Time course dynamics of dry matter yield and quality of barley in the Gezira (Sudan)

The increase in the dry matter yield of forage crops with the advancement in the crop age is usually associated with concurrent reduction in the quality attributes (Khair, 1999). Such reductions were found to be sharp in some temperate legumes (Abd-Elmoniem et al., 1990), some tropical legumes (Khair and Rihawi, 1993), temperate grasses (Corral, 1979) and forage sorghum (Khair, 1992). For instance, at the age of 70 days (the usual age for harvesting sorghum for forage in the Sudan), the crude protein (CP) of the whole crop of sorghum was only 5.3% (Khair, 1992). At a similar age, the CP of some tropical legumes was adequate (Khair and Rihawi, 1993), but their fibre content was high enough to interfer with avoluntry intake by animals (Pigden, 1969). An ideal forage crop should therefore be characterized with little changes in the quality attributes with the advancement in the crop age. The objective of this study was therefore, to monitor the time course dynamics of both quantity and quality of barley forage to determine the physiological age for harvesting the maximum quality forage. The materials of this study were obtained from a trial conducted at the Gezira Research Farm. The experiment comprised four seed rates and several sowing dates during 2001/2002 and 2002/2003 seasons. The experimental details were reported by Salih (2004). Among the sowing dates, planting on 1st Dec. was selected for this study as it resulted in the highest dry matter yield (Salih, 2004). Starting 15 days from sowing, five samples were taken fortnightly from an area of 0.3 m2 from each seed rate treatments, oven dried at 85ºC for 48 hours and then the dry matter yield was determined. Prior to drying, a sub sample was taken and separated into leaves and stems to obtain the leaf/stem ratio. Both dry matter and the leaf/stem in each sample were statistically analyzed for the four seed rates, three replicates and two seasons, (split plot analysis where the season was the main plot and the seed rates were the sub plot). For quality assessment, the tissues from the samples of the four seed rates at each sampling date were thoroughly mixed, ground and four sub samples were randomly taken for proximate analysis