Variability in Leaf Characteristics and Water Loss in the Weeping Lovegrass Complex
Tischler, C. R. | Voigt, P. W.
Epicuticular wax restricts water loss across the cuticle of plant leaves and is considered to aid in drought resistance. This conserving effect is roughly proportional to the amount of wax present. We measured wax levels, water loss, and leaf width and rolling characteristics of 19 lovegrasses, Eragrostis curvula (Schrad.) Nees, to determine if variation existed for these characteristics and the relationships among them. A broad range of germplasm that could be characterized as belonging to the curvula or. robusta forms of E. curvula was established in field plots in 1979. Each characteristic was studied on at least two different dates between 1980 and 1982. Epicuticular wax levels ranged from 0.212 to 0.589 g/m², leaf width ranged from 2.2 to 5.7 mm, and water content ranged from 60 to 104 g/m². Values for mean cumulative water loss per amount of water contained in detached leaf sections ranged from 71 to 218 g/kg, while rate of water loss per amount of water contained ranged from 1.93 to 4.53 g kg⁻¹ min⁻¹. In general, genotypes with high wax had a high leaf water content, low water loss, and a low rate of water loss. The amount of epicuticular wax appeared responsible for some of the reduced cuticular transpiration. High water content per unit leaf area was associated with a low rate of leaf rolling. The interaction between wax and leaf rolling (which reduces effective leaf area) and leaf water content tended to prevent an unequivocal determination of the influence of varying wax levels on leaf water loss. Germplasm with a narrower genetic base and a wide range in leaf wax would be useful to more precisely characterize the relationship between leaf wax and leaf water loss in E. curvula.
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