The effects of different irrigation levels on yield and quality in the 'çakildak' hazelnut cultivar under a drip irrigation system

Türkiye is a leader global hazelnut production and export. However, our yield of hazelnuts per acre is lower than that of other producing countries. Many factors affect hazelnut yield, one of which is irrigation. Water deficits, particularly during the nut development period, have a negative impact on both the quantity and quality of the crop. Water stress can lead to incomplete filling of the kernel, an increase in empty nuts, leaf fall and reduced tolerance to diseases. Irregularities in rainfall patterns due to climate change further exacerbate this issue. In this context, effective, properly planned irrigation practices are important for increasing the yield and quality of hazelnuts. In this study, four different irrigation levels (control, 33%, 66%, and 100%) were applied using drip irrigation on the 'Çakıldak' hazelnut cultivar grown in the Çarşamba district of Samsun province, and the effects of these applications on yield and nut traits were investigated. Except for nut thickness and defective kernel ratio, the effect of irrigation levels on the other investigated tarits were found to be significant (p<0.01). Depending on the irrigation levels, the nuts per cluster was 2.52 (control)-2.78 (%100), yield was 457.90 (control)-602.85 kg ha⁻¹ (%100), and nut weight was 1.89 (control)-2. 31 g (100%), kernel weight 0.91 (control) - 1.31 g (66%), kernel ratio 48.39% (control) - 57.92% (100%), nut thickness 0.73 (100%) - 0.93 mm (control), internal cavity 0.59 (100%)–1.14 mm (control), nut size 17.08 (control)–17.55 mm (100%), kernel size 12.69 (control)–13.56 mm (66%), good kernel ratio 83.3% (control) - 94.1% (66%), defective kernel ratio 2.22% (66%) - 7.37% (control), blank nut ratio 3.61% (66%) - 9.33% (control), ash content 2.62% (33%)–2.80% (66%), and oil content 52.55% (control)–58.67% (100%). Overall, the differences between the 66% and 100% irrigation levels were found to be insignificant in terms of many yield and nut traits. In this context, the 66% irrigation level yielded remarkable results for the more efficient use of limited water resources and the increase of yield and quality in hazelnut.