both the gravimetric soil water content (θ) of each pot and the predawn leaf water potential (Ψ L ) on days 0, 2, 4, 5, and 6 of the drought cycle. At the beginning of the experiment, the plants were overwatered, drained overnight, and pot weight was
middle section of the canopy. Leaf and fruit retention was measured in all ‘Hamlin’ orange field trials. Leaf water content, leaf dry weight, midday leaf water potential, and leaf chlorophyll fluorescence and chlorophyll content were measured as described
decreased ( Björkman et al., 1980 ). However, no relationship was found between leaf water potential and leaf stomatal conductance ( g S ) for oleander ( Gollan et al., 1985 ). Two representative commercial cultivars, Hardy Pink and Hardy Red, and two
Abstract
Two cultivars of Seashore Paspalum (Paspalum vaginatum Swartz.), ‘Adalayd’ (‘Excaliber’) and ‘FSP-1’, were grown in solution culture at 6 levels of salinity derived from synthetic sea water. Cultivars differed in changes of leaf water potential, leaf water potential components, and in growth responses to increased salinity. ‘Adalayd’ exhibited a linear decrease whereas ‘FSP-1’ exhibited a quadratic decrease in leaf water potential with increasing salinity. Leaf osmotic potentials decreased linearly for both cultivars, but there was a significant interaction. Leaf turgor potential decreased linearly for ‘Adalayd’ but quadratically for ‘FSP-1’. ‘FSP-1’ had greater tolerance to salinity in solution culture than Adalayd.
constant SMCs (9%, 15%, 22%, and 32%), Nemali and van Iersel (2008) found that gas exchange, chlorophyll fluorescence, and leaf water potential were similar between 32% and 22% SMC for impatiens ( Impatiens wallerana Hook.) and salvia ( Salvia splendens
Technologies, Inc., Plainfield, IL) and the Accumet 950 pH/ion Meter (Fisher Scientific, Pittsburgh, PA), respectively. Seedlings were sampled on a different five dates (21 June, 7 July, 29 July, 14 Aug., and 10 Sept. 2007) for predawn leaf water potential
, for each treatment were measured. Leaf water potential. The third fully expanded leaf on each plant was used to measure midday leaf water potential (ψ). After cutting a leaf with a sharp blade, it was put in the chamber of a pressure bomb (PMS
Growth of potted Ligustrum was controlled by uniconazole at 3.0 mg a.i./pot. Uniconazole inhibited growth by inducing shorter internodes with smaller diameter and by reducing secondary branching and new leaf production. As a result, the total leaf area of the treated plants was 6396 less than the control plants. The chlorophyll content of recently expanded leaves was 27% lower in treated than in control plants, even though there were no visual differences in leaf color. Leaves of treated plants also had a 28% higher stomatal density than the control. The liquid flow conductance of Ligustrum was 3.7 × 10-14 m·s-1·Pa-1 and was similar for plants in both treatments. Differences in daily water, use between the two treatments began to appear at the same time as differences in growth. Total water use of treated plants was 13% less than that of the control. When daily water use was normalized on a-leaf-area basis, water use between treatments was similar, suggesting that differences in total water use were primarily due to differences in leaf area. For plants in both treatments, peak sap flow rates in the main trunk ranged between 60 and 100 g·h-1·m-2. Leaf conductance, transpiration rates, and water potential were also similar for treated and control plants. Chemical name used: (E)-1-(4-chlorophenyll) -4,4, -dimethyl-2-(l,2,4-triazo1-l-y1)-l-penten-3-ol (uniconazole).
Abstract
The addition of (2RS, 3RS)-1-(4-chlorophenyl)-4,4-dimethyl-2-1,2,4-triazoI-1-yl-) pentan-3-ol) (paclobutrazol, PP333) at 0.05 or 0.20 ppm to a nutrient solution in which 4-month-old apple (Malus domestica, Borkh.) seedlings were growing, reduced terminal growth and increased root to leaf ratio. Plants pretreated with 0.20 ppm PP333 did not show a reduction in transpiration due to subsequent applied water stress induced by polyethylene glycol (PEG), whereas untreated plants decreased their transpiration in response to PEG stress at −0.5 and −0.75 MPa. The PP333 pretreatment at 0.20 ppm improved water balance of the seedlings since they had a higher water potential than untreated seedlings at equal or higher transpiration rates. Leaf osmotic adjustment to lower water potentials was shown to be leaf age-dependent irrespective of PP333 pretreatment.
( Ehleringer et al., 1993 ; Farquhar et al., 1989 ), and chlorophyll fluorescence ( Feser et al., 2005 ; Percival and Sheriffs, 2002 ) are physiological attributes that delineate the fitness of a plant for drought. Predawn stem or leaf water potential is a