Some factors affecting the establishment and growth of bud grafts of roses : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Botany at Massey University

A brief review of abnormal growth of rose scion buds and the high proportion of buds which fail to produce normal growth in the production of rose plants by bud-grafting in New Zealand, introduces the subject. The history of investigations, prior to 1968, into this problem is outlined. A description of normal growth patterns of shoots on roses, of axillary buds and of production methods in New Zealand is followed by a detailed description of the abnormal teratomatous growth, known as proliferation, which is characteristic of a proportion of affected buds. The proposal is put forward that this condition is caused by infection with an organism that initiates galling similar in appearance to crown gall and that subsequent symptoms develop consequent to such a tumorous transformation but not necessarily due to the continued presence of the causal organism. In this study no causal organism was successfully isolated. The claims of a number of possible other causal agents are examined including development of the graft union, chemical factors, non-transforming bacteria, mites, fungi and viruses. Reasons are advanced why none of these provide a satisfactory explanation in agreement with experimental and observational evidence. This evidence is discussed in relation to the etiology and development of the disease syndrome. The evidence presented is strongly in support of a tumorous transformation, initiated by a soil-borne pathogen, occurring at the proximal end of the original stock cutting at the time of its insertion in the ground. Root initiation may be restricted by the position of the gall and the first shoot growth at the top of the stock may show slight symptoms. The infected plant is predisposed to show subsequent symptoms but these are dependent on subsequent operations and the time and conditions when they are carried out. These symptoms are the development of excessive callus at the point of excision of the stock top and at the incision of the bud-graft, the production of teratomatous shoots, known as proliferation, by the scion bud or failure of the scion bud to grow despite a successful graft union. These symptoms may be reduced or prevented by successful normal growth of the scion. A comparison of the etiology and development of the syndrome of proliferation disease is made with the classical characteristics of the crown gall syndrome. Recent research publications on crown gall are reviewed to establish that recent findings are not contrary to the proposal that rose proliferation disease is caused in a manner directly analagous to crown gall. It is proposed that the evidence supports the assumption that a particular strain of Agrobacterium tumefaciens or some bacterium closely related to it is the etiological agent causing rose proliferation disease

The morphology and exine ornamentation of fresh pollen from four dipterocarp species in Sabah

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RP979-56 Long-Term Installment Land Contracts

The installment land contract is both an instrument of transfer and a method of financing sales of land. If properly drawn, it can have a number of advantages for both the buyer and seller. Both parties should contact their attorneys to be sure that the terms of the contract are clearly stated and understood. This research publication discusses how long-term installment land contracts are used in the agricultural community

Structural and dielectric studies of the phase behaviour of the topological ferroelectric La1-xNdxTaO4

We thank the University of St Andrews and EPSRC (via DTG studentships to CALD and JG) for funding,The layered perovskite LaTaO4 has been prepared in its polar orthorhombic polymorphic form at ambient temperature. Although no structural phase transition is observed in the temperature interval 25° C < T < 500 °C, a very large axial thermal contraction effect is seen, which can be ascribed to an anomalous buckling of the perovskite octahedral layer. The non-polar monoclinic polymorph can be stabilised at ambient temperature by Nd-doping. A composition La0.90Nd0.10TaO4 shows a first-order monoclinic-orthorhombic (non-polar to polar) transition in the region 250° C < T < 350 °C. Dielectric responses are observed at both the above structural events but, despite the ‘topological ferroelectric’ nature of orthorhombic LaTaO4, we have not succeeded in obtaining ferroelectric P–E hysteresis behaviour. Structural relationships in the wider family of AnBnX3n+2 layered perovskites are discussed.Publisher PDFPeer reviewe

VLBI study of water maser emission in the Seyfert 2 galaxy NGC5793. I: Imaging blueshifted emission and the parsec-scale jet

We present the first result of VLBI observations of the blueshifted water maser emission from the type 2 Seyfert galaxy NGC5793, which we combine with new and previous VLBI observations of continuum emission at 1.7, 5.0, 8.4, 15, and 22 GHz. Maser emission was detected earlier in single-dish observations and found to have both red- and blueshifted features relative to the systemic velocity. We could image only the blueshifted emission, which is located 3.6 pc southwest of the 22 GHz continuum peak. The blueshifted emission was found to originate in two clusters that are separated by 0.7 milliarcsecond (0.16 pc). No compact continuum emission was found within 3.6 pc of the maser spot. A compact continuum source showing a marginally inverted spectrum between 1.7 and 5.0 GHz was found 4.2 pc southwest of the maser position. The spectral turnover might be due to synchrotron self-absorption caused by a shock in the jet owing to collision with dense gas, or it might be due to free-free absorption in an ionized screen possibly the inner part of a disk, foreground to the jet. The water maser may be part of a maser disk. If so, it would be rotating in the opposite sense to the highly inclined galactic disk observed in CO emission. We estimate a binding mass within 1 pc of the presumed nucleus to be on the order of 10^7 Msun. Alternatively, the maser emission could result from the amplification of a radio jet by foreground circumnuclear molecular gas. In this case, the high blueshift of the maser emission might mean that the masing region is moving outward away from the molecular gas surrounding an active nucleus.Comment: 20 pages, 6 figures, to appear in ApJ, Oct. 200