[1] Weizmann Inst Sci, Dept Environm Sci & Energy Res, IL-76100 Rehovot, Israel
[2] Univ Basel, Inst Bot, CH-4056 Basel, Switzerland
[3] ETH, Inst Agr Sci, Zurich, Switzerland
[4] Hebrew Univ Jerusalem, Robert H Smith Fac Agr Food & Environm, IL-76100 Rehovot, Israel