اثر زمان برداشت علوفه بر عملكرد بيولوژيك و ذخيره بذر خاك در ارقام يونجه يكساله در شرايط ديم

Effects of harvest time on biological yield and soil seed bank reserves of annual medic cultivars in dry farming

The effects of forage harvest at different phonological growth stages on biological yield and soil seed bank reserves of different annual medic cultivars were evaluated in climatic research station of Khoramabad during 1380 and 1381 growing seasons. The treatments were arranged as split plots based on a Complete Randomized Block Design with three replications. Six annual medic cultivars (Robinson, Kelson, Rigidula, Caliph, Orion and Mogul) were assigned to the main plots and forage harvest at different phonological growth stages (early and 50% flowering) to the subplots. Forage harvest at early flowering stage significantly increased biological yields as well as soil seed bank reserves compared to 50% flowering stage. Annual medic cultivars performed different reactions to harvest treatments due to their growth periods. The long season cultivars produce more seed while harvested at early growth stage. However, forage harvest at 50% flowering stage caused their re-growth encountered with unfavorable weather conditions, which caused a poor soil seed bank. Caliph cultivar produced the richest soil seed bank while Rigidula was the best biological yield producer among different annual medic cultivars.