Yield and Technological Characteristics of Sugar Beet as Affected by Sowing Date, Nitrogen Level and Harvesting Age

Abstract

In order to investigate the effect of nitrogen fertilizer levels, sowing date and harvesting age on growth yield and root quality of sugar beet. Four field experiments were conducted at Mallawi Research Station, El-Minia Governorate during 2015/2016 and 2016/2017 seasons. Sugar beet sown at two dates (the 1 st of September and October) fertilized with three nitrogen levels (80, 100 and 120 kg N/fed.) and harvested at three ages (180, 195 and 210 days after sowing). The results showed that all studied traits of sugar beet were significantly affected by sowing date in both seasons. The highest values of root length, diameter, root fresh weight, as well as α-amino N, Na, K, sugar lost to molasses, root and corrected sugar yields were obtained by delaying sowing date from September 1 st to October 1 st . On the contrary, an higher sucrose, quality and corrected sugar percentages were detected in beets sown earlier in September. Raising nitrogen fertilization level from 80 to 100 and 120 kg N/fed. resulted in a gradual and significant increases in root fresh weight, root length and diameter, root yield, sugar lost to molasses and corrected sugar yield in both seasons. While, alkalinity coefficient and quality percentages were decreased. The highest sucrose and corrected sugar percentages were recorded by applying 100 kg N/fed. The studied traits were markedly influenced by plant age at harvesting in both seasons. Root length and diameter, root fresh weight and yield/fed, sucrose, quality, corrected sugar percentages and corrected sugar yield/fed. were increased gradually with increasing plant age at harvest from 180, 195 to 210 days, in both seasons, while Na, sugar lost to molasses and alkalinity coefficient were decreased. Under these conditions of the present work, sowing sugar beet on October 1 st , with nitrogen fertilization at rate of 120 kg N/fed. and harvested at 210 days from sowing could be recommended to obtain the highest root yield/fed., while harvesting it after 195 or 210 days to get the highest sugar yield/fed.

Response of Some Sugar Beet Varieties to Nitrogen and Zinc Application in Sandy Soil

“…This result may refer that sugar beet varieties cannot make full use of vegetation space when nitrogen is low availability in the experimental site and/or the inadequate applied dose (Table 2), where nitrogen fertilizers role in enhanced growth and increase leaf area per plant. This observation agrees with those reported by Elwan and Helmy (2018) and El-Mansuop et al (2020).…”

“…These findings are related to nitrogen's role as a crucial structural element in developing plant organs and promoting their growth. These results are in agreement with those stated by Elwan and Helmy (2018). As for the effect of zinc spray levels in the same Table , doubling the dose of sprayed zinc sulphate level (4.5 g/L) significantly increased root diameter, fresh weight/plant and LAI of sugar beet plants in both seasons.…”

“…Data in Table 6 manifested that an addition of 25 kg N/fed (the difference between adding 120 kg and 95 kg N/fed) was enough to produce the highest root, top sugar yields/fed, compared with plants that received 70 or 95 kg N/fed in both seasons. These results align with Elwan and Helmy (2018) who reported that raising nitrogen levels to 110 kg N/fed gave the highest root dimension, root, top and sugar yields per fed. However, sucrose content and quality index decreased.…”

“…Therefore, adding 120 kg nitrogen/fed may result in more foliage than the beetroot's ability to transport and store sugar. (Elwan and Helmy 2018). At the same time, the alpha-amino N contents gradually increased by increasing the N-dose to 120 kg/fed in both seasons.…”

“…Additionally, they noted that an excessive amount of nitrogen application reduced the quality of the extracted sugars in terms of purity and sucrose percentages. Elwan and Helmy (2018) stated that raising the nitrogen rate to 120 kg nitrogen per fed, significant increases in fresh weight per plant, root diameter, sugar lost to molasses%, root and corrected sugar yields/fed in both seasons. However, the quality index decreased.…”