Volume 24 (2012): Issue 1 (June 2012)

The responses of red cabbage (Brassica oleracea L. var. capitata f. rubra) plants to a low Zn supply and cold conditions (10°/7°C day/night temperature) were investigated in a hydroponic growing medium. A low Zn supply caused a significant reduction of shoot and root dry weight - up to 55% and 45% for the control and 62% and 52% for cold-treated plants, respectively. The total soluble carbohydrates and starch declined in Zn-deficient plants. Exposure to low temperatures, however, led to a decline in starch but an increase in soluble sugars. In Zn-sufficient plants, low temperatures increased the excitation capture efficiency of open photosystem II (PS II) reaction centres (RCs) (F'_v/F'_m), the quantum yield of PS II (Φ_PSII), the electron transport rate (ETR) and the proportion of active chlorophyll associated with the RCs of PS II (F_v/F₀). Low temperatures did not affect net CO₂ uptake in Zn-sufficient plants, though a reduction of stomatal conductance occurred. The results demonstrated that although cold-treated plants were slightly more susceptible to Zn deficiency, cold treatment caused greater shoot biomass (up to 32%) in plants supplied with adequate Zn. The adaptation of red cabbage plants to cold conditions is attributable to improved photochemical events in the leaves, a maintenance of the net CO₂ assimilation rate, lower water loss and the accumulation of anthocyanins as antioxidants.

Tomato plants (Rumba Ożarowska cultivar) grown in the greenhouse of the University of Warmia and Mazury in Olsztyn were treated with the biological control agent Polyversum WP, the growth promoter Biochikol 020 PC, the growth regulator Asahi SL, a mycorrhizal inoculum, and the fungicide Bravo 500 SC. Untreated plants served as the control. After fruit harvest, soil, stem and root samples were collected, and fungi were isolated in the laboratory. The applied biological and chemical control agents effectively reduced the abundance of fungi, including pathogenic species, colonising tomato plants and soil. The fungicide Bravo 500 SC showed the highest efficacy. Amongst the biological control agents, Biochikol 020 PC and the mycorrhizal inoculum were most effective in controlling stem colonisation by pathogens, while Polyversum WP offered the best protection of tomato roots and soil.

The field experiment focused on three high-inulin vegetable crops: chicory (Cichorium intybus L. var. sativum Bisch), black salsify (Scorzonera hispanica L.) and common salsify (Tragopogon porrifolius L.), and took into account two cultivation methods (flat soil and ridges) and a phacelia (Phacelia tanacetifolia L.) intercrop, the biomass of which was mixed with the soil during pre-winter ploughing. Cultivation without an intercrop served as the control. The studies aimed at evaluating the influence of ridge cultivation using a phacelia intercrop on the species composition and population of vegetable weeds as compared to traditional flat-soil cultivation with no intercrop. In total, 24 taxa in the primary and 31 taxa in the secondary weed populations (mostly characteristic for vegetable crops) were recorded in high-inulin species plantations. Monocarpic species such as Senecio vulgaris, Chenopodium album and Lamium amplexicaule dominated in the spring, while Stellaria media, Capsella bursa-pastoris and Urtica urens were most numerous at the end of the vegetation period. Applying phacelia as the intercrop and ploughing its biomass before winter significantly reduced the primary weed population for all of the cultivated crop species as compared to the no-intercrop cultivations. Phacelia grown as the intercrop reduced the occurrence of Senecio vulgaris, while favouring the development of Lamium amplexicaule. The cultivation system affected the primary weed infestation of vegetables, whereas it had no impact on the level of secondary weed infestation. At the beginning of the vegetation periods, fewer weeds grew in ridges than in the flat soil system. The crop species had no effect on the primary weed infestation, while it influenced weed numbers in the secondary. The lowest number of weeds was recorded in the secondary weed infestation of chicory, the well-developed leaf rosettes of which efficiently eliminated most of the weeds.

The study examined the effects of the sowing date (5, 15 and 25 May) and plant spacing (1 × 0.6 m, 1 × 0.8 m and 1 × 1 m) on the content of carotenoids and L-ascorbic acid in the fruits of two cultivars of spaghetti squash (‘Makaronowa Warszawska' and ‘Pyza’). The field experiment was carried out in central-eastern Poland. Fully mature spaghetti squash fruits were harvested from the beginning of September to the beginning of October. The content of total carotenoids and β-carotene was the greatest in the fruits of plants sown on 15 May. The sowing date did not affect the content of L-ascorbic acid. Increasing the plant spacing from 1 × 0.6 m to 1 × 1 m resulted in an increase of total carotenoid content, particularly for the spaghetti squash sown on 25 May. Plant spacing did not have a significant effect on the content of β-carotene and L-ascorbic acid. Fruits of the ‘Makaronowa Warszawska’ with light orange flesh contained more total carotenoids and β-carotene than fruits of the ‘Pyza’ with cream-coloured flesh. The content of L-ascorbic acid in the fruits of both cultivars did not differ significantly.

The effects of boron (B) deficiency and water stress were studied in tea plants (Camellia sinensis [L.] O. Kuntze) grown in growth chambers in perlite irrigated with a nutrient solution. Dry matter production was reduced significantly by both low B supply and water stress. Shoot-root translocation of B declined in water-stressed plants. In addition, the re-translocation of B was impaired under drought, which was reflected in a significantly lower ratio of B content of young to old leaves in both B-deficient and B-sufficient plants. Leaf photochemical parameters were negatively influenced by B deficiency and water stress in the old but not in the young leaves. Although B-deficient plants were more conservative in relation to water loss following elevated stomatal limitation, their water potential was lower than in B-sufficient plants irrespective of the watering regime. Under the combined effects of B deficiency and water stress, the reduction in the CO₂ assimilation rate was more prominent than that under a single stress factor. The reduction of the net assimilation rate (A) in B-deficient plants due to water stress and in water-stressed plants due to low B supply were not accompanied by significant changes in the stomatal conductance, suggesting an involvement of non-stomatal factors. The activity of antioxidant enzymes and proline content increased under B deficiency and water stress conditions. Our results suggested that, in young leaves that have been developed under water stress, an acclimation to water stress conditions occurred that was well reflected in their more stable photochemistry, water relations and an efficient antioxidant defence system compared with the older leaves.

The study examined the differences between 10 accessions of common bean and cowpea during the vegetation period. Different stages of development and elements of yield were analysed in the climatic conditions of Sadovo (Bulgaria), which is characterised by hot summers and insufficient rainfalls. All genotypes were planted in the second 10 days of April. They emerged 10-15 days after sowing. The flowering stage occurred after 28-34 days in common bean and 45-60 days in cowpea. The vegetation period duration was much longer in cowpea (over 98 days) than in the common bean (less then 80 days). The reproductive organs (number of pods and seeds per plant, size of pods and seeds, weight of pods and seeds per plant) were quite different for the two crops. The mean number of pods per plant was 8.84 in common beans and 13.22 for cowpea; the number of seeds per pod was 4.05 for beans 10.56 for cowpea; the number of seeds per plant was 25.65 for beans and 93.47 for cowpea. The bean seeds were larger than the cowpea seeds, with 100-seed weights of 41.86 g and 15.73 g, respectively. Under the climatic conditions of Sadovo, the cowpea accessions showed a more stable yield, resulting in more pods and seeds per plant and weight of seeds per plant, when compared with common bean accessions.

In the years 1996-1999, a study was conducted on the estimation of the growth and yielding of northern highbush blueberry on a brown soil developed from loess. The study comprised bushes from five highbush blueberry cultivars - ‘Bluecrop’, ‘Bluejay’, ‘Darrow’, ‘Herbert’ and ‘Jersey’ - aged from six to nine years since planting. ‘Bluecrop’ bushes were the tallest and those of ‘Darrow’ the shortest, but ‘Darrow’ was characterised by the largest number of annual shoots. The best yielding was ‘Darrow’ and its berries were the largest. ‘Bluejay’ and ‘Jersey’ produced the lowest yields. In the study, the highest estimate was awarded to ‘Darrow’ (number of annual shoots, yielding, fruit size), and ‘Bluecrop’ also proved to be a valuable cultivar.

The growing of sage (Salvia officinalis L.) and balm (Melissa officinalis L.) in pots for the purpose of obtaining fresh culinary herbs was conducted during four terms from spring to autumn. The objective was to determine the possibility of using stem cuttings taken at different developmental stages of the mother plants and to compare this method of plant propagation with that based on seeds. The period of sage growth was shorter when it was raised from cuttings than from seeds. In the case of balm, the use of cuttings was more effective than generative propagation in the period from summer to autumn. In both species, the best results of rooting were achieved when cuttings were taken before plant flowering in spring and after flowering in August. The poorest balm rooting was recorded when taking cuttings at plant flowering, and at flowering and after flowering in July for sage.

Ornamental grasses have become a popular group of plants for use in landscaping. The aim of the present experiment was to assess the influence of seed age on the germination of ornamental grasses. In the glasshouse experiment, seeds of three grass genera, Melica, Pennisetum and Stipa, were tested. The seeds came from the Plant Breeding and Acclimatisation Institute in Bydgoszcz. They were harvested in 2005, 2006 and 2007 (so they were three years old, two years old, and one year old, respectively). In all the genera, the youngest seeds showed the highest germination, which varied between 61% (Melica transsilvanica) and 74% (Melica ciliata ssp. taurica). The germination process of the oldest seeds (three years old) proceeded at various rates, depending on the species, but the highest ability to germinate was observed in Pennisetum flaccidum (39%) and Stipa tenuissima (42%). After germination, Melica sp. and Stipa sp. plants were repotted and treated with Hydrocote (a slow-release fertiliser). The results obtained indicated that the fertilisation of the grasses significantly increased the height of the plants. Plants of Melica altissima ‘Atropurpurea’ also formed three times more inflorescences than the control plants. The application of the fertiliser had a positive effect on leaf colour (a more intense green) in all of the tested genera.

The CIE L^* a^* b^* colour system is used to evaluate food colours. Its advantage is that the base skin colour in apples can be measured on the same fruit before and on the optimum harvest date. The aim of the research conducted between 2002 and 2006 was to evaluate a quick and non-destructive method of determining the optimum harvest date of apples intended for long storage based on the changes observed in the base skin colour. Another important research aspect was to compare this method with other methods or indicators used to determine the harvest date. The colour measurement was conducted on two apple cultivars, Šampion and Royal Gala, with the aim of, amongst other factors, establishing a standard for each that could be used in practice in fruit production. From amongst the evaluated colour indicators L^*, a^*, b^*, Hue_ab angle and chroma, changes in the base colour were best illustrated by the a^* coordinate value and Hue_ab angle value. Based on the evaluation of the quality of fruits after storage, it can be stated that the fruits had the best quality when the a^* coordinate during harvest ranged between -7 and -8 for ‘Šampion' and between -3 and -5 for ‘Royal Gala’. The Hue_ab angle assumed a value between 100 and 101 for ‘Šampion' and between 96 and 99 for ‘Royal Gala’ during the optimum harvest date. Therefore, the a^* coordinate and the Hue_ab angle can be used to indicate harvest maturity.

Following the winter of 2009/2010, an assessment of frost damage was carried out on the vines of 40 wine cultivars and 32 table grape cultivars grown in central Poland (Skierniewice, latitude 51° 57' N, longitude 20° 08' E). The minimum winter temperature of -28.1°C was recorded on 26 January 2010. Cultivars were assigned to five classes of different frost tolerance, according to information on the percentage of frozen buds: very resistant (below 1.9%), resistant (2 - 24.9%), medium susceptible (25 - 74.9%), susceptible (75 - 95.9%) and very susceptible (above 96%). The numbers of wine and table cultivars in each class were as follows: very resistant - 5 (wine) and 3 (table), resistant - 2 and 5, medium susceptible - 15 and 10, susceptible - 13 and 9 and very susceptible - 5 and 5. The most tolerant were the ‘Alwood’, ‘Delaware’, ‘Fredonia’ and ‘Zilga’ interspecific hybrids of the Vitis labruscana group; the ‘Aurore’, ‘Marechal Foch’ and ‘Leon Millot’ hybrids originating from V. vinifera, V. rupestris, V. riparia and V. lincecumii and ‘Sibera’ originating from V. vinifera and V. amurensis. More than 96% of buds froze on the vines of some interspecific hybrids (‘Arkadia’, ‘Fanny’, ‘Kodrianka’ and ‘Lilla’). ‘Ortega’, ‘Nektar’, ‘Cserszegi Fueszeres’, ‘Riesling’ and ‘Chasselas Dore’ from the V. vinifera cultivars showed the best tolerance to frost damage (42.5-62% of frozen buds). The buds of the V. vinifera cultivars ‘Acolon’, ‘Dakapo’ and ‘Favorit’ all froze. Plant parts covered with soil and snow were not exposed to significant damage, even in the case of susceptible cultivars.

During each season, pears were harvested on three dates at four-day intervals. The fruit was stored for 150 days in temperatures of 0-0.5°C in common cold storage (NA - normal atmosphere) and also in controlled atmospheres (CA) of different gaseous content: 0.8% CO₂ + 2% O₂, 2% CO₂ + 2% O₂ and 3% CO₂ + 3% O₂. After removing the pears from storage they were additionally stored for seven days in a temperature of 17°C - simulated shelf life. The content of chlorophyll pigments (chlorophyll a + b) was determined after each harvest date, storage time and simulated shelf life. Based on the results, I concluded that the a + b chlorophyll content in the peel of both pear cultivars significantly decreased along with the subsequent harvest date. In addition, the storage conditions had a significant influence on the studied factor. Compared to the normal atmosphere, the controlled atmosphere conditions were more efficient in slowing the yellowing of the fruit due to reduced chlorophyll degradation. The atmosphere consisting of 3% CO₂ + 3% O₂ or 2% CO₂ + 2% O₂ was more favourable for the higher content of chlorophyll a + b in the peel of ‘Conference’ pears than 0.8% CO₂ + 2% O₂. In the case of ‘Concorde’ pears, the influence of particular compositions of CA on the content of chlorophyll a + b changed over the years.