1,721,000 research outputs found
A Comprehensive Approach to Evaluate Durum Wheat–Faba Bean Mixed Crop Performance
Full text linkPlant breeding for intercropping is lagging because most varieties currently available in the market are selected for sole cropping systems. The present study analyzed the response of durum wheat (12 varieties) and faba bean (3 varieties) in pure and mixed cropping. Field trials were conducted in 2019 and 2020. The performance of each variety in mixed and pure cropping was evaluated using both univariate and multivariate analyses of the grain yield and land equivalent ratio (LER). For durum wheat, grain protein content was also evaluated. Durum wheat varieties were characterized by good performance in both years, whereas faba bean varieties were more affected by the growing season, suggesting that much breeding effort is warranted to improve the latter as a pure and mixed crop. Moreover, the relative performance of all varieties was affected by their combination in mixed cropping, as evaluated based on the ratio (LERratio) between LER for wheat (LERw) and LER for faba bean (LERfb). To further evaluate the overall performance of wheat and faba bean in mixed cropping, total yield, LERtotal (LERw + LERfb), and ln(LERratio) were subjected to principal component and cluster analyses. The first principal component combined the total yield and LERtotal in a single index of the overall performance of each mixed crop combination. The second principal component, based on ln(LERratio), highlighted the relative performance of varieties in each mixed crop combination. The proposed multivariate approach can be applied in the breeding programs for intercropping to identify variety combinations based on crop performance and the relative importance of the proportion of cereal and legume grains in the total harvest
Environmental influence on the frequency and viability of meiotic and apomeiotic cells in a diploid mutant of alfalfa.
No full textApomixis involves the parthenogenetic development of apomeiotic eggs. It has the potential of cloning plants through seed, and thus furnishes a unique opportunity in alfalfa breeding for developing superior cultivars with permanently fixed heterosis. Megasporogenesis of a meiotic mutant of alfalfa Medicago sativa subsp. falcala (L.) Arcang. (2n = 2x = 16), named PG-F9, that produced 2n second division restitution (SDR) and apomeiotic eggs at high frequencies, was cytologically analyzed by both stain-clearing and sectioning techniques. The restitutional 2n egg formation was mainly due to the omission of the second meiotic division. The absence of cytokinesis was also documented after a normal second meiotic division. The concurrent examination of integument growth, cell appearance, and nucleolus size associated with either the absence of degenerating meiotic products or aposporic initials in the ovules allowed the production of apomeiotic 2n megaspores to be ascribed to a diplosporic pathway. The mutant PG-F9 was grown in the field and in a growth chamber and the frequencies of normal, restitutional, and diplosporic cells were recorded under both environments. Restitutional 2n megaspore formation (dyads and triads with 2n chalazal megaspores) and the suppression or modification of meiosis leading to apomeiotic 2n megaspore production were influenced by environmental conditions. The frequency of normal tetrads was three times higher in the field (23.08%) than in the growth chamber (7.91%). The same trend was found for functional reduced chalazal megaspores. The frequency of restitutional cells was largely preserved in the two environments (51.92% in the field versus 50.31% in the growth chamber). The omission of normal meiosis resulting in diplosporic cells increased from 16.35% in the field to 26.27% in the growth chamber. The fertility of seed set and seeds per pod values of PG-F9 in controlled matings carried out in the field and in the growth chamber using different diploid and tetraploid pollen sources furnished information on 2n egg viability and partially supported the cytological results. The discrepancy observed indicated that some 2n megaspores were unable to develop into a functional embryo sac
L'osservazione citologica ed istologica come mezzo d'indagine nello studio dei sistemi riproduttivi.
No full textThe recent developement of stain-clearing techniques allowed an increase in the information concerning cytological mechanisms responsible for 2n egg formation. Using these methodologies, our research group has already characterized several diploid alfalfa mutants producing 2n eggs at high frequency. Moreover, it was verified that stain-clearing techniques can be efficiently applied also to the cytological analysis of microsporogenesis and therefore they will be useful for a quick cytological analysis of mutants producing both 2n pollen and 2n eggs. In the present paper, our results, together with the potential applications of stain-clearing techniques in advanced breeding programs based on the use of 2n gametes, are discussed
Molecular markers as a tool for the characterization and exploitation of genetic resources in the Medicago sativa complex
No full text
Mapping of amplified fragment length polymorphisms linked to apomeiosis in Medicago spp. and parthenogenesis in Poa pratensis L. by bulked segregant analysis.
No full textCytological and molecular characterization of reproductive mutants of lucerne with a breeding interest.
No full textCyto-embryological analyses based on stain-clearing techniques were employed to investigate sporogenesis and gametogenesis of lucerne (Medicago sativa) with the aim of establishing the mechanisms responsible for 2n gamete formation
Conservazione delle risorse genetiche agrarie e forestali in aree protette
No full textAtti 'Gestione delle risorse agro-forestali in aree protette', Ancona, 19-21 febb., 199
AFLP fingerprinting in Medicago spp.: its development and application in linkage mapping.
No full textCultivated alfalfa (Medicago sativa L., 2n= 4x= 32) is one of the most important forage crops in temperate climates. The genus Medicago includes diploid species that are a valuable source of wild germplasm for studying the reproductive system of alfalfa and its abnormalities. A linkage map of an apomeiotic mutant of Medicago falcata (L.) Arcang. (2n= 2x= 16) that spanned 368.6 cM and included 29 amplified fragment length polymorphism (AFLP), 35 random amplified polymorphic DNA (RAPD) and three restriction fragment length polymorphism (RFLP) loci was constructed using a one-way pseudo-testcross mapping strategy. The success of such a strategy depends on the presence of sufficiently high levels of heterozygosity in the individual plant which is being mapped and on the informativeness of the marker system that is used. In general: (1) highly informative and reproducible RAPD and AFLP fingerprints were generated and several genome-specific primers selected; (2) of 67 marker loci mapped, 51 were arranged in 11 main linkage groups and eight additional couples of linked marker loci were detected; (3) mapping of an F1 population theoretically allowed a better estimation of linkage distances since it avoided segregation distortion (x2 analyses revealed segregation distortion in only 5.2% of marker loci); (4) the high frequency of unlinked marker loci obtained suggests that, in this alfalfa genotype, DNA markers are distributed throughout the genome. This type of genetic map should find application and prove useful in marker-assisted selection and map-based breeding programmes in meiotic mutants of alfalfa for which there is a lack of suitable genetic markers
- …
