Introduction: Like cereals, sugar beet does not have a certain physiological maturation and maturity, and the best time to harvest it is when the sugar percentage and root performance are at their optimum. Considering that it is difficult to determine this date, it is better to use farm invoices. The aim of this study is to investigate the traits that may be estimated based on their measurement in the field, the optimal agricultural and technological ripening time of sugar beet. For this purpose, the effect of planting date on the trend of some agronomic and laboratory traits was carried out in the research farm of the agricultural research station of Kerman province in Bardsir region on the sweet commercial variety of sugar beet.
Materials and Methods: In order to investigate the effect of planting date on the trend of some agricultural and laboratory traits, an experiment was carried out on the commercial sweet sugar beet variety in the research farm of Kerman Agricultural Research Station in the Bardsir region. The experiment was performed on two planting dates. The first planting date was on the 21st of April and the second planting date was on the 5th of June. The studied traits include white sugar yield, mark value, shoot dry weight, root length, root diameter, and the number of live and dead leaves per plant, changes in purity, leaf chlorophyll, and petiole nitrate, and root fresh and dry weight traits and the trend of changes in their amount during four months (nine harvests) was measured.
Results and Discussion: The trend of harvesting sugar beet for root fresh and dry yield traits showed that the cultivation of sugar beet on the first planting date (21st April) causes the amount of yield traits to be higher than on the second planting date. Although the amount of root dry weight is almost constant in the last harvests. The amount of white sugar yield in both planting dates increased with the high harvesting time. The highest amount of white sugar yield was observed in the last four harvests for the first planting date and in the last two harvests for the second planting date. The results showed that on the first planting date, the dry weight of aerial parts, root length, root diameter, number of dead leaves (dried), and degree of purity were higher than on the second planting date. The amount of petiole nitrogen for both planting dates had a decreasing trend. The trend of changes in the degree of purity between the two planting dates in the first harvests differed, but they approached each other from the fourth harvest onwards. The first planting date with a maximum purity of 80% was superior to the second planting date with a maximum purity of 76%. The amount of marks in all harvest dates was higher on the second planting date than on the first planting date. This state can be related to the smallness of the roots on the date of the second planting. The trend of leaf chlorophyll is almost similar for both planting dates and the amount of leaf chlorophyll has decreased sharply after an increasing trend. The decrease in the amount of chlorophyll in the last two harvests can be attributed to the cold weather at the end of the season. Considering that the plant regularly produces new leaves during the season and leaf number 5 is always young, therefore, instead of measuring this index, it is suggested in the next of research to use the color change obtained in the field by using the appropriate method, including accurate and standard photography.
Conclusion: In general, the results of this study showed that the trend changes of traits in sugar beet are different based on the date of different crops. In the Bardsir region, the cultivation of sugar beet on the sowing 21th April can finally produce more yield for the farmers. Also, the harvest date of 6th November is the best harvest time for sugar beet in this region. It is possible to use the indicators of root dry weight, root length, and degree of purity for the agricultural and technological maturity of sugar beet.