Determination of a critical sowing date for the discrimination among winter sown forage cereals in khartoum

Predicated by the short winter season of the central Sudan, winter crops such as barley and wheat in the Gezira are disadvantaged by the strictly narrow optimum sowing time. The growth of summer crops such as Abu Sabeen on the other hand, if sown early in winter, is seriously impaired by the noncondusive growing temperatures which eventually resulted in longer growing periods and low yields. Hence, the determination of a critical sowing date to grow either of the two groups during winter in Khartoum state is of utmost importance. To determinate such a sowing date, an experiment was conducted for two consecutive winter seasons viz 2004/05 and 2005/06 in Shambat Research Farm. The treatments comprised four crops viz a local variety of barley (Hordium vulgare), maize (Zea maize), sorghum bicolor cv. Abu Sabeen and Pannar 888, a hybrid of sorghum bicolor and Sorghum sudanese. The four crops were sown on five sowing dates viz 1st Dec. 15th Dec., 1st Jan., 15th Jan. and 1st Feb. The treatments were arranged in spilt plot design, the sowing dates were the main plot and the crops were the subplot and were replicated 3 times. The data collected were: number of culms at the age of 10 days after sowing (DAS) (initial) and at harvest (final), days to 50% flowering, days to harvest. At harvest, plant height, fresh matter, dry matter yield and leaf/stem ratio on dry matter basis, were estimated. Mean temperature of the growth of all crops was calculated over the whole growing period for each crop in each sowing date. The results showed that both barley and maize were characterized by the lowest mean temperatures for growth, earliness to attain the stage of 50% flowering and days to harvest. In addition, barley had the shortest plants, the highest numbers of culms/ square m and leaf/stem ratio. The study pinpointed 1st of January as a critical sowing date. When sown before it the dry matter (DM) yield of barley were evidently the highest while the differences among those of the other species were limited. Conversely however, when sown after it, the DM yield of Abu Sabeen was markedly the highest while those of barley and maize were the lowest. During this latter period, the DM yield, of Pannar 888 were lower than those of Abu Sabeen but were higher than those of barley and maize. Hence, 1st Jan. could be considered as a critical sowing date for the crop choice among winter sown forage cereals in Khartoum