Drought stress affects on growth, water use efficiency, gas exchange and chlorophyll fluorescence of Juglans rootstocks

Seedlings of three selected Juglans rootstocks (Juglans mandshurica Maxim, Juglans nigra L. and Juglans regia L. cv. Jizhaomian) were analyzed in terms of growth, water use efficiency (WUE), chlorophyll fluorescence and photosynthetic response to drought stress. Significant differences among seedlings of the three analyzed Juglans rootstocks were observed on performance in response to water deficit. Juglans mandshurica Maxim. and Juglans regia L. cv. Jizhaomian showed larger increase in WUE and smaller reduction in growth rate, chlorophyll fluorescence and gas exchange parameters than Juglans nigra L. under drought-stressed condition. It suggests that Juglans mandshurica Maxim. and Juglans regia L. cv. Jizhaomian are more tolerant to drought stress and more suitable as walnut rootstock in water deficit regions as compared with Juglans nigra L.