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result(s) for
"DORDAS, Christos A."
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Impact of Nitrogen Fertilization on Rosemary: Assessment of Physiological Traits, Vegetation Indices, and Environmental Resource Use Efficiency
2025
Rosemary (Salvia rosmarinus L.) is a versatile and resilient plant with significant culinary, medicinal, and ecological value. This study evaluates the impact of four nitrogen (N) fertilization levels (0, 50, 100, and 150 kg N ha⁻¹) on the morphological, physiological, and agronomic traits, as well as vegetative indices, of rosemary over two growing seasons (2022 and 2023). The results indicate that plant height and leaf area index (LAI) increased with N application. Additionally, physiological characteristics such as chlorophyll content, photosynthetic efficiency, and assimilation rates (A) increased by an average of 32%, 17%, and 55%, respectively, compared to the control. Biomass production also improved with N fertilization, with yields rising by 32% in 2022 and 58% in 2023. Furthermore, both essential oil concentration and essential oil yield were enhanced by N application. Radiation use efficiency (RUE), water use efficiency (WUE), agronomic efficiency (AE), and partial factor productivity (PFP) also increased, indicating more efficient utilization of environmental resources. Moreover, higher N rates consistently enhanced vegetation indices, reflecting improved plant health, greenness, biomass, photosynthetic activity, and energy utilization. Therefore, this study highlights that the optimal N range appears to balance biomass yield and essential oil yield while maximizing the efficiency of environmental resource use.
Journal Article
Corm size and planting density affect the yield and longevity of saffron (Crocus sativus L.)
by
RALLI, Parthenopi E.
,
DORDAS, Christos A.
,
MENEXES, George
in
Agricultural production
,
Climate change
,
corm size
2024
The effect of the corm size of saffron (Crocus sativus L.) and the planting density was determined on a field study for six years. The objective of the present study was to determine the impact of the corm size and planting density on flower and stigma yields. Two corm sizes were used: corms with a diameter up to 2.5 cm and corms with a diameter greater than 2.5 cm, and five planting density: 22, 27, 33, 44 and 67 corms/m2 with planting distances 30, 25, 20, 15 and 10 cm on the plant row, respectively. The results showed that the year (growing season) and the interaction of year (growing season) with corm size affected all the characteristics that were studied. Over the six-year study period, there was a gradual increase in flowering from the first to the third year, followed by a decline in the fifth and sixth years. The yield of larger corms (greater than 2.5 cm) was higher during the first three years, while smaller corms (less than 2.5 cm) produced higher yields in the fourth through sixth years. On the contrary, the planting density, did not significantly affect the characteristics studied over the six years of cultivation and therefore did not affect the stigma yield of saffron. Therefore, corm size together with the environment are important factors that can affect the productivity and the longevity of the crop and should be considered when planting a new saffron cultivation.
Journal Article
Intercropping of Faba Bean with Barley at Various Spatial Arrangements Affects Dry Matter and N Yield, Nitrogen Nutrition Index, and Interspecific Competition
by
LITHOURGIDIS, Anastasios S.
,
DORDAS, Christos A.
,
GALANOPOULOU, Kalliopi
in
Agricultural practices
,
Barley
,
Beans
2019
Intercropping is the cultivation of two or more crop species on the same area of land, and can improve yield, forage quality, and soil health. Despite the fact that intercropping is an old practice, it received significant attention the last years because of the environmental impact that it has. However, the effect of the various spatial arrangements of the different species that are used in an intercropping system was not determined. The objective of the present study was to study the yield, growth and nitrogen (N) uptake rate, N nutrition index (NNI) of barley, interspecific competition, quality and financial outcome of intercrops of faba bean (Vicia faba L. var. equina) and barley (Hordeum vulgare L.) with various spatial arrangements (1:1, 2:2, 2:1 alternate rows, and mixed in the same row). The land equivalent ratio (LER), relative crowding coefficient (K), actual yield loss (AYL) and system productivity index (SPI) values were greater for the FB:B intercrop of 2:1, indicating the advantage of intercropping in terms of dry matter and N yield. Sole cropping of barley showed a reduction in NNI by 7 %, whereas NNI for barley increased by an average of 14% in intercropping treatments. Based on biomass production and the competition indices for dry matter and N yield, and NNI the FB:B intercrop of 2:1 was more advantageous than faba bean and barley monocrops, as well as the other intercropping treatments that were tested. *** In press - Online First. Article has been peer reviewed, accepted for publication and published online without pagination. It will receive pagination when the issue will be ready for publishing as a complete number (Volume 47, Issue 4, 2019). The article is searchable and citable by Digital Object Identifier (DOI). DOI link will become active after the article will be included in the complete issue. ***
Journal Article
Application of liquid cattle manure and inorganic fertilizers affect dry matter, nitrogen accumulation, and partitioning in maize
by
Lithourgidis, Anastasios S
,
Barbayiannis, Nikolaos
,
Matsi, Theodora
in
Agriculture
,
Agrochemicals
,
Biomedical and Life Sciences
2008
Efficient use of N applied in the form of organic and inorganic fertilizers is important in maize (Zea mays L.) production to maximize producer's economic returns and maintain soil and water quality. A field study was conducted for three consecutive years (2003-2005) in Thessaloniki, Greece to investigate whether liquid cattle manure can be used to replace inorganic fertilizers and also whether inorganic fertilizer can be applied preplant or as a combination of preplant and sidedress and can affect maize growth, development and N use efficiency. The treatments were control (unfertilized), liquid dairy cattle manure (Manure), application of 260 kg N ha-¹ year-¹ as basal dressing (N-single), application of 130 kg ha-¹ year-¹ N as basal dressing before sowing and 130 kg N ha-¹ when plants were at the eight-leaf stage (V8) (N-split). In 2 out of the 3 years of the study there was a significant positive effect of fertilizer application on maize growth, development, N uptake, and partitioning compared with the control. Dry matter production was increased by an average of 39% during the 2 years in plots fertilized either with manure or inorganic fertilizers than the control plots. Also from the yield components kernel weight per ear and number of kernels per ear were increased by an average of 35% and 32%, respectively in the fertilized plots compared with the control plots. Chlorophyll level was affected as it was increased by an average of 18%, 14%, and 18% at the ten-leaf stage (V10), silking and milk stage, respectively in the fertilization treatments compared with the control. Similar trend was observed in the other parameters that were studied. No differences were found between the manure and the different times of N application which indicates that manure can be used to replace inorganic fertilizer. Applying N either preplant in a single application or in split application (half of N preplant and half as sidedress) did not have any effect on any characteristics that were studied indicating that preplant application can be used as it is more cost effective. The present study indicates that liquid cattle manure can be used to replace inorganic fertilizers and also that there was no difference between preplant and sidedress application of N.
Journal Article
Effect of Liquid Cattle Manure on Corn Yield, Composition, and Soil Properties
by
Dordas, C.A
,
Lithourgidis, A.S
,
Matsi, T
in
Agronomy. Soil science and plant productions
,
Biological and medical sciences
,
Cattle manure
2007
The effects of liquid dairy cattle (Bos taurus) manure on corn (Zea mays L.) yield and composition were studied in a 4-yr field experiment conducted under a Mediterranean environment. In addition, long-term impact of (8-yr) manure application on soil-available NO3-N, P, and K; organic C; Kjeldahl N; and salinity was investigated. Four treatments were established in plots, previously used for a similar 4-yr experiment with winter wheat (Triticum aestivum L.). Treatments were: (i) application of 80 Mg manure ha-1 yr-1; (ii) single application of the equivalent N-P as inorganic fertilization (260 kg N ha-1 yr-1 and 57 kg P ha-1 yr-1); (iii) identical to (ii), but with split N application; and (iv) no fertilization. Corn grain and silage yields, N-P-K plant concentration, and uptake were significantly increased by manure or inorganic fertilizer addition relative to the control. During the 4-yr corn experiment, the amounts of available NO3-N in the soil profile of manure plots were higher than control, but similar to both inorganic fertilization treatments. Manure application maintained the amounts of soil available NO3-N, P, and K at desirable levels, almost each year of the total 8-yr application. However, soil organic C and Kjeldahl N remained unchanged. At the end of the experiment, soil salinity below 30 cm was significantly increased on manure or inorganic fertilizer addition relative to the control, but at levels acceptable for most crops. In conclusion, soil application of liquid dairy cattle manure at a rate equivalent to the recommended inorganic fertilization can enhance corn yield and composition and maintain soil fertility at desirable levels, without increasing soil salinity at unacceptable levels.
Journal Article
Multiple Pro197 Substitutions in the Acetolactate Synthase of Corn Poppy (Papaver rhoeas) Confer Resistance to Tribenuron
by
Eleftherohorinos, Ilias G.
,
Kaloumenos, Nikolaos S.
,
Dordas, Christos A.
in
acetolactate synthase
,
alleles
,
ALS-herbicide resistance
2009
Variations in the acetolactate synthase (ALS) gene sequence were determined from 28 populations of corn poppy resistant (R) to tribenuron and from 6 populations susceptible (S) to this herbicide. The ALS gene fragment (634 bp) sequence revealed in R populations five point mutations at the codon Pro197, and among them the substitution of Pro197 by Ala was the most common. The sequencing chromatograms revealed that nine R individuals had only the mutant ALS gene and were homozygous (RR), 18 R individuals had both the wild type and the mutant ALS gene and were heterozygous (RS), whereas one R individual was heterozygous but with two different mutant ALS alleles (R1R2). The use of restriction digestion profile analysis to verify the DNA sequence results by detecting the existence of point mutations at the codon 197 managed to distinguish the R and S alleles and confirmed the results obtained from the sequencing chromatograms analysis. The secondary protein structure prediction suggested the formation of novel β-strands for each of the five mentioned amino acid substitutions that was not present in wild type ALS around the mutant site. These findings support the hypothesis that the substitution of Pro197 by Ser, Thr, Ala, Arg, or Leu resulted in altered secondary structure, which stabilizes an ALS tertiary conformation that prevents tribenuron binding and thus confers resistance to this herbicide.
Journal Article
Multiple Pro 197 Substitutions in the Acetolactate Synthase of Corn Poppy ( Papaver rhoeas ) Confer Resistance to Tribenuron
Variations in the acetolactate synthase ( ALS ) gene sequence were determined from 28 populations of corn poppy resistant (R) to tribenuron and from 6 populations susceptible (S) to this herbicide. The ALS gene fragment (634 bp) sequence revealed in R populations five point mutations at the codon Pro 197 , and among them the substitution of Pro 197 by Ala was the most common. The sequencing chromatograms revealed that nine R individuals had only the mutant ALS gene and were homozygous (RR), 18 R individuals had both the wild type and the mutant ALS gene and were heterozygous (RS), whereas one R individual was heterozygous but with two different mutant ALS alleles (R 1 R 2 ). The use of restriction digestion profile analysis to verify the DNA sequence results by detecting the existence of point mutations at the codon 197 managed to distinguish the R and S alleles and confirmed the results obtained from the sequencing chromatograms analysis. The secondary protein structure prediction suggested the formation of novel β -strands for each of the five mentioned amino acid substitutions that was not present in wild type ALS around the mutant site. These findings support the hypothesis that the substitution of Pro 197 by Ser, Thr, Ala, Arg, or Leu resulted in altered secondary structure, which stabilizes an ALS tertiary conformation that prevents tribenuron binding and thus confers resistance to this herbicide.
Journal Article
Role of nutrients in controlling plant diseases in sustainable agriculture. A review
by
Dordas, Christos
in
Agricultural and farming systems
,
Agricultural production
,
Agricultural sciences
2008
In recent years the importance of sustainable agriculture has risen to become one of the most important issues in agriculture. In addition, plant diseases continue to play a major limiting role in agricultural production. The control of plant diseases using classical pesticides raises serious concerns about food safety, environmental quality and pesticide resistance, which have dictated the need for alternative pest management techniques. In particular, nutrients could affect the disease tolerance or resistance of plants to pathogens. However, there are contradictory reports about the effect of nutrients on plant diseases and many factors that influence this response are not well understood. This review article summarizes the most recent information regarding the effect of nutrients, such as N, K, P, Mn, Zn, B, Cl and Si, on disease resistance and tolerance and their use in sustainable agriculture. There is a difference in the response of obligate parasites to N supply, as when there is a high N level there is an increase in severity of the infection. In contrast, in facultative parasites at high N supply there is a decrease in the severity of the infection. K decreases the susceptibility of host plants up to the optimal level for growth and beyond this point there is no further increase in resistance. In contrast to K, the role of P in resistance is variable and seemingly inconsistent. Among the micronutrients, Mn can control a number of diseases as Mn has an important role in lignin biosynthesis, phenol biosynthesis, photosynthesis and several other functions. Zn was found to have a number of different effects as in some cases it decreased, in others increased, and in others had no effect on plant susceptibility to disease. B was found to reduce the severity of many diseases because of the function that B has on cell wall structure, plant membranes and plant metabolism. Cl application can enhance host plants’ resistance to disease. Si has been shown to control a number of diseases and it is believed that Si creates a physical barrier which can restrict fungal hyphae penetration, or it may induce accumulation of antifungal compounds. Integrative plant nutrition is an essential component in sustainable agriculture, because in most cases it is more cost-effective and also environmentally friendly to control plant disease with the adequate amount of nutrients and with no pesticides. Nutrients can reduce disease to an acceptable level, or at least to a level at which further control by other cultural practices or conventional organic biocides are more successful and less expensive.
Journal Article
Alternative Cropping Systems for Climate Change
2023
Climate change and increased climate variability are significant contemporary issues and create new challenges for agriculture and the whole food production chain [...]
Journal Article
Phosphorus Fertilization Affects Morphological, Physiological and Agronomic Characteristics of Faba Bean Cultivars
2023
Faba bean (Vicia faba L.) is an important legume crop grown worldwide, especially under rainfed conditions. Faba beans require phosphorus (P) fertilization to maintain high N2 fixation rates and to obtain high yields. However, farmers in many countries use low quantities of P because of its cost and the risk of drought, which reduces the crop’s response to P fertilization. The objective of the present study was to determine the effect of P fertilization on two faba bean cultivars, examining several key traits to identify the most efficient genotype. Seed yield was influenced by the main effect of variety, the two-way interaction between year and variety, and the three-way interaction among year, treatment, and variety. In the KK-14 cultivar, seed yield increased by 99% during the first year. Similar trends were observed for the yield components. Additionally, the morphological and physiological characteristics were affected by the fertilization treatments and the interaction between cultivars and year. Therefore, the use of appropriate cultivars, along with proper management in cropping systems, can significantly impact growth, biomass yield, and productivity under different conditions, leading to higher yields and greater economic returns for farmers.
Journal Article