Abstract: Boron may affect total uptake of various nutrients and their nutrient use efficiency (NUE) which results in high productivity and low fertilizer cost. Therefore, the objective of this study was to investigate the effect of boron concentration in nutrient solution on total uptake of the various nutrients and their utilization efficiency in pepper plants (Capsicum annuum L.). Four cultivars (Osho, Solario, Odysseo and Arlequin) were treated with 0.5-10 mg B L-1. Each treatment included five replications with 3 plants and after 20, 40 and 70 days in culture one plant per pot was removed, divided into leaves, shoots and roots and analysed. The cultivars Odysseo and Arlequin have the greatest total phosphorus absorption at 0.5-2.5 mg B L-1 and more Ca at 1-2.5 mg B L-1, while Odysseo absorbed more magnesium (Mg) per plant at 1 mg B L-1 and 70 d per plant than the other cultivars. Furthermore, Solario, Odysseo, and Arlequin absorbed at 70 days more B. Differences were recorded also among the cultivars concerning the rest of the nutrients. The maximum nutrient use efficiency of Solario and Osho for phosphorus and potassium was recorded at 5 mg B L-1, and in Solario for calcium. Boron use efficiency was maximum for Solario, Osho and Odysseo at 0.5 mg B L-1 and for Fe at 10 mg B L-1 for all the cultivars. The effect of boron on magnesium, manganese and zinc use efficiency was variable.

Grafting is a vegetative plant propagation technique. In a grafted plant, the upward supply of water and mineral nutrients as well as the downward flow of photosynthesis are modified. In this context, the objectives of this work were to find out whether the grafting of pepper plants (Capsicum annuum L. family Solanaceae) reduces leaf boron concentration of some commercial cultivars under boron toxicity and to examine the effects of grafting and scion-cultivars on the levels of phenols, flavonoids and antioxidant capacity. Ungrafted plants of the cultivars Century, Twingo, Imperial and Arlequin, as well as grafted Twingo, Imperial and Arlequin plants as scions, and Century as rootstock were used. The plants were treated with 5 mg L-1 boron for 7, 14, 21 and 28 days. After 21 and 28 days of treatment, grafting significantly reduced the boron concentration in the leaves of the scion-cultivars while it was increased by 80% in the non-grafted plants. After 21 days of boron treatment, it was found that grafting reduced the concentration of leaf phenol to 60-70% in ungrafted Century plants. In Century x Twingo there was a 33% increase in the flavonoid concentration of leaves after 7 days grafting; while in the Century x Imperial and Century x Arlequin combinations this was decreased by 75-92% compared to non-grafted Century plants. The antioxidant capacity of leaves after 21 days treatment increased in all rootstock-scion combinations by 28% as measured by the FRAP and DPPH methods. In conclusion, grafting reduced boron concentration in the leaves of the tested scion-cultivars, as well as having an effect on the phenol and flavonoid concentrations and antioxidant capacity of the leaves.

Rooted leafy cuttings of three Greek olive (Olea europaea L.) cultivars (Koroneiki, Kothreiki and Chondrolia Chalkidikis) were grown for six months in three soil types, in an experimental greenhouse, in order to investigate: i) if their root system was colonized by arbuscular mycorrhiza fungus (AMF) genus and, ii) if genotypic differences concerning growth and mineral nutrition of olive plants existed. Gigaspora sp. colonized the root system of the three cultivars studied, while Glomus sp. colonized only the root system of 'Koroneiki'. Furthermore, in most cases root colonization by AMF differed among cultivars and soil types. The maximum root colonization, in all soils, was found in 'Chondrolia Chalkidikis'. In the three soils studied, the ratio shoot dry weight (SDW)/ root dry weight (RDW) was higher in 'Chondrolia Chalkidikis' than in the other two cultivars. Furthermore, root system morphology of the three olive cultivars was completely different, irrespectively of soil type. Leaf Mn, Fe, Zn, Ca, Mg, K and P concentrations, as well as total per plant nutrient content and nutrient use efficiency, differed among cultivars under the same soil conditions. These differences concerning root morphology, SDW/RDW, as well as nutrient uptake and use efficiency, could be possibly ascribed to the differential AMF colonization by Glomus sp. and Gigaspora sp.