Sweet sorghum or sorgho [Sorghum bicolor var Saccharatum, Moench (L.)] is grown in Egypt on a small scale as a summer forage crop and has a potential future for sugar production. Available information, however, is few on its cultural practices as a dual-purpose crop for sugar and forage. This study was conducted to determine the effects of plant density (70000, 93333 and 140000 plants/fed.) and some weed control treatments (hand hoeing once at 15 or 28, or twice at 15 and 28 days from sowing; using Gesaprim 80% or 90%, Herbazen 90%; and un-wedded) on growth, yields of sweet sorghum and associated weeds on newly reclaimed soils in Sohag Governorate, Egypt. Two field trials were carried out in summer of 2003 and 2004 seasons at the Experimental Farm of the Faculty of Agriculture, Sohag.
planting 140000 plants of sweet sorghum/fed. resulted in a significant redaction in dry weight of narrow and broadleaf weeds as well as total dry weight of weeds compared with planting 70000 plants/fed. The application of Herbazen 90%, Gesaprim 80% or Gesaprim 90% reduced significantly the dry weight of narrowleaf weeds, while practicing hand hoeing twice at 15 and 28 days after sowing was the best in reducing dry weight of broadleaf weeds. Applying Gesaprim 90%, Gesaprim 80% or Herbazen 90% reduced the dry weight of total weeds. The interaction between plant density and weeding control methods was almost significant on the studied weed traits. Increasing planting population from 70000 to 140000 plants/fed. resulted in a significant increase in stalk height, yield of stripped stalks. The stripped stalks yield in the higher density plots was 5.44 t/fed. higher than the lower density of 70000 plants/fed. However the mid plant density (93333 plants/fed.) seams to produced the highest forage yield/fed. Insignificant differences were detected in the percentages of total soluble solids (TSS%), sucrose, purity and reducing sugars percentage as affected by planting densities. Practicing hand hoeing twice at 15 and 28 days after planting had the highest values in stalk length, stalk diameter, stripped stalk yield, forage yield, TSS %, sucrose % and purity % and reducing sugars percentage of sweet sorghum. Under such conditions of this study, planting 140000 plants of sweet sorghum/fed. and practicing hand hoeing twice could be recommended for sweet sorghum production.