The Effect of Plant Density and Supplementary Irrigation on Nutritional Value of Two Safflower (Carthamustincturius L.) Forage Crops

Safflower (Carthamustinctorius L.) is an important forage. An experiment was carried out to investigate the effects of planting density and supplementary irrigation on quantitative and qualitative forage yield of two safflower cultivars as a split-factorial at the research farm of the Agricultural Faculty of Ilam University, Iran during 2015-2017. The main factor was irrigation at two levels (supplementary irrigation and dry-land) and sub-factors included density levels (20, 30, 40, 50, and 60 kgseed/ha) and cultivars (Goldasht and Faraman) in three replications. In both growing seasons, supplementary irrigation (SI) increased Ash, neutral detergent fiber (NDF), Phosphorus (P) and fresh forage yield (FFY), while rain-fed (RF) increased crude protein (CP), ethereal extract (EE) and potassium (K). Faraman had better FFY, Ash, EE and K in terms of these traits, while Goldasht was better than Faraman. Improving FFY through increasing in plant density per unit area was considered appropriate, so that the densities of 50 and 60 (kg/ha(-1)) in SI treatment in both cultivars were concluded as more effective, while in RF treatment for having better nutritional value (in terms of protein and fat content) lower density was observed as more appropriate and in order to have less NDF higher density was more suitable. Due to the two-year data of nutritional values and yields, it was concluded that the crop had the ability to adapt to and tolerate drought condition and increase yield in semi-arid regions. Also, it is suitable in terms of nutritional value and forage production in dry-land areas of experiment.

Automated summary

This study investigated the effects of planting density and supplementary irrigation on forage yield and nutritional composition of safflower. The results showed that supplementary irrigation increased forage yield and phosphorus content, while dry-land cultivation enhanced protein, ether extract, and potassium content. The Faraman cultivar exhibited better yield and certain traits compared to Goldasht. Increasing planting density improved forage yield, but lower density was more suitable for nutritional value and higher density for reducing neutral detergent fiber. The study concluded that safflower could adapt to drought conditions and increase yield in semi-arid regions, making it suitable for dry-land areas as well.