The grasses were
trimmed once a week to 6.35 cm.
The dry down procedure followed the methodology described by Johnson et al. (2009) with minor changes. The pots were arranged in a completely randomized design in a greenhouse (30 ◦C days and 22 ◦C nights). The experiment was initiated on 04 April 2010 and repeated on 30 April 2010. Four pots of each genotype were maintained as well-watered pots and six pots were subjected to a controlled dry down. The day prior to the dry down all pots were trimmed and fully watered in the late afternoon so that water drained freely from each pot. The following afternoon the initial weight of each pot was obtained for the upper limit of extractable water in each pot. To obtain the evapotranspiration rate (ET) for a period of ≈ 24 h, the weight of each pot was recorded at ≈1300 h each day. For the well-watered control, water was added daily to return its weight to 30 g less than its initial weight (≈0.1 total transpirable water in the pot), which prevented the soil from being water-saturated yet maintained the soil