoculation on growth and quality of roselle (Hibiscus sabdariffa L.) grown in soilless culture system

Abstract

The effect of arbuscular mycorrhizal fungi (AM) and organic plant waste on the growth and calyx quality of roselle cultivated in a soilless system was investigated. Three treatments were compared in the study, viz. (i) control, (ii) AM, comprising a mixture of Glomus sp., Gigaspora sp. and Scutellospora sp. and (iii) AM supplemented with organic plant waste. Inoculation of soilless grown roselle resulted in the proliferation of fungal spores in the culture medium (varying from 55 to 61 spores per 10 gram substrate), while successful root infection ranged from 59% to 64%. The most significant observation in this study was the doubling of root volume and dry weight in the inoculated plants as compared with the control plants. Thus, AM inoculated plants showed significantly increased vegetative growth mainly below the ground level. In addition, total anthocyanin concentration in the calyces was also significantly improved. However, roselle yield and other quality attributes such as soluble solids concentration (SSC), titratable acidity (TA) and ascorbic acid were unchanged with the introduction of AM. It is concluded that while the AM treatments did not affect the growth and yield of soilless-grown roselle, AM infection of roselle roots increased their growth substantially. AM increased significantly the anthocyanin content of the calyces in cultures supplemented with organic plant waste.