Volume 25 (2013): Issue 1 (June 2013)

The impact of abiotic and biotic factors (rainfall, temperature, host plant and natural enemies) on population dynamics of the Plutella xylostella L. diamondback moth was investigated. The experiments were conducted during the rainy and dry seasons for two years (June 2009-April 2011) on unsprayed cabbage plots in Malika (Senegal). Every 10 days, 10 cabbages were randomly selected. Plutella xylostella larvae, pupae and parasitoid cocoons were recorded on each plant. Before each sampling, the diameters and ages of plants were recorded. Temperature and rainfall were also recorded during this study. Larvae and pupae of P. xylstella were higher for the dry season than the rainy season. There was a negative correlation between temperature and P. xylostella populations, and a strong relationship between P. xylostella populations and the age of cabbages. Females oviposited on young cabbages where the presence of young larvae was important, whereas older immature stages were mainly found in older cabbage plants. Parasitoid populations were higher for the dry season than the rainy season. High temperatures did not increase the pest populations and parasitism rate. There was no effect found on pest, plants and natural enemies due to rainfall. There was a positive correlation between pest populations and parasitism. Four Hymenoptera species were found: Oomyzus sokolowskii, Apanteles litae, Cotesia plutellae and Brachymeria citrae, but they were not efficient to control the P. xylostella populations. These results are important for understanding the factors that promote or inhibit pest populations and their natural enemies, and therefore essential for effective crop protection.

The decorative value of 24 fescue (Festuca trachyphylla) ecotypes from natural habitats in the Lublin region was assessed in the years 2004-2011. Plants with desirable ornamental characteristics were selected and the cuttings were planted in experimental plots in the Maria Curie-Skłodowska University Botanical Garden in Lublin, where they grew in uniform habitat conditions. During the study years, 18 morphological traits that determine the decorative value of grasses were analysed; 11 quantitative traits (length and number of the culm, length of the panicle, number of spikelets in the panicle, number of vegetative stems, length, width and thickness of the leaf blade, length and width of the cauline leaf and diameter of the tuft) and seven qualitative traits (plant growth habit, greenness index of the leaf blade [SPAD], winter greenness, culm colour, waxy coating on the leaf blade, flowering periods and plant condition after 8 years). The analysis of quantitative and qualitative traits demonstrated that F. trachyphylla is a morphologically variable species. The variability is mainly manifested in the inflorescence morphology, length of the leaf blades and number of culms, which have been statistically corroborated by the results of the ANOVA analysis. A considerable degree of variability was also exhibited by plant habit, colour of leaves and culm, wax deposits on the leaves and flowering period. The high morphological variability of this species allowed for the selection of two interesting types among the plant individuals studied, which were characterised by desirable decorative traits. The most decorative features of the selected ecotypes include the shape and colour of the leaves and the plant habit.

The effect of silicon (Si) supplementation (0.35 g Na₂SiO₃ kg-1 soil, 2.73 mmol Si kg^-1 soil) was studied in drought-stressed pistachio (Pistacia vera L. ‘Ahmadaghaii’) plants under field conditions. Silicon treatment significantly increased plant dry weight and relative water content under drought stress. The application of Si for drought-stressed plants improved the maximum quantum yield of PSII. A reduction in the net assimilation rate due to drought stress was alleviated by Si application, accompanied by an increase in stomatal conductance. Silicon treatment resulted in higher catalase and superoxide dismutase activities and lower lipid peroxidation in the leaves of drought-stressed plants. The results suggest that supplementation of water-deficient pistachio plants with Si alleviates the adverse effects of drought due to its enhancement of photochemical efficiency and photosynthetic gas exchange, as well as an activation of the antioxidant defence capacity in this species.

Research was carried out during the 1999-2007 growing and storage season using ‘Ligol’ apples from trees grafted on M.26, and fertilised in accordance with recommendations for commercial orchards. The approximate optimum harvest date was determined mainly on the basis of starch index measurements and Streif index calculations, evaluated 7-8 times every 4-5 days each year. In addition to samples collected to determine OHD each year, there were four harvests of fruit intended for storage. The apples were stored in a cold storage room at 1-2°C and RH of around 90% for about five months. Following a storage period lasting the same number of days for each harvest, the quality of fruits was examined and the correlation between the concentration of minerals in apples and all fungal diseases and physiological disorders was calculated. In years with high precipitation in the period preceding the harvest, the share of fruits affected by fungal diseases and physiological disorders after storage depended more on weather conditions prevailing in the growing season than on the harvest date. The incidence of bitter pit increased with the number of days preceding OHD. Other recorded losses were caused by internal breakdown and superficial scald, but they were small and did not seem significant for ‘Ligol’ apples. Each characteristic mineral concentration in the fruit at harvest (N, P, K, Ca and Mg) was correlated with the incidence of physiological disorders and/or fungal diseases. The incidence of bitter pit and lenticel blotch pit and the sum of physiological disorders increased along with the increase in nitrogen concentration. The feature that best predicted the storability of ‘Ligol’ was the K/Ca ratio.

The experiment was carried out in the winter and autumn of 2011 using lamb’s lettuce (Valerianella locusta Laterr. Em Betce) as a test plant under greenhouse growing conditions. The aim of the study was to evaluate the effect of a prolonged day with modern SSL LED (Solid State Lighting Light Emitting Diodes) technology on photosynthetic parameters and plant yield. Two kinds of LED lamps with different spectral properties were used. The first emitted a white light and the second a mixture of red and blue light. Measurements of chlorophyll fluorescence and gas exchange were taken in natural and artificial light. Control plants were not treated with additional lighting. During the day with natural light in March (winter growing), photosynthesis intensity, stomatal conductance and transpiration of lamb’s lettuce leaves were higher than in November (autumn growing). In the evening hours of March and November, during artificial plant lighting, similar photosynthesis intensity was observed. This intensity was significantly higher than in the afternoon hours (by natural light) in the autumn. The highest content of chlorophyll a, b and carotenoids was found in the treatment with red+blue LEDs in winter growing. Supplemental lighting with red+blue LED light stimulated the high efficiency of the photosynthetic apparatus, which was manifested by the highest Performance Index (PI). The highest weight of the rosettes was noted in the autumn growing period in plants that were under the influence of the red+blue supplemental lighting followed by the white LED. This could be the result of a significant stimulation of photosynthesis during supplemental lighting with the LED lamps during this period.

This study investigated the effect of plant extracts (Azadirachta indica and Piper guineense) on the growth and yield of jute (Corchorus olitorius L.) (Cor) under sole and mixed cropping with Amaranthus hybridus (Ama) and Celosia argentea (Cel). The highest percentage increase in plant height, number of leaves, number of branches and stem girth (130.6, 865.0, 220.4 and 114.0%, respectively) was found in untreated Cor + Cel, cypermethrin treated Cor + Ama, cypermethrin treated Cor and A. indica extract treated Cor + Ama, respectively. The highest percentage increase in shoot weight (71.0%), marketable yield (53.9%) and total biomass (51.5%) was in A. indica treated C. olitorius. Extract treatment had no effect on the number of branches at four, five and seven weeks after planting (WAP) in Cor + Ama + Cel; four, five and six WAP in Cor + Cel; four and six WAP in Cor + Ama; as well as four and five WAP in Cor. The highest percentage increase in leaf fresh weight was obtained in cypermethrin treated Cor (53.3%) and Cor + Ama + Cel (52.2%), while the smallest increase was in P. guineense treated Cor (1.1%) and Cor + Ama (2.5%). The activity of A. indica was independent of time of application while P. guineense was not. Among the extract treated groups, the highest percentage increase in shoot weight (71.0%), marketable yield (53.9%) and total biomass (51.5%) was in A. indica treated Cor. The activity of the extracts against insect pests of sole cropped Cor increased significantly (p < 0.05) with increasing extract concentration. The highest efficiency with the use of P. guineense was 250 g dm-3 at four, five and six WAP (94.0, 92.7 and 90.3%, respectively) and 200 mg dm-3 at seven WAP (81.7%). In the case of A. indica extract, the highest efficiency was found with the use of 200 g dm-3 at four, six and seven WAP (92.7, 85.3 and 100%, respectively). A. indica extract (250 g dm-3) treatment gave the highest efficiency at five WAP (100%).

During this two-year experiment (2008-2010), the ‘Kenton’ leek cultivar was grown in the field from July to March/April of the following year. During the winter months the plants were kept under biodegradable nonwoven covers (Bionolle - polybutylene succinate, 59 and 100 g m^-2). The control treatments were left uncovered. Some cracks and tears in the biodegradable nonwoven covers were observed. The covers resulted in better leek yields. In the first season the bleached parts of the leek contained more ascorbic acid when kept under the Bionolle 100 g m^-2 cover. The lighter nonwoven (59 g m^-2) cover caused a grater accumulation of soluble sugars. Biodegradable films, used in the winter cultivation of leek, increased the soil temperature by 1°C on average.

The importance of functional products on the world food market is increasing systematically. This has resulted from enhanced consumer awareness that health improvement may be attained through appropriate nutrition. Functional products are targeted to different groups of consumers who have increased nutrient requirements or are designed to improve specific functions of the organism. The market for functional food is also developing in Poland, but its growth rate is much slower than in other European countries. Moreover, knowledge on issues concerning functional food among Polish consumers is also low. Vegetables and mushrooms occupy an important position among functional food products due to their contents of many bioactive components that have a beneficial effect on human health and sense of well being. Vegetables in an everyday diet are natural sources of dietary fibre, vitamins, minerals, anthocyanin, carotenoids and substances with an anti-carcinogenic effect. The fruiting bodies of both cultivated and wild-growing mushrooms contain several active substances, including polysaccharides, triterpenoids, specific proteins and phenolic compounds. Their positive effect for humans results from the interaction of different active components contained in their fruiting bodies. Several health-promoting properties of mushrooms have been documented, including anti-cancer, immunostimulatory, antioxidant, antibacterial, antiviral and anti-diabetic effects. Consumers should have knowledge on the potential for health improvement thanks to the inclusion of vegetables and mushrooms in their everyday diets.

This review provides a summary of haploid induction methods and factors affecting the efficacy of specific methodologies as applied to cucumber (Cucumis sativus L.), melon (Cucumis melo L.), watermelon (Citrullus lanatus (Thunb.) Matsum. & Nakai), winter squash (Cucurbita maxima Duch. ex Lam.), summer squash (Cucurbita pepo L.) and other cucurbits. This report is focused on studies that were carried out during the last 20 years.

The main objective of the research on the production of haploid cucurbit plants is to accelerate breeding programs through the use of homozygous double haploid lines (DHL) and to facilitate the selection of desired (e.g. disease-resistant) genotypes for breeding. Unfortunately, currently used protocols result in a low number of double haploids (DH). The most common and best-known method of obtaining haploid cucurbit plants is via pollination with irradiated pollen, which induces parthenogenetic development of haploid embryos in planta. The embryos are extracted from immature seeds and cultured in vitro to facilitate the maturation and development of plants. The studies described below were primarily aimed at the determination of an appropriate dose of radiation and the evaluation of the impact of the genotype and the time of year on the number of haploid embryos and plants obtained.

A less popular method of haploid production - ovule and ovary culture - is based on in vitro gynogenesis. The studies related to this method concentrated on optimising the composition of the medium and pre-treatment conditions (primarily temperature) to which the flower buds were subjected.

Recently, increasing attention has been paid to anther and microspore culture. As in the case of in vitro ovule and ovary culture, the medium composition and flower bud pre-treatment conditions were optimised. The most recent studies suggest that anther culture is comparable in effectiveness to the irradiated pollen technique.