EFFECT OF PLANTING DATE ON THE GROWTH AND YIELD OF IRRIGATED SUNFLOWER (HELIANTHUS-ANNUUS)

The effect of planting date on the growth and yield of irrigated sunflower was investigated in 1992 and 1993. Two sunflower hybrids, Islero and Upsol-veraflor, were sown at three different dares (3 October, 4 November, 2 December 1992 and 5 October, 6 November, 4 December 1993) in Sultan Qaboos University Agricultural Experiment Station on the Batinah Coast of Oman in a desert climate. Sunflower planted in December emerged later, flowered later and matured later than that planted in October or November. Severity of stalk lodging was closely related to the extent of stem weevil infestation, which was more serious in the early planted sunflower. Sclerotina head rot was also most severe in the October plantings and least severe in the December plantings. Head diameter, number of seeds per head and percentage of large seeds increased with delay in planting date. Seed yield and oil yield were highest in the December planted sunflower bur oil concentration was not affected by the planting date. Based on these results, a December planting date was recommended for the Batinah Coast of Oman and other areas with similar climatic conditions.