Physiological responses of apricot plants grafted on two different rootstocks to flooding conditions

Abstract

The effects of soil flooding on plant water relations and vegetative growth was studied in potted two-year-old apricot plants (Prunus armeniaca L., cv. Búlida) grafted on two different rootstocks: Pollizo prune (P. insititia L.) (P) and Real Fino apricot (RF). Plants were submitted outdoors to three treatments: T0, not flooded (control), and two flooded treatments for 3 (T1) and 6 (T2) days. Apricot water relations were seen to be adversely affected from first day of the flooding onwards. These effects were more pronounced in Búlida/RF than in Búlida/P plants. The T1 plants developed an early stomatal regulation (decrease in leaf conductance (gl)), which prevented leaf tissue dehydration, together with decrease in net photosynthesis (Pn) and the increase in resistance to water flow (R(p+s)). This early gl and Pn response suggests that porometric and/or photosynthetic changes are reliable bio-indicators of the altered behaviour caused by flooding in apricot plants. The lowest gl and Pn, and highest R(p+s) values occurred with more prolonged flooding (6 days), when a decrease in leaf water potential (Ψl) and leaf turgor was noted, together with epinasty, which in Búlida/RF plants led to a decrease in Ψl to -6.0 MPa, and the death of all plants. These results indicate Búlida apricot plants grafted onto Pollizo prune rootstock is a more appropriate combination than Búlida/Real Fino to resist occasional soil flooding situations.