. Bulletin. Science; Natural history; Natural history. WATER RELATIONS OF BROMUS DIANDRUS 57 Predawn On - - - Midday J L J L 16 19 January 26 16 February 23 11 March 24 30 April Fig. 2. Water potential (MPa) of Bromus diandrus through the course of the growing season. The upper and lower lines represent values at predawn and midday, respectively. Vertical bars are 95% confidence intervals. an analytical balance. Mean fresh weights were determined immediately after plant sample collection. Plants were then placed in distilled water for a minimum of 3 h and saturated weights
. Bulletin. Science; Natural history; Natural history. WATER RELATIONS OF BROMUS DIANDRUS 57 Predawn On - - - Midday J L J L 16 19 January 26 16 February 23 11 March 24 30 April Fig. 2. Water potential (MPa) of Bromus diandrus through the course of the growing season. The upper and lower lines represent values at predawn and midday, respectively. Vertical bars are 95% confidence intervals. an analytical balance. Mean fresh weights were determined immediately after plant sample collection. Plants were then placed in distilled water for a minimum of 3 h and saturated weights were determined. Barrs and Weatherley (1962) reported nearly all the water uptake by excised plant parts occurs in the first three hours of submersion. Finally, the same plants were placed in an oven at 60°C and dried for 24 hours to a constant weight. RWC in percent was calculated as: RWC = Mean fresh wt. — Dry wt. Saturated wt. — Dry wt. x 100 The calculated RWC was theoretically independent of dry weight (Moore and Chapman 1986). Soil moisture measurements were made at 5 cm and 20 cm throughout the experimental period. A "Quickdraw" Soilmoisture Probe was used (Soilmoisture Equipment Corp., model 2900F, Santa Barbara, CA). The instrument acted as a tensiometer so that water was extracted from the porous sensor by the soil. When the vacuum created in the tensiometer was just sufficient to overcome extraction of water by the soil, an equilibrium and an estimate of "soil suction" were achieved. Growth was estimated from dry weight data collected throughout the experi- mental period and reported per plant for the aboveground whole plant component. Significant differences in water potential and relative water content were de- termined by assessing separation in 95% confidence intervals. Growth of B. dian- drus was tracked by using best-fit polynomial regression models. Results No rainfall event larger than mm occurred in the 21 days prior to the star
Size: 2125px × 1176px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, booksubjectnaturalhistory, booksubjectscience
