Chapter 1: Antarctic fishes are extremely cold adapted. Despite their inability to upregulate heat shock proteins, recent studies have demonstrated a capacity for heat response in these animals. A cDNA microarray study looked at the Notothenioid fish Trematomus bernacchii and revealed heat sensitivities for hundreds of genes, two of which code for members of the CCAAT/Enhancer-binding protein (C/EBP) family of transcription factors. These molecular switches are best known for their roles in apoptosis, inflammation and cell cycle arrest. This dissertation further elucidates the role of C/EBP-delta in the Antarctic fishes T. bernacchii and Pagothenia borchgrevinki. Chapter 2: C/EBP-delta is constitutively expressed in unstressed, field-acclimated (ca. -1.86°C) animals in a highly tissue-specific manner. White muscle tissue contains the highest C/EBP-delta concentration, which is further increased in response to sublethal heat stress at 2.0 or 4.0°C. This response is mostly acute and transitory, but a lesser upregulation was observed in fishes held for one month at 4.0°C. Chapter 3: The heat-induced nuclear translocation of C/EBP-delta--as determined by immunohistochemistry--appears to be time, tissue and species specific with spleen, heart and retinae being particularly responsive in certain situations. Chapter 4: Protein concentrations of proliferating cell nuclear antigen are tissue specific and variably heat responsive. Surprisingly, levels appear to be positively correlated with C/EBP-delta. Chapter 5: Flow cytometry revealed increasingly high temperatures reduce the proportion of G1 cells while increasing the abundance of apoptotic cells. Chapter 6: These findings are discussed in the context of global climate change and the cellular stress response.

Pacific lamprey is a culturally valuable species to indigenous people, and has significant ecological importance in freshwater and marine ecosystems. Over the past several decades, constrictions in range and reductions in Pacific lamprey abundance have been observed in Western North America, and may be indicators of range-wide declines. In the face of declining populations, the U.S. Fish and Wildlife Service has partnered with tribal, state, federal, and local entities to implement a regional Pacific lamprey conservation agreement aimed at reducing threats to Pacific lamprey and improving their habitats and population status. Research needs identified in the conservation agreement include assessing larval Pacific lamprey occupancy and distribution, habitat requirements, and the limiting factors of larval distribution in the freshwater ecosystem. As part of the effort to address these knowledge gaps, we investigated the potential for larval lampreys to occur in tidally-influenced estuarine environments. Research of this type may be valuable for future conservation, management or recovery efforts of Pacific lamprey throughout its range. We employed a two-phased approach, consisting of laboratory and field components to address our aims. We first conducted a series of controlled laboratory experiments to evaluate osmotic stress tolerance and osmoregulatory status of larval Pacific lamprey exposed to a range of (1) fixed salinity in various dilutions of saltwater and (2) oscillating salinity treatments designed to simulate tidal activity. Tolerance was assessed by monitoring and comparing survival of larvae in various treatments through 96 h. Osmoregulatory status was assessed by quantifying and comparing total body water content, plasma osmolality, and plasma cation (i.e., sodium) concentrations among larvae surviving various treatments. In fixed salinity experiments, 100% survival was observed in 0‰, 6‰, 8‰ and 10‰ through 96 h, while 0% survival was observed through 48 h in 12‰, 30 h in 15‰, and 12 h in 25‰ and 35‰. In oscillating salinity experiments, on the other hand, a significant increase in survival (100%) was observed through 96 h in treatments that oscillated between 12‰ and 0‰ (freshwater) at about 6 h intervals versus fixed 12‰ salinity experiments. A significant increase in survival also occurred in oscillating 15‰ treatments (60%) versus fixed 15‰ through 96 h. Linear regression analysis indicated higher environmental salinity in laboratory experiments was significantly related to increases in plasma osmolality and plasma sodium (the most abundant osmotically active plasma cation) concentrations, and concurrent decreases in total body water content among larvae that survived various treatments. Tidal oscillations in salinity appeared to temper the desiccating effects of salinity, as changes in body water content and sodium ion concentration were less abrupt than fixed salinity treatments. These results suggest larvae cannot osmoregulate in hyperosmotic environments, but are able to tolerate some fixed and oscillating hyperosmotic salinity exposure. Consequently, larvae may be able to occur in certain areas of estuaries, such as oligohaline habitats that are characterized by low levels of salinity. Experimental results were used, in part, to guide larval sampling in a tidally-influenced habitat. Occurrence of larval Pacific lamprey and Lampetra spp. (western brook and river lampreys) was subsequently investigated across a gradient of salinity in Ellsworth Creek (Pacific County, Washington) by electrofishing. Larval Pacific and Lampetra spp. were detected within an approximately 300 m long tidally-influenced segment of the study area. Salinity monitoring was conducted in six tidally-influenced reaches where larvae were detected for up to 14 d following electrofishing. Maximum tidal cycle salinity exceeded 15 ppt during 52% to 80% of tidal cycles within tidally-influenced reaches where larvae were detected. These results suggest potential for larval lamprey to occur in certain portions of tidal estuaries. However, long-term residence of larvae in tidally-influenced habitats and whether larvae are able to subsequently survive, grow, transform, and out-migrate is not known and requires further study. Given the potential for tidally-influenced habitats to be occupied by larvae, assessments of larval occurrence in other areas, such as the lower Columbia River, may be warranted. Knowledge of larval lamprey distribution in estuarine environments may be valuable for habitat restoration, and mitigating potential impacts from dredging and other human disturbances.

Indiana University-Purdue University Indianapolis (IUPUI) / The MDM2-p53 feedback loop is a well-characterized pathway. p53 is a transcription factor and regulates the transcriptional expression of genes that encode proteins responsible for cellular senescence, cell cycle arrest, apoptosis, and DNA repair. Various cellular stresses can result in p53 activation, including hypoxia, DNA damage by agents such as UV or IR, oncogenic signaling, nucleotide depletion and nucleolar stress from perturbation of ribosomal biogenesis. Under normal conditions, MDM2’s role in the pathway is to inhibit p53 function by directly binding to this protein and facilitating its ubiquitylation and 26S proteasome-mediated degradation. Under stressful cellular conditions, certain proteins interact with and rescue MDM2’s inhibition of p53. For example, upon exposure to small amounts of Actinomycin D, rRNA transcript synthesis is stalled resulting in the release of various ribosomal proteins including RPL5, RPL11 and RPL23; each of which has been shown to bind MDM2 within its central acidic domain and inhibit its ability to destabilize p53. Although the RPL5 binding region of MDM2 have been mapped in prior investigations, the MDM2-binding region(s) of RPL5 have yet to be characterized. By employing RPL5 deletion mutagenesis and in vitro GST-fusion protein-protein association assays with purified proteins, this dissertation attempts to elucidate those regions of RPL5 that may interact with MDM2. Normalizing RPL5-WT to 1.00, our study reveals that the basic N and C-terminals of RPL5 appear to bind with MDM2 while RPL5’s central region displays negligible binding to the central acidic domain of MDM2. Also, the possible meanings of these RPL5 MDM2 binding domains are discussed along with their utilization in potential future applications.

La vitamina E incluye una serie de compuestos amfipáticos esenciales en la dieta tanto para humanos como para animales y que únicamente puede ser sintetizada por organismos fotosintéticos, los tocoferoles y los tocotrienoles. Descubierta a principios del siglo XX, no fue hasta los años 60 que se asoció a propiedades antioxidantes. En plantas, se sabe que los niveles de tocoferol (la forma mayoritaria en hojas) aumenta en respuesta al estrés y que está implicado en el control de los niveles de las especies reactivas del oxígeno, la síntesis de las cuáles suele aumentar drásticamente en condiciones de estrés y pueden ir asociadas a graves daños celulares si no se regulan adecuadamente sus niveles. También interviene en la prevención de la propagación de la peroxidación lipídica en condiciones de estrés oxidativo, además de otras nuevas funciones que poco a poco se van descubriendo, como la importancia durante la germinación de semillas, la implicación en el transporte de fotoasimilados o un posible papel en señalización celular. En esta tesis se estudió la regulación de la biosíntesis de α- y γ-tocoferol en condiciones de estrés abiótico (déficit hídrico y estrés salino), así como su posible implicación en señalización celular en la planta modelo Arabidopsis thaliana y en la planta con metabolismo CAM, Aptenia cordifolia. Pero la vitamina E no actúa sola. Como antioxidante, puede trabajar coordinadamente con el ascorbato o con carotenoides además de con diversas fitohormonas, por lo que además, se estudió el papel como mecanismo fotoprotector, juntamente con los carotenoides y los niveles hormonales, tanto en condiciones de estrés como influenciados por la edad de la hoja. Los estudios en A. thaliana se llevaron a cabo utilizando diversos mutantes ya fueran de etileno o de tocoferol como aproximaciones a sistemas deficientes de ambos compuestos. Se observó que el etileno promueve la síntesis de tocoferol en A. thaliana, de forma especifica a través de las proteínas EIN2, EIN3 y EIL1. Además, niveles elevados de etileno promueven aumentos de tocoferol en hojas viejas y mutaciones en el gen que codifica para la proteína EIN3 es capaz de resistir dosis moderadas de salinidad, cambiando el balance hormonal foliar y aumentando el estrés oxidativo. Sorprendentemente, la biosíntesis de tocoferol no resultó estar regulada a nivel transcripcional. En el modelo de planta CAM, la A. cordifolia, el ABA jugó un papel importante en la regulación de la biosíntesis de tocoferol en condiciones de déficit hídrico. Juntamente con el β-caroteno y el ciclo de las xantofilas, los tocoferoles ayudan a la protección del PSII en condiciones de déficit hídrico y estrés salino cuando la demanda de fotoprotección es elevada, pero cuando los carotenoides se empiezan a degradar, el tocoferol es incapaz de substituirlos. Además, el γ-tocoferol parece tener funciones específicas además de precursor del α-tocoferol influenciando de forma específica los niveles de expresión de genes implicados en la biosíntesis, percepción y señalización del etileno en A. thaliana. Finalmente, cabe destacar que el tocoferol interviene en la comunicación cloroplasto-núcleo a través de regular los niveles de expresión de genes relacionados con el etileno, formando parte de la intrincada red de señalización retrógrada. / Vitamin E includes different amphipathic compounds, tocopherols and tocotrienols, essentials in the diet of humans and animals. It can be synthesized only by photosynthetic organisms and it was discovered in the early twentieth century but it was not until the 60‘s when it was associated with its antioxidant properties. In plants, it is known that the levels of α-tocopherol (the major form in leaves) increase in response to stress and they are involved in the control of the levels of reactive oxygen species (ROS). Under stress conditions the levels of ROS tend to increase dramatically and they could be associated with serious cell damage if their levels are not properly regulated. Moreover tocopherols are involved in prevention of the lipidic peroxidation propagation under oxidative stress conditions. Furthermore, new functions are gradually being discovered, like their importance in the process of seed germination, their role on the transport of the photoassimilates or their possible function in cell signalling. During this PhD I have studied the regulation of the biosynthesis of α- and γ-tocopherol under abiotic stress conditions (water and salt stress) and their possible role in cell signalling in the model plant Arabidopsis thaliana and in the CAM plant, Aptenia cordifolia. As an antioxidant, it might work in coordination with ascorbate or carotenoids as well as with some phytohormones. That is why we have studied their role as photoprotective mechanism together with carotenoids and the hormone levels in both stress conditions and the influence of leave age. The studies in A. thaliana were carried out using tocopherol or ethylene mutants as approximations to deficient systems of both compounds. It was observed that ethylene promotes synthesis of tocopherol in A. thaliana, specifically through EIN2, EIN3 and EIL1 proteins. In addition, elevated levels of ethylene induced tocopherol increase in old leaves. ein3-1 mutant plants were able to withstand moderate doses of salinity, changing leaf hormonal balance and increasing oxidative stress. Surprisingly, the biosynthesis of tocopherol was not being regulated at the transcriptional level. In the model CAM plant, A. cordifolia, the ABA played an important role in the regulation of tocopherol biosynthesis under water stress conditions. Together with β-carotene and the xanthophyll cycle, tocopherols help in the protection of PSII under both water and salt stress conditions when the demand for photoprotection is high. When carotenoids were beginning to degrade, tocopherols were unable to replace them. In addition, the γ-tocopherol seemed to have specific functions not only as α-tocopherol precursor. It can specifically influence the expression levels of genes involved in ethylene biosynthesis, perception and signalling in A. thaliana. Finally, in this PhD thesis it is demonstrated that tocopherol is involved in the chloroplast-nucleus communication by regulating the expression levels of genes related to ethylene as part of the intricate network of retrograde signalling.

Stress-related cognitive changes are still a matter of debate. In some particular neuropathological conditions such as focal ischemia, cognitive functions have been shown to be significantly impaired. These conditions, however, may be improved by some factors such as steroid hormones. The purpose of the current thesis was to assess the structural and functional effects of corticosterone-related experiences on the hippocampus before and after endothelin-1 (ET-1)-induced stroke. We found corticosterone-related experiences enhance the hippocampal recovery, and improve its function in both wet and dryland tasks after ET-1-induced focal stroke. Structural and functional effects of such experiences prior to the focal ischemia in the hippocampus, however, showed that stress, not corticosterone is a strong inhibitor for hippocampal recovery. / xii, 252 leaves : ill. ; 29 cm. --

Maize (Zea mays L.) is the principal crop of Southern Africa but production is threatened by gray leaf spot (Cercospora zea-maydis L.) and phaeosphaeria leaf spot (Phaeosphaeria maydis L.) diseases, drought and the use of unadapted cultivars, among other constraints. There are few studies of gray leaf spot (GLS) and Phaeosphaeria leaf spot (PLS) resistance, drought tolerance, yield stability and maize cultivar preferences in Southern Africa. The objective of this study was to: a) determine farmers’ preferences for cultivars; b) investigate the gene action and heritability for resistance to GLS and PLS, and drought tolerance; and c) evaluate yield stability and its relationship with high yield potential in Southern African maize germplasm. The study was conducted in South Africa and Zimbabwe during 2003 to 2004. A participatory rural appraisal (PRA) established that farmers preferred old hybrids of the 1970s because they had better tolerance to drought stress. Farmers also preferred their local landrace because of its flintier grain and better taste than the hybrids. The major prevailing constraints that influenced farmers’ preferences were lack of appropriate cultivars that fit into the ultra short seasons, drought and low soil fertility. Thus they preferred cultivars that combine high yield potential, early maturity, and drought tolerance in all areas. However, those in relatively wet areas preferred cultivars with tolerance to low soil fertility, and weevil resistance, among other traits. A genetic analysis of 72 hybrids from a North Carolina Design II mating revealed significant differences for GLS and PLS resistance, and drought tolerance. General combining ability (GCA) effects accounted for 86% of genetic variation for GLS and 90% for PLS resistance indicating that additive effects were more important than non-additive gene action in controlling these traits. Some crosses between susceptible and resistant inbreds had high resistance to GLS suggesting the importance of dominance gene action in controlling GLS resistance. Resistance to GLS and PLS was highly heritable (62 to 73%) indicating that resistance could be improved by selection. Also large GCA effects for yield (72%), number of ears per plant (77%), and anthesis-silking interval (ASI) (77%) under drought stress indicated that predominantly additive effects controlled hybrid performance under drought conditions. Although heritability for yield declined from 60% under optimum to 19% under drought conditions, heritability for ASI ranged from 32 to 49% under moisture stress. High heritability for ASI suggested that yield could be improved through selection for short ASI, which is positively correlated with high yield potential under drought stress. The stability analyses of the hybrids over 10 environments indicated that 86% had average stability; 8% had below average stability and were adapted to favourable environments; and 6% displayed above average stability and were specifically adapted to drought stress environments. Grain yield potential and yield stability were positively correlated. In sum, the study indicated that farmers’ preferences would be greatly influenced by the major prevailing constraints. It also identified adequate genetic variation for stress tolerance, yield potential and yield stability in Southern African maize base germplasm, without negative associations among them, suggesting that cultivars combining high yield potential, high stress tolerance and yield stability would be obtainable. / Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2005.

Sorghum breeders have not made much yield improvement in new sorghum varieties in Kenya since Serena in was released in the late 1960s. KARI Mtama-1 which was released in 1993 has no yield advantage over Serena. A yield plateau for sorghum in Kenya is apparent. A new breeding approach was adopted to break that yield barrier. Development of hybrid sorghum was proposed and is expected to break the yield barrier and also deliver cultivars that meet farmers' main requirements. The objectives of the study were to (1) identify farmers' requirements in sorghum cultivars, constraints to sorghum production and why improved cultivars from research are not being adopted, (2) characterize male and female parents and establish if genetic distance could identify superior parent populations for hybrid production (3) estimate genetic variance components and determine the possibility of using GCA and SCA estimates in choosing parents for use in hybrid production, (4) test hybrids and open pollinated variety (OPV) parental lines for stress tolerance and identify tolerant hybrids for further testing and, (5) compare single cross hybrids and OPV varieties in yield performance. Participatory rural appraisal in Kitengei and Nzambani areas of Kambu showed that sorghum was especially important in semi-arid parts of Kenya. Food, trade, feed, nursing food and thatching were the most important uses of sorghum. High grain and stover yield, large grain size, early maturity, drought tolerance, pest and disease resistance, coloured grain and intermediate plant height were the major requirements of farmers. Fifty-three pollinators and forty-one male sterile parents were introduced from four sources and screened together with 27 pollen parents from Kenya. Parents and hybrids were tested in 4 environments: high and low plant density, in high and low moisture regimes laid out in a triple square lattice design in Kenya, with parents having two additional tests in South Africa. Males, females, sexes and parental sources differed significantly in head weight. There were sex x country and sex x environment interactions for head weight. Genetically distant parents' populations had higher chances of superior heterosis. Parents showed significant additive genetic variance in head weight. The regression of non-additive to additive genetic variance was roughly one and significant. Three female and five male parents were suitable for production of hybrids adapted to multiple environments. Hybrids and OPV lines significantly varied in head weight. Hybrids were superior to OPV lines in most agronomic traits. Economic superiority of the hybrids was sufficient to cover cost of hybrid production and distribution in Kenya. Hybrids and OPV lines varied significantly for plant density stress. Hybrids were less sensitive to stress and more productive than OPV lines under population density stress. KARI varieties were sensitive to plant density stress. In general low sensitivity to stress was beneficial and hybrids had superior yield to inbred varieties. / Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2006.

Wild mustard is an indigenous leafy vegetable. Its use is limited by a lack of knowledge of its agronomy. However, it is a rich source of nutrients and other minerals. Nowadays, the use of indigenous crops has been replaced by exotic crops. Climate change is affecting agricultural productivity. South Africa is a water scarce country with uneven rainfall distribution. Therefore, studies on water stress effects on plant growth were promoted by the Water Research Commission and the University of KwaZulu-Natal to understand plant responses to water stress for commercial and subsistence farming. The objective of the study was to characterise local wild mustard cultivars morphologically and physiologically with respect to production, and for the purposes of identifying their drought tolerance. Three experiments were conducted at the University of KwaZulu-Natal in order to evaluate the responses of local wild mustard cultivars to water stress. Seeds of wild mustard cultivars were characterised according to seed coat colour. Seed quality was determined by a standard germination test. Vigour was then tested using electrolyte conductivity. Seeds were sown in seedling trays under two water regimes of 25% field capacity (FC) and 75% (FC) on pine bark growing media. The experiment was terminated at 21 days when root and shoot lengths were measured. The effect of water stress on protein content and seedling growth parameters was determined. Soil was collected from the University of KwaZulu-Natal Research Farm for a pot trial. Seeds of wild mustard were sown in 81 pots, each filled with 2 kg of soil, under three water regimes (25% FC, 50% FC and 75% FC). Pots were maintained at the corresponding field capacity level by re-weighing the pots, three times a week. Measurements of plant height and leaf number were recorded weekly. The experiment was terminated at the flowering stage. At the end of the experiment, plant growth parameters (plant height, leaf area and number, dry and fresh mass) were measured in order to evaluate the effects of water stress at the vegetative stage. A field trial was conducted at the University of KwaZulu-Natal Ukulinga Research Farm in Pietermaritzburg. The experiment was conducted during the winter and spring of 2009. A completely randomised design was used for non-irrigated and irrigated (25 mm/week) trials. Emergence was measured as well as plant height and leaf number. Plant growth parameters were also measured at the end of the experiment. Leaf samples were taken for proline determination. There was a significant interaction (p<0.05) between seed colour, landraces and days to germinate with respect to germination capacity. Isaha and Masihlalisane landraces showed higher germination percentages than Kwayimba. There was also a significant interaction (p<0.05) between landraces and seed colour with respect to electrolyte conductivity. Lighter seeds of wild mustard landraces showed higher solute leakage. Isaha and Masihlalisane had higher solute leakage than Kwayimba. Significant interactions (p<0.05) between landraces and field capacity with respect to emergence, leaf number, root and shoot length and total proteins were also observed. Isaha and Masihlalisane showed higher emergence than Kwayimba. Leaf number was reduced for all landraces under water stress. Total protein content was high in black seeded landraces under water stress. There was a significant interaction (p<0.05) between landraces and field capacity with respect to seedling fresh and dry masses. Under moderate water stress conditions, Isaha and Masihlalisane showed increased biomass accumulation. There were highly significant differences (P<0.001) in plant height, leaf area, fresh and dry mass with respect to planting date. Plants performed significantly (p<0.05) better in spring than in winter. Isaha and Masihlalisane performed significantly (p<0.05) better than Kwayimba. There was a highly significant interaction (p<0.001) between landrace and irrigation treatments with respect to proline accumulation. Under water stress, Kwayimba black seeded landrace accumulated more proline. It is concluded that light-coloured seeds of wild mustard landraces were associated with good seed quality. Masihlalisane brown seeds have good early seedling establishment. Kwayimba black seeds showed tolerance to water stress through accumulation of proteins. Isaha and Masihlalisane showed an increase in biomass accumulation under moderate water stress. Water stress tolerance in some of wild mustard landraces was negatively correlated with proline accumulation. Masihlalisane brown type can grow well, with good yields, under water stress. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2010.

D.Litt. et Phil. / In recent research studies that have been done within the cadre of family sociology, researchers have emphasised the fact that the role of the man in the family is an important topic. This interest in the role of the husband/father has been facilitated by significant trends and changes of our time, manifesting world-wide, as well as in South Africa. These trends, such as the continuous rise in the rate of married women entering the labour market and the accompanying issues raised by changes in terms of the spouses' participation in household and childcare responsibilities, affect family life extensively. More researchers and theorists are now focussing on the shift from the man's role in the family as sole breadwinner to that of the active nurturant father within the context of a marital relationship characterised by companionship and an equal partnership between the spouses. For several decades the focus in South Africa, as in the case of other countries, fell on the increasing interface between work and family life, within the work/family spillover model, as experienced by the working married woman and how her marital and familial relationships are influenced by it. While it is clear from these research results, especially from those studies conducted in South Africa, that most men are no longer the sole or primary breadwinner in the family, it is less clear what new patterns of commitment and involvement these men are developing with regard to their family life. A related methodological shortcoming of sociological research on the husband/father role to date is that much of these research projects have relied on the wife/mother's report on her husband's attitude towards domestic responsibilities, his spousal and paternal conduct and the quality of the father-child relationship. As a result of this perspective on the changing role of the husband/father, the question arose as to what the situation in South Africa might be. The aim of this research was to shed light on the man's perception of his roles as husband and father in the dual-earner family and to what extent this perception may or may not stand in relationship to his experience of marital integration. In this quantitative research project the respondents were selected from the Gauteng area by means of purposive and snowball sampling.

MSCAGR (Plant Production) / Department of Plant Production / Smallholder farmers in Sub-Saharan Africa still obtain low grain yields in maize largely due to low soil fertility. The soils are inherently low in nitrogen (N) that is required for the proper development of the maize plant. Currently there are no commercial cultivars for low N tolerance locally. The combining ability approach can be used as a tool for breeding desirable cultivars. In order to improve grain yield in maize, it is important to consider ear prolificacy which is a major yield component. Therefore this study was designed to estimate combining ability in maize. Exotic germplasm from the International Maize and Wheat Improvement Center and the Institute of Tropical Agriculture as well as the local germplasm from the Agricultural Research Council was used in the study to generate crosses. One hundred and two crosses were evaluated together with a standard commercial check under low N and optimum N conditions. The specific objectives of the study were to determine general and specific combining ability for prolificacy among local and exotic inbred lines and evaluate the response of prolific hybrids to low N conditions. The hybrids were planted in the 2014/2015 summer season under irrigation in Potchefstroom, Cedara and Taung in field plots consisting of 0.75m x 0.25m spacing in a 0.1 alpha lattice design replicated twice. Data for agronomic attributes were recorded and subjected to analysis of variance using SAS version 9.1.3. Genetic correlations were analyzed using the Principal Components Analysis and factor analysis based on the correlation analysis and major traits. The results showed variation in agronomic performance among the inbred lines and their F1 hybrids. Inbred lines including TZEI63, T1162W, L15 and L17 showed positive GCA estimates for ear prolificacy at the different locations. Specific combining ability for prolific hybrids was positive at all locations and environments. The GCA:SCA ratio was close to unity; indicating that the number of ears per plant showed highly significant (P<0.01) correlation with grain yield. The hybrids showed ear prolificacy under the low N conditions. This trait can be used effectively in stress tolerance maize breeding programmes. / NRF