Broccoli (Brassica oleracea var. italica) is one of the most important winter season vegetables and a rich source of chemoprotective molecules, including glucosinolates (GSL). The aim of this study was to investigate the impact of nitrogen (N) and sulfur (S) fertilization on GSL concentration and composition in different parts of broccoli plants. A greenhouse experiment was performed, with four different treatments of sulfur (10, 30, 70, and 150 kg/ha) and three treatments of nitrogen (50, 250, and 600 kg/ha). GSL concentrations and plant growth responded to the N supply, but this was not observed above the 250 kg N/ha dose. On the contrary, plant growth did not respond to the S supply, whereas GSL concentrations showed a sharp response to the whole range of S applications (from 10 to 150 kg/ha). Glucosinolate composition was altered differentially in the examined plant parts. Aliphatic GSL were more abundant in the florets and leaves, whereas indolyl GSLs were dominant in roots, in which aromatic GSL were also observed. High nitrogen fertilization had a higher impact on indolyl compared to aliphatic GSLs concentration. More importantly, a high concentration of aliphatic GSL, >2.4 micromol/g dry weight (dw), and high S assimilation into aliphatic GSL were consistently observed in the florets compared to other broccoli parts, indicating adaptable processes for nitrogen and sulfur regarding synthesis and transport of aliphatic GSL for these organs.

Under rainfed Mediterranean conditions the dominant crops are cereals and legumes, with the most common crops being barley (Hordeum vulgare) and vetch (Vicia sativa). These two species are grown in rotation, where the cycle length depends on the productivity and the value of the products in the market. In order to study the productivity of cereals and legumes growing in various rotation combinations, an experiment was conducted during the 1982–2000 period, at Athalassa. The experimental site had a calcareous soil and is located in the central plane of Cyprus. The average rainfall is 250 mm per year. The rotation treatments tested were: (a) continuous barley, (b) continuous vetch, (c) vetch–barley, (d) vetch–barley–barley, (e) vetch–vetch–barley–barley and (f) vetch–vetch–vetch–barley–barley. Barley plots were equally divided to accommodate two rates of N fertilizer (0 and 60 kg N/ha) which were applied at seeding. Production of both vetch and barley was lower in monocultures than when the two species were grown in rotation. Vetch yield was similar in all rotations, irrespective of the position in the cycle. Productivity of barley was increased by nitrogen application only when grown as a second barley after vetch. However, in years with low productivity due to the rainfall amount and distribution, barley did not respond to nitrogen application. The first crop of barley after vetch gave maximum production without any nitrogen fertilizer application. Nitrogen fertilizer had a decreasing effect on the size and weight of barley grains. These results enable the farmers to select any of the rotation systems studied, based on the economics of the two species, without risking productivity. Nitrogen fertilizer should be applied only to the second crop after vetch in years with high rainfall.

No abstract

No abstract

The increasing need for protein at low cost has created a need to evaluate the biological nitrogen fixing potential of legumes in Cyprus, In field studies which were conducted over the growing years of 1982 3 and 1983-4, legumes which are traditionally grown in the country were evaluated for dry matter and nitrogen yield and biological nitrogen fixation (BNF). The legumes studied were medic (Medicago truncatula Gearth), ochrus vetch (Lathyrus ochrus L.), bitter vetch (Vicia ervilia L.) and faba bean (Viciafaba L. var major) in the first year and in addition chickpea (Cicer arietinum L.), woollypod vetch (Vicia dasycarpa Ten.) and tickbean (Vicia faba L. var minor) in the second year.Using the A-value method with barley and oats as reference crops, nitrogen (N) fixed by the various legumes in the first year was 30-50% and from 55-67% of total N yield for the two reference crops, respectively. In the second year the estimates of N fixed ranged from 70 to 80% with similar results obtained for the two reference crops barley and ryegrass. However, in the second year chickpea, which had limited nodulation, fixed only 40% of its N yield.Estimates of nitrogen from the atmosphere (Ndfa) obtained by the difference method (DM) were 10 to 14% lower than those from the A-value method. These results were obtained after correcting for the amount of N derived from the applied fertilizer. The two methods were highly correlated (r = 0.98) for estimates of amount of BNF. The rates of N2 fixation of uninoculated legumes which are nodulated by the indigenous populations of Rhizobium in Cyprus are comparable to those of legumes inoculated with selected strains of Rhizobium in other countries. An exception was the amount of N fixed by chickpea. The appearance of the first nodules at late stages of growth may be the reason for the low BNF of this crop.