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Radish anthocyanin extract has potential as a natural colorant because of its pigment stability and attractive red hue. Presence of undesirable aroma compounds could limit its applications in foods. The pungent principle of radish, 4-methylthio-3-butenyl isothiocyanate (MTBI), is produced enzymatically upon cell injury from its glucosinolate precursor, 4-methylthio-3-butenyl glucosinolate (MTBG), and undergoes subsequent degradation to produce a number of volatiles. To evaluate the potential of flavor formation, juices were prepared from winter and spring radish cultivars. Whole radishes, peels and flesh, as well as radish extracts, were analyzed for glucosinolates and isothiocyanates. Aroma intensities of radish juice extracts were evaluated using sensory analysis. MTBI was monitored by HPLC (detection level 160 ppb). MTBG was extracted from freeze-dried radish tissue with boiling methanol, purified by anion exchange and enzymatically desulfated. DesulfoMTBG was quantified by HPLC, using desulfosinigrin as internal standard. Identification was performed by fast atom bombardment and electrospray mass spectroscopy. MTBI formation was higher in winter than in spring cultivars (1.5-2.8 and 0.8-1.3 mg/100g fresh weight, respectively), and higher in flesh than in peels. MTBG ranged from 30-65 mg (spring cultivars) to 260-320 mg/100g fresh weight (winter cultivars) with greater concentration in peels than in flesh. Isothiocyanates and glucosinolates were not detected in radish juices. Overall aroma intensities of radish juice concentrates, diluted to 150, 300, 600 and 1200 mg anthocyanin/L in water, were rated using a 16-point scale. Radish concentrates from cultivars Fuego (pigmented peels) and Red Meat Takii (whole red flesh) were compared to commercial red cabbage and radish colorants. Aroma intensities followed first order relationships with anthocyanin concentrations. The commercial colorants were rated slight to moderate, while radish extracts (Fuego and Takii) were rated moderate to large. The aroma intensity of red flesh radish extract was more potent than those prepared from radish peels. Further work includes development of purification techniques which would provide an odorless aqueous extract. / Graduation date: 1997

Thesis (Ph.D.) -- University of Western Sydney, 2002. / "A thesis submitted for the degree of Doctor of Philosophy (Ph.D.) in the Centre for Landscape and Ecosystems Management, University of Western Sydney ... May 2002" Includes bibliography (leaves 159-177) and other bibliographical references.

The most apparent symptom of boron deficiency in higher plants is a cessation of growth. Deficiency causes a reduction in ascorbate concentration and the absorption of nutrient ions. Addition of ascorbate temporarily relieves deficiency symptoms. In boron sufficient plants the addition of ascorbate to media causes an increased uptake of nutrients. In an attempt to discover if ascorbate addition to deficient plants causes increased ion uptake, radish plants were grown hydroponically in four different strengths of boron solution. A colorimetric assay for phosphorus was performed both before and after supplementation. Results, however, were inconclusive.

Presented as Thesis (Ph. D.)--University of Wisconsin--Madison, 1913. / Reprints from Journal of agricultural research. Part 1: vol. IV, no. 2 (15 May 1915), p. 135-168, plates xvi-xxvi -- Part 2: vol. V, no. 1 (4 Oct. 1915), p. 55-57, plates i-ii -- Part 3: vol. IV, no. 4 (15 July 1915), p. 279-291, plates xliv-xlviii. Includes bibliographical references.

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Radish plants (Raphanus sativus L. cv Cherry Belle) were exposed to 0.10 μl l⁻¹ ozone (O₃) or 0.50 μl l⁻¹ sulfur dioxide (SO2) for 4 h d⁻¹, 3 d wk⁻¹ for 3 weeks. From these fumigated plants, individuals were selected that were resistant or sensitive to these pollutants. The selected plants were used as parental material in a breeding program to produce lines differing in resistance to O₃ and SO₂. Non-selected (NS) plants from the original populations served as controls. F₁ populations were raised and exposed to O₃ or SO₂ with the same fumigation regime used for the parents. The plants were harvested 30 days after emergence and dry weights were determined. Plants selected for O₃ resistance (O3R) weighed significantly more than either plants selected for sensitivity to O₃ (O₃S) or NS plants when exposed to either O₃ or SO₂. The hypocotyl was most affected by pollutant exposure, leading to reduced root/shoot ratios. Plants selected for resistance or sensitivity to SO₂ generally had biomass production similar to that of NS plants. Growth analysis at early stages of growth indicated that both O₃R and O₃S plants had less growth under O₃ fumigated conditions; however, by maturity O₃R plants had similar amounts of growth under fumigated or non-fumigated conditions. Ozone fumigations tended to decrease free sugar concentrations in leaves at early stages of growth in both O₃R and O₃S plants, and caused some accumulations of carbohydrates during late stages of growth in O₃S plants. Allocation of Mc was significantly lower to hypocotyls and roots of O₃ fumigated O₃S plants. Allocation to hypocotyls of O₃R plants was not affected, although both O₃R and O₃S plant groups had lower photosynthetic rates due to O₃ fumigation. Ozone did not significantly affect chlorophyll concentrations in leaves of either sensitive or resistant plants, nor was the time of new leaf production affected by fumigation. These experiments demonstrated the potential of O₃ to influence the composition of sensitive plant populations. However, SO₂ was a much less powerful influence on the composition of these populations. / Ph. D.

The objective of this Ph.D. research was to identify new and novel mechanisms of wild radish (Raphanus raphanistrum L.) resistance to photosystem II (PSII) inhibitors, auxinics, and acetohydroxyacid synthase (AHAS) inhibitors. PSIIinhibitor resistance was demonstrated to be target-site based, and conferred by a Ser264 to Gly substitution of the D1 protein. Auxinic resistance was associated with reduced herbicide translocation to the meristematic regions of resistant wild radish plants. Two new resistance mutations of wild radish AHAS were discovered, including one encoding the globally rare Asp376 to Glu substitution, and another encoding an Ala122 to Tyr substitution, which has never been identified or assessed for resistance in plants previously. Characterization of the frequency and distribution of AHAS resistance mutations in wild radish from the WA wheatbelt revealed that Glu376 was widespread, and that some mutations of AHAS are more common than others. Computer simulation was used to examine the molecular basis of resistance-endowing AHAS target-site mutations. Furthermore, through the computer-aided analysis, residues were identified with the potential to confer resistance upon substitution, but which have not previously been assessed for this possibility. Results from this Ph.D. research demonstrate that diverse, unrelated mechanisms of resistance to PSII inhibitors, auxinics, and AHAS inhibitors have evolved in wild radish of the WA wheatbelt, and that these mechanisms have accumulated in some populations.

Graduation date: 1993