Effect of some tapping tools and intensity on gum Arabic yield of Acacia Senegal and Acacia seyal trees in clay soil of Gedarif State, Sudan

Abstract

This research aimed to study the effect of some tapping techniques on gum Arabic yield of A. Senegal and A. seyal in clay soil of Gedarif State in eastern Sudan. Tow Experiment were conducted. The objective of the first experiment was to investigate the effect of tapping tool and tapping intensity on gum yield of A. Senegal. This experiment was conducted for two consecutive seasons 2014/2015 and 2015/ 2016 at Elrawashda Reserve Forest ( latitude 14˚6' - 14˚24'N and longitude 35˚32' - 35˚49'E) in Gedarif State on 15 years old A. senegal plantations.. Randomized complete block design with four replicates arranged in a factorial setting (3×2) was used. The first factor was tapping intensity with three levels, being tapping seven, five and three branches and the second factor comprised two types of tapping tool, namely, axe and sonki. Tree tapping for both seasons commenced in 15th of November and the first picking was conducted after 45 days, and then three subsequent picks were made with two weeks interval. Collected gum was air dried and weighed in grams for each picking. Analysis of variance was conducted using SAS statistical software version 9. (SAS Institute Inc., 2003). Duncan Multiple Range Test was used to separate between means.Results showed the effect of both tapping intensity and taping tool to be significant on mean gum yield per tree during both seasons (p=0.001). Gum produced under seven branches tapping intensity was 62.1 and 59.5 g/tree for both seasons (2014/2015 and 2015/ 2016 successively)which was not significantly different from that produced under five branches level 56.4 and 52.1 g/tree. However, the three branches intensity level produced significantly less gum (33.3 and29.4 g/tree). The effect of tapping tool was observed to be significant during both seasons (p˂0.05).Trees tapped with the sonki gave higher yield (58.6 and 55.7 g/ tree) during seasons 2014/15 and 2015/16 successively, than those tapped with the axe which gave 42.5 and 38.2g/ tree.During the first season 2014/2015 the effect of tapping intensity on gum yieldg/picking) was significant (p> 0.05) for all pickings. The second picking at seven branches level produced 21.7 g, whereas the fourth picking at level three branches gave 6.5 g. The effect of tapping tool on gum yield (g/picking) was significant (p˂ 0.001). In all pickings, except in the second, sonki produced significantly higher gum yield than the axe. During the second season 2015/16 variations in mean yield (g/picking)followed the same pattern as in the previous season. Except in the second picking the tool type effect was observed to be significant on gum yield (g/picking). Trend in gum yield (g/picking) in relation to season showed that maximum yield was obtained in the second picking, followed by a steady drop in the third and the fourth picking.The second experiment was carried out at Saraf Saeed forest in Gedarif State to study the effect of induced injury and tree size on gum yield of A. seyal. A factorial (2×4) experiment was carried out. The first factor comprised two levels of tree size: medium (15-20 cm in diameter) and large (20-25 cm in diameter). The second factor constituted four levels of induced injury being: 1, 3 and five injuries, besides the control. Injuries were made on the main stem. A randomized complete block design (RCBD) was used with three replications. Tapping was carried out on the 1st of November, then first and subsequent picks were done in interval of one month. After having been dried at room temperature for 48 hours, the collected gum was then weighed and recorded. Analysis of variance was conducted using SAS statistical software version 9. Duncan Multiple Range Test was used to separate between means. The effect of both tree size and number of induced injuries was found to be insignificant (P = 0.252 and 0.458 respectively). A. seyal trees subjected to five injuries produced the higher gum yield (30.8 gram) which is not significantly different from yield of trees subjected to one and three injuries which gave gum yields of 28.8 and 27.8 grams respectively. Gum yield of the control trees (31.2 g) was higher than the yield of trees injured one and three times, but there is no significant difference between them. The effect of tree size was found to be insignificant. Large trees gave mean gum yield of 26.2 grams whereas medium trees gave 30.5 grams. The study recommended tapping five branches of A. Senegal trees using sounky as a tapping tool in Gedarif State.