Effect of Percent and Stage of Leaf Defoliation on the Quality of Sugarcane, at Arjo - Dedessa Sugar Factory, in Western Ethiopia
Abstract
The research was conducted at Arjo-Didessa Sugar Factory which is located in East Wollega Zone of Oromia Regional State with the objective to determine the effect of leaf defoliation at different stages of sugarcane (Saccharum officinarum) on the quality. Sugarcane (Saccharum spp.) is unusual among field crops in that it is not the seed that have economic values, but rather the stalk. Sucrose is extracted from the large stalks that are produced by sugarcane plants. The effect of percent and stage of leaf defoliation on sucrose content as well as recovery percentage of sugarcane is still unknown. Effect of leaf defoliation at three different stages on quality of sugarcane juice was studied under field conditions. The methodology used include seven percent of leaf defoliation comprises of 10%, 20%, 30%, 40%, 50%, 60% and 0% as a check and three growth stages of defoliation at 9, 10 & 11 month of sugarcane was arranged in Randomized Complete Block Design. The results depicted that, significant variation among leaf removal and cane age was noted for quality parameters. Thus, significantly higher percent of sucrose percent (11.70%) at 30% of leaf removal and (11.50%) at20% of leaf removal were obtained from 11 and 10 month age of NCO-334 sugarcane variety respectively ,however, lower percent of sucrose (9.03%) at 11month age was recorded from undefoliated (check).In addition to these results the sugarcane plants that could be partially defoliated with changing sucrose production and retention of defoliated leave between furrow providing advantage, that increase soil moisture leads to water conservation especially for sugarcane grown under rainfall condition like Arjo Dedessa sugar factory, reduce weed growth, and prevent substantial losses of C and N due to sugarcane leaf burning at harvesting time. However, further future research is required to strengthen the investigation by confirming similar research on different location are necessary to recommend to all Ethiopian sugar factories.
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Introduction
Sugarcane is one of the most important crops in the world (Dagar et al., 2002). Sugarcane belongs to the genus (Saccharum L.,) of the grass family (Poaceae) and originated in Papua New Guinea, as original habitat and from where it spread to southEast Asia and India in the course of few thousand years (Bull, 2000).
The Office of Agricultural Economy, (2008) reported that the sugarcane burned in the field had many disadvantages such as weight reduction, microorganism destroyed easily, rapid decrease of sweetness, high production cost of plant, that organic material and structure in soil were destroyed and decreased sugar production. Sugarcane harvesting is a critical step that must be managed to maintain good quality and quantity of sugarcane production. Farmers harvesting sugarcane have a leaves-removing or leave defoliating step and cut the stem closing to the soil, then cut the top of sugarcane stem. Leaves and leaf sheaths of sugarcane caused delay of harvesting. Moreover, the sugarcane crop that has not been fully leaves-removed (leave defoliations) could carry some soil, sand and mud, thus damaging the downstream sugarcane process machine and reduced sugar yield (Yangyeun and Wongpicheth, 2008).
The contamination will be increased more when using the car to grip sugarcane to the truck. Sugarcane leaf-defoliating tools could help to speedup sugarcane harvest and reduce contamination. However, researchers in the past had focused on tools or equipments used to help harvest sugarcane crop; for example, sugarcane harvester, knife used for sugarcane crop on performance to sugarcane harvester. However, leaf-removal machinery can solve the problems of sugarcane burning and reduce contaminants. Retention of unburned residues can increase nutrient conservation, reduce weed growth, and conserve soil moisture on the other hand substantial losses of C and N due to sugarcane residue burning have been reported (Viator et al., 2006).
In general physiological and morphological responses of individual plants to defoliation was evaluated in chronological sequence beginning with plant function during "steady state" growth prior to defoliation, followed by the short-term effects of defoliation, and concluding with long-term processes contributing to the reestablishment of "steady-state" growth (Steingraeber et al., 1993). Particularly according to Gutierrez et al (2004), mechanical defoliation of sugarcane plants (Saccharum spp.) will provide leaves that can be used as fodder but the effect of partial mechanical defoliation on sucrose content, enzyme activities and agronomic parameters of sugarcane is still unknown and also the concentration of sucrose in the stems of partial defoliated plants was significantly different from that found in intact plants. Similarly, Dendooven et al (2004) indicated that some agronomic parameters and enzyme activities were different in defoliated plants compared with intact plants except for the moisture content which was higher in defoliated plants than in intact ones. These makes sugarcane plants could be partially defoliated changing sucrose production and agronomic parameters while providing leaves that could be used as fodder.
The Ethiopian Government is building modern sugar factories and expanding the existing ones with the aim of maximizing the production volume to alleviate the scarcity of sugar in the country (EIA, 2008). This work was conducted in view of the limited information on the effect of leaf defoliation at different stages of sugarcane on biomass yield and quality but the hypotheses tested in these studies, the effect of leaf defoliation at different stages of sugarcane on biomass yield and quality were superior in defoliated than undefoliated sugarcane. This research was initiated with the objective of to evaluate the effect of defoliation at different stages on quality, and response of sugarcane crop to defoliation and its advantage to increase sugar recovery at Arjo-Didessa Sugar Factory which is located in East Wollega Zone of Oromia Regional State.
Conclusion
In light of the results obtained, the different levels and stages of defoliation have a significant effect on all the parameters studied .Partial defoliation in sugarcane (i.e. removal of half leaves) has been shown to not have a long-term negative effect on the quality parameters. Generally the results obtained in this study are based on data of superimpose experiment and, hence do not warrant the formulation of a clear-cut recommendation, However, suggestive enough to draw the following recommendations: When defoliation was applied on 30 % of leaf removal at 11 month growth stage in relative to other percent of defoliation and stage higher recovery percentage was recorded. On the other hand trash or leave without defoliating that is delivered with the stalks to the factory could also reduce the quality of sugarcane juice. However, further study is required to support some leaves defoliated in the field should be utilized as a soil fertilizer there is still plenty available for use as biomass; retention of unburned leave can increase nutrient conservation, reduce weed growth, conserve soil moisture and also defoliated leaves could be used as animal fodder after 9month of crop age without affecting sugarcane yield. Defoliation could also be used to renew, refresh and increase growth and photosynthetic rate in sugarcane plants under abiotic stress conditions. However, further research is required to strengthen the investigation and repeating similar research on different location are necessary to recommend to all Ethiopian sugar factories.
