Effects of Plant Population Reduction Time and Rate on Sugar Beet Yield and Quality

Plant population is an essential factor affecting yield and quality of sugar beet. To determine the effects of plant polpulation reduction time and rate during the growing season on quantitative and qualitative yield of sugar beet in 2011 and 2012, a factorial experiment based on a randomized complete blocks design (RCBD) with four replications was conducted in Karaj. The studied factors included density reduction time (at four levels of 30, 60, 90 and 120 days after sowing) and final density levels (at six levels of 12.5, 9.375, 8.375, 6.25, 4.125, and 3.125 plantm-2). Results showed that plant population reduction time significantly affected the crop produced by the plants in most cases and the highest root yield (1.49-1.53 kgplant-1) and crude sugar yield (0.20-0.21 kgplant-1) was obtained by plant reduction during 30-60 days after sowing. The highest yield per plant (1.74-1.92 kg root and 0.24-0.26 kg sugar) and per unit area (89.81-95.54t oot per ha and 12.06-12.97t sugar per ha) was obtained from the densities of 3.4-4.5 and 7.7-10.2 plantm-2, respectively. Overall, reduction time during 30-60 days after sowing and reaching to the plant population of 8.4-12.5 plantm-2 after reduction would ensure the maximum crop yield in moderate regions, Iran (like Karaj).