**4. Economic analysis**

In 2014, we estimated that the Turkish population was 77,695,904 [14] and that annual consumption of vegetable oil per capita should be 21 kg, corresponding to 1,630,000 tons of vegetable oil needs. Accordingly, 800,000 tons of this was met with domestic production, and a shortage of 835,000 tons of crude oil was identified [15]. In 2014, 795,000 tons of crude oil was obtained from sunflower.

Turkey paid 1194 US dollars for importing 1 ton of vegetable crude oil in 2014, and 835,000 tons of crude oil met by imports would be 996, 990,000 US dollars [15]. In 2014, oil-type sunflower seeds were sown over an area of 5,524,651 decares in Turkey and 1,480,000 tons of sunflower seeds were produced; the seed yield was 269.00 kg/da [16]. The crude oil yield in the sunflower was 143.90 kg/da.

According to the results obtained in this study, when leaves are reduced in sunflower cultivation, the seed yield per decare will increase from 269.00 to 297.13 kg, a 10.46% increase, and the crude oil yield will increase from 143.90 to 165.95 kg, a 14.98% increase. This means that crude oil production in Turkey from sunflower will be 914,054 tons (165.45 × 5,524,651). In other words, when the method described in the current study based on defoliation is applied to the production of sunflower, the production of crude oil in Turkey will increase to 119,054 tons (914,054–795,000). Considering that 1194 US dollars was paid for 1 ton of crude oil import, it is seen that 142,150,476 dollars (119,054 × 1194) will be retained domestically by applying the method developed in our research.
