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  • Author or Editor: Suman Singha x
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Abstract

Rapid propagation of crabapple (Malus spp.) cultivars was achieved in vitro. Proliferation of shoot tips was induced on Murashige and Skoog (MS) medium containing 6-benzylamino purine (BA). Rapid shoot proliferation was obtained at 1 or 2 mg/liter BA. Higher levels (4 or 8 mg/liter) resulted in good shoot proliferation, but a greater percentage of shoots were small or rosetted. Rooting was achieved by transferring individual shoots to MS medium containing naphthaleneacetic acid (NAA). Low NAA levels (0.1 or 0.2 mg/liter) resulted in good root development. Plantlets were successfully transferred to soil.

Open Access
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Abstract

Shoot tips of ‘Almey’ crabapple [Malus baccata (L.) Borkh. × M. pumila var. niedzwetzkyana (Dieck) Schneid.] and ‘Seckel’ pear (Pyrus communis L.) were cultured on Murashige and Skoog (MS) medium containing 2 mg/liter 6-benzylamino purine (BA). The culture medium contained either TC agar or Bacto-agar at concentrations ranging from 0% to 1.2%. Optimum shoot proliferation in ‘Almey’ was obtained on media containing 0.3% of either agar. Increasing agar levels reduced shoot proliferation and shoot growth, but the reduction was especially severe with Bacto-agar. The differences in shoot proliferation between the 0.3% and 0.6% agar concentrations continued to be exhibited with Bacto-agar but not with TC agar when Mason jars, rather than 25 × 150-mm tubes, were the culture vessels. Shoot proliferation in ‘Seckel’ was best on medium containing 0.6% Bacto-agar; higher concentrations decreased shoot proliferation and shoot growth. TC agar did not influence fresh weight of ‘Seckel’ cultures, but increasing concentrations resulted in increased shoot proliferation.

Open Access
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Abstract

Shoot tips of ‘Almey’ crabapple [Malus baccata (L.) Borkh. × M. pumila var. niedzwetzkyana (Dieck) Schneid.] and ‘Secke!’ pear (Pyrus communis L.) were cultured on Murashige and Skoog medium supplemented with 2 mg/liter 6-benzylamino purine and agar levels ranging from 0 to 1.2%. The greatest shoot proliferation and shoot growth in ‘Almey’ occurred on medium containing 0.3% agar. Higher agar concentrations decreased both shoot proliferation and shoot growth. Increasing agar concentrations resulted in decreased shoot growth in ‘Seckel’, but shoot proliferation was significantly greater at concentrations of 0.6% and higher as compared to 0.3% or lower. Autoclaving caused an acidification of the medium. The addition of agar reduced media acidification. This pH variation does not explain the effect of agar on shoot proliferation and growth.

Open Access

Abstract

Abscisic acid (ABA) inhibited bud break and shoot elongation in seedling stem explants of apple (Malus domestica Borkh cv. Northern Spy) cultured in vitro. Inhibition was complete in culture medium containing 100 μM ABA. Transfer of buds from ABA-containing medium to basal medium resulted in increases in both bud break and shoot elongation. ABA levels in such buds declined rapidly following transfer, and growth began when ABA concentration in the buds dropped below a threshold value.

Open Access

Shoots of `Almey' crabapple [Malus baccata (L.) Borkh. × M. pumila var. niedzwetzkyana (Dieck) Schneid.], `Seckel' pear (Pyrus communis L.), and `Mrs. Bradshaw' geum (Geum quellyon Sweet.) were cultured on Murashige and Skoog (MS) medium supplemented with 8.8 μm BA and containing 0.1% to 0.4% Gelrite. Comparative shoot proliferation and vitrification were determined on Phytagar-solidified medium. Shoot proliferation, culture fresh weight, and vitrification declined in crabapple and geum with increasing Gelrite concentration. Pear proliferation and fresh weight increased with increasing Gelrite levels, but all shoots were vitrified. There were differences in the vitrification response between pear and the other two genera. The percent dry weight of vitrified cultures on Gelrite-containing media was generally higher than that of nonvitrified cultures on medium containing Phytagar. Vitrification precludes using low Gelrite concentrations for propagating these plants. Chemical name used: N-(phenylmethyl) -1H-purin-6-amine (BA).

Free access

Abstract

The chlorophyll content of leaf tissues can be accurately determined in the laboratory by spectrophotometric measurement of the leaf extract obtained with ethanol (Knudson et al., 1977), acetone (Blessington and Rasberry, 1980), or N,N-dimethylformamide (Moran and Porath, 1980). However, extraction is laborious and destructive. A rapid, nondestructive method to estimate leaf chlorophyll using a portable chlorophyll meter (SPAD-501, Minolta Corp.) was recently reported (Marquard and Tipton, 1987; Yadava, 1986). However, the manufacture of this instrument has been discontinued.

Open Access

Differences in color development between exposed and shaded fruit during the growing season were determined for `Loring' and `Raritan Rose' peach (Prunus persica L. Batsch). The surface color of fruit exposed to sunlight in the upper canopy, and in the shade in the lower canopy, was measured with a tristimulus calorimeter, and L* a* b* values were recorded for each fruit from 17 July through harvest. Color changes (ΔE* ab) during maturation for both cultivars at either canopy position were characterized by large changes in hue (Δ H*ab) and lesser changes in lightness (Δ L*ab) and chroma (Δ C*ab). Upper canopy fruit of both cultivars were redder and darker than the lower canopy fruit initially and at harvest. Flesh firmness for `Loring' and `Raritan Rose' tended to correlate with color change from initial sampling to harvest.

Free access