Classification of Zoysiagrass Genotypes on Rooting Capacity and Associated Performance during Drought

Abstract

Characterization of rooting capacity in the greenhouse is a routine screening procedure for assessing a plant's ability to cope with drought stress. However, an association between rooting capacity in the greenhouse and turf performance in the field during drought is not always found. The objectives of the study were (i) to classify zoysiagrass (Zoysia spp.) rooting characteristics under well‐watered conditions in the greenhouse, (ii) to compare zoysiagrass performance under drought conditions in the field, and (iii) to relate the results from the greenhouse to the drought responses in the field. The greenhouse study included 17 zoysiagrass genotypes grown in clear acrylic tubes. Root morphological traits and dry weight at different depths (0–30, 30–60, 60–90, and 90–120 cm) were evaluated. Visual responses of zoysiagrass to field dry down were evaluated, and total turf performance index (TTPI) was used to rank the genotypes. Genotypes with higher root length density and root dry weight at 30 to 120 cm, deeper maximum root depth, and lower fraction of surface root length in the greenhouse study were better performers (high TTPI) in the field dry down study and included ‘UF 182’, ‘Emerald’, ‘JaMur’, and ‘Palisades’. The correlation between the greenhouse study and the field dry down study suggests that improvement of drought resistance may be achieved by screening for root traits in the greenhouse.

Drought Avoidance Traits in a Collection of Zoysiagrasses

“…Previous research found differences in rooting characteristics among 25 zoysiagrasses, with root depth and numbers of roots deeper in the soil found to correlate significantly with drought performance based on percentage green cover (Marcum et al, 1995). Another study that also looked at rooting characteristic of wellwatered plants in greenhouse conditions, and then compared those results to field conditions, also found that RLD and root biomass from the middle and lower soil profile were positive predictors of drought performance, whereas shallow-rooted plants that had much of their roots in the upper soil profile correlated negatively with drought performance (Christensen et al, 2017). Although in the current study no single root trait accounted for drought avoidance, differences in rooting characteristics can help explain some of the results of individual genotypes, as well as account for differences in transpiration.…”

“…The goal of our experiment was to measure drought avoidance traits in a collection of zoysiagrasses subjected to water-limited conditions. Several studies have examined rooting traits (Carrow, 1996b;Christensen et al, 2017;Fuentealba et al, 2015;Marcum et al, 1995) and supplemental water requirements (Qian and Engelke, 1999;Wherley et al, 2014;White et al, 1993) as they relate to drought performance in zoysiagrasses, but there is a lack of research that looks at belowground root traits and aboveground drought avoidance traits (such as g S ) integrated in a single study. We hypothesize that zoysiagrass genotypes that can use both extensive rooting and reduced transpiration through regulation of stomatal aperture will display the best drought performance.…”

Aboveground and belowground traits of turf‐type bahiagrass (Paspalum notatum Flügge) genotypes under simulated drought

“…Grasses with a more uniform root distribution generally have better turf performance (Christensen et al 2017;Fuentealba et al, 2015). Christensen et al (2017) found that under dry soil conditions, zoysiagrass genotypes with shallower root distribution had lower turf performance, showing a negative correlation between the fraction of surface root length (i.e. root length from surface upper depth divided by total root length) and drought avoidance.…”

“…Grasses with a more uniform root distribution generally have better turf performance (Christensen et al. 2017; Fuentealba et al., 2015). Christensen et al.…”

“…Other studies suggest that high RLD in the upper soil depths may be a desirable trait when combined with an even distribution of roots (Christensen et al. 2017). In this study, genotype ArgM27 had these characteristics, high RLD in the 1–30 cm soil depth, even distribution of roots, and late TQ midpoints.…”