Flea beetles (Phyllotreta spp.), cabbage stink bugs (Eurydema ventrale) and onion thrips (Thrips tabaci) cause significant economic problems to cabbage growers in Slovenia. The aim of our study was ...to assess the potential effect of the epicuticular wax on leaves as defence mechanism against these three cabbage pests. The impact of epicuticular wax content in relation to damage levels of cabbage pests was studied under field conditions at the Experimental Field of the Biotechnical Faculty in Ljubljana on 12 cabbage cultivars (Brassica oleracea L. var. capitata). These insect pests showed weak preference on cabbage heads with high epicuticular wax. There was a strong negative relationship between epicuticular wax content and the level of plants infested (r2 = -0.8399 for flea beetles, r2 = -0.7413 for cabbage stink bugs and r2 = -0.7042 for onion thrips). The cv.‘Holandsko pozno rdeče’, showed itself to be the most resistant to the cabbage stink bugs and onion thrips, while cv. ‘Red Dinasty’ was the most resistant against flea beetles.
Kapusov bolhač (Phyllotreta spp.), pisana stenica (Eurydema ventrale) in tobakov resar (Thrips tabaci), povzročajo gospodarsko pomembne težave pridelovalcem zelja v Sloveniji. Cilj naše raziskave je bil oceniti potencialni učinek epikutikularnega voska na listih kot obrambnega mehanizma proti naštetim škodljivcem. Vpliv količine epikutikularnega voska na poškodbe, ki jih povzročajo škodljivci, smo proučevali na 12 kultivarjih zelja (Brassica oleracea L. var. capitata), vzgojenih na Laboratorijskem polju Biotehniške fakultete v Ljubljani. Škodljivci so pokazal majhno preferenco do zeljnih glav, ki imajo visoko vsebnost epikutikularnega voska. Med koncentracijo epikutikularnega voska in poškodovanimi listi je bila namreč ugotovljena močno značilna negativna povezava (r2 = -0.8399 za kapusovega bolhača, r2 = -0.7413 za pisano stenico in r2 = -0.7042 za tobakovega resarja). Cv.‘Holandsko pozno rdeče’, se je pokazal kot najbolj odporen kultivar ob napadu tobakovega resarja in pisane stenice, medtem, ko je bil cv. ‘Red Dinasty’ najmanj odporen proti napadu kapusovega bolhača.
Raziskava o vplivu nekaterih biofizikalnih (vsebnost epikutikularnega voska) in biokemičnih (obarvanost listov, skupni polifenoli in antioksidacijski potencial) dejavnikov na odpornost zelja ...(Brassica oleracea L. var. capitata) proti poškodbam, ki jih povzročajo kapusovi bolhači (Phyllotreta spp.), kapusove stenice (Eurydema spp.) in tobakov resar (Thrips tabaci), je potekala v letu 2010 na Laboratorijskem polju Biotehniške fakultete v Ljubljani. V poljski poskus je bilo vključenih 20 genotipov zelja in sicer 9 zgodnjih, 5 srednje zgodnjih in 6 srednje poznih genotipov (glede na dolžino rastne dobe), 3 rdeči in 17 belih genotipov (glede na barvo listov) ter 14 hibridov in 6 sort (glede na poreklo). Statistična analiza je pokazala, da biofizikalna in biokemična sestava listov zelja najbolj vpliva na odpornost te vrtnine na napad kapusovih bolhačev. Ti namreč kažejo šibko preferenco do zgodnjega in rdečega zelja ter do hibridov, ki imajo visoko vsebnost epikutikularnega voska (r2 = –0,6137, r2 = –0,7603 in r2 = –0,6812). Prav tako smo pri kapusovih bolhačih ugotovili močno negativno korelacijo med antioksidacijskim potencialom in obsegom poškodb pri srednje poznem zelju (r2 = –0,7185), pri rdečem zelju (r2 = –0,7811) in pri sortah zelja (r2 = –0,7802).
The plant spacing of early cabbage (Brassica oleracea L. var. capitata) was studied at the Experimental Field of the Biotechnical Faculty in Ljubljana, during the 2001 and 2002 growing season. The ...cultivars, which included "Vestri", "Parel", "Delphi", "Destiny" and "Hermes", were each spaced at 20, 30 and 40 cm within rows and 30 cm between rows or populations equivalent to 166,000, 108,000 and 82,000 plants ha-1. The experimental variables measured were marketable yield (per head and per hectare), yield characteristics (head diameter and head volume), quality characteristics (core volume, head density, soluble solids and dry matter) and onion thrips damage ratings. There was no interaction effect of cultivar and planting spacing on the measured variables. Marketable yield per head, head diameter and volume, core volume and head density generally increased as the within-row plant spacing increased, whereas, dry matter was significantly decreased at lower plant spacing. Soluble solids were not affected by plant spacing. The yield potential of cabbage was higher at cv. "Vestri" than at the other cultivars. The onion thrips damage rating was severe at the lowest plant spacing and contributed to the reduced yield. A higher damage rating was established in the cv. "Parel" but this didn't have a statistically significant influence on the weight loss of yield.
The impact of water-soluble carbohydrate composition in relation to damage levels of onion thrips (Thrips tabaci Lindeman), were studied under field conditions at the Experimental Field of the ...Biotechnical Faculty in Ljubljana on 7 cabbage cultivar (Brassica oleracea L. var. capitata). Onion thrips showed weak preference on cabbage heads with high amount of total carbohydrate, fructose and glucose and higher preference on heads with high concentration of sucrose. While amount of total carbohydrate, fructose and glucose were negatively correlated with damage levels (r2 = -0.7667; r2 = -0.6947; r2 = -0.8263), sucrose amount was not. There was a strong positively relationship between sucrose amount and the level of plants infested (r2 = +0.7378). The cv."Hinova", which had the highest amount of total carbohydrate, showed itself to be the most resistant to the onion thrips.
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