In organic agriculture, intercropping is receiving increasing attention as it offers potential advantages for increasing sustainability in crop production. However, intercropping can increase competition between crops and weeds. In this study, we analyzed the effects of maize-legume intercrops on the weed community in an organic cropping system. We were concerned only with competition between crops and weeds for light. We recorded a statistically significant negative correlation between the fraction of photosynthetically active radiation (F int PAR) intercepted by the canopy, and both weed density and weed dry matter. Maize-legume intercropping led to a higher soil canopy cover (leaf area index) than sole crops. The lowest values for F int PAR were received in sole crops. Thus, in maize-legume intercrops the decrease in available light for weeds led to a reduction of weed density and dry matter, compared to sole crops. Intercropping maize and legumes considerably reduced the weed density in the intercrop compared with the maize pure stand. Weed suppression by crops was also greater on a low-productivity site than on a highproductivity site. Our results indicate that intercropping could be useful for weed suppression in organic row-crops such as maize and cotton.

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Field experiments were conducted to determine the effects of tillage systems and varieties on growth, yield and quality of wheat crop (Triticum aestivum L.). The experiments conducted at two sites were laid out in a split-plot design with four replicates, three main plots [conventional tillage (CT), no-tillage (NT) and minimum tillage (MT)] and four sub-plots (‘Siette’, ‘Panifor’, ‘Myrto’, ‘Estero’). The soil porosity and total nitrogen were higher in soils subjected to conservation tillage systems (NT and MT) than under conventional tillage. There were no differences in root growth neither between the tillage systems nor among the varieties. Yield was influenced by the tillage system and variety. The highest grain yield (421-459 kg ha-1) was found under the CT system with ‘Siette’, ‘Myrto’ and ‘Estero’ varieties. In contrast, the highest grain yield was observed under conservation tillage (NT and MT) with ‘Panifor’ variety. There were no significant differences between the tillage systems concerning the protein content and Zeleny value. In contrast, the highest Hagberg falling number was found with MT. Zeleny value was positively and significantly correlated with protein content. High flour quality, as demonstrated by high protein content and Zeleny value, and low Hagberg falling number, was produced in the ‘Estero’ variety.

Organic cotton is a new industrial crop product. Field experiments were conducted to determine the effects of cultural systems and varieties on the growth, fiber quality and yield components of cotton crop (Gossypium hirsutum L.). The experiments, conducted during 2006 and 2007, were laid out in a split plot design with four replicates, two main plots (organic and conventional system) and two sub-plots (cotton varieties: Athena and Campo). There were no significant differences between the organic and conventional system for cotton growth, yield and fiber quality. The results suggest that the soil N released from both the inorganic (80 : 40 : 40 kg ha -1 N : P 2 O 5 : K 2 O) and organic pool (green manure) were sufficient to maintain good growth. Inferior-quality fiber was produced in the variety. Campo, which had the lowest fiber fineness (micronaire), strength, length and reflection. In addition, this variety had the highest fiber elongation and yellowness. There were no significant differences between varieties as far as uniformity and leaf trash ratio are concerned. A positive correlation was observed between fiber strength and length. However, a negative correlation was found between lint yield and fiber strength.

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).

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Field experiment was conducted in western Greece to determine the effects of organic fertilization on root growth of medicinal plants oregano (Origanum vulgare L.) and milk thistle (Silybum marianum L. Gaertn.). The experimental design was completely randomized with four replications. Two treatments were applied; compost 2000 kg ha -1 (F1) and compost 4000 kg ha -1 (F2). The results indicated that the soil properties were in luenced by organic fertilization. The highest organic matter and total nitrogen content were found under F2 treatment. Also, F2 treatment improves soil porosity. Moreover, there were signi icant differences in root growth between fertilization treatments. For both medicinal plants the highest root length density, root mass density and root surface density were found under F2 treatment. Furthermore, there were signi icant differences in arbuscular mycorrhizal (AMF) root colonization between fertilization treatments. The greatest values were observed for F2 treatment. The highest AMF root colonization was found for oregano. A positive correlation was found between AMF root colonization and root surface density. Our results indicated that oregano and milk thistle root growth was improved with increasing compost application rates.

Medicinal and aromatic plants are known to be used by a large portion of global population for their medicinal therapeutic effects. Water is among the most important factors for the development, yield and quality of medicinal plants since its de iciency may cause serious growth damages and yield losses. The objective of the present study was to evaluate the effect of two irrigation rates on the development and characteristics of the root system of medicinal plants Hyssopus of icinalis L. and Passi lora incarnata L. The experiments were conducted in 2013 in western Greece in the region of Agrinio according to completely randomized design. The root parameters that were determined were root density, root diameter, root surface and root volume, while some soil parameters and abscular mycorrhiza colonization were also measured. The results indicated that for both medicinal plants the increase of irrigation rate had a positive effect on density and volume of the root system, and the other characteristics of the root correlated with the growth and the forage yield of the plants. In conclusion, irrigation can positively affect the growth and development of the root system of H. of icinalis and P. incarnate with a bene icial impact on overall plant growth and productivity.