Determination of Optimum Planting and Harvesting Date of New Sugar Beet Hybrids Cultivars

Field experiments were carried out at Dezful (as autumn planting), Karaj, Miandoaab, Mashhad, and Shiraz (as spring planting) in 1382, 1383, and 1384. The experimental design was split-split-plot with a randomized complete block arrangement with four replications. The main factors were planting dates (PD) of 20th Shahrivar, 15th Mehr, and 10th Aban in Dezful, 25th Esfand, 25th Farvardin, 25th Ordibehesht in temperate regions, the sub factors were three sugar beet cultivars, and the sub-sub plots were four growing season length (GSL) 180, 205, 230 and 255 days in Dezful or 150, 180, 210, 240 days in temperate regions. From the five new cultivars releases that include Shirin, Jolgeh, 276, 428, and Gadok, each cultivar was studied at least in two regions beside the Rasul cultivar (as a check). Results indicated sugar content (SC), white sugar content (WSC), and purity (PUR) increased as the planting date delayed in temperate regions. Delayed planting date in Karaj, Mashhad, and Shiraz decreased root yield (RY), sugar yield (SY), and white sugar yield (WSY). Increase of the growing season length in Mashhad and Shiraz, all quantitative and qualitative characteristics were increased. Delayed planting date in Dezful, decreased SC, WSC, and PUR, and Jolgeh produced greatest RY, SY, and WSY, but Rasoul had a best quality. Yields and quality increased as prolonged GSL to 230 days in Dezful. In all regions, GSL was considerably important. In order to acquire the highest possible yields, the following suggestions are made: i) In Karaj, planting of either one of the three cultivars 428, Jolgeh or Rasoul; in a period range of two months from the 25th of Farvardin; and a growing seasonal length of 150 days, ii) In Miandoaab, the planting date of 25th Farvardin; and a growing seasonal length of 210 days, iii) For Mashhad, either one of the three cultivars Gadok, 276 or Rasul; planting date range of 25th Esfand to 25th Farvardin; and a growing seasonal length of 210 days, iv) For Shiraz, the cultivar 436; planting date of 25th Esfand and harvesting at the end of Azar, v) For Dizful, the cultivar Jolgeh; planting date of 15th Mehr; and a growing seasonal length of 230 days. It should ultimately be mentioned that due to the presence of different climatic conditions in Iran and also the presence of climatic limitations in the production regions (regarding the different growing seasonal lengths and water limitations), preparations of specific cultivars with different growing seasonal lengths should be considered in the plant breeding programs.