Inter and Intra Row Competition Effects on Growth and Yield Components of Sunflower (Helianthus Annuus L.) Under Rainfed Conditions

Abstract

Sunflower (Helianthus annuus L.) is an important oilseed plant with high adaptability to semi-arid conditions for reasonable vegetable oil production. The aim of this study was to determine the agronomic responses of Bosfora hybrid sunflower cultivar sown inter-row (50 and 70 cm) & intra-row (20, 25, 30, 35 and 40 cm) spacing in rainfed conditions. The field experiment was laid out on split plots in randomized blocks with three replications for two years (2016 and 2017). Inter row spacings were placed in the main plots and intra row spacings were placed in the subplots. Narrower inter-row (50 cm) and intra-row (20 and 25 cm) plant spacing caused taller plant development but decreased stem thickness, head diameter, thousand-seed weight, number of seeds in a head, dehulled seed ratio, seed weight of per plant, crude oil ratio, day to flowering and maturity. The highest yield (2759.9 kg ha-1) was obtained in 50x20 cm spacing while the lowest (1963.8 kg ha-1) yield was obtained in 70x20 cm spacing, more likely, due to the increase in the number of plants per unit area. The crude oil ratio was decreased by narrower spacing. However, oil yield was increased with seed yield (kg ha-1) and reached the highest amounts (1221.9 and 844.2 kg ha-1) in narrow row spacing, attributed to the plant population per unit area. To conclude that the highest seed yield was obtained from narrower (50x20 cm and 50x25 cm) seeding rates in rainy year (2016), while the highest yields were obtained from lowest plant population (70 x 20 and 70 x 25 cm) rates in dry year (2017).

Effect of Plant Density and Ethephon Spraying on some Growth Traits of the Sunflower (Helianthus aannus L.) (Shamos variety)

“…Table (2) shows a significant decrease on plant height as a result of spraying with ethephon, The E3 level gave the lowest average (189.25 cm), levels E1 and E2 gave averages (202.75 and 193.58 cm), while the E0 level was a high mean, amounting to 203.25 cm. The reason for this may be due to the release of ethylene in the plant, because ethylene prevents the movement of Indole Acetic Acid (IAA) in plant tissues, therefore, it reduces stem elongation and thus reduces plant height [8], this result agreed with [9,10]. Table (2) show treatment E0D1 gave the highest mean (216.33 cm), while the E3D4 treatment gave the lowest mean (180.33 cm).…”