Kenaf Varietal Comparisons
Growing conditions for Kenaf were not as favorable in 1997 as in 1996 lowering the highest yield to less than 5 tons per acre. The highest yielding variety, C118-92K, was also the highest yielding variety in 1996.
After several years of testing many of the same varieties of Kenaf, two newly developed varieties were acquired in 1996. One of these varieties C118-92K showed a higher yield potential than the others in the trial. The 1997 study was instituted to verify the strength of this variety under another year╠s climatic conditions.
Materials and Methods
This trial was designed as a replicated small plot trial with four replications. The plots were planted with a cone-type planter which distributes a given weight of seed uniformly over the length of the plot. Six pounds of seed were planted per acre for each variety and the seed was placed approximately one and a half inches below the surface of the soil, the plots were then irrigated to sprout the seed. The plots were planted on 36" row spacings. The following crop history provides the information on how the crop was managed:
Irrigation was terminated in early September after peak growth had occurred to promote drying down of the plants. The frosts in October started the defoliation process. Harvests were not performed until January as a convenience to the experiment station operations, this was probably detrimental to maximum yields. Twenty-four square foot sub-plots were harvested for yield. Eight one-foot samples were collected from each plot at both the ground level and between four and five feet up on the stalk. Diameters of these samples were measured with a dial micrometer to determine the total diameter of the stalk with and without the bark. Bast and core fiber percentages were then calculated using these diameters.
Results and Discussion
A comparison of yield data between 1996 and 1997 is shown in Table 1. The 1997 plots were planted on saltier ground, this coupled with unfavorable weather factors, lead to a decline in yield for the 1997 crop. The variety ranking came in nearly the same order both years in spite of the yield difference, with C118-92K producing the highest yield. The C118-92K yields were 10% and 8% higher than that of Everglades 71 for 1996 and 1997, respectively. Unfortunately the plants per acre information for 1997 was not obtained. The slightly smaller stem size for 1997 would lead one to believe that there were a few more plants per acre. Even though the stem diameters were smaller in 1997 than in 1996, the ratios between the stem size at the base of the plant and stem size up 4 to 5 feet on the stem remained about the same. In 1996 that ratio was 1.44 and in 1997 the ratio was 1.38. Variability between varieties within a given year and same variety over the two years was about the same.
Bark and fiber characteristics in the 1997 trial are shown in Table 2. In every case the bark thickness declined from the base of the plant to a level 4 to 5 feet up the stem, but the percent cross section of the bast fiber (from the bark) on most of the varieties increased slightly. Differences between varieties were small and no statistical analyses were performed on the data.
Table 3 is a comparison of bark and calculated fiber characteristics for 1996 and 1997. The percent bast fiber was much higher in 1997 than that seen in 1996 or reported by us in 1994 (1). The current values are probably more in line with what is commonly seen in the industry.
This is a part of publication
AZ1059: "1998 Forage and
Grain Agriculture Report," College of Agriculture,
The University of Arizona, Tucson, Arizona, 85721.