Comparison of selenium treatments of crops in the field

Field experiments with spring and winter barley and ryegrass were carried out to compare the effect of fertilizers enriched with selenate or selenite with foliar application on the selenium (Se) concentrations in the crops. Application of about 20 g Se/ha given as selenate or about 100 g as selenite in a PK fertilizer and about 5 g Se/ha sprayed on the plants increased the Se-concentrations from insufficient levels to levels that met the animal nutritional requirement. Ryegrass obtained sufficient Se concentrations at lower levels of added Se than did the barley. Toxic concentrations did not occur. The choice of method thus depends on the farming practice in the individual cases.     

Glycoalkaloid and nitrate content of potatoes as affected by method of selenium application

A comparison of two methods of selenium application, banding and foliar spray, of sodium selenite (Na₂SeO₃) on total glycoalkaloid (TGA) and nitrate nitrogen (NO₃-N) was studied during each of two consecutive years. The levels of application used were 0.0, 1.6 (0.75), 3.36 (1.5), and 5.6 (2.5) kg/ha (ppm soil). Both TGA and NO₃-N were significantly reduced by application of 1.5 and 2.5 ppm of sodium selenite. Tuber selenium levels were significantly increased at all levels of application, using either banding or foliar spray, but were well below the toxic range for human consumption. Banding resulted in greater uptake of Se, and greater decreases in TGA and NO₃-N as compared to foliar spray.     

Effects of Different Selenium Application Methods on Wheat (<i>Triticum aestivum</i> L.) Biofortification and Nutritional Quality

Mineral nutrient malnutrition, especially deficiency in selenium (Se), affects the health of approximately 1 billion people worldwide. Wheat, a staple food crop, plays an important role in producing Se-enriched foodstuffs to increase the Se intake of humans. This study aimed to evaluate the effects of different Se application methods on grain yield and nutritional quality, grain Se absorption and accumulation, as well as 14 other trace elements concentrations in wheat grains. A sand culture experiment was conducted via a completely randomized 3 × 2 × 1 factorial scheme (three Se levels × two methods of Se application, foliar or soil × one Se sources, selenite), with two wheat cultivars (Guizi No.1, Chinese Spring). The results showed that both foliar Se and soil Se application methods had effects on wheat pollination. Foliar Se application resulted in early flowering of wheat, while soil Se application caused early flowering of wheat at low Se levels (5 mg kg⁻¹ ) and delayed wheat flowering at high selenium levels (10 mg kg⁻¹ ), respectively. For trace elements, human essential trace elements (Fe, Zn, Mn, Cu, Cr, Mo, Co and Ni) concentrations in wheat grains were dependent of Se application methods and wheat cultivars. However, toxic trace elements (Cd, Pb, Hg, As, Li and Al) concentrations can be decreased by both methods, indicating a possible antagonistic effect. Moreover, both methods increased Se concentrations, and improved grain yield and nutritional quality, while the foliar application was better than soil. Accordingly, this study provided useful information concerning nutritional biofortification of wheat, indicating that it is feasible to apply Se to conduct Se biofortification, inhibit the heavy metal elements concentrations and improve yield and quality in crops, which caused human health benefits.     

Protective role of selenium status on T3/T4 kinetics in rats under hyperlipidemia

The effect of high fat diet (HFD) on thyroid hormones (T3/T4) and protective role of selenium (Se) were studied in rats. Se levels in serum and liver decreased significantly, whereas glutathione peroxidase (GSH-Px) in liver and lipid levels (cholesterol and triglycerides) in serum increased after 1, 2 and 3 months of HFD feeding in comparison to controls in all the three Se status i.e. deficient (0.02 ppm), adequate (0.2 ppm) and excess (1 ppm) groups. Levels of T3/T4 decreased significantly on HFD feeding, as compared to respective controls in all the groups. Within the deficient group, as Se deficiency progressed, T3/T4 levels decreased after 2 and 3 months in comparison to 1 month. A significant increase was observed in T3/T4 concentration on feeding 1 ppm (excess) Se supplemented diet, in comparison to adequate group. Also, in 1 ppm Se supplemented group as the Se deposition increased i.e. after 2 and 3 months, levels of T3/T4 increased significantly. So, the present study indicates that Se supplementation up to 1 ppm normalizes the T3 and T4 concentrations or regulates the hypothyroidism induced by hyperlipidemia.     

Selenium in Australia: selenium status and biofortification of wheat for better health.

Selenium (Se) is an essential micronutrient for humans and animals, but is deficient in at least a billion people worldwide. Wheat (Triticum aestivum L.) is a major dietary source of Se. The largest survey to date of Se status of Australians found a mean plasma Se concentration of 103 microg/l in 288 Adelaide residents, just above the nutritional adequacy level. In the total sample analysed (six surveys from 1977 to 2002; n = 834), plasma Se was higher in males and increased with age. This study showed that many South Australians consume inadequate Se to maximise selenoenzyme expression and cancer protection, and indicated that levels had declined around 20% from the 1970s. No significant genotypic variability for grain Se concentration was observed in modern wheat cultivars, but the diploid wheat Aegilops tauschii L. and rye (Secale cereale L.) were higher. Grain Se concentrations ranged 5-720 microg/kg and it was apparent that this variation was determined mostly by available soil Se level. Field trials, along with glasshouse and growth chamber studies, were used to investigate agronomic biofortification of wheat. Se applied as sodium selenate at rates of 4-120 g Se/ha increased grain Se concentration progressively up to 133-fold when sprayed on soil at seeding and up to 20-fold when applied as a foliar spray after flowering. A threshold of toxicity of around 325 mg Se/kg in leaves of young wheat plants was observed, a level that would not normally be reached with Se fertilisation. On the other hand sulphur (S) applied at the low rate of 30 kg/ha at seeding reduced grain Se concentration by 16%. Agronomic biofortification could be used by food companies as a cost-effective method to produce high-Se wheat products that contain most Se in the desirable selenomethionine form. Further studies are needed to assess the functionality of high-Se wheat, for example short-term clinical trials that measure changes in genome stability, lipid peroxidation and immunocompetence. Increasing the Se content of wheat is a food systems strategy that could increase the Se intake of whole populations.     

Selenium and sulfur supplementation to steers grazing tall fescue

Forty steer calves averaging 257 kg were allotted to a randomized complete block design experiment containing 10 animals per treatment. Four tall fescue pastures of 5.7 ha each were utilized during the 84-d grazing study. Each pasture treatment block contained 10 calves. Calves were fed a control supplement of 96.9% ground corn and 3.1% trace mineral salt in two pastures, or a sulfur supplement that contained 94.3% ground corn, 3.1% trace mineral salt, and 2.5% elemental sulfur in the remaining two pastures. Each supplement was fed at the rate of 0.45 kg/head daily. One-half of the calves in each pasture were injected with 15 mg selenium (Se) as sodium selenite initially and at 28-d intervals throughout the trial. The treatments were as follows: (1) control-no sulfur, no selenium; (2) selenium, no sulfur; (3) sulfur, no selenium and; (4) selenium plus sulfur. Calf weights were monitored and certain blood parameters measured every 28 d. Average plasma Se values were increased (P < 0.001) from 0.021 ppm in calves not receiving Se to 0.043 ppm in those receiving Se. Plasma urea nitrogen levels were not affected by Se administration, but were lowered (P <0.05) from 16.6 to 15.8 mg/100 mL by sulfur administration. All plasma amino acids measured, except methionine, phenylalanine, argi-nine, and citrulline, were cleared from the blood in response to Se supplementation as reflected by their lower concentrations when compared with other treatment groups. Overall average daily gains were not significantly (P > 0.10) increased by sulfur supplementation, but were increased (P < 0.05) from 0.33 kg/d in calves not receiving Se to 0.43 kg/d in those receiving Se injections. Significant interactions between fulfur and Se were not noted.     

The effect of sodium selenite toxicity on tissue distribution of zinc,iron, and copper in rats

Male Sprague-Dawley rats were used to determine the effects of suptoxic and toxic concentrations of selenite in the drinking water on tissue distribution of zinc (Zn), iron (Fe), and copper (Cu). Se (as sodium selenite) was provided in drinking water at concentrations of 0, 2, 4, and 8 ppm. At 19 d, half of the rats in 4 and 8 ppm Sesupplemented groups were kept on drinking water alone for additional 13 d. All rats were sacrificed at the end of 32 d of experiment. Heart, liver, and kidney were analyzed for the concentrations of Fe, Zn, and Cu by atomic absorption spectrophotometry and of Se by a fluorometric method. Results indicated that rats receiving 4 and 8 ppm Se in drinking water showed a marked reduction in food intake and a reduced growth rate. These adverse effects were quickly reversed when high Se intake was discontinued. Se toxicity caused minimal change in zinc status, reduced tissue iron concentrations and caused a marked increase in copper contents in heart, liver, and kidney. The latter findings were only partly reversed after removal of Se in drinking water. The accumulation of Cu in the tissues of Se-toxic rats provides the evidence of some interaction between Se and Cu.     

Effects of dietary lead,cadmium, mercury,and selenium on fatty acid composition of blood serum and erythrocyte membranes from chicks

A series of experiments was conducted to study the effects of dietary and injected lead (as Pb acetate-3H₂O) and of dietary Cd, Hg, and Se on fatty acid composition of serum lipids of chicks as measured by gas-liquid chromatography. The effect of dietary Pb on fatty acid composition of erythrocyte membranes was measured also. Dietary Pb (1000 ppm) increased the serum concentration of arachidonic acid (20:4, first no. = no. of carbon atoms:second no. = no. of double bonds) and decreased the concentration of linoleic acid (18:2) and the ratio 18:2/20:4. Intraperitoneal injection of Pb (52 mg/100 g body weight) did not alter serum fatty acid composition by 4 h post-injection. The separate effects of 2000 ppm Pb, 60 ppm Cd, 500 ppm Hg, and 10 ppm Se added to the diet on serum fatty acids were measured in a single experiment. In comparison to controls, Pb and Cd lowered serum concentration of 18:2. Only Pb raised serum 20:4. Pb lowered the ratio 18:2/20:4, whereas Cd and Hg raised the ratio and Se was without effect. Dietary Pb (2000 ppm) raised the concentration of 20:4 and lowered the ratio 18:2/20:4 in erythrocyte membranes. The different effects of injected and dietary Pb on the serum 18:2/20:4 ratio suggest that Pb alters 20:4 synthesis from 18:2 rather than mobilization of 20:4 from tissues. The Pb-induced increase of lipid peroxida-tion in erythrocytes observed by other workers may be a reflection of increased 20:4 level in erythrocyte membranes.     

Effect of time and sex on tissue selenium concentrations in chicks fed practical diets supplemented with sodium selenite or calcium selenite

An experiment was conducted with 384 1-d-old male and female broiler-chicks. The basal corn-soybean meal diet (.07 ppm Se DM basis) was supplemented with 0, .1, .2, or .3 ppm added Se as either sodium selenite (Na2SeO3) or calcium selenite (CaSeO3), and fed for 1, 3, or 5 wk. There was no effect of Se source or level on feed intake or gain, but males consumed more (P less than .01) feed than females. There was no effect (P greater than .10) of sex or Se source on plasma, liver, or kidney Se concentration. The Se concentration of all tissues increased (P less than .01) with time and increasing dietary Se concentration. Based on multiple regression slope ratios of liver, kidney, and plasma Se concentrations, Se from CaSeO3 was as available (103%) as Se from Na2SeO3.     

Effect of Feeding Selenium-Fertilized Alfalfa Hay on Performance of Weaned Beef Calves

Selenium (Se) is an essential micronutrient in cattle, and Se-deficiency can affect morbidity and mortality. Calves may have greater Se requirements during periods of stress, such as during the transitional period between weaning and movement to a feedlot. Previously, we showed that feeding Se-fertilized forage increases whole-blood (WB) Se concentrations in mature beef cows. Our current objective was to test whether feeding Se-fertilized forage increases WB-Se concentrations and performance in weaned beef calves. Recently weaned beef calves (n = 60) were blocked by body weight, randomly assigned to 4 groups, and fed an alfalfa hay based diet for 7 wk, which was harvested from fields fertilized with sodium-selenate at a rate of 0, 22.5, 45.0, or 89.9 g Se/ha. Blood samples were collected weekly and analyzed for WB-Se concentrations. Body weight and health status of calves were monitored during the 7-wk feeding trial. Increasing application rates of Se fertilizer resulted in increased alfalfa hay Se content for that cutting of alfalfa (0.07, 0.95, 1.55, 3.26 mg Se/kg dry matter for Se application rates of 0, 22.5, 45.0, or 89.9 g Se/ha, respectively). Feeding Se-fertilized alfalfa hay during the 7-wk preconditioning period increased WB-Se concentrations (P _Linear<0.001) and body weights (P _Linear = 0.002) depending upon the Se-application rate. Based upon our results we suggest that soil-Se fertilization is a potential management tool to improve Se-status and performance in weaned calves in areas with low soil-Se concentrations.     

In vivo and in vitro influence of selenium on DNA/RNA synthesis in spleen and lymphocytes in culture--possible mediation of changes in GSH/GSSG ratio

Effect of superanutritional levels of selenium (Se) as sodium selenite (0.5 and 1.5 ppm) given orally to Balb/c mice for one and two weeks was observed on the rate of DNA/RNA synthesis, levels of reduced as well as oxidized glutathione (GSH and GSSG) and glutathione peroxidase (GSH-Px)/glutathione-S-transferase (GSH-S-transferase) activities in spleen. Similar effect of three different concentrations of Se (10(-7), 10(-5) and 10(-3) M) in culture media was also observed on the rate of DNA/RNA synthesis in proliferating lymphocytes taken from mice spleen. The results of the present study indicated that with increasing concentration and duration of Se treatment in vivo and in vitro, a marked inhibition of the rate of DNA/RNA synthesis was observed. Levels of total glutathione and GSSG in spleen were elevated significantly only after two weeks in 1.5 ppm treatments. Glutathione peroxidase activities in spleen decreased (p < 0.05) in 1.5 ppm group at one week and in 0.5 ppm group at two week treatment. At higher Se treatment, the activity recovered towards control. However, GSH-S-transferase in spleen remained unchanged at all treatment intervals. The results indicated that changes in glutathione system by increasing Se concentration might account for inhibition of rate of DNA/RNA synthesis.     

Enhancement of the repair of carcinogen-induced DNA damage in the hamster pancreas by dietary selenium

We measured single strand breaks (SSB) in pancreas DNA produced by N-nitrosobis(2-oxopropyl)amine (BOP) in hamsters fed purified diets containing added sodium selenite (Se) at 0.0, 0.1 and 5.0 ppm. There were fewer SSB in those given the 5.0 ppm Se diet throughout the experiment. One hour after dosing with BOP (20 mg/kg), there were 2.26 ± 0.47, 2.83 ± 0.43 and 1.74 ± 0.43 SSB per 10⁸ daltons (mean ± S.E.M.) respectively in the three groups. The SSB were repaired faster in the 5.0 ppm Se-fed group. The approximate half-lives of the SSB were 33, 30 and 8 days, respectively. In the hamsters fed 5.0 ppm Se there was a small, statistically significant increase in pancreatic DNA synthesis. Autoradiographic analysis indicated that this was repair synthesis. In a second experiment, hamsters were fed one of the three diets prior to and for 2 days after administration of a single dose of BOP (20 mg/kg). They were then fed the 5.0 ppm Se diet for 5 days. The number of SSB was compared with those in hamsters fed their original diet for 7 days after BOP dosing. There was a statistically significant difference in the number of SSB in the hamsters fed 0.1 ppm Se before and for 2 days after BOP. In these hamsters there were 1.21 ± 0.24 SSB per 10⁸ daltons compared with 3.19 ± 0.4 (mean ± S.E.M.). These results suggest high levels of dietary Se stimulate the repair of carcinogen-induced DNA damage.     

Field evaluation of 4-n-butyl-1,2,4-triazole for the control of leaf rust of triticale*

Severe epidemics of triticale leaf rust were controlled by a single treatment with 4-n-butyl-1,2,4-triazole (triazbutyl) as a foliar spray or as broadcast application on soil followed by irrigation. A single foliar spray of triazbutyl at 0.5 litre a.i./ha approached the control obtained by 1.0 litre a.i./ha. Effective control was obtained by spraying 10 days before or 10 days after the rust appearance but later spray applications were less effective.     

Evaluation of the naturally-derived insecticide spinosad against Culex pipiens L. (Diptera: Culicidae) larvae in septic tank water in Antalya, Turkey.

The naturally-derived insecticide spinosad (Conserve SC) was evaluated against larval Culex pipiens L. (Diptera: Culicidae) under laboratory and field conditions in Antalya, Turkey. Laboratory bioassays showed that the 24 h LC50 and LC90 against late 3rd and early 4th instars were estimated at 0.027 and 0.111 parts per million, respectively, while adult emergence was eliminated at concentrations above 0.06 ppm. Larval mortality from septic tanks that were treated with spinosad at rates of 25, 50, 100, and 200 g ai/ha ranged between 22 to 78% 1 day after application. At 7 days post-treatment, larval mortality ranged from 2 to 50% and at 14 days mortality was <10% for all treatments. Larval bioassays of the water from those septic tanks treated at 100 and 200 g ai/ha resulted in an elimination of Cx. pipiens larvae 7 days after treatment. After this time, larval reduction declined to 79 and 83%, respectively, 14 days after treatment. Larval reduction in septic tanks treated at the two lowest rates (i.e. 25 and 50 g ai/ha) ranged from 14 to 74% during the 14-day study. These results indicated that spinosad can be considered an effective larvicide for treatment of septic tanks against Cx. pipiens.     

Effect of selenium depletion and supplementation on the kinetics of type 1 5′-iodothyronine deiodinase and T3/T4 in rats

Presently, the effect of selenium (Se) deficiency and excess of Se (1 ppm) on the activity of selenoenzymes type 1 5′-iodothyronine deiodinase (5′-DI), glutathione peroxidase (GSH-Px), and level of thyroid hormones (T₃ and T₄) was studied in rats. Se levels in the serum and liver, T₃ and T₄ in the serum, GSH-Px levels in the liver, and 5′-DI activity in the liver/aorta/thyroid were estimated after 1, 2, and 3 mo of Se-deficient (0.02 ppm), Se-adequate (0.2 ppm), and Se-excess (1 ppm) diet feeding. All of these parameters decreased significantly in the Se-deficient group as compared to the adequate group. Within the deficient group, as the Se deficiency progressed, all of the parameters except 5′-DI decreased after 2 and 3 mo in comparison to 1-mo data. Thyroidal 5′-DI activity in Se deficiency showed the maximum increase. A significant increase was observed in all of the above parameters in the 1 ppm Se-supplemented diet group when compared with the adequate Se group; also, as the Se deposition increased within the Se-excess diet group, a significant increase was observed in all of the above parameters. However, as observed by others, the intake of excess of Se (i.e., 2 ppm in the diet) did not elevate the activities of selenoenzymes and thyroid hormones; rather, it had adverse effects. The present study concludes that Se supplementation at least up to 1 ppm enhances the selenoenzyme activities, and above this level, it may not be considered as an indicator of selenoenzyme activities.     

Evaluation of strontium as a trace-element marker for dispersal studies on Heliothis armigera

A method of preparing moth specimens for strontium (Sr) analysis by atomic absorption spectrophotometry is described. A screenhouse experiment demonstrated that foliar sprays of SrCl₂ at 5 kg/ha successfully marked late instar Heliothis armigera larvae feeding on chickpea. Laboratory experiments, in which larvae were reared from the 4th instar on artificial diet containing, concentrations of SrCl₂ up to 5000 ppm,showed no adverse effects on development and even at 50 ppm moths were unequivocally marked above the highest recorded background level. Sr level did not decline appreciably after the second day of adult life, unlike rubidium which declined at a faster rate. Female moths had consistently higher Sr levels than males. Following a single field application of SrCl₂ at 5 kg/ha on pigeonpea heavily infested with H. armigera larvae, 61.8% of emergent moths were marked.

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Le strontium comme marqueur pour l'étude de la dispersion d' Heliothis armigera

Résumé La méthode de préparation des papillons pour l'analyse du strontium (Sr) en spectrophotométrie par absorption atomique est décrite. Une expérience en serre a montré que la pulvérisation des feuilles avec SrCl₂ à raison de 5 kg/ha a permis de marquer le dernier stade des chenilles de H. armigera sur Cicer arietinum. En laboratoire, des chenilles ont été élevées à partir du quatrième stade sur un régime artificiel avec des concentrations de SrCl₂ allant jusqu'à 5000 ppm: aucun effet sur la biologie n'a été observe. A 50 ppm le marquage des pappilons exclut déjà tout risque de confusion avec le bruit du fond. Le taux de Sr ne diminue pas considérablement apres le second jour de vie imaginale, contrairement au rubidium qui diminue à une plus grande vitesse. La teneur en Sr des femelles est significativement plus élevée que celle des mâles. Après un traitement unique de SrCl₂ dans la nature, à raison de 5 kg/ha, sur des C. arietinum trés attaqués par des chenilles de H. armigera, 61.8% des papillons obtenus étaient marqués.

     

Selenium in cereals: improving the efficiency of agronomic biofortification in the UK

Wheat, despite its relatively low selenium (Se) concentration in the UK, is still an important dietary Se source and its biofortification by use of Se fertiliser may be an efficient means to increase the relatively low Se status of the population. We need to know more about the fate of Se applied to the soil and how to ensure the efficiency of Se application, and the three studies reported in this issue of Plant and Soil are timely and informative. Selenium in soil, both globally and locally, is notoriously variable; however, the soils in these studies yielded wheat grain Se concentrations in the narrow range of 16–44 ng/g. The low plant Se levels reported here are not surprising, given that selenite is the dominant Se form in these soils. A regression equation (which used total and extractable Se and extractable S as variables) explained a high proportion of the variance in grain Se concentration. Sulphur application (a common practice on UK wheat growing soils) had variable effects on grain Se concentration, depending on soil S status, pH and possibly other factors. A fertiliser methodology study investigated ways to optimise Se application for the purpose of biofortification. It was calculated that an application of a modest 10 g Se/ha as selenate would increase the grain Se concentration of UK wheat from around 30 ng/g to 300 ng/g. The national Se fertiliser program in Finland shows that this increase would have a large effect on population Se status. However, Se recovery in grain at this application rate is only 14%, and it can be argued that large-scale agronomic biofortification of cereals with Se would be somewhat wasteful of a relatively scarce trace element. Selenium’s effects and interactions in soil, plants, animals and humans are complex and often surprising and will keep researchers busy well into the future.     

Effect of dietary selenium concentration and duration of selenium feeding on hepatic glutathione concentrations in rats

Studies were conducted in rats to determine the effect of dietary selenium (Se) concentration on hepatic glutathione concentrations and enzyme activities associated with the maintenance of the cellular glutathione status. Male rats were fed 0.1, 3.0, or 6.0 ppm Se as Na2SeO3 for 2, 4, or 6 weeks at which time they were killed and analyses were performed. Both 3.0 and 6.0 ppm Se caused a significant dose-dependent increase in hepatic-reduced glutathione (GSH) by 4 weeks of feeding compared to 0.1 ppm Se. The increase in GSH was preceded by significant, dose-dependent increases in oxidized glutathione (GSSG) as well as the GSSG to GSH ratio. Increases in GSSG and the GSSG to GSH ratio as well as in glutathione reductase and glucose-6-phosphate dehydrogenase activities were observed by 2 weeks of high Se feeding. The current findings substantiate previous results demonstrating effects of high Se on hepatic glutathione concentrations (R. A. LeBoeuf and W. G. Hoekstra, J. Nutr. 113:845-854, 1983) and further suggest that increased cellular GSSG concentrations or the GSSG to GSH ratio caused by 3.0 and 6.0 ppm dietary Se signals for "adaptive" changes in hepatic glutathione metabolism.     

Effect of mefluidide on growth and heading ofTriticum aestivum L.

Previous studies have shown that N-[2,4-dimethyl-5[[(trifluoromethyl)sulfonyl]amino]phenyl]acetamide (mefluidide) represses seedhead formation in gramineae. The objective of this study was to determine the effect of mefluidide on growth and reproduction of wheat (Triticum aestivum L. cv TAM 105). Mefluidide was applied to field grown wheat at 140 and 280 g/ha on March 4, 1985 and at 70, 140, and 280 g/ha on March 18, 1985. Mefluidide suppressed heading to a greater extent when applied 6 weeks after the onset of spring growth than when applied 2 weeks earlier. Leaf area index was reduced by the higher application rates at the second date of application but not the first. Total biomass was reduced to a greater extent at the second application date. Both seed weight and number of seeds per spike were reduced with the higher rates of mefluidide especially at the second application date.     

Combined effects of selenium and drought on photosynthesis and mitochondrial respiration in potato.

The possible effects of selenium (Se) foliar spraying and drought were studied for 3 months in potato (Solanum tuberosum L.) cultivar Desiree in Ljubljana, Slovenia. Four combinations of treatments were conducted: well-watered plants with and without Se foliar spraying, and drought exposed plants with and without Se foliar spraying. The following parameters were monitored 2 and 4 weeks after treatments: net photosynthesis, transpiration rate, quantum yield of photosystem II (PSII), and respiratory potential measured by electron transport system activity. After 3 months of treatments, leaf water potential and tuber yield were determined. The content of Se in tubers was measured after harvesting time. Several effects of drought and Se foliar spraying and their combinations were found. Net photosynthesis and respiratory potential were lower in drought exposed plants 4 weeks after treatments. Se induced higher respiratory potential in the leaves 4 weeks after treatments. Higher efficiency of energy conversion in PSII, expressed by a higher effective quantum yield, was observed in Se treated plants 2 weeks after treatments. Foliarly applied Se was efficiently absorbed by plant leaves and transported to the tubers.