., 2000a , 2000b ). Changes in root growth and development may subsequently influence soil water extraction and translocation of root-derived signals ( Rogiers et al., 2010 ). Moriana et al. (2003) found that the leaf water potential and stomatal
Abbreviations: ET c , crop evapotranspiration; DOY, day of year; K c , crop coefficient; LWP, leaf water potential; RWC, leaf relative water content; VPD, air vapor pressure deficit. 1 Plant Physiologist. 2 Agronomist. 3 Agricultural Engineer. 4
Abbreviations: DAFB, days after full bloom; DC, drying cycle; E pan , potential water use measured from a Class A pan; ET, evapotranspiration; k c , crop coefficient; WU, water use; Ψ 1 , leaf water potential. 2 Senior Lecturer. 3 Professor. Current
( Hinckley et al., 1978 ) and growth. Transplanted trees are considered to be established when leaf water potential (ψ L ), gas exchange, and growth are similar to those of nontransplanted trees ( Beeson and Gilman, 1992 ). However, research on gas exchange
, y i and y i + 1 are the values of the severity scale that were obtained at every evaluation time, and ( t i + 1 − t i ) is the time interval between evaluations. g S and leaf water potential. g S and leaf water potential (Ψ wf ) were
µmol·s −1 ). Leaf water potential. Leaf water potential was measured on young, fully expanded leaves, nine leaves from each replicate, on the same day that observations of gas exchange parameters were made (on the third or fourth leaves from the plant
, medium, or high salt-tolerant. We monitored changes in leaf water potential and plant quality of sea hibiscus, a high salt-tolerant plant, exposed to increasing EC and Na levels. Because measuring water potential is impractical for a grower, for
Peach trees [Prunus persica (L.) Batsch cvs. Loring/Halford] were grown in boxes 100 × 60 × 36 cm (length × width × depth) to evaluate the effect of K-31 tall fescue sod (Festuca arundinacea Schreb.) on peach root growth and development. The entire soil surface was kept bare in one treatment, while a fescue sod was established in one-third of the box for the second treatment. Trees were planted 17 cm from one edge of the box in bare soil in both treatments. Sod reduced tree growth. The length of roots ≥1 mm in diameter was unaffected by the sod at any position in the box. The length of roots <1 mm in diameter was reduced beneath the sod and in the area between the sod and tree compared to the bare soil treatment. The plant resistance to water flow/cm root (Rp) was unaffected by the presence of grass under both stressed and nonstressed conditions. Rp was relatively constant (9.4 × 109 s cm-1) over a range of transpiration flux levels until the flux dropped below 0.3 cm3 s-1. Below 0.3 cm3 s-1 Rp increased due to soil resistance to water flow.
Two groups of 8-year-old ‘Murcott’ [Citrus reticulata Blanco × C. sinensis (L.) Osbeck hybrid?] trees on rough lemon (C. jambhiri Lush.) rootstock were transplanted with a Vermeer tree digger in March and July, respectively. Root and shoot pruning and a 2% (v/v) spray of a pinolene-based antitranspirant (Vapor Gard) formed the treatments either individually or in combination. Canopy size at transplanting had the greatest effect on tree water-stress and subsequent tree growth and yield. The antitranspirant and root pruning tended to reduce leaf water-stress, but the effects generally were small and nonsignificant. Root pruning also seemed to stimulate new root growth. After transplanting, roots grew 2 to 3 m beyond the soil ball in one year. Four years after transplanting there were virtually no differences in tree height or canopy volume. Cumulative yield was less for trees with 30% and 85% of their foliage removed as compared to those with 50% removed. Trees pruned 50% bore fruit the year after transplanting and consistently yielded more throughout the study.
Mature lemon trees (Citrus limon (L.) Burm. f.) were subjected to a long period of severe water stress. Free proline accumulated in leaves of water stressed trees, and returned to normal soon after irrigation was resumed. There was a linear relationship between free proline contents and noon xylem pressure potential.