Effect of Plant Density on Nut Traits, Nut Yield, Cluster Distribution and Chemical Components in Çakıldak (Corylus avellanaL.) Hazelnut Cultivar

The research was carried out during the 2015–2017 in an organic certified hazelnut (cv. ‘Çakıldak’) orchard established at 6 × 5 m spacing with ‘ocak’ system (multi-stemmed bush) in Samsun, Türkiye. The aim was to determine effects of plant density on nut traits, nut yield, cluster distribution, kernel oil content, fatty acid composition, total phenolics content (TPC), total flavonoids content (TFC) and total antioxidant activity (TAA) in ‘Çakıldak’ hazelnut cultivar. Plant density (D) in orchard was arranged as 5 (D5), 6 (D6), 7 (D7), 8 (D8), 10 (D10), 12 (D12) and 14 (D14) plants per ocak, respectively. The highest nut yield per hectare was achieved with 2344 ± 129.1 kg in D14, and the highest nut yield per plant was determined with 534 ± 2.0 g in D8. Depending on the plant density, nut weight, kernel weight and kernel ratio ranged from 2.06 ± 0.01 g (D10) to 2.26 ± 0.02 g (D8), 1.18 ± 0.02 g (D10) to 1.27 ± 0.01 g (D8) and 55.10 ± 0.55% (D14) to 57.47 ± 0.40% (D7), respectively. The number of nuts per cluster also varied between 2.24 ± 0.03 and 2.41 ± 0.08. ‘Çakıldak’ kernels contained oil between 58.0 ± 0.02% (D14) and 63.5 ± 0.40% (D8). TPC was determined between 9.10 ± 0.64 and 13.09 ± 0.76 mg GAE g−1. TFC varied from 8.62 ± 0.06 to 13.17 ± 0.32 mg QE 100 g−1. TAA was measured between 39.05 ± 1.24 and 70.27 ± 2.13 mmol TE kg−1by FRAP test and between 25.54 ± 1.49 and 37.37 ± 0.12 mmol TE kg−1by DPPH assay. Results indicated that nut traits, nut yield, oil content, fatty acids, TPC, TFC and TAA were affected by plant density in Çakıldak cultivar.