Volume 20 (2008): Issue 2 (December 2008)

The aim of the investigations was to determine the best method of eggplant (Solanum melongena L.) pruning in greenhouse production. The investigations were carried out in 1999 - 2001 in the experimental greenhouse of the University of Agriculture in Krakow, Poland. The ‘Tania F1’ hybrid was used in the early spring-summer production in a heated greenhouse. Plants were pruned to one or two shoots. In the case of two-shoot plants, the second shoot was led out from the first, third, sixth and ninth node. The intense pruning positively affected the PAR conditions in the plant profile. The most effective fruit setting was observed in the intensely pruned plants. The greatest number of fruits was set at the lowest nodes. Pruning affected the total but not marketable yield of fruits. Two-shoot plants with the second shoot led out from the sixth node produced the greatest fruits, both in early and total yield. A high level of reducing sugar was found in the fruits of moderately pruned plants. Fruits of two-shoot plants with the second shoot led out from the sixth node and pruned to one shoot contained the greatest level of L-ascorbic acid. The greatest levels of reducing sugar and starch were found in the leaves of moderately pruned plants, having the best PAR conditions. The method of pruning slightly affected the level of pigments in the eggplant leaves.

A pot experiment conducted in a growth chamber studied the effectiveness of foliar fertilization of spinach (Spinacia oleracea L.), with different forms of nitrogen applied with the air temperatures: 5°C, 15°C and 25°C. Nitrogen was supplied three times in the form of 1% water solutions of CO(NH₂)₂, NH₄NO₃, NH₄HCO₃ and Ca(NO₃)₂ × 4 H₂O, with water as the control. The obtained results showed that nitrogen in the form of Ca(NO₃)₂ × 4 H₂O - independent of the air temperature during solution application - is the least useful in foliar fertilization of spinach leaves, whereas the effectiveness of the other forms was similar, although the best effects were given by NH₄NO₃. Application of all forms of nitrogen at the air temperature of 25°C had the most positive effect on the course of gas exchange (stomatal conductivity, photosynthesis, transpiration). Despite that, the highest leaf yield with the highest content of nitrogen, total chlorophyll (a + b), carotenoids and vitamin C, and the lowest content of nitrates, was given by plants with foliar application of all nitrogen forms at the temperature of 15°C.

In order to examine the effect of plant age on asparagus yielding, the number and weight of spears were analyzed. The experiment was carried out on 1-, 4- and 7-year-old plants in the aeroponic system with recirculation. The results showed that the spear number and thus also the yield were not plant age dependent, while spear diameter and their weight were. Taking into account both crown weight and the age of plants, a 26% variation in spear diameter and a 27% variation in mean spear weight were explained. Determination of dry weight and carbohydrate contents in storage roots showed these traits to be independent of asparagus plant age, except for total carbohydrate content per plant. During harvest dry weight, % Brix, sucrose, fructan and total carbohydrates contents losses were also recorded.

Two years experiment was carried out to compare the nutritional composition in bulbs of ten onion cultivars grown in the field conditions. Pyruvic acid, ascorbic acid and soluble sugars were determined in the edible part of onion bulbs. In most cultivars the content of pyruvate as the pungency index was ranged between 3-7 μmol g^-1 fresh weight (medium pungency), however, three of them exceeded 7 μmol g^-1 fresh weight (high pungency). A higher level of pyruvate corresponded in most cases with higher sugar content but was not correlated with that of ascorbic acid.

In the years 1996 - 1999 an estimation of the growth and yielding of highbush blueberry cultivated on soil developed from weakly loamy sand was carried out. The study covered the initial years of fruit bearing (3-6 years after planting) of six cultivars of highbush blueberry: ‘Bluecrop’, ‘Blueray’, ‘Darrow’, ‘Ivanhoe’, ‘Northland’ and ‘Spartan’. The strongest vegetative growth was characteristic for bushes of ‘Northland’ and ‘Bluecrop’ cultivars, while the weakest was found in ‘Darrow’ and ‘Spartan’. ‘Northland’ proved to be the best yielding cultivar, although its fruits were the smallest. Berries of the ‘Darrow’ cultivar were the largest. In the study, the highest ranking was awarded to ‘Bluecrop’ (for growth, yielding, fruit size) and ‘Northland’ (for growth and yielding).

Three cultivars of chrysanthemums from the Time group were grown in the spring and summer-autumn seasons in 2003 - 2004. Three nutrient solutions with different nitrogen and potassium contents were applied. Samples of healthy, fully developed leaves were taken for chemical analyses when inflorescence buds appeared, and in the phase of full blooming. The concentration of total N, P, K, Ca and Mg in plant tissue was determined. The nutritional status of plants was very similar in spite of the fact that the plants were grown in different light conditions and different nutrient solutions were used. The paper also contains a proposal of more precise guide values for nitrogen (N 4.35-5.53% d.m.) and for potassium (K 6.36-7.97% d.m.).

The effect of tuber dressing and plant spraying with Biochikol 020 PC (B.A.S. chitosan) and with Polyversum bio-preparation (B.A.S. Pythium oligandrum) on the infestation of stored tubers by Helminthosporium solani was studied. Vitavax 2000 FS (B.A.S. karboxin and thiuram) was used as a standard fungicide. The effect of these preparations applied at three different concentrations on H. solani mycelium linear growth was investigated under in vitro conditions according to the Kowalik and Krechniak method (1961). The application of all tested preparations during potato vegetation resulted in both lower (in comparison to the control) mean infestation degree and lower percent of tubers infected by this pathogen. Results showed that all preparations inhibited H. solani mycelium linear growth.

The purpose of the present study was to conduct pathogenicity tests for salsify seedlings in a soil environment colonised by selected fungi species, after the cultivation of cover crops such as oats, common vetch and tancy phacelia. A growth chamber experiment used the seeds of ‘Mamut’ salsify and soil overgrown with Altenaria alternata, Fusarium culmorum, F. oxysporum, Pythium irregulare, Rhizoctonia solani and Sclerotinia sclerotiorum. The pathogenicity of these microorganisms towards salsify seedlings was established on the basis of the grown plants, their health and a disease index calculated on the basis of a fivedegree scale. The examined isolates considerably weakened the emergence and health of salsify. Based on pathogenicity tests, such species as R. solani, S. sclerotiorum and P. irregulare were considered as the major cause of seedling necrosis and root rot of the plants of the Tragopogon porrifolius var. sativus. Among the studied soil-borne plant pathogens, the most pathogenic ones towards salsify seedlings proved to be the isolates of R. solani, S. sclerotiorum and P. irregulare, whereas the least harmful included A. alternata and F. culmorum.

‘Tina’ and ‘Libra’ cultivar seeds of the common bean (Phaseolus vulgaris L.) beginning germination capacity of 98%, were subjected to artificial ageing. In the thermal chamber, they were twice treated for 72 hours at 45°C. After the treatment, the seeds had lower viability. They germinated at 12% and 0% for ‘Libra’ and ‘Tina’ cultivars, respectively. The dynamics and rate of seed drying were measured in samples with high and low viability. It was found that the seeds of both cultivars with high viability, expressed by high germination capacity, dried at a slower rate than ones with low viability. In the future, this method of estimating the drying rate could probably be used to test seeds with different degrees of viability.

The micropropagation efficiency of four interspecific Cattleya hybrids (clones: 69, 75, 149 and 150) infected with Cymbidium mosaic (CyMV) and Odontoglossum ringspot (ORSV) viruses was assessed. The aim of experiments was to evaluate with that model to what extent viral infection affects the morphogenesis in vitro in orchid hybrids of different origin. The effectiveness of plant material exposure to therapeutic levels of plant growth regulators supplied with media in order to suppress infection was also verified. The vitality of proliferating infected shoot cultures was limited, and the symptoms of senility were frequently observed. Regardless genotype of the studied clone, during acclimation to ex vitro conditions considerable losses become visible what indicates the necessity of testing the donor material for possible latent viral infections. Infection with CyMV and ORSV mostly persisted in every tested clone.

The effect of tuber dressing and plant spraying with Polyversum (B.A.S. Pythium oligandrum) and Biochikol 020 PC (B.A.S. chitosan) bio-preparations on the infestation of potatoe tubers by Streptomyces spp. was studied during the 2005-2007 years. The Vitavax 2000 FS (B.A.S. karboxin and thiuram) was used as a standard fungicide.

The results received from field experiments indicate that, during all years of study these preparations significantly reduced tubers infestation by Streptomyces spp. The Polyversum bio-preparation, which was applied to tuber dressing and sprayed on plants four times during vegetation period, showed the best protective effect against Streptomyces spp.