Monitoring water relations in hazelnut plantations located in Dellapool, Narrandera (SE Australia) SUMMARY OF RESULTS FOR THE GROWING SEASON 2015-2016

The analysis on sap flows and stomatal conductance, together with the data collection of micro-meteorological parameters is of key importance for a deeper understanding on the soil-plant-atmosphere continuum. At the same time, a proper elaboration on these data can provide useful insights for the improvement of sustainable hazelnut management in dry areas such as SE Australia. The study site, located in Dellapool, Narrandera (34°48’S, 146°40’E; 155 m.a.s.l), is characterized by severe vapor pressure deficit (VPD), twice the maximum value of hazelnut native habitat. Despite data gaps occurred along the period, we derived important parameters as VPD, the most important driver for sap flow. Results shows that, beyond 16hPa, VPD is not accompanied by the expected decline in sap flow, rather trees showed to have a consistent water loss despite stomatal closure at high VPD. Because of stomata closure and increased water loss, the potential productivity decline during the season could be estimated around 60%. In addition, remote calculation on soil holding capacity of water suggest a difficult water uptake in absence of frequent irrigation regime. The correlation between stomatal conductance and carbon assimilation at leaf level resulted to be linear (R2 0.79). This suggest that modelling g could be predictive for the carbon assimilation. In the last section of the report, we provide an example of g modelling.