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Disinfestation using microwaves can be an alternate to chemical methods of killing insects in grain. A pilot-scale industrial microwave dryer operating at 2.45 GHz was used to determine the mortality of life stages of Tribolium castaneum (Herbst), Sitophilus granarius (L.) and Cryptolestes ferrugineus (Stephens) adults in wheat, barley, and rye. Grain samples of 50 g each at 14, 16, and 18% moisture content were infested with stored-grain insects. The samples were then exposed to microwave energy at 200, 300, 400, and 500 W for exposure times of 28 and 56 s. Complete (100%) mortality was achieved for adults of three insect species at 500 W, 28 s and at 400 W, 56 s in barley and wheat. In rye, complete mortality of adult T. castaneum and S. granarius was achieved at 400 W, 28 s and at 300 W, 56 s whereas for C. ferrugineus, complete mortality was achieved at 500 W, 28 s and at 400 W, 56 s. The average temperature of wheat, barley, and rye at 500 W and 28 s was around 80, 71 and 82oC, respectively, and moisture loss was 2.0, 1.9 and 2.5 percentage points, respectively. Among the life stages of T. castaneum in wheat, eggs were the most susceptible followed by larvae, and the least susceptible were the pupae and adults. Among the life stages of T. castaneum in barley and rye, eggs were the most susceptible and adults were the least susceptible with no significant difference between pupae and larvae. There was no significant difference in the mortality of adults at 14, 16, and 18% moisture content barley and rye and the life stages of T. castaneum and S. granarius in rye. Germination of seeds decreased with an increase in power level or exposure time or both. There was no significant difference in the quality characteristics of microwave-heated wheat and rye except for reduced flour yield in rye. The quality of the barley treated at 500 W, 28 s was the same as the control, whereas, there was significant decrease in the quality of barley treated at 400 W, 56 s.

The 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.

Disinfestation using microwaves can be an alternate to chemical methods of killing insects in grain. A pilot-scale industrial microwave dryer operating at 2.45 GHz was used to determine the mortality of life stages of Tribolium castaneum (Herbst), Sitophilus granarius (L.) and Cryptolestes ferrugineus (Stephens) adults in wheat, barley, and rye. Grain samples of 50 g each at 14, 16, and 18% moisture content were infested with stored-grain insects. The samples were then exposed to microwave energy at 200, 300, 400, and 500 W for exposure times of 28 and 56 s. Complete (100%) mortality was achieved for adults of three insect species at 500 W, 28 s and at 400 W, 56 s in barley and wheat. In rye, complete mortality of adult T. castaneum and S. granarius was achieved at 400 W, 28 s and at 300 W, 56 s whereas for C. ferrugineus, complete mortality was achieved at 500 W, 28 s and at 400 W, 56 s. The average temperature of wheat, barley, and rye at 500 W and 28 s was around 80, 71 and 82oC, respectively, and moisture loss was 2.0, 1.9 and 2.5 percentage points, respectively. Among the life stages of T. castaneum in wheat, eggs were the most susceptible followed by larvae, and the least susceptible were the pupae and adults. Among the life stages of T. castaneum in barley and rye, eggs were the most susceptible and adults were the least susceptible with no significant difference between pupae and larvae. There was no significant difference in the mortality of adults at 14, 16, and 18% moisture content barley and rye and the life stages of T. castaneum and S. granarius in rye. Germination of seeds decreased with an increase in power level or exposure time or both. There was no significant difference in the quality characteristics of microwave-heated wheat and rye except for reduced flour yield in rye. The quality of the barley treated at 500 W, 28 s was the same as the control, whereas, there was significant decrease in the quality of barley treated at 400 W, 56 s.

This study has examined the rate at which the seeds of certain species disappear from woodland soils, and whether the composition of the seed banks beneath stands of known age can be used to reveal management history. Associated with this is an investigation of the spatial distribution of the stored propagules. A question arises as to whether species with long lived seeds can survive as buried seed long enough to take advantage of the opening of the canopy and soil disturbance resulting from the falling of old trees. Given the great life span of most trees, this is a strategy open only to species with exceptionally long lived seed banks. One such species is Hypericum pulchrum, which, as the seed bank surveys carried out in this study show, can exist as viable seeds beneath woodlands of great age in the Tavistock Woodland Estate in Devon. Is this germination and reproduction on tree falls sufficient to maintain Hypericum in the seed bank indefinitely ? To answer this question, a computer model was developed to examine the effect of various parameters on the survival time of a Hypericum seed bank beneath a simulated woodland. The model allowed prediction of both the mean density of buried seeds in a unit area, and the development of pattern within the seed bank. Analysis of the simulation results established that the dispersal of Hypericum was insufficient to maintain a seed bank by a "chain reaction" of windthrown reinforcement. The implications of this are discussed with respect to pioneer species within both temperate and tropical forests.

Thesis(M.S.)--Auburn University, 2008. / Abstract. Vita. Includes bibliographic references (p.18-20).

Thesis (Doctoral)--University of Stockholm, 1983. / Includes articles on which author's Review is based. Includes bibliographical references.

Thesis (Ph. D.)--University of Wisconsin, 1967. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (Ph.D.)--Ohio University, November, 2006. / Title from PDF t.p. Includes bibliographical references.

Seeds are very complex and diverse plant organs. Seed germination is the most sensitive stage of plant life and is influenced by various environmental signals including phytohormones, salt, light, temperature and water potential. Seeds have an innate mechanism called dormancy that blocks germination, and plants have developed several dormancy-inducing strategies to optimise the timing of germination. Seed germination vigour is an important factor in crop yield. Seedling vigour is defined as the sum of the seed properties which determine the level of activity and performance during germination and seedling emergence. A poor seed lot can be improved by post-harvest treatment such as hydro-priming as it is used in the seed industry, but the biological mechanism is unknown. The aim of this study is to understand the mechanism(s) of hydro-priming in order to improve seed vigour and seed germination. I set seeds at different temperatures to produce variation in seed vigour and it showed that germination of seeds with low vigour can be improved by hydro-priming. Using LC-IT-ToF/MS I characterised compounds that leach from seeds during hydro-priming, and showed that some of these are putative germination inhibitors. Adding these compounds to the water during hydro-priming showed that the inhibitory effect of these compounds is not the main mechanism that regulates germination. Also, transcriptomic analysis showed that genes involved in OPDA pathway are expressed during hydro-priming as well as during endosperm weakening cap associated genes. I concluded that hydro-priming improves the speed of germination of low temperature set and its efficiency is dependent of activation of metabolic activity.