|Webber, Charles - Chuck|
Submitted to: Industrial Crops and Products
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/14/2002
Publication Date: N/A
Citation: Interpretive Summary: Additional information is needed to determine the ideal harvest age to maximize the various kenaf (Hibiscus cannabinus L.) yield components for different plant products. The plant maturity at harvest not only influences the total plant material harvested but also the composition and quality of the plant. The objective of this research was to determine the effects of kenaf plant age on the plant's composition. A 3-year field study was conducted at Lane, Oklahoma on a fine sandy loam soil with the kenaf variety Everglades 41. The crop was harvested at four harvest dates, 60 days after planting (DAP), 90 DAP, 120 DAP, and 150 DAP. The harvest ages did not significantly affect plant populations, but did have a significant effect on all other yield parameters. The total weight of plant material consistently increased from 60 DAP (5,067 lb/ac) to 150 DAP (18,655 lb/ac). Although the growth rates did level off or even decrease after 120 DAP, the significant increase in stalk yields after 120 DAP justify the additional 30 days of growth for stalk production. Stalk yields ranged from 1.7 t/ac for 60 DAP to 8.6 t/ac for 150 DAP. The percentage of leaf material (32%, 60 DAP to 12%, 150 DAP), and leaf digestible protein (18.3%, 60 DAP to 15.5%, 150 DAP) decreased with each harvest date. Leaf yields increased from 1.1 t/ac (60 DAP) and 1.8 t/ac (90 DAP) to 2.0 t/ac at 120 DAP and then decreased to 1.7 t/ac for the 150 DAP harvest. This research provides valuable information to assist managers to maximize the plant's composition to enhance its intended use, whether for fiber or feed production.
Technical Abstract: Kenaf (Hibiscus cannabinus L.), an alternative fiber crop for paper pulp production, is normally grown during the entire summer growing season (150 plus days) to maximize fiber yields produced by the stalks. It may be advantageous to harvest the kenaf crop earlier than 150 days after planting (DAP) depending on the harvesting conditions (e.g. soil moisture or equipment availability) or marketing opportunities (price fluctuations or alternative uses). In addition to affecting the final stalk yield, harvesting kenaf at an earlier maturity may significantly alter the composition of the kenaf plant. The objective of this field study was to determine the effect of kenaf plant maturity on kenaf yield components. Kenaf variety 'Everglades 41' was planted at Lane, Oklahoma, USA, in the spring of 1996, 1997, and 1998 on 76-cm row spacing at 250,000 plants/ha. Kenaf plots were harvested at four harvest dates, 60, 90, 120, and 150 DAP. .Harvest age did not significantly affect plant populations, but did have a significant effect on all other yield parameters. Kenaf plant height, stalk yield, stalk percentage, and total plant biomass consistently produced significantly greater values at 150 DAP than at 60, 90, and 120 DAP during the three years of research. Although the growth rates per day did level off or even decrease after 120 DAP, the significant increase in stalk yields after 120 DAP justify the additional 30 days of growth. This research provides valuable information that can be applied to both kenaf fiber and forage production, especially in gaining a greater understanding of the relative response of the kenaf yield components and partitioning of dry matter during the growing season.