Trichoderma harzianum, as a natural endophytic biocontrol agent, can ameliorate plant development, nutrient uptake, and resistance to biotic and abiotic stresses. This study aimed to investigate the effect of Trichoderma harzianum inoculation on agronomical and quality characteristics of two monoecious hemp (Cannabis sativa L.) varieties, Fedora 17 and Felina. A greenhouse pot experiment was conducted in a completely randomized design of two treatments of Trichoderma harzianum with a low and high dose of the fungus (T1 and T2). The significance of differences between treatments was estimated by using a Fisher’s test with a significance level p = 0.05. The root density of both varieties was significantly affected by treatments, and higher values were recorded in Fedora 17 (2.32 mm cm−3). The Arbuscular Mycorrhizal Fungi (AMF) colonization of the root system and the soil emission of CO2 were higher after the inoculation of Trichoderma harzianum. The highest values of plant height and dry weight were noticed for T2, especially in variety Felina. Trichoderma harzianum positively influenced characteristics of inflorescences such as their number, fresh weight moisture, and compactness in both varieties, while the dry weight, length, and dry yield of inflorescences were not improved. Finally, the fertigation of Trichoderma harzianum in hemp plants was beneficial by increasing the cannabidiol (CBD) content, especially in T2 treatment (4 × 1012 CFU kg−1).

The cultivation of cotton and in particular the quality characteristics of the fiber are mainly influenced by the growing conditions, the cultivation techniques as well as the climatic changes of the environment. The current study aimed to quantify the impact of environment, season, and their interactions on cotton fiber quality of different areas where cotton is grown in Greece. A large-scale database was created, consisting of more than 20,000 fiber samples from cotton fields of the four major cotton-producing regions of Greece (Thrace, Macedonia, Central Greece, and Thessaly) during 2016–2020, in order to evaluate thirteen fiber quality traits that were divided into four groups (fiber maturity, fiber length, color, and trash traits). The results of this work demonstrated that the effect of the environment and the interaction of the environment with year (season), were the important source of variance for almost all the qualitative characteristics studied. Regional climatic characteristics such as temperature, humidity and rainfall also significantly affected to a greater or lesser extent all quality characteristics. In conclusion, the different cultivation regions, in the broader sense of an environment that incorporates both climatic and management parameters, show stability in terms of the studied groups of quality parameters. This stability is independent of the high or low performance of the group features.

While processing tomato cultivation (Solanum lycopersicum L.) is considered one of the most important industrial crops in Greece, a waste known as tomato pomace is growing significantly high. Notably, the tomato pomace presents enormous opportunities for the creations of organic fertilizers. The aim of this study was to investigate the use of tomato pomace as a fertilizer in the same crop. A field experiment was established at the Agricultural University of Athens during 2018 and 2019 in a randomized complete design with five treatments (control, inorganic NPK (NPK), Tomato pomace and Biocycle Humus Soil (Tp and BHS), Tomato pomace and Farmyard manure (Tp and FYM), and Tomato pomace and Compost (Tp and CM). Physical soil properties such as soil porosity and penetration resistance were improved by the application of organic blends. Additionally, soil nitrogen content ranged from 0.10% (control and NPK) to 0.13% (Tp and FYM). A significant increase of yield was noticed under organic fertilization where the highest yield of 8.00 tn ha−1 was recorded in Tp and BHS (2018). Lycopene content was significantly affected by fertilization and its highest values were 87.25 (Tp and BHS; 2018), and 88.82 mg kg−1 fresh (Tp and FYM; 2019). Regarding fruit firmness, the three organic blends did not have statistically significant difference. In addition, the Total Soluble Solids (TSS) was significantly affected by the fertilization and the maximum value was 4.80 ◦Brix (Tp and CM; 2018). In brief, tomato pomace blended with organic fertilizers was yielded considerable since it improved soil quality and increased yield.

Field experiments were conducted during 2019 in two different locations in Greece (Athens and Farsala) to evaluate the effect of urea and urea fertilization with inhibitors on the agronomic yield and quality characteristics of two cannabis varieties (Cannabis sativa L.), “Uso31”and “Fedora 17”. The experimental design was split-plot with four different fertilization treatments—control, Urea (U), urea with Urease Inhibitor (UI), and urea with Nitrification Inhibitor (NI) and urease inhibitor (UI). The significance of differences between treatments was estimated by using Tukey’s test with a significance level of p = 0.05. The plant height was significantly affected by the different fertilizations and different varieties as well as by the two locations. The maximum plant height was 197 cm for “Fedora 17”in Farsala. The seed yield was higher forthe urea with inhibitors treatment in both varieties. The Cannabidiol (CBD) content was significantly affected by the fertilization—it was higher in urea with inhibitors in “Uso31”and “Fedora 17” treatments. The lowest CBD content value was 1.29% (control) and the highest was 1.69% (urea NI + UI). In conclusion, in both varieties, it seems that urea with inhibitors has a positive effect on their growth, as well as on the increase in cannabidiol (CBD) content.

Through the last century, the increased greenhouse gases emissions altered the atmosphere’s composition and resulted to the phenomenon known as climate change. Climate change threatens the sustainability of the agricultural sector in the Mediterranean region. Droughts and extreme heat waves will probably become more frequent in the next few decades, thus maintaining sufficient yields in heat and drought susceptible major crops will be challenging. In Greece, cotton is of paramount economic importance. Besides the fact that it is regarded as the most significant fiber crop, Greece is the main cotton producer of the European Union. The aim of the present review was to examine the environmental factors that might affect cotton production in Greece and assess whether (or not) climate change has the potential to limit the productivity of this crop in the near future. According to the existing literature, cotton can adapt to the changing climate. Climate change-induced elevated CO2 levels and temperatures might even benefit cotton. The mitigation of the adverse effects of climate change is possible via the adaptation of site-specific agronomic practices. A simplistic framework, based on the literature and the goals of the European Union, that aims to the preservation of sufficient cotton yields in Greece is proposed in the present study.