Response of two sunflower hybrids to planting dates and densities

Abstract

This investigation was carried out at the Experimental Farm of Assiut University during the summers of 2000 and 2001 to study the responses of two sunflower hybrids (Vidoc and Euroflora) to planting dates (May 1 st , June 1 st and July 1 st ) and planting densities (55,533, 83,300 and 166,600 plants/ha). The results indicated that the two varieties differed highly significantly in all studied traits except oil yield/ha. The highest seed yield (3.64 t/ha) was obtained with the variety Vidoc. In addition, the results revealed that the planting date exerted a highly significant influence on all vegetative growth traits along with yield and its components. Increasing plant density increased the seed and oil yield/ha. By contrast, the stem diameter, head diameter, 100-seed weight and seed yield/plant decreased with increasing plant density.The interaction between varieties and plant density had a highly significant effect on head diameter. The greatest head diameter (20.06 cm) was recorded for the variety Vidoc planted at lower density. Concerning the interaction between planting density and planting date, the highest seed yield (4.47 t/ha) was obtained from dense plants at the early sowing date, and the highest oil % (45.32) at the late planting date and the lowest plant density.The second order interaction exerted a highly significant influence on stem and head diameter in addition to seed yield/plant, where the highest value (78.13 g/plant) was obtained with the variety Vidoc planted on May 1 st at the lowest plant density.

Effect of Sowing Density on the Growth, Yield and Nutrient Uptake of Hybrid Sunflower (Helianthus annuus L.) in Rabi Season

“…This may be due to the sufficient of environmental conditions in wide spacing and less competition between plants as well as increase light penetration within plant canopy which increased assimilation rate and oil formation. These results are in a good line with those obtained by Yakout et al, (1992), Sharief (1998), Allam et al, (2003), Ruffo et al, (2003), Ali and Osman (2004), And Tenebe et al, (2008). The sowing density and different nutrient levels had exerted a significant positive influence on seed yield of sunflower.…”

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

“…The increase in plant sowing density has also caused stress in plants, resulting early flowering and physiological maturity. The results of current study are agree with those reported by Esechie et al (1996); Allam et al (2003) and Ibrahim and El-Genbehy (2009). The head diameter, number of seeds in a head and thousandseed weight which are considered as the main yield criteria, which were affected by the change in interrow and intra row spacings.…”

Effect of Planting Density on the Growth and Yield of Sunflower under Mulched Drip Irrigation

“…However, with plant density increases, the competition for light between plant increases, which result in the decrease in vegetative and reproductive plasticity of plant [5], while a lower plant density, results in a decreased absorption of light by the plants, as well as decrease in crop yield per unit area [6,7]. Theoretical research and practical experience have shown that the high yield per unit area is usually associated with low competitiveness among plants [8,9], while head diameter, plant biomass, 100-seed weight, seed yield per plant, non-saturated fatty acids, and seed oil percentage decreased with an increase in plant density [10].…”