Pages: (6-13 )
Abstract
Pinching had been found to regulate plant shape and size, control flowering and fruiting. A pot experiment was carried out at the National Centre for Genetics Resources and Biotechnology (NACGRAB), Moor plantation Ibadan ( latitude; 7o24'42"E and longitude; 3o 49' 47" N) between March and October, 2014 to determine the effects of pinching height on the growth and calyx yield of Roselle. The Roselle seeds (NGB01277), used for the experiment were collected from the Seed Testing Unit of NACGRAB. The Roselle plants were grown in polythene bags containing 20 kg of forest top soil. At 8 weeks after planting, the plants were pinched into different heights which made the treatments. Main axis was pinched at 30 cm, 40 cm, 50 cm and 60 cm above soil level, while the control pots were allowed to grow unpinched making 5 treatments, each treatment replicated 4 times. Data were taken on growth parameters: plant height (cm), number of leaves/plant and number of branches/plant. Data were also taken on yield parameters which include number of flowers, number of aborted calyx, number of harvested calyx and weight of harvested calyx. Data collected were subjected to statistical analysis using Analysis of Variance (ANOVA) and the means were separated using Duncan Multiple Range Test (DMRT). Pinching had a positive effect on the enhancement of growth in roselle and increased the productivity of the calyx, compared with the unpinched plants. Roselle plants pinched at 60 cm height gave the highest weight of harvested calyx of 6.22 t/ha which was similar with plants pinched at 40 cm height producing 3.98 t/ha calyx yield. It is recommended to pinch Roselle plants at 60 cm height for economic yield but not below 40 cm height.
Keywords: Calyx yield, Growth, Pinching height, Roselle.,