Univrsity of Tehran Press Iranian Journal of Field Crop Science 2008-4811 56 3 2025 09 23 Effect of Planting and Harvesting Dates on the Quantitative and Qualitative Characteristics of Autumn Sugar Beet in Gonbad Kavous Effect of Planting and Harvesting Dates on the Quantitative and Qualitative Characteristics of Autumn Sugar Beet in Gonbad Kavous 1 19 104261 10.22059/ijfcs.2025.381054.655098 FA Saeed Yarahmadi Horticulture-Crops Research Department, Golestan Agricultural and Natural Resources Research and Education Center, Agricultural Research, Education and Extension Organization (AREEO), Gorgan, Iran 0000-0001-9526-2430 Alireza Saberi Horticulture-Crops Research Department, Golestan Agricultural and Natural Resources Research and Education Center, Agricultural Research, Education and Extension Organization (AREEO), Gorgan, Iran 0000-0001-9306-9557 Journal Article 2024 09 03 Introduction. Developing autumn sugar beet cultivation in suitable regions of the country can be an appropriate strategy to reduce water consumption for sugar production. The water requirement of autumn sugar beet is half compare to spring sugar beet, and only by changing the cropping pattern in the country and developing autumn cultivation of this crop, the water use efficiency in sugar production can be doubled. Choosing the appropriate variety and planting date is important in controlling bolting and achieving yield potential. In autumn cultivation, the appropriate planting date should be determined based on the bolting resistance of each variety. Also, delaying in harvesting can reduce water use efficiency, increase the negative effects of bolting on sugar yield, and increase the likelihood of root rot. This study aimed to investigate the effect of different planting and harvesting dates on bolting, qualitative, and quantitative yield in sugar beet varieties. Materials and Methods. This study was conducted in the 2022-2023 growing year at the Gonbad Kavous Agricultural Research Station. A split-split plot experiment was carried out based on a randomized complete block design (RCDB) using four replications. Planting date is the main factor in five levels (2nd October, 17th October, 1st November, 16th November, and 1st December), cultivar is a sub-factor in three levels (Monatunno, Rosagold, and 061) and harvesting date is a sub-sub factor were investigated at three levels (10th June, 6th July, and 1st August). The traits investigated in this research included root yield, sugar yield and white sugar yield, sugar content and white sugar content, root impurities including sodium, potassium, and α-amino nitrogen, molasses sugar content, and extraction coefficient of sugar. Results and Discussion. Cultivar had a significant effect on sugar content at 1% probability level. The Rosagold cultivar had the highest sugar content (15.6%), while the Monatunno cultivar had the lowest sugar content (14.2%). The interaction effect of the planting date and harvesting date showed that the highest sugar content was obtained on July 6 for all planting dates. The cultivar significantly affected the extraction coefficient of sugar. The Rosagold cultivar had the highest extraction coefficient of sugar (79.6%). The interaction effect of planting and harvesting dates on the extraction coefficient of sugar was significant at 1% probability level. The first harvest had a higher extraction coefficient of sugar for all planting dates, and delaying in harvest time reduced the extraction rate. The planting date, harvesting date, and cultivar significantly affected root yield. A decreasing trend in root yield was observed with delaying in planting. October 2nd planting date, with an average root yield of 70.6 t ha-1, was the best planting date and showed a statistically significant difference from other planting dates. Root yield decreased by 39.2% with delaying in planting. Rosagold and Monatunno cultivars had average root yields of 54.2 and 57 t ha-1, respectively, showing no statistically significant difference between them but performing better than cultivar 061 (46.9 t ha-1). A downward trend in root yield was observed with delaying in harvesting. Although delaying harvest from June 20th to July 15th reduced root yield by 2.5 t ha-1, but this difference was not significant. A statistically significant difference was observed between harvests on June 10th and August 1st. Bolting decreased with delaying in planting. Hybrid 061 started bolting earlier than Rosagold and Monatunno. Hybrid 061 planted on October 2nd, showed the highest bolting rate (32.5%), making it the most sensitive treatment combination to bolting. Rosagold planted on October 2nd, had a bolting rate of 16.5%, indicating less resistance to bolting compared to Monatunno. The highest white sugar yield across all planting dates was achieved on June 10th. However, a statistically significant difference between harvests on June 10th and July 6th was only observed for the October 2nd planting date; this difference was not significant for other planting dates. The best harvesting date across all planting dates and varieties was June 10th. Since delaying harvest reduces white sugar yield, the harvest date of June 10th is recommended, even with a lower sugar content. Conclusion. The suitable planting date for each cultivar depends on its resistance to bolting. The Monatunno cultivar showed high resistance to bolting and can be used for early planting in the plain and lowland areas of the Golestan province. The Rosagold cultivar was better than other cultivars in terms of sugar yield and white sugar yield. The Rosagold cultivar showed only 0.5% bolting with an October 17th planting date; therefore, this cultivar can be recommended for planting from October 17th onwards. Sugar factories should consider these points when managing field harvests: Start harvesting from 10th June, prioritize fields with bolting first, and then prioritize fields based on planting date. Introduction. Developing autumn sugar beet cultivation in suitable regions of the country can be an appropriate strategy to reduce water consumption for sugar production. The water requirement of autumn sugar beet is half compare to spring sugar beet, and only by changing the cropping pattern in the country and developing autumn cultivation of this crop, the water use efficiency in sugar production can be doubled. Choosing the appropriate variety and planting date is important in controlling bolting and achieving yield potential. In autumn cultivation, the appropriate planting date should be determined based on the bolting resistance of each variety. Also, delaying in harvesting can reduce water use efficiency, increase the negative effects of bolting on sugar yield, and increase the likelihood of root rot. This study aimed to investigate the effect of different planting and harvesting dates on bolting, qualitative, and quantitative yield in sugar beet varieties. Materials and Methods. This study was conducted in the 2022-2023 growing year at the Gonbad Kavous Agricultural Research Station. A split-split plot experiment was carried out based on a randomized complete block design (RCDB) using four replications. Planting date is the main factor in five levels (2nd October, 17th October, 1st November, 16th November, and 1st December), cultivar is a sub-factor in three levels (Monatunno, Rosagold, and 061) and harvesting date is a sub-sub factor were investigated at three levels (10th June, 6th July, and 1st August). The traits investigated in this research included root yield, sugar yield and white sugar yield, sugar content and white sugar content, root impurities including sodium, potassium, and α-amino nitrogen, molasses sugar content, and extraction coefficient of sugar. Results and Discussion. Cultivar had a significant effect on sugar content at 1% probability level. The Rosagold cultivar had the highest sugar content (15.6%), while the Monatunno cultivar had the lowest sugar content (14.2%). The interaction effect of the planting date and harvesting date showed that the highest sugar content was obtained on July 6 for all planting dates. The cultivar significantly affected the extraction coefficient of sugar. The Rosagold cultivar had the highest extraction coefficient of sugar (79.6%). The interaction effect of planting and harvesting dates on the extraction coefficient of sugar was significant at 1% probability level. The first harvest had a higher extraction coefficient of sugar for all planting dates, and delaying in harvest time reduced the extraction rate. The planting date, harvesting date, and cultivar significantly affected root yield. A decreasing trend in root yield was observed with delaying in planting. October 2nd planting date, with an average root yield of 70.6 t ha-1, was the best planting date and showed a statistically significant difference from other planting dates. Root yield decreased by 39.2% with delaying in planting. Rosagold and Monatunno cultivars had average root yields of 54.2 and 57 t ha-1, respectively, showing no statistically significant difference between them but performing better than cultivar 061 (46.9 t ha-1). A downward trend in root yield was observed with delaying in harvesting. Although delaying harvest from June 20th to July 15th reduced root yield by 2.5 t ha-1, but this difference was not significant. A statistically significant difference was observed between harvests on June 10th and August 1st. Bolting decreased with delaying in planting. Hybrid 061 started bolting earlier than Rosagold and Monatunno. Hybrid 061 planted on October 2nd, showed the highest bolting rate (32.5%), making it the most sensitive treatment combination to bolting. Rosagold planted on October 2nd, had a bolting rate of 16.5%, indicating less resistance to bolting compared to Monatunno. The highest white sugar yield across all planting dates was achieved on June 10th. However, a statistically significant difference between harvests on June 10th and July 6th was only observed for the October 2nd planting date; this difference was not significant for other planting dates. The best harvesting date across all planting dates and varieties was June 10th. Since delaying harvest reduces white sugar yield, the harvest date of June 10th is recommended, even with a lower sugar content. Conclusion. The suitable planting date for each cultivar depends on its resistance to bolting. The Monatunno cultivar showed high resistance to bolting and can be used for early planting in the plain and lowland areas of the Golestan province. The Rosagold cultivar was better than other cultivars in terms of sugar yield and white sugar yield. The Rosagold cultivar showed only 0.5% bolting with an October 17th planting date; therefore, this cultivar can be recommended for planting from October 17th onwards. Sugar factories should consider these points when managing field harvests: Start harvesting from 10th June, prioritize fields with bolting first, and then prioritize fields based on planting date.

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