بررسي تاثير تاريخ كاشت ، آبياري و كلسيم بر عملكرد دانه و وقوع نكروز براكته آفتابگردان در منطقه گنبد

Effects of sowing date, irrigation and Ca on yield and incidence of bract necrosis on sunflower in Gonbad

In order to study the effects of sowing date, irrigation and fertilizer levels on vegetative charactersʹ yield, yield components and bract necrosis of sunflower (Golshid variety) an experiment wasʹ conducted at agricultural research station of Gonbad in 2001. The experiment was a factorial split p1o arranged in a RCBD with 3 replications. Two irrigation regime (without irrigation and irrigation a three stages head visible, flowering and grain filling) and two sowing date (Mar. 1st and 30th) were a main plots in a factorial arrangement and four fertilizer levels (without fertilizer, applying of 100 kg Cacl2/ha in soil and spraying of CacI2 and complete fertilizer (at the dose of %5 before head visibi c and flowering stages) were subplots. Plant height, head diameter and the number of days from. emergence to physiological maturity decreased significantly with a delay in sowing date. Sowing datti did not have any significant effect on 1000-grain weight, whereas incidence of bract necrosis increases with a delay in sowing date. Irrigation increased head diameter, plant height, the number of days from emergence to physiological maturity and 1000-grain weight, but it decreased incidence of brac necrosis. Fertilizer did not have any significant effect on plant height, head diameter, the number o days from emergence to physiological maturity, 1000-grain weight, grain yield and incidence of brace necrosis. The effect of irrigation and sowing date significant on grain yield at 1% level. The grain, yield of irrigation treatment (1862 kg/ha) was more than that of without irrigation treatment (9a kg/ha). The grain yield of first and second sowing date was 1669 and 1161 kg/ha, respectively.