Influence of cut-off irrigation practices on sweet sorghum production, yield and juice quality

摘要

Two sweet sorghum varieties were subjected to field and laboratory studies on two successive seasons 1998 and 1999 at Mallawi Res. Station (El-Minia Governroate) to find out the influence of prolonging cut-off irrigation timing before harvesting onqualitative and quantitative criteria of sweet sorghum varieties. A split plot design with four replicates was used where cut-off irrigation timing were allocated in the main plots (3, 4 and 5 weeks before harvesting), while sweet sorghum varieties (Honey and Roma) were randomly distributed in the sub plots. The results indicated that increasing cut-off irrigation before harvesting up to 5 weeks decreased significantly stalk and tops yield (ton/fed.), juice yield and extraction (%), while, the values ofBrix (%) and syrup extraction (%) were raised. Middle treatment (4 weeks) recorded best yield and highest juice quality (sucrose and purity %) with excellent syrup. However, the first time cut-off irrigation (3 weeks) attained the highest reducing sugars (%) (RS%). Also, it could be noticed that "Honey" variety has a superiority over "Roma" variety to stalk yield, juice quality (sucrose and purity %), juice and syrup yield and percentages. While, Roma variety exceeded Honey in bagasse yield, brix and reducing sugar percentages. Water consumptive use of sweet sorghum plants decreased with increasing cut-off irrigation timing before harvesting up to five weeks. However, the highest values of water use efficiency by sweet sorghum plants were gained whenirrigation water was cutting-off four weeks before harvesting. Honey variety consumed more water than Roma one and it was the highest effciency of water use. Finally, cutting-off irrigation four weeks before harvesting could be recommended at Mallawi toachieve the maximum yield and syrup production per the unit of water consumption by sweet sorghum.