The influence of different fertilizer forms and rates on nitrogen, phosphorus and potassium contents, nitrate accumulation and yield in red head chicory (Cichorium intybus var. foliosum L.) was investigated. Field fertilization trials were set up at two localities inNorthwest Croatia in 1999 and 2000. Trials were laid out according to the Latin square scheme in five fertilization treatments: manure 5 kg/m2, three rates of complex mineral fertilizer NPK (5:20:30) - 50, 100 and 150 g/m2, and an unfertilized control variant. The results of investigations indicate that there were no significant differences between treatments in the plant nitrogen and phosphorus contents. Significant fluctuations of the chicory potassium content (3.27-4.75% K) depending on the fertilization variant were recorded only in 1999 while in 2000 all values (4.13-5.12% K) were uniform. Plant nitrate levels were influenced by weather conditions more significantly than by the form and rates of fertilizers. All the recorded values are within the limits tolerated for leafy vegetables. Comparing the trial years, yields were generally higher in 1999 (1.58-4.95 kg/m2) than in 2000 (0.40-2.70 kg/m2). No significant differences in yield were recorded between the application of stable manure and the lowest mineral fertilizer rate.
Global climate changes have enabled the expansion of tropical and subtropical crops cultivation areas in moderate climate. The aim of study was to determine the possibility of cinnamon yam (Dioscorea oppositifolia L.) production, using three growing systems. Seedlings were grown in a heated greenhouse and planted to the open field in the first decade of May. Conventional technology, which involves free development of tubers in the soil, was used as control. Also, planting in channels buried in the soil at the angle of 25° and in vertical peat-filled basins placed at the soil surface were tested. Depending on the applied growing system plant density was between 5.5 plants per m2 in conventional technology and 9 plants per m2 in vertical basins. Developed tubers were significantly different in length, which ranged from 0.36 m in conventional technology to 0.95 m in vertical basins. The highest diameter of basal part (8.6 mm) is determined at the tubers grown in the channels and was significantly higher than the others. Apex diameter of the tubers was statistically equal and varied from 19.6 to 23.3 mm. Tubers with the lowest weight (149.7 g) were produced by conventional method, while the highest tuber weight (225.1 g) was achieved in vertical basins. Tubers grown in the vertical basins had equable weight, what can be concluded from the standard deviation value (19.5 compared to 41.5 and 58.6 for the control and channels). The highest yield (2.03 kg•m-2) was achieved in vertical basins and was significantly higher than yields gained by other technologies. Beside plant density, which is higher than at the other growing systems, the higher tuber mass and length contributed to achieving the highest yield in vertical basins.
The advantage of closed soilless systems is protection of surface and ground water from pollution with nutrients and pesticides. Beside that, savings of water and nutrients could be made. The aim of the research was to determine amounts of added and leached nutrient solution during tomato growing period, their composition and possibility of reusing leached nutrient solution for fertigation after filtration and UV-sterilization. Tomato plants were planted on 11th February. During the harvest period from 12th May till 27th October 39.1 kg m-2 of marketable fruits were harvested. Number and duration of fertigation rates depended on the plant development stage and weather conditions. Amounts of leached nutrient solution were measured with installed percolate collectors. Leached nutrient solution was collected, filtered and UV-sterilized. After sterilization it was mixed with a new nutrient solution in a 1:3 ratio. Composition of nutrient solution was determined periodically (every two weeks) at the laboratory, while pH- and EC-values were measured with a portable pH- and EC-meter once a week. During growing period 919 L m-2 nutrient solution was added and 371 L m-2 was leached. The ratio between added and leached nutrient solution ranged from 18.7 % to 55.4 %. For all macro elements, with the exception of phosphate, higher concentrations (from 43 % for K+ to 101 % for Mg2+) were recorded in leached than in added nutrient solution. Phosphate concentration was 58 % lower in leached than in added nutrient solution. Reuse of leached and sterilized nutrient solution is feasible but requires constant control of the composition and pH- and EC-values of nutrient solution to avoid higher deviations, which might have a negative effect on tomato yield. Closed soilless system is ecologically acceptable because excess nutrient solution is adequately disposed of and reused in the production cycle.
Pak choy, in Croatia a less known oriental leafy vegetable species, can be found on the Croatian market in the winter period as an import from other Mediterranean countries. The purpose of the investigation was to obtain information about its agronomic traits and dietary value in different growing periods (two spring and a summer-autumn in the open, and an overwinter period in an unheated high tunnel) from 1998 to 2000. Open field trials were laid out according to the split-plot scheme in five replications, with plant density as the main factor (16.7 and 22.2 plants/m2) and harvest dynamics as the sub-factor [(30, 37 and 44 days after planting (DAP)]. The mono factorial overwinter trial was set up so as to involve supplementary direct covering with polypropylene material (PP) and no covering, at a plant density of 16.7 plants/m2. Undesirable bolting was recorded in spring growing periods (0%, 0 to 9% and 5 to 40% at harvest 30, 37 and 44 DAP, respectively) and in the winter period (with PP covering 2 to 10%, without covering 6 to 20%). Contents of leaf petioles and blades in the rosette mass were about equal in the harvest 30 DAP in both spring periods (ca 45%), and it increased as the vegetation progressed to the advantage of petioles (to 64% at 44 DAP in the summer-autumn period, to 60 % in the overwinter crop). The highest contents of total dietary fibres (0.56 to 0.79 g/100 g fresh matter) and biogenic elements (N, P, K, Ca, Mg, Fe, Mn, Zn and Cu), as well as significantly lower contents of nitrates (1104 to 1187 mg/kg fresh matter) were recorded in the spring growing periods. Closer spacing and supplementary direct crop PP covering had a positive effect on yields (P≤ 0.01) and mainly no significant effect on the other traits studied.
To identify white cabbage cultivars of suitable agronomic and physical traits for sauerkraut production, 7 domestic varieties and populations as well as 16 imported hybrid cultivars (cvs) were tested in 2001 and 2002 at the family farm. Field trials were laid out according to the randomized block scheme with four replications (plot area 10.4 m2, spacing 0.65 m × 0.4 m). A significant share of undeveloped plants (31 to 56%) was recorded in domestic varieties. Cultivars ‘ Gideon’ , ‘ Cassandra’ , ‘ Fieldwinner’ , ‘ Ramada’ , ‘ Cecile’ , ‘ Krautman’ , ‘ Krautkaiser’ , ‘ Atria’ and ‘ Azan’ stood out with statistically comparable yields (46.4 to 74.7 t/ha). Relatively uniform individual head weight (coefficient of variation less than 25%) was recorded for ‘ Arena’ , ‘ Atria’ , ‘ Krautman’ , ‘ Metis’ and ‘ Ultor’ . Domestic varieties have generally flatter heads than hybrid cultivars (head diameter-to-height ratio 1.25 to 1.55), but they also have a larger relative inner stem height (over 50%). Share of dry matter ranged from 6.39 to 9.96%, soluble solids (°Bx) from 4.0 to 7.0%, while the share of NaCl amounted to 0.10 to 0.17%. Total acidity ranged from 0.12 to 0.27%, and pH-values from 6.22 to 6.70. Considering the agronomic, physical and chemical traits of the raw material, the sensory attributes of the final product – sauerkraut, and also producer and consumer requirements, besides the leading domestic variety ‘ Varaždinski’ , ‘ Field winner’ and ‘ Krautman’ were selected for the main pickling season, ‘ Metis’ and ‘ Ultor’ for early pickling, and ‘ Arena’ and ‘ Atria’ for late pickling.