Fig. 4. Mean diurnal C exchange rates of well-watered (W) and water-stressed (D) guayule in July 2003. Diurnal measurements were taken 2 d after irrigation of the water-stressed plants. Carbon exchange measurements were recorded every 2 h beginning at 0800 and ending at 1600 h. Measurements were taken on 10 plants in each irrigation treatment (five plants in each of two replications). The vertical bar indicates ± standard error.