Impact of UV radiation on the physical properties of polypropylene floating row covers

In the intensive horticulture, various ways of protected area are used for the growth of seedlings and the cultivation of vegetables in all seasons. The easiest and the cheapest form of protected area is agrotextile, which can be laid directly over vegetable crops (row cover). Agrotextiles are nonwovens which are manufactured from textile fibres which are usually of chemical origin. Textiles, used as agrotextiles require suitable tensile strength and good permeability characteristics with no significant deterioration under the influence of weather changes and UV radiation. Properties of agrotextiles depend on the fibres made of and on the type and conditions of production. The purpose of this study was to analyse the influence of simulated sun light radiation (xenon lamp) on physical properties of polypropylene (PP) nonwoven material, which is used for the production of agrotextiles. The research showed that the properties of row cover change when radiated with UV light. Tensile, tearing and bursting properties worsen after radiation and air permeability and water vapour show little increase. The changes in the properties are a consequence of changes in fibres, molecular and supermolecular structure which is exhibited in changed fibres and consequently also nonwoven properties.Key words: Agrotextile, polypropylene, nonwovens, UV radiation, properties

Potential of eggplant peel as by-product

In this study ascorbic acid and phenolic compounds contents of eggplant flesh and eggplant peel were determined. Among the investigated eggplant cultivars generally eggplant peel had higher ascorbic acid and phenolic compounds contents than eggplant flesh. Ascorbic acid content in eggplant flesh ranged from 33.62 to 92.75 mg kg−1 and in eggplant peel from 12.45 to 111.01 mg kg−1. Phenolic compounds content ranged from 11.77 to 22.18 g kg−1 in eggplant flesh and from 13.46 to 29.42 g kg−1 in eggplant peel. Eggplant peel is usually treated as waste, i.e. byproduct, omitting its potentially beneficial characteristics. Due to higher ascorbic acid and phenolic compounds contents, further investigations should be directed on possible use of eggplant peel as natural ingredient for functional products formulation

Onion thrips ( Thrips tabaci Lindeman) damage on early white cabbage grown under mulch and non-mulch conditions

In 2005 the damage caused by onion thrips (Thrips tabaci) on a susceptible hybrid of early cabbage (cv. ‘Parel’) was studied in a block field experiment. The cabbage was grown in four treatments: 1) on non-mulched surfaces, 2) on surfaces mulched with barley straw, 3) on surfaces mulched with hay and 4) on surfaces mulched with black PE mulch. The trial consisted of two parts: the first part included plots that were mulched as indicated from the very beginning (normal), while in the second part the soil was first covered with black PE mulch for about one month, than this was removed and replaced either by organic mulches or left non-mulched (postponed). In this way, we wanted to diminish the yield loss because of low temperatures and abundant precipitation. Under cold and wet conditions in spring which led to late appearance and low levels of the pest, the growing of cabbage under black PE mulch proved most effective and these plants exhibited the greatest head mass as well as the greatest net mass, although they also suffered most damage from the pest. The cabbage in the second part of the experiment exhibited higher head mass as well as higher net head mass compared to the first part

Which plant compounds influence the natural resistance of cabbage against onion thrips ( Thrips tabaci Lindeman)?

In a field experiment on the natural resistance of cabbage ( Brassica oleracea var. capitata ) against onion thrips (Thrips tabaci) , 20 cabbage genotypes were included: 9 early, 5 mid-early, 6 mid-late (regarding the longevity of the growing period), 3 red, 17 white (regarding colour), 14 hybrids and 6 varieties (regarding genetic origin). For comparisons between genotypes, we determined significant differences in the mean index of damage on the exterior leaves of cabbage heads (1.12–2.83), the net weight of heads (281.40,151169.6 g), and yield loss (5.8–47.4%). The concentration of several compounds from cabbage leaves (epicuticular wax, α-amyrin, β-amyrin, lupeol, sucrose, glucose, fructose, vitamin C, palmitic acid, stearic acid, and arachidic acid) are measured. For all groups of cabbage genotypes the only confirmed negative correlation was between the extent of damage caused by the sucking of onion thrips and epicuticular wax content on the cabbage leaves (in groups where we artificially placed genotypes with similar characteristics). After this preliminary experiment, the research must be extended in order to determine the effect of the remaining analysed compounds in cabbage leaves for resistance (sensitivity) of cabbage to onion thrips attack