CREA Journals (Consiglio per la ricerca in agricoltura e l’analisi dell’economia agraria)
Not a member yet
791 research outputs found
Sort by
An annotated checklist of aphids surveyed in the Italian regions of Tuscany and Emilia Romagna
Get PDFThis paper deals with the aphid fauna complex of the two administrative regions of Tuscany and Emilia Romagna (N.C. Italy) where a total of 442 taxa of specific and sub-specific rank are registered of which 385 taxa belong to Tuscany and 326 to Emilia Romagna. Furthermore, additional notes are provided on a few species which have not yet been recorded or are practically unheard of in Italy. A short chorological comment on the species complex is also added
Effectiveness of plant-derived formulations against the rootknot nematode Meloidogyne incognita (Kofoid et White) Chitw. in a protected tomato crop
Get PDFThe effectiveness of two plant-derived formulations for the control of the root-knot Meloidogyne incognita (Kofoid et White) Chitw. was evaluated in a protected tomato crop in Southern Italy. A neem oil-based formulation and a commercial mixture of aqueous extracts of Quillaja saponaria Molina (80%), Yucca schidigera Roezl (10%) and Tagetes spp. (10%) were tested in comparison with the standard chemical oxamyl and an untreated control. All tested formulations significantly decreased soil nematode population and average root galling compared to the untreated control. However, nematode infestation was found significantly lower in plots treated with oxamyl or neem formulation than in those treated with quillay-based product. Tomato yield did not significantly differ among treatments. Satisfactory yield obtained by quillay-based product appears to be caused by the biostimulating effect of quillay extract on tomato plants
Association of progeny variance and genetic distances among parents and implications for the design of elite maize breeding programs
Get PDFChoice of crosses is crucial for a successful and sustainable management of breeding programs. Our objectives were to (1) investigate the association between the Rogers’ distances among parents and the genetic variance within their crosses (σ2 within) in elite maize breeding germplasm, (2) study whether this association can be improved selecting trait-specific markers, and (3) evaluate the consequences to implement the usefulness criterion based on Rogers’ distances on the optimum choice of crosses. Testcross performance of eleven segregating crosses with a total of 930 progenies was evaluated in six environments for grain yield (GY) and grain moisture content (GMC). Moreover, the 930 genotypes were fingerprinted with 425 polymorphic SNP markers. Our findings revealed that working within a heterotic group, σ2 within increased with increasing Rogers’ distances among the parents. This was more pronounced for GY (rP = 0.55 P < 0.1) compared to GMC (rP = 0.17). Selecting trait specific markers, which were associated with putative QTL affecting these traits, led for GY to a decrease in the association between σ2 within and Rogers’ distances among the parents. Consequently, using for GY a regression model based on Rogers’ distances estimated with an unselected set of markers allows a rough implementation of the usefulness criterion in maize breeding programs. Our model calculations suggested that implementing the usefulness criterion will facilitate a broadening of the diversity of elite maize breeding pools by counterbalancing a reduction in parental performance with an increase in σ2 within
Chemical composition and fatty acid content of white food sorghums grown in different environments
Get PDFThe chemical composition and fatty acid content of both white sorghum hybrids and pure lines grown in various areas of the world were studied. Various attributes were investigated including moisture, protein, carbohydrate, dietary fiber, fat contents, and fatty acid composition. Slight variations in both protein and in fiber contents were observed among cultivars. Linoleic, oleic and palmitic were the most abundant fatty acids in all samples with little difference in their percentage content among the cultivars. Enzyme-linked immunosorbent assays (ELISA) dem¬onstrated, for all sorghum flours analyzed, the absence of toxic protein sequences for celiac patients. The present results demonstrate that food-grade sorghum varieties are potentially able to be grown in Mediterranean countries in addition to regions where sorghum has been traditionally produced, i.e. either in arid tropical and sub-tropical regions of Africa and Asia or in dry regions of America
Preliminary field screening of maize landrace germplasm from northeastern Mexico under high temperatures
Get PDFNortheastern Mexico has a wide variety of maize landraces that have not been characterized, and landraces vari¬eties may be a good source of new allelic diversity for useful traits. This study evaluated 28 accessions from Tam¬aulipas, in Northeast Mexico, chosen by phenology and for agronomic characteristics to represent the diversity of germplasm in the collection and agro-ecosystems of this area. They were evaluated under high temperature in the field as a basis for an efficient use of this maize germplasm in a breeding program; in particular we investigated changes in agronomic characteristics affected by high temperatures in all growing seasons. Results indicated that in late planting dates air temperatures become excessively high during the flowering period and growing season; in these conditions a loss in grain yield can be sustained. In this study, the loss initially manifests itself as a reduc¬tion in grain yield (> 32%) because of fewer grains per ear (>26%). Landrace maize accessions C-3030, C-3049, C-3015, Pob. I, Pob. II, ZEM-148 and C-4050 were identified with high relative yield and yield components traits under high temperature conditions. These accessions have greater agronomic stability, and also are potential donors of genes to improve maize tolerance to high temperature
Screening of phytic acid and inorganic phosphorus contents in corn inbred lines and F1 hybrids in tropical environment
Get PDFSeeds of inbred lines and F1 hybrids of corn (Zea mays L) grown from late rainy season of 2007 to early rainy season of 2009 at the National Corn and Sorghum Research Center, Thailand, were analyzed to determine the contents of phytic acid (PA) and inorganic phosphorous (InP). The PA contents in the tested inbred lines and F1 hybrids ranged from 800 to 1,000 mg per 100 g seed. The two groups of Ki inbred lines (Nursery no. 122 in the 2007 late rainy season), based upon the analysis of PA, were categorized to low (L) (the value o
Estimation of quantitative genetic and stability parameters in maize under high and low N levels
Get PDFAB It is important to breed maize (Zea mays L) cultivars with high performance under variable N levels. We studied the effect of N levels and estimated quantitative genetic parameters for grain yield, quality, and other traits, and examined stability of performance for grain yield in diverse Chinese maize germplasm. From 2006 to 2008, each year 20 and in total 30 maize hybrids, including commercial hybrids currently grown in this region and other ex¬perimental hybrids as well as high-oil hybrids, were tested using nine environments (location-year combinations) in North China Plain. In each environment, two replicated trials were grown: one under high N application rate (HN, 225 kg N ha-1) and the other under low N application rate (LN, no N fertilization). Compared to HN, grain yield was significantly reduced (35.6%) under LN level, as well as kernel number per ear, 1000-kernel weight, plant and ear heights, and protein concentration. In the analysis over environments under each N level, genotypic variance was significant and heritability was high for all traits. In the analyses across N levels and environments, genotypic variance was significant for all traits and larger than the genotype × N and/or environment interaction variance components except for protein concentration. In stability analyses across N levels, hybrids differed for their linear response to environments, and some showed dissimilar response under HN and LN levels. Our results indicated that breeding maize adapted to variable N levels is feasible with the Chinese germplasm available in the summer breeding programs in North China Plain. Multi-environment tests are required to identify hybrids with high grain yield under variable N conditions, and examining yield stability separately under HN and LN would be useful
Molecular characterization of tropical sweet corn inbred lines using microsatellite markers
Get PDFGenetic variability among 13 tropical sweet corn inbred lines derived from source populations originating from five tropical countries was investigated using 95 polymorphic microsatellite markers. It was found that 92.9% of total molecular variance was due to variations among the inbred lines. This was further supported by the presence of high values of DST, FST, GST and FIT, indicating high genetic variation among the inbred lines. The average number of alleles and effective number of alleles were both close to one allele per locus per inbred line. Departure from Hardy-Weinberg equilibrium was observed with a drastic reduction of the observed heterozygosity, resulting in a lower index of genotypic diversity than expected for each of the inbred lines. The inbred lines were further assigned into six main heterotic groups based on their molecular characteristics using Fitch-Margoliash algorithm. High genetic variations among the inbred lines indicates the presence of different heterotic groups, while low level of genetic variability within the inbred lines indicates that they met the assumption of homozygosity of their loci to enable further diallel crosses to be made for analysis of their combining ability. It is therefore expected that high heterosis in yield and its components could be obtained from crosses among those inbred lines belonging to different heterotic groups
Behaviour of Quality Protein Maize (QPM) genotypes under well irrigated and water stress conditions in subtropical climate
Get PDFDrought or water stress is one of the prime problems affecting production of maize at global level. A major objective of QPM breeding programs in semi arid tropics or subtropical climatic conditions is to increase genetic potential of QPM genotypes under water stress conditions. In order to identify drought tolerant single cross QPM hybrids an experiment with 85 genotypes was conducted under well irrigated and water stress conditions. Six drought tolerance indices viz, mean productivity (MP), geometric mean productivity (GMP), yield index (YI), tolerance index (TOL), stress susceptibility index (SSI), and superiority measures (SM) were used on the basis of grain yield in water stress (Ys) and well irrigated (Yp) conditions. Highest significant positive correlations were observed among MP, GMP and YI indices. The hybrids 75, 38, 27, and 50 were more drought tolerant based on drought tolerance indices. Three dimensional plot, bi-plot and cluster analysis confirmed these results. Principal component analysis reduced six indices down to two components with 90.71% proportional cumulative variance. Genotypes were grouped by two ways cluster analysis (using Ward’s method) based on Yp, Ys and drought tolerance indices. Also, the results of correlation, 3D graphs, bi-plot and cluster analysis reveals that the most suitable indices to screen QPM genotypes in drought stress conditions were MP, GMP and YI. These indices could be used in QPM breeding programs to introduce drought tolerance in single cross hybrids