Effects of drought and nutrient deficiency on grafts originating from sound and shaken sweet chestnut trees (Castanea sativa Mill.)

Abstract

Abstract: Scions taken from felled, shaken or sound sweet chestnut trees (Castanea sativa Mill.) were grafted and grown for one year in a polythene tunnel in order to compare their responses to water and nutrient stresses. Phenological characteristics of the original trees were strongly reproduced in the grafts grown both in this controlled environment and later on in the field. Grafts originating from shaken trees flushed up to six days later, senesced earlier and produced larger spring vessels. Artificially imposed drought reduced stomatal densities by 5.6% and xylem vessel diameters by up to 35%. Fertiliser additions significantly increased stem increments and promoted earlier flowering, with hermaphrodite flowering filaments more common in grafts from shaken trees. It is considered that, because of their larger spring vessels, shaken trees may be more vulnerable to cavitation and therefore to drought, even though moisture stress is mitigated by some plasticity in earlywood vessel diameter.