Potentialities of Indigo plant (Indigofera tinctoria) Production in the Sudan for Domestic Use, and Exportation

Abstract

Four field experiments were conducted for two growing seasons (2001/2002 and 2002/2003) at Shambat Research Station (Sudan). The objectives of the study were to determine the management practices needed for crop establishment in the field. The main objectives were to determine the optimum cultural practices affecting yield and dye content of the Indigo plant (Hennat elgroud) including the effect of growing season on the performance of the plant, the effect of sowing date and plant spacing, effect of water management and cutting frequencies and the effect of fertilizer application and stage of harvest. The performance of the plants was measured in terms of leaves dry weight and dye content. In the first experiment, the seeds were sown in the winter season, in the summer and in the autumn season. The second experiment comprised four monthly sowing dates, commencing in June as an early date up to September as the late sowing date. Three plant spacing were used 75cm, 100 cm or 120 cm between plants. The third experiment was designed to study the effect of three watering intervals (i.e. 7-10 or 15 days) and the effect of watering stoppage at 7-10 or 15 days before harvesting in combination with two cutting treatments. In the first treatment the plants were subjected to two cut, after one month from planting and a second cut after two months and in the second treatment, the plants were cut once after two months. The fourth experiment, the Indigo plants were harvested at four stages: after one month from planting, before flowering, at full flowering and at fruit setting stage. Four different treatments of fertilizer were also studied, control, (no fertilizer), composted chicken manure at the rate of 2.5 tons /fed, nitrogen fertilizer in the form of urea \\\\\\\"46% N,\\\\\\\" at the rate of 50kg/fed and 100 kg/fed. In the winter season, the seeds failed to germinate and the results of this season were excluded. The results of the combined analysis between the summer season and the autumn season showed the total yield obtained in the summer season was more than 12.8% of the autumn season. The total dye content obtained from the summer season out-yielded the dye content obtained from the autumn season by 9.5%. The results of the second experiment showed that in both seasons, the total yield and total dye content decreased progressively with delayed sowing. The highest yield and dye content were obtained from the closest plant spacing (75 cm). The results of water management in both seasons showed that the yield and dye content were increased with decreasing irrigation intervals. The effect of watering stoppage showed that yield and dye content were decreased by increasing time of watering stoppage before harvest. The results of the effects of cutting treatment on yield and dye content showed that the plants subjected to two cuts, out-yielded the plants subjected to one cut after two months from planting. In the fourth experiment the results showed that harvesting at full flowering stage produced the highest total yield in both seasons. Similar results were obtained in the dye content. Addition of Nitrogen fertilizer at 100 kg/fed gave the highest yield and dye content, and the control gave lower yield and dye content than the rest of the treatments in both seasons. The extraction of dye content was investigated using different solvents. The results showed that the highest dye content was obtained by using ethanol (80%). The most suitable solvent systems for separation were Benzene: Petroleum ether at ratio of 20:1 and Benzene: Ethyl acetate at ratio of 80:20. TLC technique showed that the dye content possesses more than three components according to Rf values and color of bands. The colors ranged between blue- violet and Rf ranged between 0.24-0.83.