Effect of planting density and supplementary irrigation on quality and quantity of forage yield of two safflower (Carthamus tinctorius L.) cultivars

Safflower (Carthamus tinctorius L.) is considered to be a suitable crop for drylands because of its relatively high resistance to environmental stresses especially drought resistance. This research was carried out to investigate the effects of planting density and supplemental irrigation on quality and quantity of forage yield in two cultivars of safflower at the farm of Faculty of Agriculture, Ilam University. The experiment was conducted in a split-factorial-design. The main factor was irrigation at two levels (with supplementary irrigation and dry-land) and Sub factor included the mixture treatments of density levels (20, 30, 40, 50 and 60 kg/ha) and cultivars (Goldasht and Faraman) which were performed in three replications. The highest amount of total carbohydrate with 68.32% was found in Goldasht cultivar, cultivated in 50 (kg ha-1) density and the lowest amount of it with 65.17% was in density of 30 (kg ha-1) and Faraman cultivar. The highest non-fibrous carbohydrate was recorded from Goldasht cultivar under supplementary irrigation condition. Both dry-land condition (19.35%) and interaction of 40 kg ha-1 density × Faraman cultivar (19.98%) had the highest protein content of the shoot. Forage yield was affected by all three double interactions. In general, Goldasht cultivar with high density under supplementary irrigation conditions had higher carbohydrate, while Faraman cultivar had a better protein yield under dry-land conditions and with lower density. Farman cultivar and Goldasht cultivar had better performance in terms of supplementary irrigation and high density, respectively. Also, the performance (yield) increased when density rise under supplementary irrigation conditions. Finally, it seems that in most of the above-mentioned traits supplementary irrigation has caused better results in high densities.