Influence of Spacing and Plant Age at First Harvest on the Growth, Development, and Yield of Three Roselle (Hibiscus sabdariffa L.) Cultivars

Abstract

A field experiment was conducted to examine optimum plant population and compare yields of three local roselle cultivars; namely Bihi, Mogla 1 and Mogla 2 planted at four different spacings and harvesting at 31 days after planting by pruning the plant at 13.0 cm high. Subsequent harvesting of shoots was done at fortnightly intervals. The spacings were; 30cm x 30cm, 30cmx 35cm, 30cm x 40cm, and 30cm x 45cm. A pot experiment was also carried out to determine the appropriate plant age at first harvest (PAFH) of two of the roselle cultivars; Bihi and Mogla 1. Three PAFH used were 31, 38 and 45 days after planting. The field and pot experiments were conducted at the University of Ghana Farm, Legon from June 2012 to January 2013. A randomized complete block design was used and replicated four times for the field experiment and three times for the pot experiment. In the field experiment, plant growth parameters studied were harvested leaves, stems and petioles numbers, fresh and dry weights were recorded at 31 days after planting and depending on the type of treatment of PAFH in the pot experiment. Other data collected were; plant height at first harvest, number of leaves per plant, number of new shoots per plant, new stem diameter, leaf area, leaf area index, yield and yield components. Results revealed that subsequent harvesting did not significantly enhance the production of more harvested leaves and stems in the field experiment; and reduced new shoots length in both field and pot experiments. The Bihi cultivar was taller at first harvest than Mogla 1 and Mogla 2 at closer spacing than wider spacing. PAFH of 45 days produced taller plants, more harvested leaves and stems than 31 and 38 days with insignificant differences between 38 days PAFH . The studies showed that optimum spacing was 30cm x 30cm (222,222 plants/ha). Mogla 1 produced higher fresh leaves,stems, shoot yields (t/ha), leaf/stem ratio than Bihi and Mogla 2. Appropriate plant age at first harvest of 38 days after sowing is recommended for continuous harvesting by pruning as a leafy vegetable to maximize production.