Volume 22 (2010): Issue 1 (June 2010)

The aim of this study was to investigate the effect of organic fertilization on growth, several physiological parameters and yield of pepper plants (‛Buketen 50’). The field experiment was carried out at the experimental field of the Agroecological Centre of the Agricultural University of Plovdiv (Bulgaria), which is certified as an ecological farm. For the purpose of the research, the bio-fertilizer Lumbrical, produced by the Californian earthworm (Lumbricus rubellus), was used. Just before planting, two levels of the bio-fertilizer were applied 50 and 100 ml per plant. Thirty days after planting, a part of the plants were additionally fed with a solution of Lumbrical (200 ml per plant). During plant vegetation some biometrical indices characterizing plant growth were measured. The content of the plastid pigments and the leaf gas exchange were taken into account. The fertility of the pollen of the flowers was determined. The total amount of pigments in the dried and ground red pepper was analyzed.

The aim of this study was to determine the effect of fresh and dry weight, as well as the number and length of roots and number of crowns of different types of plants, on the yield of strawberry grown for the spring and autumn harvests. Three different types of frigo strawberry plants (waiting bed plants, plug plants, A+ plants) and two strawberry cultivars (‘Honeoye’ and ‘Elsanta’) were compared in the experiment. The plants were grown in polypropylene bags in an unheated glasshouse in the years 2002-2005. The correlation coefficients were calculated to estimate the relationship of the strawberry plants’ parameters to the yield quantity. An analysis of regression for the plant parameters that most significantly correlated to the strawberry yield was carried out, which determined that the fresh and dry weight of the strawberry plants, crown number, as well as length of roots were positively correlated to the quantity of the strawberry yield. The highest positive correlation coefficient was found for the fresh weight of a whole plant and the lowest one for the number of roots.

The content of calcium and potassium and lipoxygenase (LOX) activity as well as the expression of LOX encoding gene in the fruit of apple cultivars that are both susceptible and resistant to bitter pit were evaluated. Fruits were collected and analyzed after harvest in the 2004 growing season and again after four months of common cold storage. The main reason was the explanation of relationship between those LOX activity and K:Ca ratio on bitter pit occurrence during storage. The biggest differences between the tested cultivars were noted in LOX activity and Ca content, followed by K:Ca ratio and the lowest potassium content. The cultivars that were resistant and susceptible but without symptoms of bitter pit exhibited higher calcium content compared to cultivars with signs of bitter pit, and with a drop in LOX activity after storage. A negative correlation was found between LOX activity and Ca content and a positive correlation was found between K:Ca ratio and LOX activity.

In the heads of four red cabbage cultivars and two DH lines (one of red and one of white type), as well as in the standard white cabbage ‘Lennox F1’ cultivar, the contents of phenolic substances (total, phenylpropanoids, flavonols and anthocyanins) were estimated. Antiradical scavenging activity was determined using the DPPH and ABTS methods. The level of phenolics of all the groups, especially that of the anthocyanins, as well as RSA, was much higher in red cabbage in comparison to white. Among red cabbage assays, also a considerable variability of antioxidative parameters was observed. Four-month commercial storage resulted in a significant reduction in phenol compounds in red cabbage, but this was not the case in the white cultivar.

Radical scavenging activity did not significantly change after cold storage, except in 2005/06, when a decrease in RSA measured by the DPPH method was noticed. The values of RSA determined by the ABTS method exceeded those determined by DPPH.

The period of vegetation and flowering of carrot usually is very long, and the flowers are formed in different parts of the mother plants. This leads to the formation of seeds with different qualities. Often heterogeneity is of a maternal type, which depends on the position of the umbels on the mother plants. The main goal of the present study was to investigate the quality differences in carrot seeds from different parts of the mother plant. The seedstalks from ‘Nantski’, a typical Bulgarian cultivar, were grown by the conventional method for seed production technology. In botanical maturity the seeds from the primary, secondary and tertiary umbels were extracted separately. The seed yield from umbels, dry weight of the seeds, seed size, length, width and thickness, weight per seed, 1000 seed weight, germination energy (first count), germination capacity (final count), mean germination time, uniformity of germination, fresh weight of seedlings, length of radicle, length of hypocotyls and vigour indexes were investigated. The contents of raw protein, sugar, lipids and the basic calorific values were also analysed. The germination was the highest for the seeds from primary umbels, followed by the ones from secondary umbels and lowest for those from the tertiary umbels. The difference between the highest and the lowest value was 6.30%. These results suggest that it is better to harvest the carrot seeds depending on their position on the plant and divide them into separate lots with different qualities.

Seasonal and cultivar variations of the phenolic, thiol, and ascorbate compound contents as well as the antioxidative enzyme activity in six cultivars of highbush blueberry were investigated. Berries of the ‘Earlyblue’, ‘Patriot’, ‘Bluecrop’, ‘Duke’, ‘Darrow’ and ‘Lateblue’ cultivars were sampled in 2005 and 2006. Chlorogenic acid, (-)-epicatechins, and ascorbate contents and CAT activity were found to be at the lowest degree affected by growing season conditions. ‘Seasonal effect’ had, however, a huge impact on the GR activity, as well as L-cysteine and glutathione content, suggesting that the glutathione system was highly influenced through growing factors in blueberry fruit. Berries of ‘Earlyblue’ were the richest source of antioxidants, at the same time revealing their quite stable quantity over the examined years. The second highest in bioactive stability was ‘Duke’, classified as medium with respect to antioxidant content.

This study investigates the effects of two types of polyethylene films covering the greenhouse, differing in PAR transmittance, as well as two forms of nitrogen fertiliser (100% N-NO₃ vs. 57% N-NO³+ 43% N-NH₄), and the use of foliar nutrition on the quality and yield of lettuce grown in the spring and summer-autumn seasons. Lettuce was grown on rockwool in a film greenhouse divided into two parts, each covered with one type of film. Three times per season the plants were sprayed with a solution of molybdenum, benzyladenine, urea with molybdenum, urea with benzyladenine, and the three substances combined. The yields were examined for dry matter, nitrates, ammonia nitrogen, protein nitrogen, soluble sugars, vitamin C, and macronutrients (phosphorus, potassium, calcium and magnesium). In both seasons, lettuce cultivated in the greenhouse covered with film having a higher PAR transmittance resulted in heavier heads and contained significantly lower levels of nitrates, NH₄⁺, P and Mg. The effect of plot (type of film) on vitamin C content depended on the season. The form of nitrogen fertiliser influenced dry matter, vitamin C, protein nitrogen, P and Mg contents; in the summer-autumn season it also affected head weight. The plants grown on a nitrate medium produced a higher single head mass and accumulated a larger amount of nitrates than those cultivated on a nitrate-ammonia medium. No effects were observed of foliar nutrition with salt solutions on the yield and quality of lettuce in either season.

The experiment was carried out in the Garlica Murowana Experimental Station of University of Agriculture in Krakow, Poland, between 2005 and 2008. Fruit yield, mass of 100 berries, content of total soluble solids, vitamin C, anthocyanins and titratable acidity were estimated. It was shown that ‘Atut’ honeysuckle started vegetation, flowering and cropping periods earlier than ‘Duet’. However, greater marketable yield and mass of 100 berries were obtained for ‘Duet’. ‘Atut’ fruit revealed a significantly higher content of anthocyanins. The studied honeysuckle cultivars did not differ if estimated on the basis of total soluble solids and vitamin C content in the fruit.

In the years 2004-2006, 37 F. rubra L. ecotypes and 35 F. nigrescens Lam. ecotypes were evaluated for their main lawn traits: the general aspect of the plant, slow re-growth, overwintering, winter greenness, leaf fineness and disease resistance. The lawn properties of the ecotypes were assessed with the use of the IHAR 9-grade scale of the visual quality classification system. The study individuals were compared with the model varieties: F. rubra ‘Areta’ and F. nigrescens ‘Nimba’. The ecotypes originated from natural localities in the Lublin region. The experiment was conducted using the method of randomly chosen blocks in three repetitions. One repetition contained six plants of one ecotype grown at a distance of 75 × 30 cm. The aim of the study was to analyze the variability of lawn traits in the examined F. rubra and F. nigrescens ecotypes and to estimate the suitability of the selected material for the breeding of new lawn varieties. Analyses indicated that most of the ecotypes that grow in natural localities in the Lublin region display high-grade lawn traits. This confirms the great suitability of the wild plants for further breeding. Ecotypes of both species obtained high scores comparable with model varieties for their disease resistance, leaf fineness and winter greenness, and also for general aspect and slow re-growth.