Xylematic Water Potential and Stomata Density in Three Cultivars of Hazelnut (Corylus avellana L.) in Region del Bio Bio, Chile

Xylematic potential and stomata density were measured in the field during a growing period in three cultivars of hazelnut with the aim of determining if these parameters would explain the growth response of these cultivars in Chile. 'Tonda di Giffoni' and 'Barcelona' cultivars have demonstrated a very high yield potential, reaching close to 4 t/ha, and they constitute the main acreage planted in commercial orchards, however 'Tonda delle Langhe' has demonstrated a very low potential and growth rate in the same locations. With the purpose of determining if some physiological traits of the plant, such as xylematic potential and/or stomata density, explain such behavior, a trial was carried out comparing those three cultivars. The study was done between January and March 2007 in Region del Bio Bio, Chillan. Measurements were taken every ten days, at 6am (pre-dawn), 10am, 2pm and 6pm. At 6am, the values of xylematic potential varied between -0,05 and 0,25 Mpa. At 10am the values varied between -0,2 and 0,5 Mpa. At 2pm, the values were between -0,4 and -0,8 Mpa, and at 6pm the values varied between -0,3 and -0,8 Mpa. There was not any difference among the three cultivars at any time of the day and during the study. Stomata density was 42,7; 46,6 and 39,5 stomata/mm(2) in 'Barcelona', 'Tonda di Giffoni' and 'Tonda delle Langhe' respectively, however the difference was not significant between them. This result does not provide an explanation of the difference.