Effect of Leaf Harvesting on Yield Parameters and Seed Quality of Kenaf (Hibiscus cannabinus L.)

Abstract

Kenaf (Hibiscus cannabinus L.) is an African Leafy Vegetable (ALV) which has a wide range of uses but mostly known as a fibre crop as opposed to vegetable. There is limited information on the seed quality aspects of kenaf and how farmers’ practices like leaf harvesting may affect the plant growth characters and yield parameters. A greenhouse experiment was set up at the University of Eldoret, Kenya, in a completely randomised design in a factorial arrangement with six leaf harvesting stages and two capsules harvesting stages in four replications. The leaf harvesting stages were 2 weeks before flowering (78 DAP), 1 week before flowering (85 DAP), at flowering (92 DAP), 1 week after flowering (99 DAP), 2 weeks after flowering (106 DAP) & no harvest (control). A standard germination test was conducted in the seed physiological lab of the University of Eldoret, Kenya, and data collected on germination percentage, seedling vigour index I, seedling vigour index II and germination velocity index (GVI). Data on yield parameters was collected on seed size, 1000 seed weight and number of seeds per capsule, and data analysed using R software. Seed number per capsule was significantly influenced by leaf harvesting (p<0.05) but was not affected by capsule harvesting (p>0.05). Leaf harvesting and capsule harvesting stage did not affect seed size (p>0.05). 1000 seed weight varied significantly among the capsule harvesting stages (p=0.01031) but wasn’t affected by leaf harvesting. Highest 1000 seed weight of 18.60g was recorded from seeds in greenish yellow capsules when leaves were harvested at flowering. The germination percentage varied significantly among the leaf harvesting treatments (p< 2.2e-16) and stage of harvesting the capsules (p=0.0004456). Highest seed germination (94%) was attained in seeds obtained from greenish yellow capsules when leaves were harvested at 1 week after flowering. GVI was significantly influenced by leaf harvesting stage (p=1.5e-06) and stage of capsule harvesting (p=0.00052). Greenish-yellow capsules had seeds with higher germination velocity index than brown capsules. The highest germination velocity index of 17.65 was observed in seeds attained from brown capsules when leaves were harvested at 1WAF. Leaf harvesting of Kenaf significantly influenced its seed quality with harvesting at 1 week after flowering having higher seed quality. Seed harvested from greenish-yellow capsules (180 DAP) had better quality in terms of germination and vigour (GVI) compared to those harvested from brown capsules (195 DAP).