Effect of Row Spacing and Stage of the First Cutting of Forage on Seed Production in Alfalfa (Medicago sativa L.)

To produce alfalfa (Medicago sativa L.) seed, application of appropriate harvesting time and appropriate agronomic techniques are useful. These factors were studied in a field experiment using of stripe split plot arrangements with four replications. Seed yield and its components and forage of alfalfa cv. Hamedani were evaluated. Row spacing in three levels including 40, 50 and 60 cm and stage of the first cutting of forage (ht1) including four phenological stages were studied. Analysis of variance showed that ht1 had a significant effect on seed yield per unit area,1000-seed weight, duration of seed ripening and plant height. Row spacing also had significant effect on the forage yield of the 1st cut at the 5% probability levle. The interaction between two factors was significant on the forage yield of 1st cut and 1000-seed weight at the 5% probability level. Seed yield after ht1 at the onset of flowering time was three times greater than the end of reproductive stage. Seed yield from the 60 cm row spacing was 2.5 times more than the 40 cm row spacing. Seed yield of 130 kg ha-1 was produced from one year old alfalfa stand with 60 cm row spacing.