.5, and 8.0. A 10 m m 3-(N-morpholino)propanesulfonic acid (MOPS) buffer was tested at pH 6.5, 7.0, and 7.5. A 10 m m 2-( N -morpholino)ethanesulfonic acid (MES) buffer was trialed at pH 5.5, 6.0, and 6.5. A 10 m m tris(hydroxymethyl)aminomethane (tris
Patrick J. Conner
Luiz A. Biasi and Patrick J. Conner
sucrose, 10 g·L −1 agar, 50 mg·L −1 boric acid media, which had a pH of 6.0 adjusted with either the addition or 0.1 n N HCl or using a 10 m m 2-( N -morpholino)ethanesulfonic acid (MES) buffer. Boric acid concentration was tested in a high
Fazeeda N. Hosein, Adrian M. Lennon, and Pathmanathan Umaharan
; shown subsequently), supplemented with 0.05% S240 and 100 μM acetosyringone and cocultivated for 2 d as before, and assayed for GUS activity: IF1 – 1% glucose; IF2 – 5% sucrose; IF3 – 0.5% glucose, 10 m m 2-(N-morpholino) ethanesulfonic acid (MES), 10 m
L.E. Hinesley and Sylvia M. Blankenship
Cut branches of Fraser fir [Abies fraseri (Pursh) Poir.] were subjected to solutions with different molarity, pH, and solutes. Citrate-phosphate and Na-phosphate buffers induced heavy needle loss at concentrations as low as 10 mm, whereas needle loss was negligible for MES buffer, sucrose solutions, and distilled water. Needle drop increased in response to higher solute concentration and/or greater duration of exposure. Needle loss was almost 100% at pH 3.0 and 9.0, but minimal at pH 6.0 and 7.0. Chemical name used: 2-(N-morpholino) ethanesulfonic acid (MES).
James F. Harbage and Dennis P. Stimart
Involvement of pH and IBA on adventitious root initiation was investigated with Malus domestica Borkh. microcuttings. The pH of unbuffered root initiation medium (RIM) increased from 5.6 to 7 within 2 days. Buffering with 2[N-morpholino] ethanesulfonic acid (MES) adjusted to specific pHs with potassium hydroxide prevented pH changes and resulted in a 2-fold higher root count at pH 5.5 compared to pH 7 or unbuffered medium. As pH decreased, lower concentrations of IBA were required to increase root counts. Colorimetric measurement of IBA in buffered RIM showed greater IBA loss and higher root count were associated with lower pH levels in all cultivars. This suggests that IBA loss from RIM depends on medium pH, which affects root count. Root count differences between easy-to-root through difficult-to-root cultivars were not consistent with amount of IBA loss from RIM. Cultivar differences in root count could not be explained solely by IBA loss from RIM.
Chad E. Finn, James J. Luby, Carl J. Rosen, and Peter D. Ascher
Progenies from crosses among eight highbush (Vaccinium corymbosum L.), lowbush (V. angustifolium Ait.), and V. corymbosum/V. angustifolium hybrid-derivative parents were evaluated in vitro at low (5.0) and high (6.0) pH for vitality, height, and dry weight. Succinic acid and 2[N- morpholino]ethanesulfonic acid (Mes) effectively maintained pH in the medium and rhizosphere. The pH regime did not affect percent radicle emergence from seed or survival; however, percent seed germination was slightly lower at high pH. The parental general combining ability (GCA), reciprocal and maternal, but not the specific combining ability (SCA) variance components were significant for plant vitality, height, and dry weight. The GCA variance components were six to 26 times larger than the SCA variance components for the plant growth traits. Variation due to pH regime was significant for vitality and dry weight but not for plant height. The progenies of parents with high percent lowbush ancestry were taller at both pH levels than those with less such ancestry. Little variation was apparent for higher pH tolerance as measured by dry weight; however, the GCA effects suggested that the progenies of some parents performed better than others at high pH. Vaccinium angustifolium parents differed in the extent to which tolerance to high pH was transmitted. In vitro screening in concert with a traditional breeding program should be effective in improving blueberry tolerance to higher pH.
Jay Frick and Cary A. Mitchell
2-[N-morpholino] ethanesulfonic acid (MES) buffer or Amberlite DP-1 (cation-exchange resin beads) were used to stabilize substrate pH of passive-wicking, solid-matrix hydroponic systems in which small canopies of Brassica napus L. (CrGC 5-2, genome: ACaacc) were grown to maturity. Two concentrations of MES (5 or 10 m m) were included in Hoagland 1 nutrient solution. Alternatively, resin beads were incorporated into the 2 vermiculite: 1 perlite (v/v) growth medium at 6% or 12% of total substrate volume. Both strategies stabilized pH without toxic side effects on plants. Average seed yield rates for all four pH stabilization treatments (13.3 to 16.9 g·m-2·day-1) were about double that of the control (8.2 g·m-2·day-1), for which there was no attempt to buffer substrate pH. Both the highest canopy seed yield rate (16.9 g·m-2·day-1) and the highest shoot harvest index (19.5%) occurred with the 6% resin bead treatment, even though the 10 mm MES and 12% bead treatments maintained pH within the narrowest limits. The pH stabilization methods tested did not significantly affect seed oil and protein contents.
James F. Harbage and Dennis P. Stimart
Many physiological responses in plants are influenced by pH. The present chemiosmotic hypothesis suggests that auxin uptake into plant cells is governed by pH. Since auxin is used widely to enhance rooting, the influence of pH on 1H-indole-3-butyric acid (IBA) induced adventitious root formation was examined. Roots were initiated aseptically in 5 node apical shoot cuttings of micropropagated Malus domestica 'Gala'. Initiation was induced using a four day pulse in IBA and 15 g/L sucrose at pH 5.6 and 30C in the dark. Observations showed pH rose to 7.0 or greater within 1 to 2 days from microcutting placement in unbuffered initiation medium. Root numbers from shoots in media containing 1.5 μM IBA buffered with 10 mM 2[N-morpholino] ethanesulfonic acid (MES) to pH 5.5, 6.0, 6.5 or 7.0 with KOH resulted in average root numbers of 14.2, 10.9, 8.7, and 7.1, respectively, while unbuffered medium yielded 7,6 roots per shoot. Comparison of MES buffered medium at pH 5.5, 6.25 or 7.0 in factorial combination with IBA at 0, 0.15, 1.5, 15.0, and 150.0 μM resulted in a significant pH by IBA interaction for root number. At 0, 0.15 and 1.5 μM IBA root numbers were greatest at pH 5.5. At 15.0 μM IBA, pH 6.25 was optimal and at 150.0 μM IBA all three pH levels produced equivalent root numbers. A calorimetric assay to measure IBA removal from the initiation medium by microcuttings of `Gala' and `Triple Red Delicious' showed more IBA removal at pH 5.5 than at pH 7.0. Possible reasons for the effect of pH on adventitious root formation will be discussed.
Lauren E. Deans, Irene E. Palmer, Darren H. Touchell, and Thomas G. Ranney
containing 25 mL of media. Shoot induction and maintenance medium consisted of full-strength B5 salts and vitamins ( Gamborg et al., 1968 ), 15 μ m 6-Benzylaminopurine, 0.1 g⋅L −1 2-(N-morpholino) ethanesulfonic acid, 0.1 g⋅L −1 myo-inositol, 0.75 g⋅L −1
Stephanie E. Burnett, Donglin Zhang, Lois B. Stack, and Zhongqi He
greenhouse. Electrical conductivity and pH were measured twice weekly. Lime or MES buffer [2-(N-morpholino)ethanesulfonic acid] was added to adjust pH as needed to maintain a pH of 5.5 to 6.5. Hoagland solutions were completely replaced every other week to