الفهرس 
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Abstract
Performance of eight multigerm sugar beet varieties i.e. Kawemira, Gazelle, Top, Oscar poly, Panther, Monte Bianco, Lola and Hi poly2 under three planting dates (20th Sept., 20th Oct. and 20th Nov.) and two harvesting times (after 190 and 210 days from planting) was studied during 2002/03 and 2003/04 seasons on clay soil of Faculty of Agriculture Farm, Fayoum University, Egypt. Highly significant varietal differences were observed concerning root length and top yield per feddan in the first season and significant effect on top fresh weight per plant and feddan in the second season. Oscar poly variety gave the highest root length without significant difference from Hi poly 2 and Gazelle varieties in this respect. Top variety produced heaviest fresh weight per plant while, Oscar poly variety produced the lowest one. Regarding top yield per feddan, the superiority was for Lola variety in the first season and Top variety in the second one. The lowest top yield per feddan was produced from Oscar poly variety in both seasons. Insignificant varietal differences on the remain characters under study were observed.
Planting dates had a highly significant effect on all studied traits except top dry weight per plant, juice purity percentage, impurities, in terms of sodium, α-amino nitrogen content as well as sugar loss to molasses in the first season and root dimention as well as potassium percent in the second season insignificant effect was observed. Planting early at September 20th resulted in highest values for all these traits except juice impurities in terms of sodium and α-amino nitrogen content as well as sugar loss to molasses percentage the lowest values were obtained.
Delaying harvest up to 210 days age significantly increased root diameter, root and top dry weight per plant as well as plant dry weight. Juice quality in terms of sucrose and purity percentages as well as extractable sugar percent increased. While sugar loss to molasses as well as sodium and α-amino nitrogen content decreased as harvest was delayed. Root and recoverable sugar yields per feddan increased while top yield per feddan decreased as harvest was delayed.
The interaction between sugar beet varieties and planting dates had a highly significant effect on sucrose and extractable sugar percentages as well as recoverable sugar yield per feddan in the first season. Significant effect for this interaction was observed on top yield per feddan in both seasons and on sugar yield per feddan in only the first season.
Planting dates x harvesting times interaction had a highly significant effect on top dry weight, plant dry weight and yields of root, sugar and recoverable sugar per feddan in both seasons. Highly significant effect also observed on top fresh weight, root dry weight and top yield per feddan in the first season as well as root length, root fresh weight, sucrose and sugar extractable percentages in the second season. Root diameter, sodium and potassium content revealed significant effect with respect to this interaction in the second season.
The interaction between the three factors under study had a significant effect on root length and yields of root, sugar and recoverable sugar per feddan in only the second season.