Evaluating water use rates and root growth characteristics of turf bermudagrass cultivars under non-limiting soil moisture conditions in Oklahoma

摘要

Evapotranspiration (ET) rates of ten bermudagrasses ( Cynodon spp.) were evaluated in the field using weighing mini-lysimeters with calcined clay as the rooting media. Similarly, root growth characteristics were evaluated in a greenhouse using 120 cm growth tubes. The purpose of this research was to identify experimental genotypes as well as commercially available bermudagrass cultivars with low water use rates, longer root length, and greater root surface area. A total of six commercial ('Tifway', 'Celebration', 'Premier', 'TGS_U3', 'Latitude 36' and 'NorthBridge') and four experimental ('DT-1', 'OKC 1302', 'OKC 1131', and 'OKC 1163') bermudagrass entries were evaluated. Before dawn, mini-lysimeters were saturated, drained to field capacity, and the initial weight was recorded. After 24 and 48 hours, mini-lysimeters were weighed again to obtain an estimate of the daily ET rate. Significant genotype and date effects were found within each year, whereas year and genotype x year effect were found significant in the overall analysis. The genotype x date effect was not significant for 2013 but significant in 2014. Data were analyzed separately for 2013 and 2014. In 2013 TGS_U3, DT-1, Premier, and NorthBridge used more water than OKC 1163, Tifway, and OKC 1131. In 2014 DT-1, Celebration, and OKC 1302 used more water than Premier, TGS-U3, Latitude 36, NorthBridge, OKC 1163, and OKC 1131. In 2013 the ET rates ranged from 4.14 mm d-1 to 4.74 mm d -1 whereas in 2014 ET rates ranged from 4.93 mm d-1 to 6.19 mm d-1. The root study showed that 65 to 90% of total root length and 65 to 96% of root surface area were located in the upper 30 cm profile. The entries TGS_U3, OKC 1302, OKC 1131 and NorthBridge were the only entries that had root growth into the 90-120 cm profile. The entry OKC 1163 had roots no deeper than the 60 cm profile while Premier, Latitude 36, Celebration, DT-1, and Tifway had roots no deeper than the 90 cm profile. The results from this study show the potential for irrigation water conservation by adopting bermudagrass cultivars with lower ET rates and longer and extensive root systems with greater surface area.