Small Leaf Mid-Rib Xylem Related to Leaf Freeze Tolerance Trait in Bahia (\u3cem\u3ePaspalum Notatum\u3c/em\u3e Flugge) Grass Lines

Controlled freeze (-60o C) trials of 31 bahiagrass selections from a breeding program for cold tolerance by Blount et al. (2001) showed diverse genotype Leaf Tissue Cold Damage (LTCD). Breman et al. (2003) defined LTCD on a rating scale (1 = no damage to 9 = 100% leaf damage). Unique midrib damage was observed as part of LTCD in bahiagrass under transpiration stress after a freeze trial. Small xylem conduit diameter and area has been strongly correlated with reduced cavitation caused by freeze thaw cycles which maintain leaf tissue in evergreen temperate woody plants; further shown in twelve woody species by Davis et al. (1999). Air bubbles in vessel ice columns prevent normal refill and function upon thawing. The purpose of this study was to test whether genotype xylem diameter and area could be used to predict LTCD

Tissue Damage and Nutritive Value of Warm-Season Grasses Following a Freeze

Bahiagrass (Paspalum notatum Flugge) is a major forage for livestock in the subtropics of the U.S.A. However, it is subject to freeze damage with minimal winter regrowth, and is generally considered a poor grass for stockpiling due to poor quality of the residue. Bahiagrass genotypes have been found showing a range of leaf freezing tolerance in the in the field (-30 C) (Blount et al., 2001). Other C4 grasses have been reported to have genotype-specific tolerances to below-freezing temperatures ranging from -3 to -100 C (Sakai & Larcher, 1987). This research was begun to try to understand the processes that take place following freeze injury to bahiagrass. Three grasses native to the Midwest, big bluestem (Andropogon gerardii Vitman cv Alamo), Indiangrass (Sorghastrum nutans (L.) Nash cv Lometa), and switchgrass (Panicum virgatum L. cv Kaw) and commonly used for stockpiling were used for comparison