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Introduction
Kenaf (Hibiscus cannabinus L.) is a fibre plant native to east-central Africa where it has been grown for several thousand years (LeMahieu et al., 1991). According to Dempsey (1975), kenaf is a short-day, annual herbaceous plant cultivated for the soft bast fibre in its stem. Kenaf grows in tropical and temperate climates and thrives with abundant solar radiation and high rainfall. Under good conditions, kenaf can grow to a height of 5-6 m in 6-8 months and produce up to 30 t/ha of dry stem material (Wood, 1998). The crop is poised to be introduced as a new, annually renewable source of industrial fibre in developed economies (Taylor, 1998).
The identification of kenaf varieties based on morphological and agronomic characters is problematic due to limited variation. Most kenaf accessions have red or green stems, yellow flowers, entire or palmate shape leaves and they are late maturing (Siepe et al., 1997; Cheng et al., 2004). In addition, the understanding of relationships between kenaf germplasm is still very limited. These factors have significantly hindered the effective utilization and conservation of genetic resources (Cheng et al., 2004). Cheng et al. (2002) indicated that RAPD (random amplified polymorphic DNA) analysis was able to identify kenaf varieties and determine their genetic relationships to a certain extent, but the genetic basis of the accessions used was narrow, and the number of DNA polymorphisms low. In order to accumulate more informative molecular data and to determine diversity and genetic relationships of kenaf germplasm worldwide, Cheng et al. (2004) applied AFLP fingerprinting, and showed that it was more effective than RAPD analysis in distinguishing kenaf varieties. The aim of the present research was to fingerprint 19 kenaf accessions using AFLP analysis and to determine genetic relationships between them.
Materials and methods
In total, 19 accessions (Table 1) were studied. Two plants per accession were grown in 8 l pots, containing red soil (Bainsvlei soil type), under standard glasshouse conditions at the University of the Free State, during January through May, which is close to the normal growing season for kenaf in South Africa. The days are long in January, and become shorter towards harvesting. The temperature was set at 20°C night...