Effect of Planting Date, spacing and manuring on growth. tuberization and productivity of some potato (Solanum tuberosum L.) cultivars under South Darfur State environment

During the first decade of the twentieth century Darfur was one of the introduction gates for the potato crop into Sudan. Eversince, the crop has been recognized as an important food and cash crop in the region. Unfortunately, it received negligible forts to improve its productivity and development. This research was one of the endeavors to address production constraints of the potato crop in South Darfur State. The research was conducted at Nyala Irrigated Research Farm at Bilal1 area, 35 km 1st of Nyala town, during the winter seasons of 2003/04, 2004/05 and 2006/07. It med at identifying an appropriate variety to replace the century old mixed population being used locally as well as determining the optimum planting date, intra row spacing and response to manure fertilization under South Darfur State environment. Three field experiments were, therefore, carried out. The first experiment was conducted to study the effect of 3 planting dates, i.e. November 15, November 30 and December 15 on growth and yield of three potato varieties; namely, Alpha, Diamant and Draga. The second experiment was carried out to evaluate the growth and yield performances of the same varieties under three intra-row spacing of 5, 25 and 35 cm. The third experiment dealt with the response of the same potato varieties to goat manure fertilization at the rates of 0, 14, 28 and 42 t/ha. The first and le second experiments were carried out for the three seasons of 2003/04, 2004/05 and 2006/07. The third experiment was conducted for the two seasons of 2003/04 and 804/05. The result showed that the optimum planting date for best sprout emergence and early vegetative growth ranged from November 15 to November 30. Planting on November 5 followed by November 30 produced significantly higher total and marketable yields than planting on December 15. Delaying planting to December 15 resulted reduction in marketable yield by an average of 73.5% compared with planting on November 15.Variety Draga exhibited the highest significant marketable tuber yield (17.62t/ha) en planted on November 30. Variety Alpha gave the lowest yield (10.49t/ha) even hen planted early on November 15 compared with Draga planted on November 30. This is because Alpha, being a late variety, required a long growing season due to its w canopy development that renders its initiated tubers to develop at prohibitive prevailing high temperature at the end of the season. Hence, planting date ranged from November 15 to 30