Multi-site evaluation on acid soils of a Phalaris aquatica × P. arundinacea × P. aquatica backcross population bred for acid soil tolerance

Abstract

Half-sib families in the AT98 Phalaris aquatica × P. arundinacea × P. aquatica backcross population bred for acid soil tolerance were compared for establishment, persistence, and yield with phalaris (P. aquatica L.) controls and cocksfoot (Dactylis glomerata L. cv. Porto) at 4 sites in south-eastern Australia with the aim of selecting the parents of a new cultivar. The sites had strongly acid soils but differed in parent material, pH profile, soil fertility, and suitability for phalaris. Establishment by AT98 was clearly superior to all phalaris controls and similar to cocksfoot in an acid soil high in Al to depth at Chiltern, north-eastern Victoria, after sowing in early spring 2000. It was considered likely that better establishment by AT98 was due to its higher Al tolerance. In contrast, little variation in establishment was observed at 3 other sites sown in late autumn 1999, possibly due to a longer period free of moisture stress compared with the later sown Chiltern site. Once established, the control cultivars of phalaris at the autumn-sown sites in general persisted and yielded similarly to the mean of the AT98 families. Significant family variation was observed and predicted heritability on a family mean basis was high for persistence measured as basal frequency and moderately high for yield in the third year. Family by site interaction was relatively low for both attributes. A cultivar based on the best families should give more reliable establishment on acid soils high in Al under conditions where rapid root growth to depth is needed for survival, and give more flexibility of sowing date on these soils. Its best performance relative to cv. Landmaster in terms of third-year yield was predicted to occur on granite-derived soils in north-eastern Victoria.

Root morphology, root-hair development and rhizosheath formation on perennial grass seedlings is influenced by soil acidity

“…While Sirosa-phalaris is sensitive to acidity, its total root length in the unamended soils was often similar to that of AT-phalaris. This cultivar displays vigorous growth in the field and this may explain why acid-soil resistant lines of phalaris do not always display a clear advantage over Sirosa-phalaris at acid field sites (Culvenor et al 2004).…”

“…The bar shows least significant difference value (P=0.05) for the interaction of soil amendment x species (LSD=0.0033, Ferrosol, 0.0062, Kandosol topsoil, 0.0058, Kandosol subsoil). Rhizosheath refers to soil held to the root system when the root system has been excavated from soil species differences in Al-resistance for AT-and Sirosaphalaris (Culvenor et al 2004). However, rhizosheaths of both genotypes were adversely affected by soil acidity.…”

“…Indeed, drier conditions exacerbate differences between acid-soil sensitive and resistant genotypes, with the better root growth of acid-soil resistant genotypes aiding water extraction (Krizek and Foy 1988;Tang et al 2002). Survival of sensitive species such as tall wheatgrass, for which the seminal root length was restricted in all three soils, is often compromised in the field (Culvenor et al 2004).…”

“…Acid soilresistant genotypes included cocksfoot (Dactylis glomerata cv Porto), a phalaris breeder's line (Phalaris aquatica, AT-phalaris; Culvenor et al 2004) and weeping grass (Microlaena stipoides cv Ovens). Acid-soil sensitive genotypes were a commercial phalaris cultivar (Phalaris aquatica cv Sirosa, Sirosa-phalaris) and tall wheatgrass (Thinopyrum ponticum (Podp.)…”

Effect of soil acidity, soil strength and macropores on root growth and morphology of perennial grass species differing in acid‐soil resistance

“…2006; Botwright Acuna, Pasuquin & Wade 2007; Blum 2009). At an acid‐soil field site, Culvenor et al . (2004) found that an acid‐soil sensitive cultivar of phalaris achieved equivalent plant establishment prior to the summer drought compared with that of an acid‐soil resistant line.…”