CREA Journals (Consiglio per la ricerca in agricoltura e l’analisi dell’economia agraria)
Not a member yet
791 research outputs found
Sort by
Swiss maize (Zea mays L) landraces. Their genetic diversity and distinctiveness in a global comparison
Get PDFSwiss maize landraces are expected to be genetically diverse, as they have been cultivated in different climatic regions of Switzerland for almost 500 years. A core collection of 35 Swiss maize landraces was recently defined. This core collection was analyzed in the present study, with the objectives (i) to resolve genetic diversity and phylogeny of the core collection, (ii) to relate these results to those obtained in a worldwide collection of maize landraces, thereby (iii) analyzing separation and admixture and (iv) to identify unique alleles that were detected only in Swiss maize landraces (Swiss alleles). A high diversity (HT = 0.61) in an international comparison and many Swiss alleles pointed at the value of this core collection as a plant genetic resource. The genetic differentiation within the core collection was in very good accordance with the geographic separation caused by the Swiss Alps. The accessions grouped into three major clusters, two northern and a southern one. Additionally, landraces from Valais built an intermediate cluster, which is probably the result of hybridization between different European germplasm. Continuous maize cultivation in remote areas may have favored genetic drift and intentional selection by farmers and may have led to this particular cluster. In the international comparison, northern Swiss accessions were related to European and American Northern Flints, whereas southern Swiss accessions were closely related to southern European Flints (e.g. Italian Orange Flints). Some northern Swiss accession combined high diversity with many Swiss alleles, which may be valuable for broadening the European Flint pool
Yield of tropical Asian maize (Zea mays L) at alternating row irrigation and at severe drought
Get PDFDrought is a major reason for inconsistent grain yield of maize in lowland tropical and subtropical areas. In bimodal rainy seasons with unequal amounts of rainfall, the shorter season requires germplasm with sufficient residual yields at various situations of low water availability. Thus farmers will avoid the risk of cultivation failure. The respective adaptation of eight Thai hybrids was tested in two dry seasons from late November 2003 to April 2005. Furrow irrigation of 40 mm was applied at seven days intervals from planting to physiological maturity (control, W1); 50% less water supply than W1 from the sixth week onwards by alternating irrigation of one of two rows (W2); withholding water from 5 weeks after planting to the beginning of anthesis (W3). At W3, three hybrids excelled with yields above 350 g m-2, i.e. residual yields of more than two of them performed very well at W2 too, with more than 650 g m-2, a residual yield of about 80%. This genetic range is encouraging to breed for earlier hybrids that can be cultivated in the minor rainy season with a reduced risk of failure
Response of nitrogen nutritional indices of maize leaves to different mineral-organic fertilization
Get PDFMaize crop growth rate during the course of vegetation is strongly dependent on nitrogen supply. The most critical stages of maize response to this nutrient are exhibited both in very early growth stages, as related to the stage from five (six) to eight leaves, and in the period from tasselling to the blister stage. Among many indicators of plant nitrogen nutritional status, the most promising include nitrate reductase and acid invertase activity, since the enzymes significantly affect the growth of new tissues. Two series of field experiments were conducted in 2009 and 2010 to evaluate the effect of six fertilization treatments, differing in the prevailing source of nitrogen (from pure mineral to classical organic), on nitrate concentration, nitrate reductase and acid invertase activity and finally on the assimilation area of a single maize plant or the ear leaf. A significant effect of each fertilization treatment on all the examined maize plant characteristics was observed, but it was mostly seasonally variable. Nitrate reductase was linearly affected by the nitrate concentration in maize leaves. Both evaluated indices of acid invertase showed a curvilinear effect on the maize plant morphological characteristics. Therefore it can be concluded that excessive acid invertase activity may inhibit the growth rate of the maize assimilation area in the flowering stage
New species of Entomobrya from Etna Mountain, Sicily (Collembola Entomobryomorpha)
Get PDFSicily is described. Entomobrya siciliana n. sp. is separated from all other known species by the following combination of characters: characteristic colour pattern, ratio antennae/head length ≈2, apical vesicle bilobated, labral papillae almost smooth, with two small projections on central ones, claw with 4 internal teeth and empodium with serrate external edge (leg III). The macrochaetotaxy is described. For the identification and description of these species we used the set of characters proposed by JORDANA and BAQUERO (2005)
Results of the study of cross-resistance and effect of herbicide on crops in the production of cycloxydim-tolerant maize (Zea mays L)
Get PDFIn Hungary, monocot weed species are present as a signiἀcant yield limiting factor. In practice there is a great demand for efἀciently applying agrochemicals against monocot weeds at a later period and without causing phy totoxicity. Field trials were carried out in 2010 and 2011. The trials aimed to understand whether the cycloxydim-tolerant (CT) maize have cross-resistance to herbicides expressing different graminicide action (quizalofop-p-tefuril, haloxyfop-r-methyl ester, propaquizalofop, Ḁuazifop-p-butyl). The obtained results conἀrm that CT maize has signiἀcant tolerance to cycloxydim active substance. Lower rates of other types of graminicides neither damage maize plants nor reduce the yield, while application of higher rates used to control perennial weeds do. According to the authors’ conclusions, no other types of graminicides can be used to perform chemical weed control in CT maize. Post-emergent use of cycloxydim showed excellent efἀcacy against monocot weeds: Echinochloa crusgalli, Setaria verticillata, Panicum miliaceum. It is well-known that growing genetically modiἀed maize is greatly restricted in Europe, therefore the published scientiἀc results provide good option for the control of monocot weeds in the maize growing areas
Virus-Induced Gene Silencing in Diverse Maize Lines Using the Brome Mosaic Virus-based silencing vector
Get PDFVirus-induced gene silencing (VIGS) is a widely used tool for gene function studies in many plant species, though its use in cereals has been limited. In addition, within cereal species the varieties that best respond during VIGS screens are often not known. Using a Brome mosaic virus (BMV) vector designed to silence the maize phytoene desaturase (PDS) gene, a genetically diverse set of maize inbred lines was screened for development of gene silencing after inoculation of seeds through the novel use of a vascular puncture inoculation technique. In addition to Va35, which previously was shown to support silencing, maize lines NC300, Ki11, Oh7b, M162W and CML52 displayed significant visible photobleaching when challenged with the BMV-PDS. In these plants, targeted PDS mRNA expression was decreased 50-80% relative to levels in plants that were inoculated with BMV containing a fragment of the GUS gene or were mock-inoculated
Banded leaf and sheath blight: an emerging disease of maize (Zea mays L)
Get PDFThe basidiomycetes fungus Rhizoctonia solani is a major pathogen of maize worldwide, particularly in China, South Asian and South East Asian countries. It causes banded leaf and sheath blight (BLSB) on plants, which is considered an emerging disease, accompanied by small losses to total wipeout of the crop. This disease is more prevalent in humid weather with temperature around 28°C. The genetics of inheritance of this disease is unclear. Digenic as well as oligogenic inheritance of disease has been reported. A number of QTLs have been identified which will help to expedite breeding program against BLSB. Moreover, various chemical and biological control methods have been developed, but major emphasis is on development of maize cultivars with genetic resistance to BLSB for environment friendly control of the disease
Comparative expression of cell wall related genes in four maize RILs and one parental line of variable lignin content and cell wall degradability
Get PDFA comparison of gene expression in maize between the parental line F271 and four RILs derived from the cross F288 x F271 was investigated based on hybridization on the 17,555 probes Affymetrix micro-array, targeting nearly one third of the genes present in maize genomes. The parental line had unfavorable alleles for cell wall degradability traits at the major QTL position in bin 6.06, while the set of RILs had both the favorable allele and high cell wall degradability. 360 genes were differentially expressed in the four RIL in comparison to F271, including nine genes underlying the major QTL position and 36 underlying two other QTL positions. However, their proposed function (whenever is described) do not allow us to firmly consider their involvement in the observed variation of cell wall related traits. Only a few genes involved in monolignol biosynthesis or polymerization located elsewhere in the genome were differentially expressed between the four RILs and F271, corroborating with the fact that these genes are probably not involved in major determinants of cell wall degradability in the studied set of lines. Among the investigated regulation factors, three ZmMYB, one NAC and one C3HC4 zinc finger were differentially expressed between the four RILs and F271, but they were not located in bin 6.06. Notwithstanding, the obtained results especially strengthened the probable involvement of these genes in maize secondary wall assembly and/ or lignification
Genetic diversity assessment and relationship among tropicalyellow endosperm maize inbred lines using SSR markers
Get PDFMaize is the most important food crop in sub-Saharan Africa. Tropical-adapted yellow maize inbred lines can be used as source of provision of pro-vitamin A, needed by millions of African children that suffer from vitamin A deficiency. A substantial variation of pro-vitamin A content is known to exist among available inbred lines. The objective of this study was to assess the diversity and relationship among 38 tropical-adapted maize inbred lines. The lines were investigated using 87 SSR markers. Seventy-five (75) SSR markers were polymorphic across the 38 inbred lines and generated a total of 297 alleles. The polymorphic information content (PIC) values obtained for the polymorphic SSR markers varied from 0.17 to 0.84 with an average of 0.56 .The number of polymorphic alleles per locus ranged from 2 to 11 with a mean of 3.96. Genetic distance (GD) values among all pairs of inbred lines varied from 0.007 to 0.59 with an average of 0.45. Cluster and principal coordinate analyses based on genetic distance from SSR data showed two well defined main groups of the 38 inbred lines, consistent with their pedigrees. The study has revealed a considerable level of genetic diversity among the inbred lines. The genetic potential that exists will facilitate the selection of parents with diverse alleles for development of new maize genotypes with higher pro-vitamin A level
Natural genetic variation for root traits among diversity lines of maize (Zea Mays L.)
Get PDFMaize (Z. mays L.) is the third most important food grain for humankind after rice and wheat. Maize is mostly grown under rain-fed conditions and among the cereals, it is the second most susceptible to drought next to rice. Constitutive variation for root traits is an important adaptation under drought prone conditions. The objective of this study is to screen the twenty five diverse parental lines used in the maize nested association mapping panel along with the common parental line, B73, for constitutive root traits (including rooting depth and root biomass) and shoot traits. All the lines were grown with five replications in 72 cm deep pots containing a turface:sand mixture (2:1 v/v) for 30 days under well-watered conditions in a temperature and humidity controlled green house. Significant variation existed among the diverse lines for root length, root biomass, shoot length, and leaf area. The average root length ranged from 17.5 to 106 cm. The genotypes with a deep root system also recorded greater root biomass and leaf area. The natural genetic variation exhibited by these lines could be exploited to identify potential quantitative trait loci controlling root architecture. Using the nested association mapping populations that were developed from these diverse lines, would allow for in-depth analysis and fine-mapping of prospective candidate genes for root architecture in maize