a ratio of 1:1. Protoplast fusion was carried out by the “chemical” method based on the use of polyethylene glycol (PEG) described by Grosser and Gmitter (1990) . In this method, 4 to 5 drops (correlates to 0.5–1 × 10 6 protoplasts) of mixed
Rain-induced cracking of sweet cherry (Prunus avium L.) fruit is thought to be related to water absorption through the fruit surface. Conductance for water uptake (gtot. uptake) through the fruit surface of `Sam' sweet cherry was studied gravimetrically by monitoring water penetration from a donor solution of deionized water through segments of the outer pericarp into a polyethyleneglycol (PEG) containing receiver solution. Segments consisting of cuticle plus five to eight cell layers of epidermal and hypodermal tissue were mounted in stainless steel diffusion cells. Conductance was calculated from flow rates of water across the segment and the difference in osmotic potential between donor and receiver solution. Flow rates were constant up to 12 hours and decreased thereafter. A log normal distribution of gtot. uptake was observed with a median of 0.97 × 10-7 m·s-1. Further, gtot. uptake was not affected by storage duration (up to 71 days) of fruit used as a source of segments, thickness of segments (range 0.1 to 4.8 mm), or segment area exposed in the diffusion cell. Osmolality of the receiver solution in the range from 1140 to 3400 mmol·kg-1 had no effect on gtot. uptake (1.45 ± 0.42 × 10-7 m·s-1), but gtot. uptake increased by 301% (4.37 ± 0.46 × 10-7 m·s-1) at 300 mmol·kg-1. gtot. uptake was highest in the stylar scar region of the fruit (1.44 ± 0.16 × 10-7 m·s-1) followed by cheek (1.02 ±0.21 × 10-7 m·s-1), suture (0.57 ±0.17 × 10-7 m·s-1) and pedicel cavity regions (0.22 ±0.09 × 10-7 m·s-1). Across regions, gtot. uptake was related positively to stomatal density. Extracting total cuticular wax by dipping fruit in chloroform/methanol increased gtot. uptake from 1.18 ± 0.23 × 10-7 m·s-1 to 2.58 ± 0.41 × 10-7 m·s-1, but removing epicuticular wax by cellulose acetate stripping had no effect (1.59 ± 0.28 × 10-7 m·s-1). Water flux increased with increasing temperature (range 20 to 45 °C). Conductance differed between cultivars with `Hedelfinger' sweet cherry having the highest gtot. uptake (2.81 ± 0.26 × 10-7 m·s-1), followed by `Namare' (2.68 ± 0.26 × 10-7 m·s-1), `Kordia' (0.96 ± 0.14 × 10-7 m·s-1), `Sam' (0.87 ± 0.15 × 10-7 m·s-1), and `Adriana' (0.33 ± 0.02 × 10-7 m·s-1). The diffusion cell system described herein may be useful in analyzing conductance in water uptake through the fruit surface of sweet cherry and its potential relevance for fruit cracking.
( Khakwani et al. 2011 ). Crop breeders reported that exposure to osmotic solutions, such as polyethylene glycol (PEG-6000), has been proven as an effective method to mimic drought stress conditions during seed germination and subsequent growth stages in
.13 MPa) respectively. To determine whether the inhibition of germination resulting from SMS was a true osmotic effect or the result of inhibitory compounds in the SMS extract, solutions of polyethylene glycol (PEG 6000; EMD Chemicals, Gibbstown, N
. Also, pH remained essentially constant (within 0.5 pH units) in presence of organic acids without pH adjustment. However, pH of nonbuffered solutions [i.e., those containing water only, carbohydrates, polyethylene glycol (PEG) 6000, or those of organic
by aquarium air pump (LifeTech, Shenzhen, China). Plants were grown for 30 d to develop new roots and shoots after which time polyethylene glycol (PEG 6000; Huada, Shantou, China) was added to the growing solution every 5 d to incrementally reduce Ψ S
the tissue culture plants were transferred from the solid half-strength B5 medium to a liquid half-strength B5 medium supplemented with 10% polyethylene glycol (PEG) 6000, 100 μM NaCl, or 100 μM ABA, respectively. The plantlets were also placed in
type. Seeds of both cultivars exhibited a high germination percentage (99 or greater). Seeds were stored at 5 °C before use. To prime seeds, 200 g were incubated for 24 h at 15 °C in an aerated 2-L solution of Carbowax PEG 8000 (336 g·L −1 , −1.45 MPa
pollen tube. However, the tube tips were enlarged and rapidly broke. The medium was amended using 5% to 20% polyethylene glycol (PEG 4500; Amresco, Solon, OH), which resulted in the generation of longer tubes that exhibited normal morphology. In vivo
polyethylene glycol (PEG). The ψ S at –0.03 MPa and –0.1 MPa corresponded to the actual ψ S of the tissue extracts used in Expts. 1 and 2. Twenty-five seeds of each species were placed on a piece of filter paper in a petri dish and 10 mL of the PEG solution