capacity (CC), available water capacity (AW), and air-filled porosity (AS) were determined using the NCSU Porometer™ as described by Fonteno and Bilderback (1993) . Unavailable water (UW), water held in the substrate at 1.5 MPa or higher, was determined
, Inc., Mount Brydges, Ontario, Canada) measuring 30.5 cm × 61.0 cm were filled to a depth of 10.0 cm with a lightweight growing substrate developed at the University of Guelph, having a dry bulk density of 0.59 g·cm −3 , 6.59% organic matter, 11.3% air-filled
.E. 1997 The interaction of air-filled porosity and irrigation regime on the growth of three woody perennial (Citrus) species in pine bark substrates Proc. Southern Nurs. Assoc. Res. Conf. 42 169 174 Mauseth, J.D. 1988 Plant anatomy. The Benjamin
.-E. Rioux, J.-A. 1996 Air-filled porosity, gas relative diffusivity, and tortuosity: Indices of Prunus x cistena sp. growth in peat substrates J. Amer. Soc. Hort. Sci. 121 236 242 Bilderback, T. 1999 Potting mix choices and recommendations Proc. North
significantly less water ( P = 0.0002) than the peat-based media; however, peat substrates are inherently fibrous and have increased microporosity, which resulted in lower air-filled porosity values than bark ( P = 0.0002; Table 1 ). Altland et al. (2011
by Wang et al. (2012) . Substrate characterization. Air-filled porosity (AFP) and water-holding capacity (WHC) of the substrates were measured using a modified version of the Australian Standards method for potting mixes (AS 3743–2003; appendix B
Master); and a vegetated Pre-Cultivated SMRM5 Sedum Blanket mat (Sedum Master). The substrate was comprised of 83% inorganic (i.e., sand, crushed brick) and 17% organic material (i.e., peat, compost, and coir) with 5.8% air-filled porosity, 0.81 g·cm −2
other common greenhouse rose rootstocks ( de Hoog, 2001 ; de Vries, 2003 ; Safi, 2005 ), is not observed under even moderate salt stress levels. Other abiotic stresses like poor air-filled porosity (i.e., poor soil aeration) have been shown to
measurements: Theory and practice Adv. Irr. 1 25 42 Caron, J. Pepin, S. Periard, Y. 2014 Physics of growing media in a green future Acta Hort. 1034 309 317 Caron, J. Riviere, L.M. Guillemain, G. 2005 Gas diffusion and air-filled porosity: Effect of some
.2% air-filled porosity, 0.93 g·cm −2 dry bulk density, electrical conductivity (EC) of 761 μS·cm −1 , and pH of 6.5], which was held in the trays by white plastic raisers. The substrate had a 42% volumetric water content, 0.013 cm·s −1 permeability