Drought-tolerance indices in a tall fescue population and its polycross progenies

Abstract

<jats:p>Development of drought-tolerant cultivars is hampered by a lack of effective selection criteria. In this research, drought tolerance of 75 genotypes of tall fescue in three sets (25 parental, 25 early, 25 late-flowering progenies) was evaluated under no soil moisture stress and soil moisture stress in the field during 2009 and 2010. Five drought-tolerance indices were calculated: stress tolerance (TOL), mean productivity (MP), geometric mean productivity (GMP), stress susceptibility index (SSI), and stress tolerance index (STI). These calculations were based on forage yield (dry matter basis) under drought (Ys) and non-drought (Yp) conditions. Soil moisture stress caused significant reduction in forage yield. Considerable genetic variation for drought tolerance was found among genotypes. A moderately high relationship was found between Yp and Ys using regression analysis, with a clear relationship in the second year. Indices GMP and STI were found to be valuable aids in the selection of drought-tolerant, high-yielding genotypes. Plots of the first and second principal components identified drought-tolerant genotypes in each set. Results indicated that selection for drought-tolerant genotypes should be planned separately for first year (establishment stage) and second year (productive stage) in tall fescue.</jats:p>

Drought tolerance in perennial ryegrass (Lolium perenne L.) as assessed by two contrasting phenotyping systems

“…In the experiments carried out by Ebrahimiyan et al. (), STI values ranged from nearly 0 to about 4. In our set of Lp populations , the highest recorded STI value was about 3 (involving root DM), a value which should be a sufficient basis for effective selection of drought tolerant genotypes.…”

Root and physiological characteristics associated with drought tolerance in Iranian tall fescue

“…After developing a broad-based population from polycross of a set of 25 parental tall fescue genotypes (Majidi et al 2009), 24 (eight early-, eight mid-, and eight late-season flowering) genotypes were selected within the progenies based on drought tolerance and susceptibility indices (Ebrahimiyan et al 2012). The genotypes were clonally propagated in a greenhouse and then transferred to the field in March 2011.…”

“…Instances are stress tolerance index (STI) introduced by Fernandez (1992), which can be used to identify genotypes that produce high yields under both stress and non-stress conditions, and tolerance index (TOL) introduced by Rosielle and Hamblin (1981) based on differences in yields measured under nonstress and stress conditions. Using drought tolerance and susceptibility indices, Ebrahimiyan et al (2012) assessed drought tolerance of 75 tall fescue genotypes in three different flowering sets. Nevertheless, little information is still available about the relationship between these indices and root and physiological traits.…”

Survival and recovery of tall fescue genotypes: association with root characteristics and drought tolerance

“…Ebrahimiyan et al . (,b) suggested that indirect selection for developing high‐yielding, drought‐tolerant varieties should be conducted under drought stress conditions. Previous studies reported that plants such as tall fescue respond and adapt to drought stress using a variety of mechanisms including escape, avoidance and tolerance, all of which serve to improve the efficiency of water uptake and minimize water loss (Wang and Huang, ; Pirnajmedin et al ., ).…”

“…Ebrahimiyan et al . (,b) reported that selection based on indices such as STI is a suitable approach for screening drought tolerance and sustainable tall fescue genotypes with a high positive correlation between STI index and drought tolerance (Talebi et al ., ; Ebrahimiyan et al ., ).…”