YIELD AND QUALITY OF SOME SUGAR BEET VARIETIES AS AFFECTED BY SOWING DATE AND HARVEST AGE

Two field experiments were conducted in 2008/2009 and 2009/2010 seasons in Sakha Agricultural Research Station, Kafr El-Shiekh Governorate. The main goal of this study was to investigate the response of five multigerm sugar beet varieties (Florima, Cleopatra, Heracule, Avantage and Alamas) to three sowing dates (1 st Sept., 1 st Oct. and 1 st Nov.) and three harvest ages (180, 195 and 210 days after sowing). A split plot design with four replications was devoted for each sowing date where harvest age was allocated in the main plots and varieties in the sub-plots. A combined analysis over the three sowing dates and two seasons was undertaken. markedly affected sucrose and purity percentages as well as root and sugar yields/fed. Over both seasons, sugar beet sown early on the 1 st of Sept., and/or 1 st Oct. recorded at par the highest root and sugar yields/fed. Sugar beet varieties differed significantly in their yield potential. Cleopatra variety recorded the highest sucrose %, while Florima and Heracule varieties produced the highest root and sugar yields/fed. Harvesting sugar beet after 210 days from sowing was the proper age to obtain the highest sucrose and purity percentages as well as root and sugar yields/fed. The interaction between sowing dates and varieties exerted a significant effect on root yield/fed. Florima variety recorded the highest root yield in the early sowing date (1 st of Sept.), while Cleopatra and Avantage varieties recorded their maximum root yields when they were planted in the second sowing date (1 st of Oct.). The interaction between sowing date and harvest age significantly affected almost all the studied traits. Regarding this interaction effect on sugar yield/fed, the response equations indicated the need for more delay in harvest than 210 days after sowing particularly for the early sown sugar beet in 1 st of September. Under the conditions of this work, sowing Florima and Heracule varieties on the 1 st of Sept. or 1 st Oct. and harvesting them after 210 days from sowing can be recommended to obtain the highest root and sugar yields/fed.