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Item Identity, taxonomy and seed-borne aspects of the gray leaf spot organism on blue lupin : a thesis submitted in partial fulfilment of the requirements for the degree Master of Agricultural Science at Massey University(Massey University, 1968) Tate, Kenneth GregoryWhile conducting studies in the Manawatu on the brown spot disease of blue lupins 1/ caused by Pleiochaeta setosa (Kirchn.) Hughes, Milne (1964) frequently encountered a Stemphylium disease characterised by necrotic lesions on leaves, stems and pods. A disease caused by a species of this genus had not previously been reported on blue lupins in New Zealand, but in the United States of America Wells, Forbes, Webb and Edwardson (1956) described two previously unrecognised diseases on this host, namely "little leaf spot" caused by Stemphylium botryosum Wallroth and "gray leaf spot" caused by S. solani Weber. Milne considered his isolates to be S• botryosum but was confused by the symptoms being typical of those recorded for S.solani (gray leaf spot). He did not pursue the matter further and at the completion of his studies on P• setosa there remained the unresolved question of the identity of the Stemphylium species present on blue lupin in the Manawatu. [From Introduction]Item The development and application of a technique for continuous measurements of plant elongation : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Botany at Massey University(Massey University, 1974) Marshall, David ClarkThe development of an auxanometer capable of detecting 0.67 um increments in plant elongation and its application to the study of hypocotyl elongation in intact Lupinus angustifolius seedlings is described. A displacement transducer, in conjunction with a carrier wave oscillator-demodulator and a digital voltmeter, was utilised to detect changes in length of the elongating hypocotyls of four day old lupin seedlings. The design of a root bathing solution chamber and environmental control chamber is outlined. With the aid of these two chambers the following environmental parameters could be varied independently:- temperature, water potential and aeration of the root bathing solution; temperature, relative humidity, and gaseous composition of the environment; composition and intensity of light within the environmental chamber. Problems encountered in effecting rapid changes of these parameters are discussed. The viability of the auxanometer as an effective tool for plant growth research was tested by its application to the study of growth rates under a variety of environmental changes. Short term growth responses of lupin hypocotyls to changes in relative humidity, root temperature, and osmotic potential of the root bathing solution, plus exposure to anaerobic nitrogen and carbon dioxide atmospheres, have yielded the following results:- 1. Variations in saturation deficits of between 2.9 and 16.2 mbar altered growth rates only marginally. 2. Fluctuations in root temperatures between 23 and 43°C scarcely effect hypocotyl growth rates. 3. Growth responses to changes in osmotic potential of the root bathing solution are similar to those described by Acevedo et al (1971) with intact maize leaves. 4. Periods of anaerobic nitrogen conditions yielded results comparative with those of Gillbank et al (1972), Who studied the effects of cyanide on growth of wheat coleoptile segments, except for nitrogen treatments of more than 30 minutes in duration. 5. Exposure of seedlings to an anaerobic carbon dioxide atmosphere stimulates hypocotyl growth rates by up to eight times, the results indicating that CO2 stimulates the utilisation of a growth precursor within the cell whilst simultaneously inhibiting its synthesis. The results illustrate both the versatility and the potential of the described auxanometer in the description of plant growth responses to environmental changes, consequently aiding in the identification of the causal mechanisms of plant growth processes.Item Aminoacid metabolism in plants : the biosynthesis of [beta]-cyanoalanine and asparagine in lupins : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Biochemistry at Massey University(Massey University, 1970) Lever, Michaelβ-Cyanoalanine synthase in etiolated seedlings of Lupinus angustifolius is found mainly in the mitochondrial fraction of the cotyledons and stems. In seedlings developing at 25°C in the dark it reaches a maximal concentration after 5 days, at the same time as asparagine accumulation is most rapid and other physiological changes occur. However, maximal ability to assimilate HCN gas to asparagine develops after 3 to 4 days, before asparagine accumulation begins. A partial purification of lupin β-cyanoalanine synthase is described and its distinction from cysteine synthase confirmed. Carbon-14 labelled substrates were supplied to etiolated seedlings of lupin in order to identify precursors of asparagine. Four carbon acids related to the TCA cycle were readily converted to asparagine i n vivo but not in vitro; the carbon skeleton of aspartate is retained in asparagine. Comparison of the distribution of label in the carbon skeletons of aspartate and asparagine from plants supplied carboxyl labelled fumarate shows a separation of the aspartate pool for asparagine biosynthesis from most cell aspartate. Metobolites that could be expected to give rise to cyanide and β-cyanoalanine are relatively ineffective as asparagine precursors. Thus the β-cyanoalanine pathway is not of major importance in asparagine biosynthesis in lupins.