Differential growth of hybrid pine families in Misiones, Argentina, is not linked to their stomatal behavior

Abstract

INTA-PINDO hybrid pine is the result of the crossing between Pinus elliottii var. elliottii and Pinus caribaea var. hondurensis. The aim of this study was to analize variables that can explain the differential growth between two hybrid pine families. Plants of the families F12 and F28 were established under field conditions in July 2020, with periodic measurements until April 2021 of Total Height (TH, cm). Since October, maximum stomatal conductance (gsmax, mmol m2 s-1) and leaf water potential (Ψl, MPa) were measured at 10 a.m. In dry and wet periods, daily curves of gs and Ψl were traced. Initial TH was different between F12 and F28 (30.1 ± 3.8 and 20.8 ± 2.5 cm respectively; p = 0.007). The accumulated increment in TH was different between families since September, being final increment in TH (April 2021) of F28 (71.4 ± 18.0 cm) higher than of F12 (33.3 ± 10.3 cm). The whole growing-season mean of gsmax and Ψl were similar between families (323.3 ± 150.4, 373.3 ± 103.1 mmol m2 s-1; -1.9 ± 0.57, -1.8 ± 0.52 MPa; p> 0.05). Daily gs and Ψl were different comparing dry and wet periods (gs: p = 0.016; Ψl: p <0.001), but not between families (p = 0.754 and 0.315), without interaction between factors (period*family) (p = 0.842 and 0.646). Family stomatal behavior was not related to initial size and morphological dynamics, which could be related to a differential allocation to aboveground vs. belowground biomass or to differences in resource use efficiency.