Guy, Andrew Cleveland2013-12-042013http://hdl.handle.net/10092/8711http://dx.doi.org/10.26021/6369The two main goals in this research were: (i) to investigate Pinus radiata seed germination methods, identifying areas where improvements could be made and developing a germination protocol applicable for studies under sterile and glasshouse conditions, and (ii) to investigate the potential of L-amino acids as nitrogen fertilisers or growth regulating substances, specifically during early seedling growth of P. radiata. There is a lack of a standard protocol for seed germination of radiata pine. Therefore, a systematic approach was undertaken to develop a germination protocol which was applicable for both commercial and scientific use. It was found that a high percentage of P. radiata seed germination was observed without the need for nutrient-rich plant tissue culture media, stratification, scarification, or elaborate surface sterilisation of the seed. This led to the development of an improved protocol that was simple and relatively inexpensive, resulting in a high percentage of rapid and uniform germination. The main features of this improved germination protocol include: (i) a single-step surface sterilisation with ethanol for 30 seconds, (ii) pre-sowing, imbibition and drying of seeds overnight, and (iii) use of autoclaved moist vermiculite as a germination substrate. L-amino acids are commonly used as organic nitrogen sources for plant nutrition. There is also evidence that exogenously supplied L-amino acids can have effects on plant growth beyond a nitrogen nutrition effect and that these effects are plant species dependent. Since these L-amino acid effects have not previously been investigated in P. radiata, the effects of each of the 20 commonly occurring protein L-amino acids on radiata pine growth were investigated. Five L-amino acids (Arginine, Aspartic acid, Proline, Lysine and Serine) were identified as having nitrogen nutrition independent effects. Under laboratory conditions these effects were determined to be concentration dependent and could therefore be of physiological significance. Under glasshouse conditions, the L-amino acid effects were subject to the influences of soil factors. The L-amino acid effects identified in this research can be considered novel and warrant further investigation.enCopyright Andrew Cleveland GuypinusradiatagerminationaminoacidTheses / Dissertations