ABSTRACT The experiment was conducted at Jute Research Sub Station (JRSS), Tarabo, Narayanganj during 2020-2021 to determine the optimum harvesting time for higher fibre yield of BJRI developed Kenaf varieties. The experiment was laid out in RCBD design with three replications. Four kenaf varieties viz., BJRI Kenaf-1, BJRI Kenaf-2, BJRI Kenaf-3 and BJRI Kenaf-4 and four harvesting age viz., 90 DAS, 100 DAS, 110 DAS and 120 DAS were used as treatment. Results revealed that BJRI kenaf-2 produced the highest fibre yield (2.62 and 3.61 t/ha) and the highest stick yield was recorded (5.22 and 6.41 t/ha) on 120DAS during2020 and 2021, respectively. The lowest fibre yield as well as yield contributing characters were recorded from          90 DAS harvested crop irrespective of varies in both years.

Key words: Kenaf, variety, fibre and stick yield

Introduction Kenaf (Hibiscus cannabinus) has become an important industrial cash crop as a source of natural fiber. In Bangladesh, Kenaf is now a promising new fibre crop and day by day the demand of kenaf fibre is increasing. In marginal land, kenaf cultivation is profitable than jute because it can be produced at minimal management practices with less labour and lower cost. The prices of jute and kenaf fibres are almost same, and as a consequence, kenaf is replacing jute in the marginal areas. At present, in Bangladesh, so many areas are covered by Kenaf like, Bhrambaria, Voirab, Netrokona, vast areas of Kishoregonj; Laksmipur, Noakhali, Shriatpur, Madaripur, some sporadic areas of Tangail, Mymensingh and Jamalpur (Islam, 2019). Harvesting time is an important factor affecting kenaf properties (Zhou et al., 1998). The suitable harvesting age for kenaf depends on the usage and kenaf variety. Various industries harvest the kenaf plants for products at different harvesting times during the plant life cycle.  Normally for the purpose of producing fibre kenaf is harvested after the fibre matures (4-5 month after planting or after flower blooming) but for other uses of kenaf especially for forage, kenaf is harvested in 7-8 weeks after planting. Masnira et al. (2015) were tested two kenaf varieties on the fibre yield showed that the tensile strength for both varieties was highest at 112 DAS and both varieties should be harvested at this age for fibre production. In Bangladesh, kenaf normally harvest at the age of 120 days. Therefore, a field experiment was designed to evaluate BJRI developed kenaf varieties of Bangladesh, BJRI kenaf-1, BJRI kenaf-2, BJRI Kenaf-3 and BJRI Kenaf -4 with different harvesting time for higher fibre yield.