No description available.

No description available.

Call number: LD2668 .T4 1962 F64

xv, 217 leaves : ill., tables, graphs, photos ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Agronomy, 1977

Thesis (MScAgric)--Stellenbosch University, 1969. / ENGLISH ABSTRACT: no abstract available / AFRIKAANSE OPSOMMING: geen opsomming

Thesis (PhDAgric)--Stellenbosch University, 1971. / ENGLISH ABSTRACT: The object of this anatomical study was to collect scientific data on the effect of Metoidogyne hapta Chitwood, 1949, on the roots of the following grapevine cultivars viz: Vitis vinifePa L. cvs. Steen and White French and the root-stocks, Jacquez, 1202 C, 99 R, Salt.Creek and Dogridge. These cultivars differed widely in their resistance to M. hapta attacks. In the roots of Steen, White French, Jacquez and 1202 C the formation of multinucleate syncytia by the destruction of the walls of groups of cells often occurred. In Salt Creek, Dogridge and 99 R roots, syncytia were observed in the stele only. The formation o,f abnormal xylem as a result of nematodal activities was a common occurrence. In the roots of these latter three cultivars, M. hapta could not complete its life cycle. Salt Creek, Dogridge, 99 R and often Steen formed a wound periderm which prevented the nematodes from reaching the xylem. Histological changes were often induced in advance of the invading nematodes. / AFRIKAANSE OPSOMMING: Die doel met hierdie anatomiese studie was om wetenskaplike inligting te versamel aangaande die uitwerking van Metoidogyne hapta Chitwood, 1949, op enkele cultivars van wingerdstokke,te wete Steen en Fransdruif van Vitis vinifera L. en die onderstokke Jacquez, 1202 C, 99 R, Salt Creek en Dogridge. Hierdie cultivars het onderling baie verskil in hul weerstandvermoe teen M. hapta. Ten gevolge van die vernietiging van die wande van selgroepe, in die wortels van Steen, Fransdruif, Jacquez en 1202 C, is veelkernige sinsiete (Eng. syncytia) gevorm. In die wortels van Salt Creek, Dogridge en 99 R, is sinsiete net in die sentrale silinder waargeneem. Die vorming van abnormale xileem weens nematodiese bedrywighede was 'n baie algemene verskynsel. M. hapta kon in laasgenoemde drie cultivars nie sy lewenskringloop voltooi nie. In Salt Creek, Dogridge, 99 R en dikwels ook in Steen, is wondperiderm gevorm, waardeur die nematodes verhinder was om die xileem te bereik. Die indringende nematodes het voor hulle uit dikwels histologiese veranderinge in die wortels teweeggebring.

The importance of root systems for soil-based resource acquisition by plants has long motivated researchers to quantify the complexity of root system structures. However, most of those studies proceeded from 2-D spatial data, and thus lacked the relevance of a 3-D analysis. In this project, helical CT scanning was applied to study root systems with an unprecedented level of accuracy, using non-destructive and non-invasive 3-D imaging that allowed for a spatio-temporal analysis. The appropriate CT scan parameters and configuration were determined for root systems of maize seedlings grown in sand and loamy sand. It was found that the soil conditions allowing for better visualization were sand before watering and loamy sand after watering. Root systems were CT scanned and visualized either at a single moment in time or repeatedly on successive days. Complexity analysis was performed by estimating the fractal dimension on skeletonized 3-D images of root systems.

No description available.

Root growth potential CRGP) is the measure of seedling ability to grow new roots. Loblolly pine (Pinus taeda L.) seedlings from 5 seedlots were raised at two widely separated nurseries (Summerville, SC and New Kent, VA). In Experiment I, RGP was determined during the fall and winter of 1984-85 and 1985-86, and several morphological traits were measured. In Experiment II seedlings from the same seedlots were lifted during February 1985 and 1986 at both nurseries, and cold stored until subsequent outplanting; subsamples of outplanted seedlings were used for RGP determinations. Root growth potential varied significantly by family, nursery, and lift date, and first order interactions were significant. Generally, the RGP of Summerville raised seedlings was higher than that of New Kent raised seedlings. RGP was not strongly correlated with common measures of shoot morphology, but RGP was consistently well correlated with lateral root dry weight. In Experiment II, RGP varied significantly by family, nursery, and storage duration. The family x nursery effect was the only significant interaction. Summerville raised seedlings had higher RGP on each planting date. During each year RGP declined rapidly in storage. First year survival was significantly correlated with RGP (r = .52, p < .001). Height increment and RGP were also strongly correlated (r = .80, p < .001). These relationships and their implications for nursery management were discussed. / M.S.

Abstract not available