Mohamed Ibrahim Ismail El Hag Hassan Abuelgasim
Evaluation of Guar as a Proposed New Crop for Rainfed Semiarid Regions of Western Sudan
Mohamed Ibrahim Ismail El Hag Hassan Abuelgasim
A set of guar varieties was tested for three seasons (1998-99, 1999-02 and 2000-01) at El Fasher Research Station under rain-fed conditions. This study was intended to evaluate the adaptability of this crop to the agro-ecological environment of the semiarid Darfur region. The average seed yields of all guar varieties in the three seasons were 1036,1088 and 490 kg/ha respectively, while the overall average across the three seasons was 781 kg/ha. These yield were higher than that of the other crops under the same environmental conditions. Although variations in yield were not statistically significant, some varieties are superior (e.g. HFG-182) and produced greater yield (951 kg/ha) across seasons. This crop did not receive any chemical pest and disease control in all experiments. Therefore, this crop is suggested to be one of the new cash crops in the region.
Guar, or cluster bean, (Cyamopsis tetragonoloba L. Taub.) is a coarse, upright, bushy, drought-tolerant summer annual legume (belongs to the family Leguminaceae). It is a native plant of India and Pakistan where it is grown principally for its green fodder and for the pods that are used for food and feed. It is grown in tropical Asia, Africa and America. The major world suppliers are India, Pakistan and the United State, with smaller acreages in Australia and Africa (Undersander et al., 2006). Guar is a new crop in Sudan, and is grown commercially in limited scale near Singa, Blue Nile, for seed processing into flour (Osman, 2005). This crop grows well in a variety of soils and thrives in alluvial and sandy loams with well-drained subsoil.
Unlike the seeds of other legumes, guar seeds contains sufficient amount of galactomannan gum, which form a viscous gel in cold water. Guar gum has 5-8 times the thickening power of starch. It is used in textile, paper manufacture, stamps, cosmetics, pharmaceuticals, food products, e.g. bakery products, ice cream and meat binder and recently in petroleum oil and mining industries, explosives and ore flotation (Undersander et al., 2006). On the other hand, guar is considered as an excellent soil improvement crop, like other legumes, with respect to available nitrogen, which improve yield of succeeding crops.
In sandy soils of semiarid regions, drought stress and lack of nutrients (mainly nitrogen) are considered as the main production constraints. Therefore, guar is expected to fit very well in this region as an important drought tolerant cash crop and soil-building crop, with respect to available nitrogen through nitrogen fixation, to maintain soil quality and sustainable productivity. It was found that inclusion of guar in the rotation had a beneficial effect on enzyme activities, nitrifying bacteria, organic matter, available nitrite and phosphorus over fallow-pear millet, resulting in a significant increase in pearl millet production (Rao et al., 1995)
Guar is expected to give an economical output in semiarid sandy soils under rainfed conditions. Guar was introduced and tested in the Sudan in early sixties under rainfed and irrigation which gave good indication of its successful, but its research works have not continued due to many factors mainly lack of high market demand. The objective of this study was to evaluate the performance of guar varieties under rainfed semiarid of Darfur region.
Materials and Methods
The experiment was conducted for three seasons (1998/99, 1999/2000 and 2000/2001) at El Fasher Research Station on sandy soil under rainfed conditions.
Ten guar varieties were tested in this experiment. Sowing was done on 23 July, 22 July and 16 July for the three years respectively. Each genotype was planted in 6 rows of 6-meter length and spacing of 60 cm between rows and 15 cm between plant holes. The plants were thinned to one plant per hole after two weeks from sowing. Treatments were arranged in a randomized complete block design with 4 replications. Data were recorded from the central four rows of each plot.
Average monthly rainfalls, during the growing periods, are presented in Table1. In general, most of rainfall was received in July and August. The total annual rainfalls were 332.5, 291.6 and 146.2 mm for the years 1998, 1999, and 2000, respectively.
Although there were variations in seed yields, differences among the guar varieties were not statistically significant due to high coefficient of variability in each of three seasons (Table 2). Seed yield was very low in the third season compared to the previous tow seasons due to low rainfall during this growing season (Table 1 and 4). The highest overall mean seed yield of the three seasons was produced by HFG-182 (951 kg/ha). The mean differences among the three seasons were statistically significant (Table 4).
Differences among the guar varieties in hay yield were not statistically significant in spite of large variations due to high coefficient of variability in each of the three seasons (Table 2). However, genotype HFG-182 produced the highest mean hay yield (1674 kg/ha), while RGC-192 produced the lowest mean yield (1149 kg/ha) of the three seasons (Table 2). The mean differences among the three seasons were statistically significant (Table 4).
Days to maturity
Genotype differences for days to maturity were not significant in each of the three seasons (Table 2). However, seasons had significant effect on it, which ranged between 73-89 days (Table 3).
Plant height variations were not statistically significant in each of the three growing seasons (Table 3). However, seasonal effects were statistically significant (Table 4).
The guar cultivars tested under rainfed semiarid region of Darfur showed high adaptability to the region compared to the other crops. The overall means of the seed yields across the three seasons was 871 kg/ha, but they varied from year to another due to fluctuation in rainfall. In the first two seasons the yields were high (1036-1088 kg/ha) compared to the third season (490 kg/ha) due to drought stress. Variety HFG-182 produced the highest mean yield across the three seasons (951 kg/ha). These guar varieties were tested earlier under rainfed conditions at El Obeid Research Station and found that variety DPS produced the highest yield (219 kg/ha) while the mean of all genotypes was 134 kg/ha (Abuelgasim, 1985). In addition, the mean yield of 2000/2001 growing season (490 kg/ha) was higher than that produced at Abu Naama (372 kg/ha) in the same season (Loggale, 2001). Under the prevailing rainfed conditions, millet produced very low mean yields (224, 118 and 219 kg/ha for the three seasons respectively), while guar produced good seed yields (1036, 1088 and 490 kg/ha for the three seasons respectively). In addition, during extremely dry season (2000/2001), guar growth did not show severe symptoms of drought stress and remained green most of the time, although its growth and yield were lower than that of the normal conditions. Therefore, guar is a promising crop for this dry environment. However, its acceptability, utilization and marketing are to be determined.
Based on the yield of guar compared to the other crops under limited rainfall and absence of economic damages by pests and diseases, guar is proposed as a new cash/fodder crop in Darfur semiarid region under rainfed conditions to increase diversification of mono-cropping millet and improve soil fertility.
Abuelgasim. E. H. (1985). Guar Variety Trial. 1985-85 Annual Report, El Obeid Research Station, ARC.
Loggale, L. B. (2001). Response of Guar to Plant Spacing and Number of Plants/Hole. 2000/2001 Annual Report, Food Legume Program, Kenana Research Station Abu Naama, ARC
Osman, M. E. (2005). Performance of Guar as a New Crop under Flood Irrigation in Gash Dulta. In: El-Siddig, K. (ed.). Proceedings of The 37th and 38th Meetings of the National Crop Husbandry Committee. Pp.73-76
Rao, A. V., Tarafdar, J. C.,Sharma, S. K., Kumar, P. and Aggarwal, R. K. (1995). Influence of Cropping Systems on Soil Biochemical Properties in an Arid Rain-fed Environment. Journal of Arid Environment, 31: 237-244.
Undersander, D. J., Putnam, D. H., Kaminski, A. R., Kelling, K. A., Doll, J. D., Oplinger, E. S. and Gunsolus, J. L.. (2006). Guar. Alternative Field Crops Manual, University of Wisconsin-Madison. www.hort.purdue.edu/newcrop/ afem/guar.html
Table 1. Rainfall data at El Fasher Research Station during 1998-2000 growing seasons.
Table 2. Mean seed yield (kg/ha) and hay yield (kg/ha) of guar evaluated under semiarid region of western
Table 3. Mean number of days to maturity and plant height of guar evaluated under semiarid region of western Sudan for the growing seasons 1998/99, 1999/2000 and 2000/2001
Table 4. Seasonal effects on seed yield, straw yield, number of days to maturity and plant height of guar varieties evaluated under semiarid region of