The effectiveness of coconut substrate and fertilization regimes during nursery culture and post-transplant response in three Quercus species

In Mediterranean countries, the intensity and length of spring and summer dry periods are becoming harsher. The frequency of such phenomena is likely to increase in the future in Mediterranean areas of Italy, and also in the northern regions, following climate change scenarios. These conditions will reduce posttransplant survival and growth and influence forest restoration planting success. To improve nursery stock quality for overcoming ‘transplant shock’ and to promote environmentally sustainable nursery production, we tested a conventional peatbased substrate versus coconut fiber substrate, in combination with three different fertilizations (nursery standard; phosphorous‐enriched; and potassium‐enriched) on Quercus ilex, Quercus pubescens, and Quercus robur, which differ in drought resistance adaptability. In 2017, seedlings were grown in a nursery in Central Italy under well‐watered conditions. Growth (48 seedlings per treatment, 2592 in total) and physiology was followed during the growing season by chlorophyll fluorescence, leaf spectroscopy and gas‐exchanges techniques. At the end of the season, above‐ and below‐ground biomass and morphological traits were measured on a sub‐sample (15 seedlings per treatment). In May 2018, a “speed water‐stress test” was performed under controlled greenhouse conditions by exposing seedlings to 3 water stress levels: control (field‐capacity irrigation), medium (50% of control irrigation) and strong (water‐suspension). Concurrently, post‐transplant establishment, growth and physiological responses are being tested in open‐field under natural environmental conditions. We present the midterm results of the project.