Seed quality and crop establishment in wheat.

Early seedling vigour of cereal crops is crucial to crop establishment and the achievement of high yields in dryland Mediterranean environments. Early vigour is achieved by sowing high quality seed and good management. Seed quality is a result of genotype and the growing environment of the mother plant from which it came. A series of experiments were conducted to investigate aspects of seed quality. A range of bread wheat genotypes important in South Australia were used for laboratory, greenhouse and field experiments. A durum cultivar, Yallaroi, was also included. A preliminary set of field trials involving seed from eight different sources of each of eleven genotypes were evaluated at eight wheat growing locations in South Australia for two years. Using two dimensional spatial analysis techniques seed source was shown to be an important determinant of grain yield. Thus in genotype evaluation experiments, such as regional trials, where seed of genotypes may be derived from different sources changes in rank due to seed source could occur. These seed source effects and interactions with genotype were more evident during early growth stages. Fanners appreciate the importance of sowing plump seed free of weather damage and disease but they have little knowledge of the physiological quality of that seed. Experiments showed that within genotypes larger seed had larger embryos which, on germinating, produced longer coleoptiles, more vigorous seedlings resulting in higher grain yields. Rate of emergence from normal sowing depths was not affected. There were genotypic differences for both seed and embryo size but the two were not related. It should be possible for breeders to select for embryo size independent of seed size. Large seed, of course, contains more nutrients than small seed with which to nourish the embryo, but, mineral nutrient analyses of different seed sizes indicated that there were differences in nutrient concentration between seed sizes. Again there were genotype differences and the patterns across genotypes varied for different minerals. The quality of seed from different positions on the mother plant was examined for ten genotypes. Genotypes showed different potential for loading nutrients, but generally seeds of the main tiller were heavier and accumulated higher levels of nutrients than those from second tillers. Seeds from the outer florets of the middle spikelets of heads similarly had better quality than seeds from other positions. Wheat cultivar Machete accumulated more nutrients than other genotypes tested. Two nutrients, zinc and manganese, were chosen for more detailed study because deficiencies of these nutrients are widespread in South Australia. High levels of Zn and Mn in seed greatly improved crop growth especially in Zn and Mn deficient soils, in fact, seed high in Mn was more effective than Mn fertiliser in improving early growth and grain yield. Genotypic variability occurred for Zn and Mn efficiency and also for Zn and Mn accumulation in the seed. Yallaroi, the durum, performed poorly in these experiments. These results suggest that farmers would do well to manage their seed crops differently than grain crops especially by attempting to increase the levels of trace elements in the seed. The distribution of mineral nutrients within seed was examined in both high and low Zn content seeds of two genotypes and the remobilisation of nutrients was followed over the first twelve days after germination. Zn and Mn were disproportionately higher relative to other nutrients in the embryo, but this was only a small fraction of the total in the seed. Most of the nutrient was in the seed coat and, under the aseptic conditions of the experiment, apart from potassium, most was never remobilised to the young seedling. It is concluded that sound healthy seed does vary in quality and this affects seedling vigour, crop establishment and grain yield. Seed source can affect genotype performance in evaluation trials. There is genetic variability for embryo size, coleoptile length, nutrient efficiency and nutrient loading in to the seed which can be exploited by breeders. Agronomically, seed quality can be improved by managing seed crops to aid accumulation of mineral nutrients in the seed and then selecting, by grading, only large seed for sowing.Thesis (Ph.D.) -- University of Adelaide, Dept. of Plant Science, 199

Reducing Nitrogen Loss By Application Of Natural Clinoptilolite Modified With Quaternary N-Alkyl Agent As Controlled-Release Fertilizer In Two Species Of Beans (P. Vulgaris And Vigna Unguiculata)

In this work, a novel controlled-release fertilizer (CRF) was designed by using new quaternary N-alkyl as an innovative surface modifier for clinoptilolite in order to adsorb the nitrate anion. So far, a few number of commercial cationic surfactants have been introduced for engineered zeolites to adsorb and slow release anions. Therefore, an organic ligand was synthesized for the first time and was applied for modification of clinoptilolite. Investigating the effect of pH and adsorbent dosage showed that the experimental adsorption data were fitted well with the Langmuir and Freundlich isotherm models. Moreover, nitrate leaching tests were performed and the results confirmed that nitrate concentration of the leachate from the soil amended with novel fertilizer was 42% lower than that of the urea fertilizer. The growth parameters including were studied and the results showed that the red beans planted in the soil amended with modified fertilizer had the best results

A differential bipolar stray-insensitive quasi-passive pipelined digital-to-analog converter with 17.664 MSps sample rate and -85dB THD

Stray-insensitive pipelined Digital-to-Analog Converters (DACs) can be implemented without an opamp in each stage. The quasi-passive circuit designed in this method dissipates less power, runs faster, has better accuracy, and takes less area than the conventional stray-insensitive architecture. A pipelined DAC designed with a differential bipolar architecture achieves close to 13 bits of linearity at 17.664 MSps conversion rate, which makes it suitable for full-rate downstream DSL signals. The converter is designed in a 0.6-μ double-poly CMOS technology and dissipates 43 mW

An experimental study of the effects of combined exposure to microwave and heat on gene expression and sperm parameters in mice

Objectives: Separate exposure to microwaves (MWs) or heat had effects on expression levels of Bax and Bcl-2 and sperm parameters in studied group. Aims: The objectives of this research were to determine the effects of separate and combined exposure to 900-MHz MW (as representative of cell phone radiation) and heat on gene expression and spermogram of male mice. Settings and Design: This experimental animal study was conducted in the school of public health. Materials and Methods: The study was done on 12 male mice randomly divided into four groups (21–23 g): control, test group 1 with separate exposure to 900-MHz MW, test group 2 with separate exposure to hot and sultry climate, and test group 3 with simultaneous whole body exposures to 900-MHz MW and hot and sultry climate. In all studied groups, gene expression and sperm parameters were measured. Results: Tissue samples in all test groups showed integrity of the seminiferous tubule followed by all types of germ line cells. Significant increases in the number of dead sperms in mice with separate exposure to heat were observed in comparison with the other studied groups (P < 0.05). The ratio of Bax expression was elevated to 0.015 ± 0.006 in mice after combined exposures to 900-MHz MW and heat. Conclusion: Separate and combined exposure to 900-MHz MW and heat may induce adverse effects on sperm parameters and gene expression of studied male mice

Effect of Supplementation of Fish and Canola Oil in the Diet on Milk Fatty Acid Composition in Early Lactating Holstein Cows

This study examined the effects of supplementation of fish oil and canola oil in the diet on milk yield, milk components and fatty acid composition of Holstein dairy cows in early lactation. Eight multiparous early lactation Holstein cows (42±12 DIM, 40±6 kg daily milk yield) were fed a total mixed ration supplemented with either 0% oil (Control), 2% fish oil (FO), 1% canola oil +1% fish oil (FOCO), or 2% canola oil (CO) according to a double 4×4 Latin square design. Each period lasted 3 wk; experimental analyses were restricted to the last week of each period. Supplemental oils were added to a basal diet which was formulated according to NRC (2001) and consisted of 20% alfalfa, 20% corn silage and 60% concentrate. Milk yield was similar between diets (p>0.05), but dry matter intake (DMI) was lower (p0.05). The proportion (g/100 g fatty acids) of short chain fatty acids (SCFA) decreased and polyunsaturated fatty acids (PUFA) increased (p0.05). The proportion of trans(t)-18:1 increased (p<0.01) in milk fat of cows fed FO and FOCO diets, but CO diet had the highest proportion of cis(c)-11 18:1 (p<0.01). The concentration of t-10, c-12 18:2, c-9 t-11 18:2, 18:3, eicosapentaenoic acid (EPA, 20:5) and docosahexaenoic acid (DHA, 22:6) increased (p<0.05) in FO and FOCO diets in comparison with the other two diets. These data indicate that including fish oil in combination with canola oil significantly modifies the fatty acid composition of milk