Evaluating seed quality and performance of low and high phytic acid maize (Zea mays L.) under varying phosphorus rates and water regimes in dryland conditions.

Doctoral Degree. University of KwaZulu-Natal, Pietermaritzburg.Maize (Zea mays) being the staple crop for many communities in Sub-Saharan Africa and also used for animal feeding, a considerable effort has been made to improve quality and yield. In recent times plant breeders have focused on reducing phytic acid (PA) on maize seeds to improve grain nutritional quality. Although studies of low phytic acid genes have been reported in temperate maize, the current research was based on the tropical genetic background which was screened for low phytic acid. This is the first report for applied breeding of the trait in the tropical maize. Little is known on the agronomy and responses of tropical maize specifically to water stress and its response to phosphorus application. No studies provided on the seed quality performance and response of low phytic acid maize to water stress and phosphorus application. Reducing Phytic acid of tropical maize could have negative effects on seed quality and yield. The primary objective of this study was to compare the performance of low phytic acid (LPA) maize seeds of tropical origin with three other varieties i.e. high phytic acid (HPA) of tropical origin, SC701 and LS8520 based on seed quality and water stress. The study consisted of two maize synthetic populations differing in phytic acid (PA) content (from the African Center of Crop Improvement (ACCI)); namely, LPA and HPA synthetic populations. Both the LPA and HPA synthetic populations were derived from a tropical second generation (F2) population and were selected based on their phytic acid (PA) content. They were produced at the Ukulinga Research Farm, University of KwaZulu-Natal (29°40'05.7"S 30°24'20.9"E), in Pietermaritzburg, South Africa. These two maize synthetic populations were compared with two commercial maize varieties (from McDonald Seeds), white maize (SC701) and yellow maize LS 8520 R (484) which in this study was coded LS8520. All seeds used in this study were produced under identical production conditions and in the same growing season, thereby ensuring that the seeds were of the same physiological age. The first experiment investigated the characterisation of LPA maize varieties for seed germination and vigour. Seed quality was evaluated using the standard germination test and accelerate aging test together with electric conductivity test (EC). The second experiment was conducted as a pot trial to investigate the effect of exogenous phosphorus application on seed quality and yield of low phytic acid maize varieties. In third experiment, a field study over two seasons (2015/2016 and 2016/2017) was conducted at Ukulinga Research Farm in Pietermaritzburg, under dryland conditions. The objective of the experiment was to evaluate the newly produced ACCI’s two genetically synthetic maize populations of LPA and HPA under dryland field condition and compare them with the commercial white and yellow tropical maize varieties their germination, growth, yield and yield components. Lastly, an experiment under controlled conditions on photosynthetic efficiency and yield responses of LPA and HPA maize tropical lines to deficit irrigation. The study was carried out under controlled environment conditions. The objective was to evaluate the photosynthetic efficiency of low phytic acid (LPA) and high phytic acid (HPA) tropical maize varieties grown under water-stressed conditions. The results of the first experiment indicated that the performance of LPA varieties was comparable to those of commercially produced varieties. This study suggests that the combination of LPA lines of tropical origin used in this study was satisfactory to meet the minimum seed quality parameters particularly seed germination and vigour. The results for phosphorus application showed that the application of phosphorus improved the growth, flowering and yield of LPA and other varieties as well. The mean germination time (MGT), germination vigour index (GVI), electrical conductivity (EC) (μS g-1), root length, shoot length and the root-shoot ratio of the harvested seeds after phosphorus application were also improved. When the LPA and HPA tropical maize exposed to dryland environments the results revealed that the SC701 variety outperformed the other three varietiess in growth and yield. It was concluded that the LPA maize performed lower under field conditions. In the water stress trial, results showed that LPA maize varieties recorded higher values of stomatal conductance (gs) and transpiration rate (T) compared to HPA and SC701 for both normal and water stress conditions. HPA showed a significantly (P< 0.001) higher value of photosynthetic rate (A) than LPA and SC701 for all the water stress treatments. HPA and SC701 were comparable in most of chlorophyll fluorescence parameters. With regard to yield, HPA showed increased performance in terms of overall yield and seed weight, and this suggests that HPA varieties are less sensitive to water stress than LPA maize varieties. The results from this study have proven that LPA maize varieties are sensitive to limited conditions and further research under a wide range of environmental conditions is required. Overall, the results indicated that the seed germination of LPA was comparable to other varieties but the yield remains low. There is a need to conduct more experiments to demonstrate the performance of LPA under field conditions in response to phosphorus application and water stress. These differences between the traits could help breed programs. The selection for LPA and HPA tropical maize should be based on their physiological performance to be planted in temperate zones to grant higher yield performance

Clinical and echocardiographic features of children with rheumatic heart disease and their serum cytokine profile

Acute rheumatic fever (ARF) and rheumatic heart disease (RHD) constitute important public health problems in developing countries. Children with ARF and RHD seen at Children’s Hospital-Sudan from May 2008-2009 were examined clinically and by echocardiography. Blood cytokines (interleukin 10 (IL10), Tumor necrosis factor alpha (TNF- alpha) and interferon gamma (IFN-gamma) were done. Thirty six children were enrolled; 63% had established RHD, and 37% ARF. Mitral regurgitation (MR) was the most common lesion (94%).Ninety five percent of the valve lesions were severe. The serum interleukin IL10 level ranged between 3-6 pg/ml. TNF alpha levels were 9- 100 pg/ml in 12 patients (40%), 101-1000 pg/ml in 10 patients (33%) , more than 1000 in 8 patients (26%). The level of IFN gamma ranged between 2-7 pg/m in all patients except 2 (84 and 135 pg/ml). RHD is manifested with severe valvular lesions and a high TNF alpha indicating and ongoing inflammation.Pan African Medical Journal 2012; 13:3

Assessment of The Effects of Winter Condition on Sweet Sorghum Yield and Sugar Content

Sweet sorghum is an important crop which is produced for food, energy and feed (Almodares and Hadi, 2009). The crop prefers warm moist soil for germination and emergence. However, it would be more beneficial if it can be grown in different seasons. A field experiment was carried to evaluate sixteen sweet sorghum genotypes [Sorghum bicolor (L.) Moench] under winter conditions in order to assess the possibility of producing the crop throughout the year since the crop consumes less water and has a short life cycle when compared with sugarcane. The genotypes we recollected from different areas of Sudan. The experiment was planted using a Randomized Complete Block Design with three replications. There were significant differences among genotypes with respect to the number of days to germination, plant height, number of leaves per plant, chlorophyll content, stem diameter, head weight, shoot fresh weight, head to shoot ratio, brix value, juice weight and number of days to maturity. A highly positive correlation (0.92) was observed between juice and shoot weight, and there was a negative correlation (-0.14) between brix value and head weight. The genotypes showed high variability in all mentioned parameters, hence, could be useful genetic resources for breeding winter adaptation