"April 2001" / Includes bibliographical references (leaves 198-214) / xv, 214, [12] leaves : ill. ; 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 and Farming Systems, 2005

Intact dark- and light-grown mung bean (Vigna mungo L.), black bean (Phaseolus vulgaris L.), pea (Pisum sativum L.) cowpea (Vigna unguicul a ta (L.) Wa lp.) and squash (Cucurbita pepo L.) seedlings on hydroponic medium were osmotically stressed by exposing their roots to PEG 8000 of various concentrations (-0.2 to -0.6 MPa) to determine stress effects on growth and tissue water status. Growth of dark-grown mung bean hypocotyls ceases within 40 sec upon exposure to any level of stress, and resumes within 10 to 45 min. Growth of all other seedlings were measured usually after 3 to 24 h stress, and in 3 h, elongation is inhibited in dark-grown and is stopped in light-grown tissues. In dark-grown mung bean, black bean and squash hypocotyls and pea epicotyls, growth rates after 24 h stress were found to be proportional to the Ψ of the medium. In mung bean hypocotyls, growth stopped before any change in Ψ or Ψ(π) occurred in the growing region. In this tissue and also in dark-grown squash hypocotyls, pea epicotyls, and in lightgrown cowpea hypocotyls, equivalent reductions in Ψ and Ψ(π) were evident in the growing region after 3 h, so turgor remained constant. In other species, osmotic adjustment with turgor maintenance was evident after 24 h in both the growing and expanded regions. The results with mung bean hypocotyls provided the first demonstration that stress causes an almost instantaneous stress-caused cessation of elongation in dicots. Since data from all plants showed that stress causes growth rate inhibition or cessation without a concomittant decrease in Ψ(p), it is concluded that turgor is not the factor regulating growth. More likely, stress-caused growth and water status changes are responses to an earlier signal, such as a stress-caused reduction in the apoplastic Ψ.

The major objective of this study was to determine whether or not food production per unit space can be increased by intercropping summer squash (Cucurbita pepo L.) with mung bean (Phaseolus aureus Roxb.) or pinto bean (Phaseolus vulgaris L.), and to identify the factors associated with growth and yield of summer squash, mung bean and pinto bean under intercropping regimes. A series of experiments were conducted during the period: Summer, 1977 to February, 1980, at both the University of Arizona, Experiment Station, Marana, and in a greenhouse at the University of Arizona, Campbell Avenue Farm. Intercropping mung beans or pinto beans with summer squash in either adjacent rows or within the row did not significantly influence the bean seed yield, although adjacent row intercropping tended to outyield the within row intercropping. Summer squash yield was more significantly reduced by within row intercropping than adjacent row intercropping. Root and shoot dry weights of container grown mung beans or pinto beans were significantly reduced by intercropping with summer squash, but summer squash root and shoot dry weights were not significantly affected. Intercropping summer squash with either mung beans or pinto beans was more beneficial at low nitrogen and phosphorus fertility levels than at higher levels. Summer squash fruit and shoot dry weights per unit space increased with increase in plant population, but they were not significantly influenced by intercropping with either mung beans or pinto beans. Intercropping high population summer squash with low population mung beans or pinto beans reduced both seed and biomass yields of the beans. However, increasing the bean plant populations had no influence on their seed and biomass yields. Harvest index of mung beans or pinto beans was neither influenced by intercropping with summer squash nor by increasing the bean plant population. Leaf area per unit space increased with increase in plant population, but intercropping had no significant influence in all cases. Specific leaf weight, leaf area-to-leaf weight ratio, and leaf weight ratio were neither influenced by intercropping nor by varying the plant populations. Mung bean seed yield was significantly to highly significantly correlated with harvest index and biomass, but highly negatively correlated with leaf area index, while pinto bean seed yield was very highly correlated with biomass and harvest index. Summer squash fruit yield was significantly to highly significantly correlated with shoot dry weight, leaf area, leaf area index and specific leaf weight. Accumulations of nitrate nitrogen and/or phosphorus in the leaf petioles of mung beans, pinto beans or summer squash were neither influenced by intercropping nor by increasing the nitrogen or phosphorus fertility levels. The economic yields of field grown mung beans, pinto beans or summer squash were not significantly correlated with petiole accumulations of nitrate nitrogen and phosphorus. While summer squash exhibited autotoxicity, mung bean root leachates tended to promote growth of pinto beans and summer squash. Food production per unit space was increased by as much as 76% by intercropping summer squash with pinto beans, while intercropping summer squash with mung beans increased food production by 63%. Under certain plant combinations, dry matter yield per unit space was increased by as much as 185% by intercropping summer squash with mung beans, while intercropping summer squash with pinto beans increased the dry weight yield by as much as 81%.

No description available.

Thesis (Ph. D.)--Michigan State University. Plant Breeding and Genetics Program, 2006. / Title from PDF t.p. (viewed on Nov. 12, 2008) Includes bibliographical references. Also issued in print.

Thesis (Ph. D.)--University of Missouri-Columbia, 1997. / Typescript. Vita. Includes bibliographical references (leaves 179-191). Also available on the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 1997. / Typescript. Vita. Includes bibliographical references (leaves 179-191). Also available on the Internet.

Please read the abstract in the section 00front of this document. / Dissertation (MSc Agric (Weed Science))--University of Pretoria, 2007. / Plant Production and Soil Science / MSc Agric / unrestricted

Drought causes considerable reduction of legume productivity and significantly threatens the food security, and this situation is expected to be aggravated due to climate change. In soybean and common bean, water resource capturing through plant root architectural plasticity and the role of symbiotic nitrogen fixation have not been investigated in greater detail yet. This study was therefore conducted to identify and apply useful morphological and physiological performance markers (traits) for selection of drought-tolerant common bean and soybean cultivars under both controlled phytotron and field conditions that might be applicable as markers in future legume breeding programs. In soybean, traits related to above ground performance, such as photosynthesis, biomasses, and stomatal conductance, were related to parameters for nitrogen acquisition in nodules. The ability to maintain vigorous shoot growth under drought-induced nitrogen limitation was identified as an important trait that can be used to select for improved drought tolerance. Further, experiments carried out growing different common bean inbred lines under controlled phytotron conditions revealed the importance of growth and gas exchange parameters as well as nitrogen fixing ability as performance markers to select superior performing bean lines for growth under drought. As a further result, the strong association of symbiotic nitrogen fixation with CO2 assimilation and stomatal conductance was also ascertained. In field experiments the effective use of water through enhanced lateral root development and maintaining the water status of the plant was found to be crucial for enhanced productivity under drought, with root morphology traits (root length, area and volume) as well as root architectural traits (first whorl angle, basal root number and adventitious root branching density) significantly related to seed yield. Measurement of these traits might be added to future bean varietal improvement programs. Further, a direct relationship between both water use efficiency (WUE) estimated using carbon isotope discrimination (CID) and nitrogen fixation (15N abundance) with root morphological and architectural traits (root length, area and volume, basal root number, 1st as well as 2nd whorl angles) was identified. CID (WUE) and 15N abundance (SNF ability) had a direct relationship with each other and also with productivity traits (seed yield and pod harvest index). Soybean field experiments verified the importance of root system architecture and morphology for providing drought tolerance with root architectural traits, tap and lateral roots (diameter and branching density) and morphological traits (root length, surface area and volume) contributing to better performance under drought. Moreover, the strong association of CID (WUE) with ä15N (SNF), root traits as well as seed yield in soybean exposed to drought was ascertained. Findings suggested that higher performance in CID under drought stress may be due to higher CO2 assimilation and better N2 fixation resulting in better root system architecture and morphology of the drought-tolerant cultivar through maintenance of the water status of the plant for efficient biological activity. Overall the study has generated new knowledge about the use of physiological markers (traits) that can be used widely for legume evaluation under drought suitable for both phytotron and field studies. / Thesis (PhD)--University of Pretoria, 2012. / Plant Science / unrestricted

Bean rust, caused by the fungus Uromyces appendiculatus (Pers.:Pers) Unger, is a disease of common bean (Phaseolus vulgaris) prevalent in the Americas and Africa. The most cost-effective countermeasure to bean rust is genetic resistance. While 17 dominant rust resistance genes (named with Ur- symbol) have been identified in common bean, not all of these genes have been genetically fine-mapped. To expand our knowledge of rust resistance genes in common bean, Ur-6 was mapped in the common bean genome. A GWAS analyses suggested that Ur-6 is present on chromosome Pv07 of P. vulgaris. Two InDel markers tightly linked to Ur-6 were developed by F2 bi-parental mapping and may prove effective for marker-assisted selection in bean breeding programs in the future. Further, 25 candidate genes were identified and are the potential focus of future gene validation research.