The Effect of Split Nitrogen Application on Patterns of Dry Matter partitioning in Sugar beet

The effect of split application of nitrogen fertilizer on dry matter (DM) partitioning patterns, yield and quality of sugar beet was studied in a field experiment at Brat Abad, Fariman during 2001 growing season. Three levels of nitrogen fertilizer (N, 70; N2, 140; N3, 210 kg N/ha) were split as S1, %100 at sowing; S2, %75 at sowing and %25 at thinning; S3, %50 at sowing and %50 at thinning; S4, %25 at sowing and %75 at thinning. Factorial experiment based on a randomized complete block design with 4 replications was used. Dry matter partitioning towards storage roots in N1 and in N2 treatments switched at 66 and 76 day after emergence, respectively. In S1 spliting pattern more DM was allocated to root in all growth stages. So that in 1400 GDD (5 Aug) amount of dry matter partitioning to storage roots and tops was equal to %50 while at this stage, partitioning of dry matters to storage roots in S2, S3 and S4 were % 47, % 44 and % 38, respectively. Nitrogen levels had significant effect on polarity, Na, K, recoverable sugar yield, white sugar content and molass sugar. However, these effects on root and sugar yield and N-amino was not significant. Higher rates of nitrogen fertilizer, led to decrease in polarity, white sugar content and recoverable sugar yield. However, root yield, Na, K, N-amino and molas sugar increased in response to N levels. Maximum net sugar yield (4.4 ton/ha) was obtained in the lowest N application. In this study, effect of different patterns of nitrogen spliting and interaction between spliting patterns and nitrogen rates on quality and quantity of sugar beet was not significant. However, maximum net sugar yield (4.8 ton/ha) was obtained in N1S1 where the lowest level of N fertilizer was applied at sowing.