Selecting for drought tolerance among Australian green couch grasses (Cynodon spp.)

Abstract

Increasing demand for scarce water resources in Australia has led to the selection of turfgrass genotypes with good drought tolerance. Here we describe the development of methodologies for screening green couch grasses (Cynodon spp.) grown in 40-cm PVC pots placed under rainout shelters. The drought tolerance of up to 8 genotypes including 4 commercial varieties (CT2, Grand Prix, Legend, and Winter Green) and 4 wild Australian ecotypes (1-1, 25-a-1, 40-1, and 81-1) was examined in 3 experiments conducted in 2007–08 and 2008–09. In the first experiment, all genotypes were grown with 2 soil types (clay and sandy soils) and 2 clipping heights (5 and 2 cm). Genotypic variation for survival period (defined as the period from the time water was withheld until 100% leaf firing had occurred) was high for the sandy soil × 2 cm clipping height treatment and, because retrieval of roots was easy, this combination was used in Expts 2 and 3 as the best system for screening drought tolerance. This method gave highly repeatable results across 2 years. Wild ecotype 81-1 had a significantly longer survival period than other genotypes, possibly associated with lower stomatal conductance early after water deficit was imposed, a greater root biomass at depth, and greater osmotic adjustment.

Dehydration survival of crop plants and its measurement

“…However, since leaf death is one means by which plants can conserve water in order to extend meristem life ( Munné-Bosch and Alegre, 2004 ), the leaf death score might represent survival via dehydration avoidance and not necessarily tolerance (e.g. Zhou et al , 2009 ).…”

Evapotranspiration Rates of Turf Bermudagrasses under Nonlimiting Soil Moisture Conditions in Oklahoma

“…A study conducted using commercially available cultivars of cool-season turfgrass demonstrated that grasses having lower ET rates during drought-stress conditions resulted in greener turf (Zhao et al, 1994). Similarly, a lysimeter study of eight bermudagrass genotypes showed that those with lower ET rates remained green for longer periods after a drought treatment (Zhou et al, 2009). It also showed that the genotypes having lower ET rates had more available soil water at later stages of the drought treatment.…”

Introduction and Adaptation of Cynodon L. C. Rich Species in Australia

“…Compared to the source germplasm (the germplasm present in the entire source population), the AC contains increased gene diversity (H = 0.18 versus H = 0.14), > 95% of the total number of alleles, and similar proportions of accessions representing specific climates, ploidy levels, and environment type. DNA extraction procedures and EST-SSR analyses have been reported previously (Jewell et al 2010;Kearns et al 2009;Zhou et al 2009). DNA from 59 international accessions representing global distribution was provided by the USDA-ARS in Tifton, GA (international collection; IC; Anderson et al 2009).…”

“…comprise perennial, widely adapted, warm-season grasses that serve multiple purposes in all continents of the world and are reported to have excellent heat and drought tolerance (Taliaferro 2003;Zhou et al 2009). Enormous morphological variability exists within the genus (Harlan and de Wet 1969;.…”