Description of development, light interception and growth of sunflower at two sowing dates and two densities

The relationship between dry matter production and solar radiation interception by plant canopies is well known for several crops including sunflower. The effects of temperature environment on sunflower development have also been subject of much research. However, under seasonal rainfall, management strategies, such as the choice of sowing dates and of plant densities may change crop responses to temperature and radiation, preventing the use of standard relationships. The object of this work is to study the influence of two sowing dates on crop development and two plant densities on light interception and growth of sunflower crops grown on stored soil water in the semi-arid Mediterranean region of southern Portugal.