A field experiment was conducted at Sakha Research Station, Kafr
El-Sheikh Govemorate, during 2006/2007 and 2007/2008 seasons to
study the influence of three sowing dates (15 September, 15 October and
15 November), three mineral nitrogen fertilizer rates (30, 60 and 90 kg
N/fed) and two sources of bio-N fertilizer (Azospirillum, Bacillus N-
fixing bacteria) in addition check treatment on sugar beet yield and its
components. Each sowing date included 9 treatments, which were the
combinations between three mineral nitrogen fertilizer rates and three
bio-N fertilization treatments. A randomized complete block design with
three replications was used. A combined analysis between sowing dates
over the two seasons was done.
Results revealed that root length and root yield were significantly
increased with early sowing on 15 October as compared to the other
sowing dates. Sowing dates of 15 September and 15 October
significantly increased root diameter, root fresh weight/plant and yields
of top and sugar as compared to the late sowing date.
Results showed, also, that root diameter and yields of top and
sugar were significantly increased with adding 90 kg N/fed, while adding
60 or 90 kg N/fed gave the same significant for the other traits under
study as compared to 30 kg N/fed.
Inoculating seeds with bio-fertilizers significantly increased most
traits under study, except leaves fresh weight/plant, however, inoculating
seeds with Azospirillum brasilense surpassed Bacillus polymyxa in top
yield.
Root diameter and top yield were significantly increased with
the interaction effect between sowing date (15 September) and adding 90
kg N/fed as compared to the late sowing date (15 November). The
different combinations between nitrogen fertilizer rates (60 or 90 kg
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