Elissavet Ninou

Density effects on environmental variance and expected response to selection in maize (Zea mays L.)

The study aimed to address the optimal plant population density in maize that maximizes phenotypic expression and differentiation, and lessens environmental effects on genotypic expression in terms of the response to selection. A set of seven short-season hybrids (Rom set) was tested under rainfed conditions (2006, 2007) in Romania, and a set of seven long-season hybrids (Gr set) was tested with irrigation (2007) in Greece. Experimentation was conducted under ultra-low (ULD), low (LD), middle (MD), and high (HD) densities (0.74, 2.51, 4.20, 8.40 plants/m2 for the Rom set, and 0.74, 3.13, 6.25, 8.33 plants/m2 for the Gr set). Phenotypic expression and differentiation for grain yield were highest at the ULD. Coefficient of variation (CV) for grain yield, ear length and kernel row number decreased as density decreased. Environmental conditions and hybrid plant-yield potential (i.e., maximum yield per plant) were crucial for the optimal density that achieved the lowest environmental variance. For the Rom set the lowest CV for grain yield was obtained at the LD in the unfavourable season and at the ULD in the favourable season. The less acquired variance was achieved at the ULD for the highest yielding hybrids and at the LD for the lowest yielding hybrids, revealing a negative association between plant-yield potential and optimal density. Concluding, a density proximal to the ULD approximates absence of competition in maize, and optimizes three determinant parameters for successful selection: selection intensity, heritability and phenotypic differentiation.

Wheat Landraces Are Better Qualified as Potential Gene Pools at Ultraspaced rather than Densely Grown Conditions

The negative relationship between the yield potential of a genotype and its competitive ability may constitute an obstacle to recognize outstanding genotypes within heterogeneous populations. This issue was investigated by growing six heterogeneous wheat landraces along with a pure-line commercial cultivar under both dense and widely spaced conditions. The performance of two landraces showed a perfect match to the above relationship. Although they lagged behind the cultivar by 64 and 38% at the dense stand, the reverse was true with spaced plants where they succeeded in out-yielding the cultivar by 58 and 73%, respectively. It was concluded that dense stand might undervalue a landrace as potential gene pool in order to apply single-plant selection targeting pure-line cultivars, attributable to inability of plants representing high yielding genotypes to exhibit their capacity due to competitive disadvantage. On the other side, the yield expression of individuals is optimized when density is low enough to preclude interplant competition. Therefore, the latter condition appears ideal to identify the most promising landrace for breeding and subsequently recognize the individuals representing the most outstanding genotypes.

The cultivation revival of a landrace: pedigree and analytical breeding

This paper aims at improving the legume landrace Fava Santorinis (Lathyrus sp.) through the study of the existing variability, and an intra-landrace pedigree, combined with analytical selection, scheme. The experiments were conducted at the farm of Aristotle University of Thessaloniki during five growing seasons (2005–2009), and the selection was applied on a spaced plant conditions. In the first stage, single-plant frequency distributions of the source landrace for grain yield and pod number plant−1 was studied, and a percentage of 60.80% of non productive plants was found. In the second stage, improvement of grain yield relied on direct pedigree selection, accomplished by analytical selection for the number of pods plant−1, plant leaf color and vigor. This procedure was followed along the first generation progenies, and, later on, along two successive generations on the offsprings of two populations, one with purple and the other with white flower color. In the third stage, the evaluation of the fourth-generation progenies of each population for grain yield, showed superiority ranging from 42.48 to 107.89% compared to the source landrace. Furthermore, the breeding procedure succeeded in: (i) decreasing the coefficient of variability of grain yield and pods plant−1, thus increasing the stability of performance, (ii) reducing by 56.41 and 39.67% the non productive plants for white and purple flower populations, respectively, and (iii) maintaining the mean and the variability for pod traits as in the original landrace. Realized heritability for grain yield was positive during all selection cycle.

Essential Oil Responses to Water Stress in Greek Oregano Populations

Abstract Origanum vulgare subsp. hirtum, known as Greek oregano, has an excellent quality and good adaptability to scarcity of water, growing in several habitats of Greece and its genetic variability could be used for the production of new products. The current study aims to investigate the response of Greek oregano genotypes, originated from different mountain districts, under different water availability. The results showed that the genotypes were differentiated for dry matter production for both years. The populations “Pelion” and “Kissavos” showed superiority over the population “Olympus” by 27.2% and 18.5% respectively, for the years of experimentation. The highest essential oil yield was recorded in “Kissavos” population which showed 12.8% and 14.5% superiority over the two other populations for 2011 and 2012, respectively. The results showed the impact of water availability to the produced dry matter and essential oil yield and the interaction with the genotypes. The population “Olympus”, accumulated the highest dry matter at the irrigation level 60%, while for the populations “Pelion” and “Kissavos” the highest value was recorded at irrigation level 80%. The additional irrigation level didn’t contribute to a further production of dry matter. In conclusion, genotype and water supply can affect the dry matter, the essential oil content and yield of oregano. Oregano plants required an optimum level of irrigation to maximize the economic results, depending on the population used in this study.

The effect of genetic variation and nitrogen fertilization on productive characters of Greek oregano

ABSTRACT This study aims to investigate the response of 10 Greek Oregano (Origanum vulgare subsp. hirtum) populations, collected across Greece, under 3 levels of N-fertilization during 2012 and 2013. The populations were differentiated for dry matter (from 32.7 to 63.3 g·pot−1), for essential oil content (from 2.31 to 5.86 ml·100−1 g dry weight) and for amount of essential oil (from 1.37 to 2.46 ml·pot−1), for both years. Those with the highest dry matter (1-“Palaiochori” and 5-“Gliki”) and the highest essential oil content (10-“Gytheio” and 9-“Achladocastro”) were superior by 30%, as compared to the general mean of the experiment. The populations 3-“Litochoro” and 5-“Gliki” had an increased amount of essential oil (24%) as compared to the general mean of the experiment. An additional nitrogen supply (N0 to N1 level) increased dry matter production and amount of essential oil per pot, while decreased essential oil content for all populations. Further increase of nitrogen supply, favored six populations for dry matter production and two populations for amount of essential oil per pot while had almost no effect on five populations for essential oil content. The superior populations could be used in a breeding program as starting material for the development of new cultivars.