Two field experiments were conducted at Cairo University, Agric,
Experimental Station, during 2001102 and 2002/03 seasons on clay loam soil. The
objective was to describe yield and quality in response to different nitrogen fertilization
rates (0, 30, 60, 90 and 120 kg N/fed) and harvesting dates 180, 195 and 210 days
from sowing). Results revealed that increasing nitrogen level up to 120 kg N/fed
increased root diameter, root length, root weight/plant and LAI, white reduced quality
traits in terms, of sucrose, purity, recoverable sucrose and quality of beet % ¡n both
seasons. Impurities in terms of Na, K and amino-N increased with increasing nitrogen
rate up to 120 kg N/fed. Sucrose loss to molasses increased significantly with the
increase in nitrogen level. Addition of 120 kg N/fed gave the highest root and top yield,
while 90 kg N/fed gave the highest recoverable sugar yield ton/fed. Delaying harvest
date up to 210 days from sowing increased root diameter, root length and root weight,
but decreased LAI.
Sucrose, purity, recoverabie sucrose and quality percentages as well as
impurities were increased with the delay ¡ri harvest. Delaying harvest date up to 210
days from sowing decreased sucrose loss to molasses from 2.10 and 2.25 % after
180 days to 1 .87 and 2.01 % after 210 days in both seasons, respectively.
Delaying date of harvest up to 210 days after sowing caused a significant
increase in root yield of 11.6% (from 21.6 to 24.1 ton/fed) on the average of both
seasons. While top yield decreased with delay harvest date.
Recoverable sucrose yie'd increased from 2.34 and 2.49 ton / fed when
harvest took place after 180 days to 3.19 and 3.30 ton/fed when harvest after 210
days from sowing.
Nitroge.i levels x harvesting dates interactions exhibited significant effect on
root diameter, root weight and LAI as well as sucrose, recoverable sucrose and
quality percentages. The highest root yield 30.4 ton/fed resulted from adding 120 kg
N/fed with harvest after 120 days from sowing in the second season, while the
highest recoverable sugar yield (3.73 and 3.80 ton/fed) resulted from 90 kg N/fed and
harvest toro variety at 210 days from sowing, in both seasons, respectively.