Bradford C. Bearce and Suman Singha
Steven R. Turner and Suman Singha
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).
Bradford C. Bearce and Suman Singha
Suman Singha and Harry O. Kunkel
Changes in the environment, in technology, and in societal needs will result in a change in the expectations from our graduates. Meeting these expectations will require a systemic change in undergraduate education in horticulture. While we do an excellent job in training students, we are not as effective in educating them. Our students must develop critical thinking skills and become adept at solving problems utilizing a multidisciplinary integrated approach rather than in a reductive manner. Achieving these skills is essential if our graduates are to be successful in the rapidly changing job market. Implementing curricular change requires faculty ownership as well as administrative support and an appropriate rewards and recognition system. These and other principles from the USDA-funded project on Theoretical Bases for Systemic Change in Higher Education in Agriculture will be discussed.
Bernard B. Bible and Suman Singha
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.
Suman Singha, Bernard Bible and Edward Corbett
Variations in the pattern of fall color development in the leaves of Acer rubrum, Acer saccharum, Quercus coccinea, Oxydendrum arboreum and Euonymus alatus were determined. CIELAB coordinates were measured with a Minolta CR-2000b calorimeter at a marked location on 5 tagged leaves from 2 plants of each species. The changes in hue follow similar trends in these species, but the time of onset varies. Onset of red color development increased variability in hue between leaves of the same species. Based on color changes in E. alatus anthocyanin development occurs prior to significant loss of chlorophyll and red coloration remains masked, whereas in A. rubrum anthocyanin development occurs in association with or following the loss of chlorophyll. This results in differences in the pattern of hue and chroma development between these species.
Walter Boswell, Bernard Bible and Suman Singha
Fruit of 34 peach (Prunus persica L. Batsch). cultivars were harvested at maturity and visually evaluated by panelists on a 1 to 10 scale, where 10 = excellent color. CIELAB coordinates (L* a* b*) of fruit color were measured at the midpoint between the stem and the calyx end with a Minolta CR-200b calorimeter on the blushed and ground areas of each fruit. Simple linear regressions of color coordinates with panel ratings indicated that blush chroma, blush L*, blush hue angle and E* (total color difference between ground and blush) all influence visual color evaluation. Not only does assessing fruit color with a calorimeter permit color to be reported in internationally accepted units, but the relationships indicate that instrumental values relate well to qualitative ratings.
Richard McAvoy, Bernard Bible and Suman Singha
The poinsettia cultivar Annette Hegg Dark Red (AHDR) is resistant to bract edge burn (BEB), while `Supjibi' readily develops BEB. In 1993, scions of both `Supjibi' and AHDR were grafted onto either `Supjibi' or AHDR rootstock (RS) prior to bract initiation. At anthesis, BEB symptoms were more prevalent on `Supjibi'/`Supjibi' than on `Supjibi'/AHDR. Four weeks postanthesis, 26.4% of the bracts on `Supjibi'/`Supjibi' developed BEB, and 10% of the bracts had severe symptoms (based on number and size of necrotic spots), while only 13.8% of the bracts on `Supjibi'/AHDR developed BEB, with 1.7% having severe symptoms. Calcium levels in `Supjibi' bracts averaged 0.41% for scions on `Supjibi' RS and 0.39% on AHDR RS. AHDR scions failed to develop BEB regardless of RS. In 1994, plants with a `Supjibi' scion on a dual RS (`Supjibi' + `Supjibi', or `Supjibi' + AHDR) were formed using an approach graft technique and the following treatments were applied: one RS severed before bract initiation to produce plants with just a `Supjibi' or AHDR RS, AHDR + `Supjibi' RS intact until anthesis then either the `Supjibi' or AHDR RS severed, or both RS remained intact until termination of the study. Scions with only AHDR RS during bract development or only AHDR RS after anthesis developed a lower incidence of BEB than bracts on `Supjibi' scions that were on just `Supjibi' RS during bract development, or just `Supjibi' RS after anthesis, or on both RS during the entire study.