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<strong>AGRONOMIJAS</strong> VĒSTIS (Latvian Journal of Agronomy), No.10, LLU, 2008Agriculture. During the growth season onions were treated with sodium- or iron selenite, 50 mg m -2 ,100 mg m -2 or 200 mg m -2 . Controls were without selenite application. The length and weight of onionleaves was determined during plant growth. Fresh and dry weight was registered at harvest. Onion bulbswere stored at different temperatures: +5 o C, +15 o C or +25 o C. The loss of weight during storage wasrecorded.The results showed that the weight of onions and the weight and length of depend on cultivar’sfeature. Sodium- or iron selenite had no significant influence on the parameters of the onion leaves.Onions of the cultivar ‘Stuttgarter Riesen’ had the highest weight, and ‘Snow Ball‘ had the lightest ones.There were significant differences in content of dry matter between cultivars. No significant effect ofselenite was observed in onions grown in the greenhouse. A positive correlation was observed betweenstorage temperature and weight loss of the onions bulbs during storage. The onion bulbs quality onstorage depended on the cultivar. Onions dressed with small and medium doses of selenite lost lessweight in comparison with control.Key wordsOnion, Allium cepa, iron selenite, sodium selenite, growth, storageIntroductionSelenium is a trace element that is essential to good health but is required only in smallamounts. Selenium is found in selenoproteins which are important antioxidant enzymes. Theantioxidant properties of the selenoproteins prevent cellular damage from free radicals that maycontribute to the development of chronic diseases such as cancer, heart disease, hypothyroidism.Selenium deficiency does not usually cause illness by itself. Rather, it can make the body moresusceptible to illnesses caused by nutritional, biochemical or infectious stresses (Thomson, 2004; Surai,2006; Goldhaber, 2003).The soils of Latvia contain 0.054-0.34 mg kg -1 of selenium (Ермаков, Ковальский,1974). Soilis considered “selenium deficient” when there is less than 0.5 mg of selenium per kg of soil. The bloodlevels of selenium of Latvian people average to 0.6 µmol L -1 , compared to the normal 1.51-2.91 µmol L -1 .Data shows that the average Latvian inhabitant suffers from selenium deficiency (ČerĦevskis, 2004).Plants are the major dietary sources of selenium. The content of selenium in food depends onthe selenium content of the soil where plants are grown. Different plant families differ in their ability toaccumulate selenium. Literature data show that Allium and Cruciferaceae vegetables accumulateselenium (Milan, 1995).Materials and MethodsExperiments were carried out in 2005 -2007 at the Institute of Soil and plant Sciences, LatviaUniversity of Agriculture for investigation of the effect of sodium- and iron selenite on the growth andstorage of onions. Onion varieties ‘Stuttgarter Riesen’, ‘Red Baron’ and ‘Snow Ball’ were grown andharvested after 110 days of vegetation. Field and vegetation (pot) experiments were designed.Field experiments in 4 replicas were placed in loamy sand with the following mineral elementcontent in mg L -1 : P 262, K 270, Ca 19,6·10 3 , Mg 3000, S 78, Fe 1475, Mn 130, Zn 18,5, Cu 5,2, Mo0,03, B
<strong>AGRONOMIJAS</strong> VĒSTIS (Latvian Journal of Agronomy), No.10, LLU, 2008Plant weight, number of onion leaves and leaves weight were determined. Fresh and dry weightof onions bulbs were tested after harvest. Onion bulbs were stored at +5 o C, +15 o C and +25 o C. Theloses of weight during storage were recorded.Results and DiscussionThe pot experiments showed that the length of onion leaves depends on the variety. Thesignificantly shorter leaves were of variety ‘Snow ball’. This conformity lasted all period of vegetation.Variety ‘Stuttgarter Riesen’ had the largest leaves. There were no significant differences between‘Stuttgarter Riesen’ and ‘Red Baron’ (Fig.1 and Fig.2).9080706050403020100152670152670152670152670152670152670152670152670152670152670152670152670The lenght of onions'leaves, cmcontrol Fe 50 Fe 100Fe200control Fe 50 Fe 100Fe200control Fe 50 Fe 100Fe200Red Baron Stutgarter Riesen Snow BallVegetation, days,Dose of selenite, mg m -2VarietyFigure 1. The effect of iron selenite on the length of onion leaves, cm.There were no statistically significant differences between different selenium treatments. In average, thebetter results are obtained with iron selenite in comparison to sodium selenite.The lenght of onions' leaves, cm9080706050403020100152670152670152670152670152670152670152670152670152670152670152670152670control Na50 Na100 Na200 control Na50 Na100 Na200 control Na50 Na100 Na200Red Baron Stutgarter Riesen Snow BallVegetation, days,Dose of selenite, mg m -2VarietyFigure 2. The effect of sodium selenite on the length of onion leaves, cm.The onions in field conditions had shorter leaves than in the pot experiments. ‘Red Baron’ wasshorter by 23.1 %, ‘Stuttgarter Riesen’- 30.8 % and ‘Snow ball’ by 38.1 %. The length of leaves of the237
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