Sugar beet is a biennial crop. Its roots have high reserves of sucrose, especially during the first growing season. Usually, the harvested roots are processed into sugar. It is preferable to have plant populations a round 30,000 -40,000 plants/acre, which produce very good yields of easily harvested of high quality Sugar beet (Cattanach, et. al.; 1991) 1. Maximum yields per unit area of small beet were achieved at high plant densities, whereas maximum yields of large beet were achieved at low plant densities (Benjamin, et. al.; 2009) 2.

Fertilization is considered as a limiting factor for Sugar beet production. Therefore, it is important to choose the optimum rate and times of application of macro and micro nutrients to attain the maximum yield and high quality of Sugar beet crop However, Nitrogen is the most important nutrient that to be considered when planning a fertilizer program for Sugar beet production. This is because Nitrogen status of the plant affects the early growth and the quality of the Sugar beet at harvest (Nemeat alla et. al.; 2008) 3. Several studies demonstrated that early canopy closure allows Sugar beet to be more efficient in utilizing the sunlight to produce more sugar.  However, an excess Nitrogen at or near the end of the growing season reduces Sugar beet quality by reducing sucrose concentration (Daniel. 2018) 4. Nevertheless, John, et. al.; 2011 5, reported that, better Nitrogen management promotes early vigorous plant growth and reduces the number of days to canopy closure which enables sugar beet to utilize the sunlight’s energy more efficiently to produce more sucrose. Excess Nitrogen at or near the end of the growing season reduces Sugar beet quality by reducing sucrose concentration and increasing impurity concentration (John, et. al. 2011) 5.

The main objective of this study was to assess the efficiency of Nitrogen fertilizer and plant spacing on sugar beet growth and yield at Alkodro area.

A field experiment was conducted during the winter season of 2016 - 2017 at the demonstration farm of College of Agriculture, University of Bahri, Khartoum State-Alkadaro (Latitude 15⁰-44⁰N; Longitude 32⁰-35⁰E, and altitudes 398m above the sea level). The soil of the study area is moderate to strong alkaline; with pH 7.5-8; and EC 1.1-8.3 dSm^-1(Hatim et. al., 2017) 6. The area is located within the semi-arid zone with mean daily maximum temperature of 45°C - 30^oC during summer and 25^oC-10^oC during winter. The annual average rainfall ranges between (0 -100) mm and relative humidity about 16% – 50%.The area is characterized by having long dry hot summer period and cool in winter. The adopted experiment was split-plot in randomized Complete Plot Design with four replications, where Nitrogen was considered as sub plot and plant spacing as main plot. The soil was well prepared by a tractor 75HP using disk plough, harrow, leveler, and moldboard implements. The land was divided into plots; each one was 5x4m² with four rows and plant space kept at 15 and 20 cm which were referred as S₁ and S₂ respectively; and 70cm between rows. Seed were sown in 13/12/2016 by planting two seeds/hole and later on thinned to one plant/hole. Irrigation was carried out every 7-10 days. As far the fertilizer concern, Nitrogen as urea was applied 4 weeks after sowing (WAS) as one dose (1N), at three levels; namely 40, 80, and 120 kg/ha which were referred as N₁, N₂, and N₃ respectively. In this study, the following plant parameters were studied, the Leaf number, Leaf dry weight (g), Root diameter (cm), Root fresh weight (g) and Leaf Area Index. Sampling was done by taking three random plants from the each plot after 7, 10, 13, and 16 weeks after sowing. The said data were subjected to statistical analysis using Statistic 8 Software Program. The results were arranged in tables.

All the results of statistically analyzed data of this study were presented in the following 6 tables.

The results table 1 showed the different plant spacing had significantly affected the leaf number of Sugar beet crop. However S₂ (20 cm) has increased the leaf number per plant compared to S₁ (15 cm). This may be due to the wide spacing which allows penetration of more sun light which increases the process photosynthesis efficiency and eliminates the competition for nutrients. Similar result was obtained by Yuji. et. al.; 1979 7, who reported that the increase in hill space from 30 to 35 cm has increased the crown and decreased the petioles.

The leaf area index was significantly increased with the increase of spacing between plants However, S₂ treatment revealed the highest value of leaf area index (7.514) compared to S₁ (7.280) 16 WAS. This result indicated that leaf area index increased due to the increase of spacing between the plants as well as the surface area. A similar trend was observed by (Varga, et. al., 2021) 8, who concluded that differences in the size of leaf area of Sugar beet plant affect the leaf growth and canopy development.

The results in table 2 showed plant spacing had significantly increased the leaf dry weight (g), where S₂ (20 cm) produced the highest value compared to S₁. Similar results were obtained by a researcher (1978)^[9]; who obtained the maximum distribution of root dry matter with 30 cm hill space. The effects of hill spacing on dry matter production are understood on the basis of growth analysis of sugar beet. Furthermore, the results displayed the different plant spacing had significant effect on root diameter of Sugar beet. Where the S₂ produced the highest root diameter (94.99 mm), whereas the lowest was obtained by S₁ (88.83 mm.) 16 WAS. Moreover, the root fresh weight was also significantly increased due to application of different plant spacing.

Table, revealed the highest root fresh weight was recorded by S₂ (695.80 g), whereas the lowest was obtained by S₁ (613.87g). These results are similar to those obtained by (Izumiyama, 1978) 9, who got the maximum distribution of dry matter to roots with 30 cm hill space

Considering table 4, the results showed the different levels of Nitrogen fertilizer had significant influenced on leaf number of Sugar beet, where N₃ recorded the higher leaf number (31) 16 WAS, whereas the lowest was recorded by N₁ (25). This result indicated the leaf number of Sugar beet crop increased with the increased level of Nitrogen fertilizer. These results agreed with that obtained by Mustafa, 2007 10, who showed that; application of Nitrogen fertilizer tends to increase the leaf number. It is known thatNitrogen fertilizer has the most profound effect on plant growth and efficient utilization of light interception in the plant canopy. Therefore, an adequate Nitrogen fertilizer is needed at the earlier seedling stage for vigorous and competitive seedling growth and for subsequent canopy development. (Amber, et. al., 2009) 11

However, significant differences were registered in leaf area index of Sugar beet due to the application of Nitrogen fertilizer 16 WAS table 4. Application of 120 kg N/ha (N₃) showed significant increase in leaf area index compared to 80kg N/ha (N₂) and 40 kg N/ha (N₁) respectively. These results indicated that, leaf area index increased with the increasing rate of Nitrogen fertilizer. These results agreed with the results found by Mustafa, 2007 10, who showed that; application of Nitrogen tends to increase leaf area index of sugar beet. Also, Hosseinpour, et. Al.; (2013) 12 obtained similar results. Regarding table 5, the results indicated the different treatments of Nitrogen fertilizer had significantly increased the leaf dry weight of Sugar beet. However, the application of N₃ had significantly increased leaf dry weight (102.47 g) compared to N₂ (87.50 g) and N₁ (72.24 g) respectively. Where N₂ had significantly increased the leaf dry weight compared to N₁. This result agreed with the results obtained by (Pytlarz, et. Al.; 2005) 13, who reported that, an increase of Nitrogen rate from 90 to 180 kg N/ha caused a significant increase of the average leaf dry matter.

The study reflected that the application of different levels of Nitrogen fertilizer had positive influential effect on Sugar beet growth and development. Where the application of N₃ produced the highest root diameter (97.96 mm) 16 WAS compared to N₂ (91.89 mm) and N₁ (85.897 mm) treatments in table 5. In this respect, El-Harriri. Et. Al.; (2001) 14, and Nawar. Et. Al.; (2003) 15, found that increasing the Nitrogen significantly increased the root diameter of Sugar beet. Ismail. Et. Al.; (2005) 16 and Nemeat Alla et al. (2007) 17 reported that root diameter significantly affected by Nitrogen levels and produced maximum root diameter with the higher dose of Nitrogen.

Results in table 6 showed that, root fresh weight was significantly increased due to applications of Nitrogen fertilizer. Where, N₃ recorded the highest root fresh weight (851.77 g) compared to N₂ (714.51 g) and N₁ (398.23 g) respectively. These results indicated that, root fresh weight of Sugar beet plant increased due to increased rate of Nitrogen levels. Similar results were obtained by (Shalaby, et. al, 2003) 18 in Egypt, who reported that application of Nitrogen fertilizer at the rate of 80 and100 kgN/fad produced the highest values of the chemical constituents of fresh Sugar beet roots. They also showed that increasing Nitrogen up to 120 kg N/fad had significantly increased the roots.

The application of (20cm) plant spacing between the sugar beet plants revealed significant effect on different parameters of sugar beet growth including leaves number, leaf area index, leaves dry weight (g), root diameter (mm) and root fresh weight (g). On the other hand application of Nitrogen fertilizer as urea (120kgN/ha) was significantly increased all Sugar beet growth parameters compared to other Nitrogen levels (80kgN/ha and 40kgN/ha).

It is recommended that this experiment to be replicated at Alkadaro and other locations in Sudan.