Kenaf (Hibiscus cannabinus L.) based substrates for the production of compact plants

Growth media based on whole-stem kenaf (Hibiscus cannabinus L.) and sand have been used to produce compact lettuce (Lactuca sativa L.) and pepper (Capsicum annuum L.) plants. Seeds were sown directly in kenaf-containing substrates and growth was recorded for up to 100 days after sowing. The presence of whole-stem kenaf (core and bark), even at a ratio of 10:90 (kenaf:sand), inhibited plant growth expressed as plant height, leaf number, and plant fresh and dry weight. When plants were subsequently transplanted to a kenaf-free substrate, growth continued at a similar rate to that of the control (sown and grown in peat and sand). The inhibitory effect of kenaf is located both in the core and bark, but is decreased by soaking the kenaf in NH4NO3 prior to use. A possible role for whole-stem kenaf (core and bark) in the production of compact plants is proposed.