Survivorship of Curly Mesquite Clones on a Severe Shrinking Clay Based Soil.

Curly mesquite (Hilaria belangeri) represents a possible low-input turf species for low-desert environments in the Southwest. This utilization requires identification of mowing-tolerant genotypes. This trait was evaluated in a collection of 140 clones of curly mesquite transplanted as replicate propagules into a field in Tucson, AZ in August 2012. In the spring of 2013 after four  mowing events, plant decline began to occur concomitant with soil surface cracking, resulting in plant shearing and stolon pegging failure, and further mowing ceased. Opportunistic measurements were taken in April 2015 to determine if survival and plant growth differed among clones. Plants were rated for green leaf production, shoot density and relative plant diameter. In May 2015, plants with the largest diameters and a canopy of fully green leaf tissue were selected.  Along with the selected plants, all remaining plants were scored as dead or alive, regardless of selection criteria.  The hypothesis that clonal replicates of selected plants were no more likely to be alive than those of non-selected plants was tested using maximum likelihood estimation for a binomial response (dead or alive) using Proc GLIMMIX (SAS).  The probability of survival of the unselected plants was significantly larger for the selected clones (0.68) compared to the non-selected ones (0.42) at (P ≤ 0.01).  This demonstrated that a “selected”  larger sized plant, devoid of necrotic tissue was more likely to have its replicate copies alive, compared to those of the unselected plants, on a clonal basis. These results suggest that genetic variation for turf-type characteristics may also exist within the original population evaluated.