Analysis of Per Se and Genetic Diversity of Maize Synthetic Populations for Grain Quality: Implications for Breeding

The objective of this research was to determine whether phenotypic and genetic diversity could be identified for maize grain quality traits (percentage of starch, protein, oil, fiber and ash) and agronomic traits. 59 maize synthetic populations which differed in earliness and for geographic origins were evaluated in the field at the Agricultural Research Station Turda - Romania, for their per se value. Each synthetic population was tested only one year and was characterized for their ear characteristics and grain quality attributes. The grain oil and ash content showed high variability among genotypes. The experiment was conducted over 2 years (2006-2007) and 2 locations (Turda and Targu-Mures). Analysis of variance showed significant differences among the genotypes for all traits studied. General combining ability (GCA) effects were more important for grain content than specific combining ability (SCA). The occurrence of low interactions between synthetic populations and testers for all characters suggested the occurrence of high statistical additive effects expressed whatever the system of population evaluation. These results support breeding effort towards the genetic improvement of grain quality traits in “Turda” maize germplasm

Genetic Variability in a Set of Early Maize Inbred Lines

Characterization of genetic variability among maize inbred lines can facilitate organization of germplasm and improve efficiency of breeding programs. A set of 83 phenotypically diverse inbred maize lines maintained in Agricultural Research and Development Station (ARDS), Turda, Romania was characterized by pedigree, phenotypically using 14 characters of the plant and ear and genetic with RFLP markers. The objective of this study was to characterize the genetic variability and to define the potential heterotic groups based on clusters formed with marker data. Inbred lines were grouped by their phenotypic differences index in twenty classes. Both the phenotypic and molecular markers analysis indicated high genetic variability and also allowed the separation of the germplasm into group of genetic similarity. The result suggested that the inbred lines analyzed could be useful in maize genetic breeding program

Comparison Between some Corn Synthetic Populations Obtained from Transylvanian

Synthetic varieties of corn are open-pollinated populations obtained by cross-pollination of a group of inbred lines. Besides the inbred lines, corn synthetics can be obtained from local populations or hybrids. In general, they are superior to local populations but not exceeding heterotic hybrids. The main advantage of corn synthetic varieties is that their heterosis does not diminish significantly in F 2 generation. Interest in this biological category increased after 1999, when CIMMYT's considered viable alternatives in areas where use of hybrid seed is too expensive (especially in developing countries). Obtaining corn synthetics from local populations aims at enriching their gene pool with a large number of valuable genes derived from local populations that are characteristic to some agricultural areas. SCDA Turda tried to exploit the large number of local populations still existing in Romania, and obtained a series of synthetics intended for areas that still practice subsistence agriculture. To assess their value, we tested six synthetics obtained from local populations in comparison with one traditional synthetic derived from inbred lines; two locations and two experimental years have been considered and the conclusions have been included in this paper. Synthetic populations derived from a combination of local populations cannot be used as such in production due to their lower yield performance and low resistance to stalk breaking and falling. Nevertheless, they can be valuable sources of genes for the following traits: vegetative period, earliness, resistance to low spring temperatures, resistance to Fusarium , precocity and the content of fat, protein, fiber and minerals

The Cytoplasm Origin Influence, the Teser Influence and the Nucleus-Cytoplasm Interactions Influence on Agronomic Traits for Maize Isonuclear Lines

The maize is one of the most important crops in the world due to its high productivity and multiplexing usage in human nutrition, animal breeding and industry. The isonucleus inbred lines study has been initiated from the demand of clarifying if the cytoplasm source has a positive or negative influence on the corn cars, plants, grain traits and some maize cultural features. The research has been conducted in the experimental field provided by the Maize Breeding laboratory from ARDS Turda, ARDB Târgu-Mureş, ARDS Secuieni, ARDS Livada, ARDS Suceava in 2009. The cell nucleus transfer activity for 12 elite inbred lines on various cytoplasm types has begun in 1992 starting from the assumption that among cytoplasm of different origin could exist differences in the genetic value. The ultimate objective of breeding works is to obtain a higher grain yield and the yield quality to be at the desired level of farmers. For this reason it was studied the effect of different types of cytoplasm on grain yield, kernel dry matter at harvest and unbroken plants percentage at harvest, all these traits are important to achieve secure yield, mechanized harvestable. The kernel dry matter at harvest is one of the indicators of vegetation period, the most used in choice of early single crosses

Combining Ability for Kernel Starch Content in Maize Synthetic Populations Obtained from Local Populations

Synthetic populations of maize (Zea mays L) are low-cost and stable varieties, obtained by cross pollination of a group of inbred lines, local population or hybrids. The main advantage of these populations is that the heterosis does not diminish significantly in F2. In order to complete the research on the combining ability of maize synthetic populations, the objective of this work was to study seven maize synthetic populations, determining their general combining ability (GCA) and specific combining ability (SCA) for kernel starch content, as well as their potential as source populations in breeding programmes.To achieve the proposed objectives, we studied top cross hybrids of the type “inbred line x synthetic population†resulted from the crossing between seven synthetic maize populations and four early inbred lines used as tester. For all experimental conditions, the differences between genotypes were statistically assured for kernel starch content. The experimental years and testing locations have provided conditions for differentiation of genotypes for starch content and interactions between the environment and genotypes were statistically significant, indicating dependence of starch content on environmental conditions. The additive effects for starch content provided by GCA were high for Tu SRR 5DR(6I)(5) and Tu SRR 5D (2I)(2). Non additive effects, corresponding to SCA were high for the following hybrid combinations: TC 233 x TuSyn 1 (3), CO 255 x Tu SRR 5D (2I)(2) and TC 209 x Tu SRR 5DR(6I)(5). In the case of synthetic maize populations, the determinism of starch is influenced equally by GCA and SCA

Variability for Young Maize Plants Characters in a Set of Inbred Lines

Root system development in maize seedlings has a influence on the further development of the plant; also length of mesocotyl and depth of coleoptile influence which can sow corn, play an important role in the uniformity of culture and plant growth and development. The area in witch has been created corn genotype, soil type and climate, but also some elements of technology have influenced the development of root system, the length of mesocotyl and coleoptile of the young plantlet. The paper presents variability in root system development of 40 inbred lines of corn , coleoptile and mesocotyl development in the same set of inbred lines and correlations between these characters

Phenotypical Variability of “TURDA” Maize Germplasm for Grain Chemical Composition

Maize grain has many and diverse uses in the food and feed industry. The diversity of applications requires characteristics of quality in accordance to that. To examine phenotypical diversity in the grain content, it was evaluated a total of 754 maize samples: 265 local populations (landraces); 59 synthetics/composites; 430 “TURDA” inbred lines for their grain quality attributes. Comparison of the inbred lines diversity is on average the most divergent in grain starch concentration (range value 19.9) from landraces (range value 11.8) and synthetics (range value 12.5). The grain oil and ash content showed high variability among the genotypes. The quality attributes in most of the cases showed positive phenotypic correlation except grain starch contents which was negatively correlated at phenotypic levels. The objective of this study was to evaluate the potential of maize “TURDA” germplasm in according to its grain quality content, such as: protein, oil, fiber, ash and starch concentration; to estimate the extent of phenotypical variability and correlation for various quality components to formulate a selection criterion in a breeding program

Variability of Young Maize Plants Traits in a Set of Local Populations

Taking into account the importance of root and coleoptile and mesocotyl length of maize young plants, we considered appropriate to analyse the variability of these traits in a set of maize local populations. The root system development, the mesocotyl and the coleoptile were studied in a number of 41 local populations at The Maize Breeding Department of ARDS Turda. The average length was 28.42 cm for embrionary roots, 17.37 cm for primary roots, 1.43 cm for mesocotyl, 3.50 cm for coleoptile and 4.92 for plantlets. The variability was low for embrionary roots, coleoptile and plantlets length and medium for primary roots and mesocotyl length. A correlation was noticed between the length of mesocotyl and the length of coleoptile and plantlets. The size of roots, mesocotyl and coleoptile is influenced by the area where the local population is formed. Local populations with high root and coleoptile length such as Tulca, Lapusneac and Biertan can be used for obtaining some valuable inbred lines of maize

Evaluation of Maize “Turda†Germplasm as Sources of Earliness in Breeding Programs

Evaluation of the early maize ( Zea mays L.) germplasm is important for the development of new inbred lines and commercial hybrids adapted to cooler regions. Choice of populations to use in improving elite maize hybrids is a critical decision in maize breeding programs. Our objectives were: I) to examine the variation for earliness in a set of 256 local populations, 56 synthetic populations and 504 inbred lines; II) to determine the performance and heterosis of this germplasm; III) to identify the genotypes (local populations, inbred lines) for the initiation of the primary cycle for directional selection for the studied characters. Seven synthetic populations and six inbred lines formed the base material of this genetic study. The seven synthetic populations and their topcrosses to four inbred lines: two flint inbred lines (TD 233 and CO 255) and two dent inbred lines (TC 184 and TC 209) and also a diallel type p(p-1) system with 30 single-cross hybrids and the six parental forms were evaluated at four environments in: two years 2009 and 2010 and two locations Turda and Targu- Mures. The highest values of additive effects for grain dry matter content were recorded at: Tu Syn Mara (Ä n = +1.80), Tu SRR 5D (2I) (1) (Än = +0.62) and Tu Syn 1 (Än = +0.45). Therefore, Tu Syn Mara, Tu SRR 5D (2I)(1) and Tu Syn 1 produced hybrids with the most early maturity. The highest general combining ability (GCA) for dry matter accumulation in grains has registered the inbred lines TC209 (Ä = +1.36) and TC208 (Ä = +0.71)