CREA Journals (Consiglio per la ricerca in agricoltura e l’analisi dell’economia agraria)
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Evaluation of maize hybrids stability using parametric and non-parametric methods
Get PDFThe purpose of the study was to compare four parametric and three nonparametric methods for the assessment of agronomic stability of eight maize cultivars chosen from postregistration trials carried out at 16 locations in Poland for a period of three years. Significant correlations were found between mean yield and two parametric measures: bi and Di. Of nonparametric statistics only the new proposed measure (RD) was significantly associated with yield (r=0.86), whereas Kang’s rank sum just missed significance (r=0.68). Correlations between parametric and non¬parametric measures were in general not significant. Full correlation was found between Wricke’s ecovalence and Shukla’s stability variance. Hühn’s stability measures S1i and S2i were also highly positively associated (r=0.92). As expected high correlation was observed between ecovalance and S2di (r=0.98). The results showed that high yield¬ing cultivars can also be stable. The new proposed method based on homogeneous groups ranks can be a useful alternative to Kang’s rank sum parameter in studies of agronomic stability of maize hybrids
Post Flowering Stalk Rot Complex of Maize - Present Status and Future Prospects
Get PDFPost flowering stalk rot complex is one of the most serious, destructive and widespread group of diseases in maize and yield losses range from 10 to 42% and can be as high as 100% in some areas. PFSR nature is often complex as a number of fungi (like Fusarium verticillioides cause Fusarium stalk rot, Macrophomina phaseolina cause charcoal rot, Harpophora maydis cause late wilt) are involved in causation of the diseases. To combat this problem, identification of quantitative trait loci for resistance to PFSR would facilitate the development of disease resistant maize hybrids. Moreover, various chemical and biological control methods have been developed but ma¬jor emphasis is on development of maize cultivars with genetic resistance to for environment friendly control of the Post flowering stalk rot complex. The current paper reviews the information on distribution, impact of the disease, symptoms, epidemiology, disease cycle; genetics of resistance and integrated disease management approaches has been enumerated to understand the present status of knowledge about PFSR complex and will try to focus on the future perspectives available to improve PFSR management
Chemical composition and phytosterols profile of degermed maize products derived from wet and dry milling
Get PDFMaize is part of the diet of populations of all socio-economic classes in many countries around the world and is an excellent source of bioactive compounds such as carotenoids, phytosterols and lignans. Phytosterols have gained considerable interest because they possess properties that significantly reduce cholesterol levels in the blood by acting as antagonists. The purpose of this study was to characterise the fractions of maize flour obtained from Italian wet and dry milling processes from a chemical viewpoint (crude proteins, crude lipids and starch) and the contents of three main phytosterols. Whole parameters exhibited a broad variability in their content. The crude protein, crude lipids and starch contents ranged from 7.43 to 18.38% dry matter (dm), 0.61 to 8.53% dm and 23.77 to 80.41% dm, respectively, and the total phytosterol content ranged from 4.6 to 53.48 mg 100 g-1 dm. Significant differences were observed in the phytosterol compositions measured in degermed maize products obtained from wet and dry milling. The campesterol content ranged from 0.54 to 6.19 mg 100 g-1 dry weight (dw), respectively, for maize flour III and dry milling maize meal feed. The stigmasterol content ranged from 0.55 to 4.77 mg 100 g-1 dw for hominy grits II and broken degermed type I, respectively. In addition, the β-sitosterol content varied significantly from 2.51 to 44.37 mg 100 g-1 dw for hominy grits II and dry milling maize meal feed, respectively
Performance-based grouping of adapted and exotic drought-tolerant maize (Zea mays L) inbred lines under stressed and non-stressed conditions
Get PDFKnowledge of the heterotic responses of elite adapted and exotic maize inbred lines can facilitate their utilization for population improvement and hybrid development. In the present study, a line x tester mating design was used to determine the combining ability of 20 elite drought-tolerant maize inbred lines developed at CIMMYT and IITA and to classify them into heterotic groups under diverse growing conditions. The 20 lines were crossed each with two inbred line testers representing the tropical and temperate heterotic pattern established in West and Cental Africa (WCA), to generate 40 testcrosses. A trial comprising the 40 testcrosses along with the cross between the two testers and three hybrid checks were evaluated at two environments in the dry season and at six environments in the rainy season. GCA effects were more important than SCA effects in controlling grain yield in both seasons. Two exotic lines in the dry season and four exotic lines in the rainy season had significantly positive GCA effects. Only EXL22 was identified as a superior line in the two seasons. Only two adapted lines had significantly positive GCA effects in either or both seasons while three adapted lines consistently had significantly negative GCA effects in both seasons. Hybrid between EXL22 and tester 9071 showed broad adaptation to all test environments. The two testers separated some of the lines into two main heterotic groups. the lines in each heterotic group and the good combiners will be utilized for developing populations for extracting new improved inbred lines
Osmolyte-related recovery of the opaque-6 lethal phenotype in Zea mays L
Get PDFEndosperm growth and development is a complex phenomenon, driven by the coordinate expression of several genes. A series of endosperm mutants with altered timing and zein synthesis rate have been studied, allowing the partial unravelling of a multifarious system, integrating carbohydrate, amino acid, and storage protein me¬tabolisms, and operating during endosperm growth and development. The exact biological function of one of these loci, the Opaque-6 (O6) gene, remains to be acknowledged. The o6 locus determines a general reduction of 19- and 22 kDa zeins as well as a number of non-zein polypeptides present in the wild type endosperm. The o6 mutants present a collapsed, dull endosperm, leaf striations and early seedling death; however, o6 seedlings can survive when grown in the presence of exogenous proline. It has been suggested that, in mutant seeds and in con¬trast with the development of the normal seeds, proline does not reach the sites of protein synthesis in adequate amounts. Yet, it has been demonstrated that amino acids other than proline are also able to restore o6 seedling le¬thality, contradicting this hypothesis. In this paper, we explored the possibility that the observed proline-mediated rescue of o6 mutant seedling lethality regarded an osmolyte-mediated mitigation of aberrant protein folding rather than the restoration of a reduced proline flux needed for protein synthesis. This hypothesis was tested by means of in vitro cultivation of o6 seedlings in the presence of putative osmolytes including a series of amino acids, me¬thylamines, and polyols. Several osmolytes were identified, which were able to restore normal growth in o6 mutant seedlings. Root reestablishment required higher osmolyte concentrations than those necessary for the recovery of the aboveground plant parts. The results presented in this paper provide sufficient preliminary evidence to assume that proline-induced recovery of the o6 mutant phenotype depends on the osmolytic properties of this amino acid
Prospects of endosperm DNA in maize seed characterization
Get PDFDNA based characterisation of maize germplasm has become the easiest and fastest approach to identify genetic diversity as compared to phenotyping. The conventional DNA source for genotyping is the leaf which required at least 2 weeks waiting period from seed planting to leaves sampling. This work exploits the use of endosperm DNA (EDNA) for the genotyping of maize germplasm. Maize endosperm was excised from maize seeds using pli¬ers, ground and used for Genomic DNA extraction (gDNA). Leaves DNA (LDNA) was also extracted concurrently. The extracted LDNA and EDNA were quantified and subjected to SSR-PCR. The mean concentrations of DNA extracted were 1575 ng/ul for the leaves and 526 ng/ul for endosperm. Though the difference in quantity of EDNA and LDNA were highly significant, the quality (A260/A280) for both EDNA and LDNA fall within 1.6-1.8 range of pure DNA index. SSR-PCR products using phi032 were similar for both EDNA and LDNA, indicating the usability of EDNA in genotyping. This seed based method of gDNA extraction takes less than 24 hours from sampling to quantification and genotyping. It also allows germination of sampled seeds, selection before planting, avoids the delay of planting and waiting in leaf sampling and saves field space
Experiences with the planting of Sorghum bicolor L (Moench) in Switzerland
Get PDFSorghum bicolor (L) Moench is one of the most important arable crops worldwide. Although the main cropping area lies in warm regions like India, Africa and America, sorghum is also cropped successfully in Europe. Surface planted with sorghum increased again during the past few years, among other reasons also because of the low pressure of insects and diseases and because its ability to outlast drought periods better compared to maize. Up to now little information about the cropping of sorghum in Switzerland was available. In order to gain information about the quantity and quality of sorghum grown in Switzerland, field trials with different varieties were established during the years 2009, 2010, and 2011. Best yields of the earliest maturing varieties in the year 2009 in the small plot experiment were satisfactory: up to 11.0 t ha-1 with a dry matter content of 84% at the time of the harvest. In order to meet the requirements for a fast development, a complete pollination and grain formation, only sites excluding natural depressions or wind-exposed sites and the prevention of too early seeding should be consid¬ered. The analyses of the grains showed, that the Swiss sorghum is of good quality and can compete for this aspect with imported sorghum. This successful cropping of sorghum in Switzerland shows, that more information on C4-species is necessary to Swiss farmers, as the availability of cultivars adapted to the climatic conditions in Switzerland can offer a solution to the changing conditions of the environment
Inbreeding in modified ear-to-row selection in maize
Get PDFThe corrected calculation of inbreeding in mass selection was shown in a previous paper; inbreeding in modified ear-to-row selection was calculated in that paper with the uncorrected equation. In the present paper, inbreeding is calculated for the modified ear-to-row selection method using the corrected equation. Establishing a detassel¬ing plot is the second phase of the aforementioned method. Inbreeding values were quite small; inbreeding was about 6% in selection cycle 100. The reason behind widespread use of modified ear-to-row selection may be smaller inbreeding values
Nitrogen and phosphorus effects on winter maize in an irrigated agroecosystem in western Indo-Gangetic plains of India
Get PDFWinter maize is an innovation in Indian cropping systems. It grows 50-60 days longer than rainy-season maize and is a heavy feeder cereal. It lacks proper management of nutrients, particularly nitrogen and phosphorous. N and P determine the photosynthetic and reproductive capacity of plants. The response of maize to these nutrients is season-dependent and location-specific, but has seldom been studied in winter maize areas in India. This study was designed to evaluate the impact of N and P independently and interactively on winter maize. Maize yield was highest at 240 kg N ha-1, but the yield obtained at 160 kg N ha-1 was comparable. Every kg N applied produced 44.34 kg grain, and the N-use efficiency was reduced with increased N dose (67.4, 38.4, and 27.2 kg grain kg-1 N for 80, 160, and 240 kg N ha-1, respectively). Phosphorus application increased yield up to 26.4 kg ha-1. A combi¬nation of 240 kg N ha-1 and 26.4 kg P ha-1, providing highest gross returns, net returns and net benefit: cost, was most profitable. The economic optimum dose for N and P was 196 kg N ha-1 and 23.4 kg P ha-1, respectively. This study shows that winter maize is responsive to higher levels of N up to 240 kg ha-1 compared to 120 kg N ha-1 recommended for rainy-season maize, but P application at 26.4 kg ha-1 remains same for both the seasons. The study provides recommendation of N and P for winter maize based on economics. The data would be useful for fitting models and simulating yields across the doses of N and P
Bulk genetic characterization of Ghanaian maize landraces using microsatellite markers
Get PDFMaize (Zea mays L) was first introduced into Ghana over five centuries ago and remains the most important cereal staple, grown in all agro-ecologies across the country. Yield from farmers’ fields are low, which is attributed in part to farmer’s preferences and/or reliance on local landraces for cultivation. Efforts are underway to improve some of these landraces for improved productivity. Seeds of maize landraces cultivated in all agro-ecologies were col¬lected for genetic characterization using a bulked fingerprinting technique and 20 SSR markers. In all, 20 popula¬tions of 15 plants each from Ghana and 4 control populations from Latin America were characterized. The cluster analysis grouped the 20 landraces into two major groups corresponding to the vegetation/climatic conditions of the north and south of the country. Genotypes from Ashanti, which is centrally located, fell into both major clus¬ters, which suggest its importance in maize seed distribution in Ghana and also the diverse climate/vegetation. A Structure analyses grouped the genotypes into two major clusters similar to the UPGMA cluster, and populations were not fully distinct according to F statistics. The results suggest that breeders should make performance data available to seed dealers for better productivity