Whole safflower seeds of the Mexican variety Kino'76 with a protein content of 17.30% (dwb) were subjected to the processes of dehulling, defatting (n-hexane extraction) and debittering (70% methanol extraction) to produce four types of meals preparations: whole safflower meal, dehulled safflower meal, debittered, whole meal and debittered, dehulled meal with protein contents of 26.90, 66.93, 26.70 and 69.92%, respectively. The proteins of each meal were studied in detail by means of protein fractionation, gel filtration chromatography and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Osborne solubility fractionation of the protein of whole safflower meal showed that the amount of protein in the alkali soluble fraction was approximately 71% of the total and the alcohol soluble fraction did not contain any protein. After dehulling and debittering, the amount of protein in the alkali soluble fraction decreased by 30%, whereas the amount of protein in the insoluble residue increased by 12%. SDS-PAGE of the proteins of the water-, salt- and alkali soluble fractions revealed that they consisted of 8, 13 and 13 distinct subunits, respectively, with apparent molecular weights ranging from 14.7 to 88.0 kDa. The number of subunits and molecular weight distribution decreased as a result of debittering. Fractionation of the proteins of each meal by gel filtration chromatography followed by SDS-PAGE demonstrated that proteins of safflower seed are highly heterogeneous. The process of debittering caused major alteration of the molecular weight profile and subunit composition of the gel filtration protein fractions.

Germination and establishment was evaluated in Arizona cottontop (Digitaria californica (Benth.) Chase), bush muhly (Muhlenbergia porteri Scribn.) and plains lovegrass (Eragrostis intermedia Hitchc.) from southern Arizona. Germination was determined in different aged seed harvested from native and irrigated plots of various populations. Results indicated variability in germination characteristics of study species that appeared unrelated to afterripening or dormancy. Germination ranged from 62 to 96% for Arizona cottontop, 34 to 99% for plains lovegrass, and 75 to 99% for bush muhly. Bush muhly had highest average velocity of germination (58.0 ± 4.1), followed by plains lovegrass (35.9 ± 1.91), and Arizona cottontop (31.4 ± 1.13). Effects of 3 surface treatments (furrows, gravel, litter) and 2 cultivation treatments on establishment of study species and yellow bluestem (Bothriochloa ischaemum (L.) Keng var. ischaemum) was investigated in the field. Bush muhly did not emerge and plains lovegrass had minimal emergence. Arizona cottontop had similar emergence in cultivated and uncultivated plots whereas yellow bluestem had greater emergence in cultivated plots. Litter promoted greater survival of Arizona cottontop. Lower survival in furrows may have resulted from fewer days with available soil moisture and interference from greater density of non-seeded species. Soil covers appear to positively influence survival rather than emergence. Effect of rainfall distribution on germination was investigated using 2 seed retrieval methods. Arizona cottontop and bush muhly germinated after at least 3 days of available soil moisture. Plains lovegrass seeds did not germinate in the field but retrieved seeds had 83% germination, possibly due to light exposure under laboratory conditions. Another study determined whether species have different density and cover under overstory species compared to open areas. Arizona cottontop had either greater, less, or no differences in density under canopied versus open areas. Cover of Arizona cottontop was greater or similar among canopied and open areas. Plains lovegrass had lower or similar density and cover under canopies than in open areas. Bush muhly had greater density and cover under canopies. Overall, studies suggested that species are easily germinated, but accept relatively narrow ranges of environmental conditions for establishment. Establishment may be enhanced by sowing species when rainfall is consistent, extending available moisture through use of soil covers, or mimicking microsites where a species occurs naturally.

The ability of different seedbed preparation treatments to enhance seedling establishment of 'Vaughn' sideoats graina (Bouteloua curtipendula (Michx.) Torr.), 'A-130' blue panic (Panicum antidotale Retz.), 'A-68' Lehmann lovegrass (Eragrostis lehmanniana Nees) and 'Cochise' Atherstone lovegrass (Eragrostis lehmanniana Nees X E. tricophera Coss and Dur.) was determined in field and greenhouse experiments. Field experiments compared seed burial and seedling emergence on undisturbed plots with that of plots lightly or heavily trampled by cattle, furrowed with a land imprinter or plowed. Seed burial was nearly always greatest in plots disturbed by these 3 latter treatments compared to undisturbed or light-trampled plots. Summer thunderstorms increased burial on treated and undisturbed plots. These seedbed treatments likewise increased seedling emergence of all species during a moderately-wet summer but not during a dry summer when emergence was limited. Sideoats graina emergence was low all 3 years. Seed burial and emergence of the small-seeded lovegrasses was high in a wet year even on undisturbed plots. Greenhouse experiments were designed to determine effects of seedbed microsites, sowing depth and soil water on emergence, survival and morphology of sideoats graina, blue panic and Cochise lovegrass. Emergence of all species was highest from seeds under gravel, followed by seeds under litter, seeds in cracks and finally seeds on the bare soil surface. Cochise lovegrass had high emergence under gravel for both continuously-wet and drying seedbeds. Cochise lovegrass had greater survival, followed by blue panic and then sideoats graina. All 3 species initiated permanent roots from nodes near the soil surface regardless of sowing depth. Seedlings from deeper-sown seeds had shallower primary roots and less survival than seedlings from shallow-sown seeds. Although seedbed treatments may increase the number of seeds buried and thereby increase seedling emergence when summer storms are frequent, treatments which bury seeds too deep may decrease seedling emergence. Seedbed treatments do not ensure successful emergence in a dry year.

No description available.

Nine cycles of recurrent selection for germination salt tolerance in alfalfa (Medicago sativa L.) were compared with their parental cultivar, 'Mesa-Sirsa'. Test seeds were produced in the same season and locale. Cycle 9 and Mesa-Sirsa showed 90% and 2.5% germination, respectively, in a -1.7 MPa NaCl medium. Cycle 8 germinated more vigorously compared to Mesa-Sirsa in stressed and non-stressed environments. Selection also enhanced germination speed and radicle length. Fresh seed and one year old seed showed similar percent germination. Scarification decreased germination in a saline solution. Mesa-Sirsa and Cycle 8 displayed the same pattern of water uptake in a salt solution. Salinity decreased water uptake in Cycle 8 and Mesa-Sirsa compared to the control. Cycle 8 and Mesa-Sirsa contained 7% galactomannan and 3.2% stachyose. Galactomannan was not an important factor in seed salt tolerance. Seed protein content was stable throughout the cycles of selection. Selection for germination salt tolerance in alfalfa significantly affected the percentage of seed amino acids.

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Very little is known about the post-shedding seed behaviour and megagametophyte development of the cycads, the most primitive extant seed-bearing plants, which pre-date the dinosaurs. In the present investigation, seeds of Encephalartos natalensis Dyer and Verdoorn were shed with relatively high mean embryo (3.33 g g-1) and megagametophyte (1.25 } 0.16 g g-1) WCs, when the developing embryo consisted primarily of the coiled, elongated suspensor bearing a rudimentary sporophyte at its tip. It was not surprising that these seeds were revealed as desiccation sensitive in the present investigation, as the embryos continued to develop after seed-shed, reaching a germinable size (.15 mm) only 4 . 6 months after seed abscission from the strobilus. Maintenance of the seeds in hydrated storage conditions was precluded by the proliferation of fungi, despite the application of the fungicide: BenlateR. Some seeds were also found to germinate in hydrated storage, despite the hard physical barrier to germination imposed by the enclosing sclerotesta. Seeds dusted with BenlateR and placed in eopen f storage in loosely closed paper bags had a longer life-span than those placed in hydrated storage; however, seeds stored in open storage were also overcome by fungi, but only around 18 months after seed-shed. Therefore, while the vigour and viability of the seeds appeared to decline slowly in the months after the embryos reached a germinable size, the life-span of stored E. natalensis seeds devoid of fungi is yet to be determined and will be the subject of further research. The current investigation also combined ultrastructural and viability retention studies to observe the post-shedding behaviour of the storage tissue, the megagametophyte. The cells of the megagametophyte became progressively packed with starch and protein as the two main storage reserves, a limited number of discrete lipid bodies, and occasional mitochondria all of which appeared to be embedded in an homogeneous matrix. When the development of the megagametophyte cells was analysed ultrastructurally, it was found that the unusual matrix was present from the inception of megagametophyte cellularisation, and contained microtubules and numerous very faintly-visible vesicles. Newly-formed megagametophyte cells were thus not highly vacuolated as previously thought, but dominated by an homogeneous matrix. Enzyme-gold localisation was employed in an attempt to determine the organelles responsible for the deposition of cell wall components during cellularisation of the megagametophyte. It appeared that ER-derived vesicles (and not Golgi-derived vesicles) were the principal contributors of the primary cell wall components, pectin and xylan. While cellularisation took place over approximately 1 - 2 weeks, subsequent development of the megagametophyte cells involved the accumulation of storage reserves, this phase lasting approximately 8 months -when the seeds were shed whether pollination/fertilisation had recently occurred, or not. At seed-shed, the cells of the megagametophyte were nucleated and contained a few mitochondria of a metabolically-active appearance. The occurrence of aerobic metabolism in these cells was confirmed by the tetrazolium (TTZ) test. Judging from the TTZ reactivity, the viability of the megagametophyte cells of fertilised seed appeared to decline slowly in the months after seed-shed, in parallel with extension growth of the embryo. The cell layer comprising the external surface of the megagametophyte showed marked ultrastructural differences from the inner cells, and may emerge as having an ‘aleurone-like’ function. It is, however, possible that the cells of the body of the gametophyte participate actively – at least in the earlier stages of post-shedding seed development – in mobilisation of stored reserves, which must support the development of the embryonic sporophyte. / Thesis (M.Sc.)-University of KwaZulu-Natal, Westville, 2009.

Call number: LD2668 .T4 1986 V47 / Master of Science / Biochemistry and Molecular Biophysics Interdepartmental Program