Plant growth promoting bacteria (PGPB) are used as biostimulants to improve the growth and yield as well as the quality of crops. In the present study, nine strains of PGPB and one solid mix consisting of two of them were evaluated on the cultivation of industrial tomato under specific soil and climatic conditions. The results showed that Bacillus licheniformis treatment increased dry weight of the tomato plants by 39%, and the photosynthetic rate was increased by Priestia megaterium 9.9%. The application of Bacillus subtilis, Bacillus amyloliquefaciens, Priestia megaterium, and Bacillus licheniformis increased mean fruit weight per plant 26.78–30.70% compared to that of control. Yield per plant was increased 51.94% with the use of Bacillus licheniformis compared to that of control. The quality of the fruits in nearly every bacteria strain was improved. Bacillus pumilus and the mix of Priestia megaterium and Azotobacter chroococcum (1:1) increased the most total soluble solids in the tomato fruits (4.70o Brix), and Priestia megaterium increased content in lycopene and total carotenoids by 52.8% and 25%, respectively; Bacillus pseudomycoides increased Pectin methylesterase (PME) activity (24.94 units/mL), and Bacillus mojavensis, along with the mix of Priestia megaterium and Azotobacter chroococcum, increased Poligalacturonase (PG) activity the most (30.09 and 32.53 units/mL, respectively). Most of the bacteria strains presented an increased antioxidant activity significantly better that that of the control up to 31.25%. The results of this study confirmed that the use of PGPB as biostimulants can improve the yield and the quality of industrial tomato.

An increase in grain yield remains a major target for all involved in maize cultivation. In this study, five maize genotypes were evaluated in a two-year (2017 and 2018) field experiment that was conducted at six locations. Additive main effects and multiplicative interaction (AMMI) analysis was used to detect the narrow adaptations of genotypes in specific mega-environments and the positive interactions of genotypes (G) and environments (E). According to the results of ANOVA, the G × E interaction effect explained 80.36% of the variation, while G explained only 12.79% of the variation, with the remainder explained by E (6.85%). The AMMI model indicated that GEN2, GEN4, and GEN5 were the most suitable genotypes for the three mega-environments delineated. Furthermore, GEN4 was found to have a large positive interaction with the environments featuring the highest rain precipitation during the cultivation period, while GEN2 had a large positive interaction with environments where the mean monthly high temperature was over 34 °C, according to the climatic data during the cultivation period. Additionally, the four environments with slightly acidic pH had a positive interaction with all genotypes of the research, except GEN2.

The use of plant growth promoting bacteria (PGPB) is increasingly gaining acceptance from all the stakeholders of the agricultural production. Different strains of PGPB species had been found to have a vast variety of mechanisms of action, while at the same time, affect differently a variety of crops. This study investigated the effectiveness of ten PGPB strains, on sweet corn cultivation under Mediterranean soil and climatic conditions. A field experiment that followed a completely randomized design was conducted at the region of Attica at Oropos. The results indicated that B. mojavensis increased yield by 16%, B. subtilis by 13.8%, B. pumilus by 11.8% and B. pseudomycoides by 9.8% compared to control. In addition, the harvested grains of the plants treated with B. mojavensis, B. subtilis and B. pumilus presented the highest values of protein and fiber content. Moreover, in most of the cases, high values of photosynthetic rate, transpiration rate and stomatal conductance during the cultivation period, resulted in high productivity. Regarding the texture, the size, the sphericity and the ash content of corn grains, it was found that they were not influenced by the application of different treatments of PGPB. The use of certain strains of PGPB, under specific soil and climatic conditions could contribute to better understand which strains are better suited to certain crops.

The interaction of genotype by the environment is very common in multi-environment trials of maize hybrids. This study evaluates the quantity and the quality of grain production and the stability of four maize genotypes in a field experiment that was conducted in five different locations for two years. In order to make a reliable evaluation of the performance of genotypes in the environments, principal components analysis (PCA) was used to investigate the correlation of the yield, soil properties and quality characteristics, while the additive main effects and multiplicative interaction (AMMI) analysis detected the narrow adaptations of genotypes at specific mega-environments. For the yield, AMMI analysis indicated that a group of five environments (ENV1, ENV8, ENV6 ENV10 and ENV9) gave higher yields than the mean value and at the same time had low first interaction principal components axis (IPC1) scores, indicating small interactions. Regarding protein and fiber contents, ENV1 and ENV2, gave the highest values and this could be attributed to the high concentration rates of nutrients like Mg, Ca and the soil texture (C). Specifically for the protein, the results of the analysis indicated that certain environment would provide more protein content, so in order to obtain higher grain protein, growers should grow in certain locations in order to improve the content of this quality characteristic, certain genotypes should be used in certain environments.

Magnetic field is a variable abiotic factor, like temperature, air, soil and water that interacts with the living organisms. The use of different types of magnetic field at many different plant species is increasing and the results are promising. A two-year field experiment was established following a completely randomized design, to investigate the effect of pre-sowing magnetic field treatment for 0, 15, 30 and 45 min on three broad bean varieties. The obtained results showed that the treatment of seeds with pulsed electromagnetic field increased germination percentage, chlorophyll content, leaf area, photosynthetic rate, transpiration rate, stomatal conductance and dry weight. In general, the exposure of seeds for 15 min, gave the highest values compared to the control treatments for the three varieties used. A very interesting result is the fact that although there was an influence of the exposure of magnetic field on the dry weight of the plants, there was not a positive or a negative influence on the seed yield for both years. This means that magnetic field enhanced the vegetative development of the broad beans, but it had no effect on the reproductive development. The results indicate that magnetic field can be used in the cases that the productive direction of the cultivation of broad beans is for livestock forage and silage, as the pre-sowing treatment of seeds had a positive effect on plant dry weight. *** In press - Online First. Article has been peer reviewed, accepted for publication and published online without pagination. The article is to be paginated when the complete issue will be ready for publishing (Volume 48, Issue 3, 2020). 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.