عنوان مقاله [English]
In order to determine of the proper sowing date of steckling (rootlet) and harvesting date of seed, an experiment was conducted in Ardabil Agricultural Research Station (Alarough) in 2004- 05 growing season in split-plot in randomized complete block design arrangement with four replications. Four different planting dates viz. 5th March, 20th March, 4th April and 19th April– were allocated to the main plot and four harvest dates viz. 15, 30, 45 and 60 days to the subplots. The first harvest was conducted 15 days after 50% flowering to the subplots. Results showed that the maximum number of main stems (2.7 per plant) and lateral stems (42.4 per plant) were recorded on first and second planting dates, respectively. The plant height reduced from 128.03 cm (first planting) to 106.50 (4th planting). The highest raw seed yield and coefficient of standard seed extraction was achieved at the first planting date. The harvest date had a significant effect on raw seed yield, seed size and the percent of the empty seed. Also, the results showed that the highest raw seed yield (2735.8 kg/ha) and the percent of seeds with the size of 3.5- 4.5 mm (36.3%) was obtained from the 3rd harvesting date. The first harvesting date had the highest percent of the empty seed (17.2%). It is recommended that the beet steckling to be planted at the first possible date (in March) and the seed to be harvested at least 45 days after 50% flowering.. The total plant dry weight on first, second, third, and fourth planting dates were 389.6, 409.14, 344.9 and 300.9 g/plant, respectively. Among harvest dates, harvest at 45 days after flowering led to significant increase in plant dry weight, seed dry weight and seed yield (2735.8 kg/ha). Seeds harvested at 15 days after flowering had 60% of a normal seed size which was less than 3.5 mm (unusable) compared with seeds harvested at 45 days after flowering. Also, the highest rate of unfilled seed (%17.2) was obtained on the first seed harvest date.