The effect of some ecological factors on pomological and chemical properties of "chandler" walnut variety fruit grown in Yozgat

This study aimed to investigate the effect of altitude on the pomological and biochemical characteristics of "Chandler" walnut (Juglans regia L.) fruits grown under continental climate conditions in Yozgat Province, Türkiye. The research was conducted in 2022 and 2023 across four selected walnut orchards located in different districts of Yozgat. The orchards, consisting of 8–10-year-old trees with similar exposure and cultural practices, were situated in Osmanpaşa village (1350 m, Yozgat central district), Kabalı village (1150 m, Kadışehri district), Cıcıklar village (950 m, Şefaatli district), and Arifoğlu village (750 m, Yerköy district). Principal Component Analysis (PCA), based on the average of two years of data, explained a significant portion of the variation in both pomological and biochemical parameters in relation to altitude. Pomological results indicated that fruits from the Arifoğlu-750 location exhibited superior quality traits, such as nut weight (13.10 g), kernel weight (5.91 g), and kernel ratio (44.88%), likely due to the longer vegetation period and warmer climate at lower altitudes. Fruits from the Cıcıklar-950 site showed a higher "a" color value (6.18), indicating enhanced pigmentation, and presented the second-best size characteristics after Arifoğlu. Biochemical analysis revealed that fruits from the Cıcıklar-950 location had the highest levels of catechin (362.41 µg/g), caffeic acid (328.35 µg/g), and linolenic acid (15.96%). Fruits from the Osmanpaşa-1350 site contained the highest levels of linoleic acid (60.74%) and oxalic acid (4.41%), while the Arifoğlu-750 site stood out with a high accumulation of oleic acid (16.91%), which is considered an indicator of adaptation to warmer conditions. In conclusion, low-altitude regions (Arifoğlu-750) favored the development of superior pomological traits, whereas mid-altitude areas (Cıcıklar-950) supported a more balanced accumulation of bioactive compounds. Overall, the Cıcıklar-950 location (950 m) produced fruits that integrated both pomological and biochemical qualities, suggesting it as the most balanced site among those studied.