Call number: LD2668 .T4 1979 N38 / Master of Science

Call number: LD2668 .T4 1986 B56 / Master of Science / Grain Science and Industry

Physiological and agronomic responses of two pearl millet (Pennisetum americanum L. K. Schum) parents and their hybrid were evaluated under different water levels on a Brazito sandy loam soil at Tucson, Arizona in 1983 and 1984. A line source sprinkler irrigation gradient was used to create the treatments. Soil moisture and physiological parameters were measured under field conditions at weekly intervals. Growth was analyzed every other week, while yield and yield components were evaluated at the end of the experiment. Harvest Index, drought tolerance index, and water use efficiency (WUE) were calculated. Percent crude protein of seeds was analyzed, and photosynthesis was measured in 1984 only. Regression analysis was used to compare the performance of the cultivars for stability. Water stress significantly affected all parameters measured, and the stress effects were more pronounced in 1983. There was no significant difference between entries at each water level for most parameters. Plant height, dry matter, and total leaf area decreased as watering level decreased. The leaf area of the hybrid was significantly higher at high water level in 1983. Firing ratio was increased significantly by stress in both seasons and was significantly lower for the male at low water level in 1983. Yield and yield components were reduced significantly by stress in both seasons, which was reflected in the reduced harvest index. Relative yield of dry matter was higher for the male in both seasons. The hybrid had the highest drought tolerance index in 1983, while the female had the highest drought tolerance index in 1984. WUE of dry matter increased with stress, while WUE of grain yield decreased with stress in both seasons. The significant reduction in transpiration was 57, 56 and 66% in 1983 and 45, 53, and 52% in 1984 for female, male, and hybrid respectively. Leaf diffusive resistance and leaf temperature were increased by water stress in both seasons. Stability regression analysis provided no adequate differentiation among cultivars. The percent crude protein (weight basis) was increased significantly by stress by 38, 43, and 28% in 1983 and by 47, 33, 46% for female, male, and hybrid, respectively.

A pearl millet hybrid (Pennisetum americanum (L.) Leeke) and its two parents were evaluated for their photosynthetic rates, diffusive resistance, canopy temperature, transpiration rates, stomatal aperture and frequency, and growth responses to various irrigation levels. The experiments were conducted on Brazito sandy loam soil at The University of Arizona Campus Agricultural Center, Tucson, AZ in 1985 and 1986. A sprinkler was used to create water treatments. Photosynthetic rates were not significantly different among genotypes at each water level. Transpiration rate, diffusive resistance, canopy minus ambient temperature, and photosynthetic rate were all significantly related to water treatments with correlation coefficients .ranging from 0.91 to 0.98. Under water stress, the female transpired more, exhibited lower diffusive resistance and had a cooler canopy compared to the hybrid and male parent. Based on these characteristics, the female seemed to expend more energy on heat dissipation than yield improvement. Water stress reduced stomatal aperture but increased stomata! frequency. The hybrid had significantly higher stomatal frequency at all water levels and smaller aperture between 63 and 125 mm irrigation levels. Dry matter, leaf area, leaf area index, and plant height were also reduced by water stress. In general, the hybrid and the male parent produced significantly more dry matter and were significantly taller than the female. The female parent had significantly higher leaf area and leaf area index late in 1986. Grain yield was reduced by water stress. Both years, the female grown under optimum moisture conditions had approximately half the grain yield as compared to the male and the hybrid. The major components contributing to the higher grain yield of the hybrid and male were larger panicles and more productive tillers.

Sorghum (Sorghum bicolor L., Moench) and pearl millet (Pennisetum americanum L., Leeke) were intercropped under soil moisture non-stress and stress at Marana, Arizona during summer 1987. Effects of soil moisture stress and inter-row competition between sorghum and pearl millet on grain yield, 50% bloom, plant height, head length, head exsertion, 1000 grain weight, and number of effective tillers were evaluated. Interplot competition significantly reduced grain yield and head exsertion of peal millet. In sorghum, only plant height was significantly different due to competition. Agronomic characters were significantly different due to the effect of soil moisture stress except head length in pearl millet and head length, 1000 seed weight, and number of effective tillers in sorghum. Sorghum growing in a neighbor plot greatly suppressed millet grain yield under soil moisture stress. Relative yield total of the cereals under intercrop was less than unity under soil moisture stress.

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Pearl millet [Pennisetum glaucum (L.) R.Br.] production under subsistence farmer management on the sandy soils of southwestern Niger is faced with many challenges, including declining soil fertility, highly variable and scarce rainfall and poor resource base of the peasant farmers in the region. This study was conducted to evaluate the potential of management to increase yield and water use efficiency of pearl millet grown on two farmers’ fields in Niger during two growing seasons, 2003 and 2004. The management practices tested were: 1) Five manure treatments (no manure, transported manure, current corralling, a year after corralling, and two years after corralling); 2) The microdose technology (20 kg di-ammonium phosphate ha-1, and 20 kg di-ammonium phosphate ha-1 + 10 kg urea ha-1); and lastly, 3) Three different pearl millet cultivars (Heini Kirei, Zatib, and ICMV IS 89305). In both growing seasons, manure had the greatest effect on the yield and water use of pearl millet at both sites. In 2003 grain yields were 389 kg ha-1 in the NM treatment and 1495 kg ha-1 in the C0 treatment at Banizoumbou whereas at Bagoua, the NM treatment had 423 kg ha-1 vs. 995 kg ha-1 in the C0 treatment. In 2004, the NM treatment at Banizoumbou had 123 kg ha-1 grain yield and the C0 treatment had 957 kg ha-1 whereas at Bagoua the NM treatment had 506 kg ha-1 vs. 1152 kg ha-1 in the C0 treatment. Residual effects of manure led to grain yields in the C1 and C2 treatments which were more than twice as high as in the NM treatment. The improved cultivars were generally superior for grain yields, whereas the local landrace was superior for straw yields at both sites. Root zone drainage was decreased by between 50 to 100 mm, and water use increased by the same amount in the current corrals at the two sites during the two growing seasons. Increased water use under corralling and presence of residual profile moisture at the end of each of the two seasons suggested that water did not limit pearl millet production at the two sites.

Pearl millet is a staple food in Namibia. It is milled into flour by traditional and industrial dry milling processes. This research was conducted to help determine how to improve the nutritional value and acceptability of pearl millet. The traditional milling process involves a lactic acid fermentation step which lowers the pH of kernels. The effects of the traditional Namibian and industrial “dry milling” processes on the physical and nutritional composition of pearl millet grain were compared. Additionally, the effect of steeping three different Namibian pearl millet varieties (Kangara, Kantana and Okashana 2) in lactic acid and water on the colour and the phenolic content of the flour were determined. Regarding comparing the milling processes, variety Kangara was conditioned and decorticated traditionally with a pestle and mortar and industrially with an abrasive decorticator. The traditional decorticated grain was steeped and sun dried for 24 h before hammer milling, whereas the industrially decorticated grain was roller milled. Tristimulus colorimetry and proximate analyses were conducted on the samples. Concerning acid steeping, kernels were steeped in a pH 3.5 solution and in water as a control. Colour, total polyphenol and c-glycosyl flavone contents were determined. The determination of cglycosylflavone content was particularly important because these compounds are considered goitrogenic. The traditionally milled flour was lighter in colour than industrial milled flour. However, it was significantly lower in protein, ash and c-glycosyl flavone contents in comparison to industrial milled flour. This was due to the removal of more pericarp and germ in the traditional process. The industrial dry milling process therefore produces flour with a higher nutrient content in terms of protein, fat and minerals. However, the traditional Namibian milling process makes the colour of the pearl millet flour lighter, which is probably the reason that it is more acceptable to consumers. Kernels steeped in a lactic acid solution were lighter in colour than those steeped in water. Irrespective of the steeping media, the total polyphenol content was significantly lower in steeped kernels compared to those unsteeped. A similar trend was observed for the cglycosyl flavone content. This indicates that some of these compounds may have leached out during steeping. For all varieties, kernels steeped in lactic acid had a significantly higher total polyphenol content than those in water, probably due to the dissociation of metal-polyphenol complexes in the acidic medium whereby these polyphenols became free and available for measurement. Thus, steeping in a lactic acid solution can lead to better colour improvement of kernels compared to steeping in water. Thus, lactic acid steeping can improve the sensory quality of pearl millet products. An industrial process can thus be designed to include tempering the grain with food grade lactic acid to produce sour taste and leach out the colour pigments, particularly the cglycosyl flavones hence lightening the colour of the industrial milled flour. This produces a product with high nutritional content, lighter in colour and has the sour taste that consumers find appealing. Copyright 2007, University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. Please cite as follows: Barrion, SC 2007, Pearl millet milling : comparison between traditional Namibian fermentation - semi-wet milling and dry milling, MSc(Agric) dissertation, University of Pretoria, Pretoria, viewed yymmdd < http://upetd.up.ac.za/thesis/available/etd-01282009-132241 / > E1209/gm / Dissertation (MSc(Agric))--University of Pretoria, 2009. / Food Science / unrestricted

Pearl millet is a staple food source for millions of African families living in semi-arid regions of the continent. Yet, despite its importance and ability to provide consistent yields, very little research and resources have been directed towards understanding mechanisms governing this crop’s resilience to biotic and abiotic stresses. The research outlined in this thesis therefore aimed to elucidate defence response mechanisms in pearl millet, a non-model cereal crop. This was accomplished through the construction and characterisation of a pearl millet defence response cDNA library, which was subsequently utilised in large scale gene expression studies to profile pearl millet’s response to the defence signalling compounds nitric oxide (NO), methyl jasmonate (MeJA) and salicylic acid (SA), and to the biotrophic rust fungus Puccinia substriata var. indica. A pearl millet cDNA library was constructed by treating pearl millet plants with the defence elicitors chitin and flagellin, and by wounding the plants. Suppression subtractive hybridisation (SSH) was employed to enrich the library for defence response transcripts. In order to characterise the cDNA libraries, a quantitative cDNA microarray-based screening method was developed that enabled identification of false positive transcripts, as well as clones that represented rare or abundant transcripts. Based on this screening method, a number of clones were selected for sequence analysis, and their identity ascertained through homology searches with previously sequenced genes. This revealed a number of genes known to play important roles during pathogen attack. The pearl millet SSH defence response library, consisting of 1920 cDNAs either up- or down regulated in defence response, was spotted onto a glass slide microarray and used in transcript profiling studies to examine pearl millet’s response to the defence signalling molecules NO, MeJA and SA. Whilst only 45 cDNAs responded significantly to NO treatment, 279 and 224 cDNAs responded to MeJA and SA sprays, respectively. Closer examination of MeJA and SA responsive genes revealed that many of the induced transcripts were common to both signalling pathways, demonstrating that a substantial network of regulatory interactions exists between the salicylate and jasmonate pathways, which were previously believed to act in an antagonistic manner. Pathology studies indicated that pretreatment of pearl millet with SA conferred resistance to a virulent isolate of P. substriata var. indica, whereas MeJA application did not significantly reduce subsequent infection levels. Transcript profiling of a susceptible pearl millet line in response to virulent rust infection revealed that genes common to both the jasmonate and salicylate pathways were induced, suggesting that the plant adopts elements from a number of defence signalling pathways in an attempt to ward off infection by the virulent rust fungus. However, in view of results obtained from pearl millet defence signalling molecule pretreatments, it is probably genes that are significantly induced in response to SA, but to a lesser extent by MeJA that actually confer resistance to an avirulent rust isolate. Treatment of pearl millet plants with an avirulent P. substriata strain and subsequent microarray analysis would answer this hypothesis by revealing whether an incompatible reaction elicits more elements of the salicylate defence response pathway. / Thesis (PhD (Botany))--University of Pretoria, 2009. / Plant Science / unrestricted