Thesis (Ph. D.)--Texas A&M University, 2005. / "Major Subject: Plant Breeding" Title from author supplied metadata (automated record created on Feb. 23, 2007.) Vita. Abstract. Includes bibliographical references.

Breeding dispersal can be a way for an individual to improve its fitness. Own reproductive success has been shown to be a cue to dispersal among many bird species. Natural selection should favor dispersal to higher-quality territories and a larger territory is predicted to improve fitness. Data from male rock pipits, Anthus petrosus littoralis, on the Swedish west coast indicated, as predicted, that dispersal follows an unsuccessful breeding year. However, no fitness improvement was detected after dispersal, leading to the conclusion that dispersing in itself does not lead to better fitness. Instead it was the acquisition of a larger territory that was the main cause of fitness improvement, unrelated to whether a male returned to an old territory or dispersed to a new one. However, remaining in one's old territory showed to be more beneficial than dispersing. There was a high variation within the rock pipit populations of Nidingen and Malön, due to year-to-year territory quality variation and individual quality among the birds, which could have had a big effect on the outcome of the analyses of the effects of dispersal. / Att byta revir kan vara ett sätt för en individ att förbättra sin fitness. Den egna reproduktiva framgången har påvisats påverka beslutet om revirbyte. Naturligt urval borde favorisera byte till ett revir av högre kvalitet och ett större revir förutsägs förbättra fitness. Data från skärpiplärkor, Anthus petrosus littoralis, tyder på att ett misslyckat häckningsår leder till spridning. Däremot påvisades ingen förbättring av fitness efter spridning, vilket leder till slutsatsen att spridningen i sig inte leder till bättre fitness. Istället var det anskaffandet av ett större revir som var den huvudsakliga orsaken till fitnessförbättring, orelaterat till om en hanne utökade sitt gamla revir eller flyttade till ett nytt. Däremot visade det sig vara bättre att stanna kvar i sitt gamla revir än att flytta. Det fanns en stor variation bland Nidingens och Malöns populationer av piplärka, på grund av årlig variation i revirkvalitet och individuell kvalitet bland fåglarna, vilket kan ha haft en stor effekt på resultatet av analyserna av spridningseffekterna.

The success of a plant breeding program depends upon the availability of useable genetic diversity. Such diversity may be enhanced depending on the type of hybridization strategy employed. Segregating progenies resulting from F2 populations, a double cross, and a top cross were compared for the amount of useable genetic diversity associated with six traits in durum wheat. The parental lines were three winter selections, H7092-11, H7092-52, and WD5, and two spring cultivars, WPB 881 and Altar 84. Traits evaluated were (1) plant height, (2) days to maturity, (3) harvest index, (4) kernel weight, (5) grain yield, and (6) pigment content. Analysis of the population mean values suggested the superiority of the F1 top cross for plant height, kernel weight, and grain yield. The F1 top cross progeny also had the highest genetic variability for grain yield. F2 population of the cross Altar 84 I H7092-52 gave the highest mean values for days to maturity and harvest index, and showed the highest genetic diversity for traits other than grain yield. The only population showing detectable genetic variance for pigment content was the F2 progeny of the single cross WPB 881 / H7092-11. When genetic diversity was detected, the double cross was approximately intermediate between the two F2 populations from which it was derived. Transgressive segregation was more frequent in the top cross population for grain yield, kernel weight, and plant height. No associations between grain yield and the other traits were noted for the F2 population of the single cross Altar 84 I H7092-52 and the top cross population. For the second F2 population (WPB 881 / H7092-11) and the double cross population, grain yield was found to be associated with harvest index and plant height. The only consistent relationship across all segregating generations was a negative correlation between plant height and harvest index. Based on the genetic diversity and the transgressive segregation observed, top crossing appears to be the more promising in improving grain yield in the experimental material investigated. For specific traits other than grain yield, it would appear that single crosses would be a more productive approach, however progress would depend on the specific parental combination. The double cross was inferior to the other crossing strategies for the traits measured. / Graduation date: 1991

Fluctuation of the seagrass ecosystem may be informative to the impacts of environmental changes. This study focuses on a small, inconspicuous triplefin blenny, Enneapterygius minutus, found in a specific tide pool of seagrass meadow on Gui Wan Bi, Green Island, Taiwan. Its high abundance and stable residence make this species a suitable candidate to monitor the condition of the seagrass ecosystem. Monthly collections were made during low tide from April 2007 to July 2008. The otolith microstructure was examined to study their age and growth circumstance. Developmental stages of the ovaries based on histological characteristics together with data of batch fecundity and GSI value were applied to estimate size at maturation and the spawning seasonality of the individual assemblages in the tide pool. A length-frequency analysis was made by using the monthly data. Enneapterygius minutus is a kind of short life species. It has a quite low batch fecundity and a year-long breeding ability with a seasonal high peak mainly from late winter to late spring. The recruitment of juvenile individuals began about a month after breeding had occurred. These data show that Enneapterygius minutus uses seagrass meadows as a hatching and nursing habitat. According to the close relationship between Enneapterygius minutus and seagrass meadow, it would be possible to monitor this ecosystem by using this species as an indicator when it is under environmental stress.

Thesis (Ph. D.)--Texas A & M University, 2003. / "Major Subject: Plant Breeding." Title from author supplied metadata (automated record created on Apr. 30, 2004.). Vita. Abstract. Includes bibliographical references.

Thesis (M.S.)--Texas A & M University, 2003. / "Major Subject: Plant Breeding." Title from author supplied metadata (automated record created on Apr. 30, 2004.). Vita. Abstract. Includes bibliographical references.

Thesis (Ph. D.)--Texas A & M University, 2003. / "Major Subject: Plant Breeding." Title from author supplied metadata. Includes bibliographical references.

M. Tech. Agriculture / Mungbean (Vigna radiata L. Wilczek) is becoming a food security crop in Africa, especially in South Africa where there is a growing Asian population. To promote its production by farmers, 15 elite mungbean varieties were evaluated for plant growth, symbiotic N (nitrogen) nutrition and grain yield at Nelspruit and Kliplaatdrift in Mpumalanga Province, South Africa. Genotypes VC6486-10-S1 and VC6493-44-1 at Nelspruit, and VC6510-151-1, VC1973A and VC3960-88 at Kliplaatdrift showed better growth and fixed significantly more symbiotic N than the other genotypes. They also seemed to obtain more N from soil. At both Nelspruit and Kliplaatdrift, two genotypes (namely, VC6510-151-1 and VC6493-44-1) exhibited much greater δ¹³C (carbon) values, and hence higher water-use efficiency. A comparison of P (phosphorus) nutrition between Nelspruit (received no P) and Kliplaatdrift (received 20 kg P.ha-1) revealed mineral P suppression of acid phosphatase activity in the rhizosphere of all fifteen mungbean genotypes at the latter site. The findings further showed that there is a direct functional relationship between water-use efficiency and N2 fixation, and between water-use efficiency and P nutrition.

We collated the literature available on the breeding activity of the Swainson’s Spurfowl Pternistis swainsonii and made use of reliable unpublished reports, nest record cards and field observations within the Springbok Flats, Limpopo Province, South Africa to establish breeding seasons and pairing behaviour. The onset of breeding (egg laying) is closely associated with rainfall, with male gonad development, population density and covey size (pairing behaviour), all correlated with rainfall. Peak breeding activity is from January–April in South Africa, February–May in Zimbabwe and March–June in Botswana. Egg laying has been recorded in all months and sporadic egg laying in the winter months is most likely the result of isolated rainfall. Mean clutch size is 5.2 eggs/hen (n = 140) with an incubation period of 23 days and brood hatching success and chick survival of 69.4% over the southern African sub-region. Current hunting seasons within Limpopo Province are in line with the recommended hunting season for this region and should remain unchanged: 15 June–30 September. The success of this phasianid can be attributed to its extended breeding season, high survival rate of hatchlings and the potential of birds to breed within their first year.

No description available.