No description available.

Call number: LD2668 .T4 1956 G46 / Master of Science

Call number: LD2668 .T4 1961 V39

No description available.

No description available.

No description available.

This item was digitized as part of the Million Books Project led by Carnegie Mellon University and supported by grants from the National Science Foundation (NSF). Cornell University coordinated the participation of land-grant and agricultural libraries in providing historical agricultural information for the digitization project; the University of Arizona Libraries, the College of Agriculture and Life Sciences, and the Office of Arid Lands Studies collaborated in the selection and provision of material for the digitization project.

Although Eucalyptus species are indigenous to Australia, they have been successfully cultivated in South Africa, where they are mainly used in the mining and paper industries. With the explosion in these industries it has been necessary to increase Eucalyptus plantations, often into areas which experience frost and chilling temperatures. To combat this, high yielding Eucalyptus species able to cope with these conditions would be desirable. The ability to rank species according to their chilling tolerance will enhance decisions as to the suitability of species for use in the field. To this aim, two biochemical and two biophysical parameters were chosen to investigate and characterise Eucalyptus nitens, E. smithii, E. macarthurii, E. grandis and E. grandis x nitens (GNI026). Ranking of these species in terms of chilling tolerance did not appear possible using the data from the biochemical parameters (proline concentration and glutathione reductase activity), but the biophysical parameters (fluorescence characteristics and onset of temperature of melt) gave results comparable to those obtained in field trials using these species. Fluorescence characteristics were particularly useful in assessing the chilling tolerance of the species in question. Fluorescence is the recommended technique for further studies as it is relatively inexpensive, rapid, does not require destructive sampling and can be used in both the laboratory and field. / Thesis (M.Sc.)-University of Natal, 1993.

Frost can be detrimental to canola (Brassica napus L.) production. Depending on the severity, the entire field can be killed. Having frost tolerance in canola would benefit growers by allowing them to plant early, utilize early season moisture, and avoid high heat during flowering. However, frost tolerance in canola has not been well studied. A protocol was developed that determined 14 day old seedlings should be acclimated at 4°C for 7 days before being exposed to overnight frost (-4°C) in a small freezing chamber. However, when a larger chamber was used for freezing, the protocol was optimized to -8°C instead. A greenhouse study was conducted on a diverse collection of 231 genotypes and genome-wide association scan (GWAS) was conducted to identify potential genes that were related to frost tolerance or abiotic stress tolerance. Thirty-eight significant single nucleotide polymorphism (SNP) markers were selected based on 10,000 bootstraps and 0.1 percent tail of the empirical distribution. The markers were located on chromosomes A01, A02, A03, A04, A07, A08, A09, A10, C03, C05, C06, C07, and C09. Stepwise regression highlighted a QTL located on chromosomes A02. Another GWAS was done on 147 canola germplasm lines phenotyped under natural conditions. Thirty-eight significant SNPs identified from this study were located on chromosomes A05, A07, A09, C01, C02, C03, C04, C05, C06, C07, and C09. Stepwise regression identified a QTL located on chromosome C04. A protocol was developed to measure the freezing induced electrolyte leakage from leaves of rapeseed/canola. A total of 157 germplasm lines were evaluated for freezing induced (-12°C for 2 h) electrolyte leakage. Thirty-six significant SNPs located on chromosomes A01, A02, A03, A04, A05, A06, A07, A08, A09, A10, C01, C02, C04, C05, C06, C07, and C09 were identified. Stepwise regression identified 10 QTL located on chromosomes A01, A02, A04, A06, A07, C02, C05, C07, C09, and one that could not be assigned. All GWAS studies identified potential genes of interest that were related to frost tolerance, abiotic stress, and transcription factors. / Northern Canola Growers Association