FOLIA BIOLOGICA ET GEOLOGICA 64/2, 381–388, LJUBLJANA 2023
FOLIAR APPLICATION OF SILICON HAS LITTLE EFFECT ON 
HYDROPONICALLY GROWN BARLEY (HORDEUM VULGARE L.)
FOLIARNO DODAJANJE SILICIJA IMA MALO UČINKA NA 
HIDROPONSKO GOJEN JEČMEN (HORDEUM VULGARE L.)
Anja MAVRIČ ČERMELJ
1
, Aleksandra GOLOB
1
, Nina KACJAN MARŠIĆ
1
 & Mateja GERM
1
http://dx.doi.org/10.3986/f bg0105
ABSTRACT
Foliar application of silicon has little effect on hydroponi-
cally grown barley (Hordeum vulgare L.)
Silicon is an element widely distributed on the earth’s 
crust. It can ameliorate stress in plants grown in unfavorable 
conditions. Barley is an important cereal used as a staple 
food. In our experiment, barley was grown on a floating hy-
droponics system in a greenhouse. Plants were stabilized in 
pots containing rockwool. Half of the plants were sprayed 
with potassium silicate (0.25 ml 6% K
2
SiO
3
 L
-1
) every ten 
days for 35 days. The vitality of plants during their growth 
was monitored by measuring the potential photochemical 
efficiency of photosystem II. After 16 and 35 days of silicon 
application, shoot length, root length, and fresh and dry bio-
mass were measured. At the end of the experiment, the 
number of leaves and shoots, specific leaf area, leaf optical 
properties, and lipid peroxidation were determined as well. 
The potential photochemical efficiency of photosystem II 
was close to 0.8 and unaffected by the addition of silicon, 
indicating a good condition of the plants. Results showed 
lower leaf reflectance for silicon-treated plants in UVA, 
UVB, and blue light wavelengths, possibly due to a layer of 
potassium silicate on leaves. After 16 days, silicon-treated 
plants’ fresh shoot weight and root length were higher than 
in control plants. Results showed that additional foliar ap-
plication of silicon does not cause stress in the barley plant.
Keywords: potassium silicate, barley, Hordeum vulgare, 
hydroponics, foliar application, silicon
IZVLEČEK
Foliarno dodajanje silicija ima malo učinka na hidropon-
sko gojen ječmen (Hordeum vulgare L.)
Silicij je pogost element v zemljini skorji in lahko znižu-
je stres rastlin, ki rastejo v neugodnih razmerah. Ječmen je 
za ljudi pomembno žito, saj spada med osnovna živila. Po-
skus smo izvedli na plavajočem hidroponskem sistemu v ra-
stlinjaku na Biotehniški fakulteti. Rastline so bile ukoreni-
njene v lončkih s kameno volno. Polovico rastlin smo škro-
pili s kalijevim silikatom (0,25 ml 6% K
2
SiO
3
 L
-1
) vsakih 
deset dni. Med rastjo smo spremljali vitalnost rastlin z mer-
jenjem potencialne fotokemične učinkovitosti fotosistema 
II. Po 16 in 35 dneh nanašanja Si, smo izmerili velikost po-
ganjkov, dolžino korenin ter svežo in suho biomaso. Na 
koncu poskusa smo prešteli število listov in poganjkov, dolo-
čili specifično listno površino, optične lastnosti listov in sto-
pnjo lipidne peroksidacije. Potencialna fotokemična učinko-
vitost fotosistema II je bila v vseh tretmajih blizu 0,8, kar je 
nakazovalo na dobro stanje rastlin. Rezultati so pokazali 
nižjo odbojnost listov pri rastlinah, škropljenih s Si v UVA, 
UVB in modrem spektru valovnih dolžin, najverjetneje za-
radi nastale plasti kalijevega silikata na listih. Po 16 dneh so 
imele s Si tretirane rastline večjo svežo maso poganjkov in 
daljše korenine kot rastline brez dodanega Si. Rezultati so 
pokazali, da škropljenje s silicijem ne povzroča stresa v je-
čmenu. 
Ključne besede: kalijev silikat, ječmen, Hordeum vulgare, 
hidroponika, foliarni nanos, silicij
 
1
 Biotechnical Faculty, University of Ljubljana, Jamnikarjeva ulica 101, 1000 Ljubljana, Slovenia. 
  anja.mavric@bf.uni-lj.si; aleksandra.golob@bf.uni-lj.si; nina.kacjan.marsic@bf.uni-lj.si; mateja.germ@bf.uni-lj.si

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382 FOLIA BIOLOGICA ET GEOLOGICA 64/2 – 2023
Silicon (Si) is an abundant element in the earth's crust. 
It is not essential for most plants, but some accumulate 
more silicon than others. One of the silicon accumula-
tors is barley (Hordeum vulgare L.), an important spe-
cies in agriculture. Silicon enters the cell through the 
pores in a way that depends on the plant species. Dif-
ferent plant species contain different concentrations of 
Si in their tissues, and it ranges between 0.1 and 10% of 
dry weight of the plant (Hodson et al. 2005). Despite 
generally high silicon levels in soils, continuous crop 
harvesting has led to a depletion of the soil pools of 
plant-available silicon, and crops will require silicon 
application in the future to maintain their yields. Fur-
thermore, silicon is only accessible to plants in the 
form of monosilicic acid, the concentration of which in 
the soil is highly dependent on the physical and chem-
ical properties of the soil (Katz et al. 2021). Plants that 
grow in silicon-deficient soils are less mechanically ro-
bust, consequently more sensitive to various disorders 
and abiotic stressors, and more vulnerable to various 
diseases. Some researchers suggested that added sili-
con can mitigate the negative effects of a variety of en-
vironmental factors, especially drought. The beneficial 
effects due to silicon are closely correlated with silicon 
accumulation levels in plants. Seven of the ten most 
abundant crops in the world are silicon accumulators 
(Guntzer et al. 2012). These include barley, a very im-
portant crop in temperate climate zones. Barley itself is 
not entirely drought-resistant, but it has effective 
mechanisms enabling it to avoid drought (Dawson et 
al. 2015). According to literature (Newton et al. 2011) 
its yield is expected to remain more reliable than other 
important crops, such as wheat. The beneficial effects 
of silicon in plants are based on a protective silicon 
layer deposited at the leaf surface, the co-localisation 
of the absorbed silicon with metal ions and other com-
pounds, and the metabolic functions of silicon in 
plants, exposed to stress conditions. Silicification of 
leaf tissues limits herbivory and pathogen infections, 
increasing plant shoots’ rigidity. It has a similar effect 
on plant stiffness to that of lignin, but at a 10-20-fold 
lower energy cost (Schoelynck et al. 2010). In grasses, 
silicon is a key structural element that prevents lodg-
ing and shading of leaves. Hosseini et al. (2017) 
showed that silicon accumulation in shoots delays os-
motic stress-induced leaf senescence in barley. It was 
recently reported, that the addition of silicon in the 
form of K
2
SiO
3
 significantly affected the concentration 
of minerals, such as Si, K, Ca, Cl, S, Mn, Fe and Zn, in 
the roots and leaves of barley plants (Mavrič Čermelj 
et al., 2022).
Our work aimed to find out the response of hydro-
ponically grown barley to foliar addition of silicon at 
physiological and morphological levels.
1 INTRODUCTION
2 MATERIALS AND METHODS
2.1 Experimental set-up 
In the experiment, barley plants were grown on a float-
ing hydroponics system that lasted 35 days. We germi-
nated seeds of barley var. Wilma (Hordeum vulgare L.) 
in germination trays with peat substrate. After nine 
days, we transferred the seedlings to plastic hydroponic 
net pots and embedded with rockwool. Plants of barley 
were grown in a greenhouse at 15 °C (day) and 10 °C 
(night) under light panels with a 16/8 light regime with 
average radiation of 300 µmol/m
2
 s). Plants were grown 
in nutrient solution for barley from Podar (2013). We 
sprayed half of the plants with potassium silicate (0.25 
ml 6% K
2
SiO
3
 L
-1
, with Si concentration 3.5 mM) every 
ten days (Figures 1 and 2). Control plants are marked in 
the tables and figures with Si0, and treated plants with 
Si+. The experiment was set up in five replicates (plots) 
and measurements were made on from 1 to 12 plants 
per each plot, depending on the measured parameter.
 
2.2 Physiological and morphological parame-
ters
Chlorophyll fluorescence was monitored with a por-
table chlorophyll fluorometer (PAM-2500; Walz, Ger-
many). The potential photochemical efficiency of pho-
tosystem (PS) II (Fv/Fm) was evaluated according to 
Schreiber et al. (1996).
After 16 and 35 days of silicon application, shoot 
length, root length, and fresh and dry biomass were 
measured. After 35 days, the number of leaves and 
shoots, specific leaf area, leaf optical properties, and 
lipid peroxidation were determined. 
2. 3 Optical measurements
The reflectance and transmittance spectra of fresh 
barley leaves were measured in the laboratory immedi-

MAVRIČ ČERMELJ, GOLOB, KACJAN MARŠIĆ & GERM: FOLIAR APPLICATION OF SILICON HAS LITTLE EFFECT
383 FOLIA BIOLOGICA ET GEOLOGICA 64/2 – 2023
ately after their collection in the growing chamber. 
The procedure is described in Klančnik et al. (2012). 
The measurements were made from the range of 300 
nm to 820 nm, at every ~1.3 nm, with a portable spec-
trophotometer (Jaz Modular Optical Sensing Suite; 
Ocean Optics, Inc., Dunedin, USA), that was connect-
ed to an optical fiber (QP600-1-SR-BX; Ocean Optics, 
Inc.) and an integrating sphere (ISP-30-6-R; Ocean 
Optics, Inc.). During measurements, the samples were 
illuminated with a UV-VIS-near infrared light source 
(DH-2000; Ocean Optics, Inc.). 
2.4 Lipid peroxidation
Lipid peroxidation was estimated according to proto-
col by Hodges et al. (1999). Five leaves per treatment 
replication were frozen in liquid nitrogen and saved at 
-80 °C until used to determine malondialdehyde 
(MDA) as an index of general lipid peroxidation.
2.5 Statistical analysis
Statistical analysis was made using the statistical soft-
ware XL Stat for Excel (Version 2112, Addinsoft, Paris, 
France). The normal distribution of data was checked 
with Shapiro–Wilk test. Upon confirmation of normal 
distribution, data were further analyzed with a t-test to 
distinct between the control and treatment. Visual re-
presentation of results was created with the use of MS 
Excel. The level of significance was accepted at p < 
0.05.
Figures 1 and 2: Experimental setup in the department of Agronomy, Biotechnical Faculty.

MAVRIČ ČERMELJ, GOLOB, KACJAN MARŠIĆ & GERM: FOLIAR APPLICATION OF SILICON HAS LITTLE EFFECT
384 FOLIA BIOLOGICA ET GEOLOGICA 64/2 – 2023
The potential photochemical efficiency of PS II was unaf-
fected by the addition of silicon. Values were close to the 
theoretical optimum (0,78) (Table 1). The absence of the 
effect of silicon on photochemical efficiency of PS II and 
values close to the theoretical optimum indicated that 
plants were not under stress and that the photosynthetic 
apparatus was not damaged (Schreiber et al., 1996).
Table 1: Photochemical efficiency of photosystem II 
in the middle (day 15) and final sampling (day 35) of 
the experiment for Si0 and Si+ treated plants.
Day Si0 Si+
Day 15 0.77 ± 0.01a 0.77 ± 0.01a
Day 34 0.79 ± 0.01a 0.78 ± 0.02 a
Data are means ± SD, n= 25. Letters indicate signifi-
cant differences (p≤0.05, Duncan test). 
Results showed lower leaf reflectance for silicon-
treated plants in UVA, UVB, and blue light wave-
lengths. The difference in the reflectance may be 
caused by a layer of potassium silicate on leaves (Figure 
3). The results differ from those of Golob et al. (2017), 
who observed a positive correlation between the 
amount of phytoliths on leaf surface of wheat and the 
reflectance spectrum in the UVB part. With Si or Ca 
incrusted surfaces of leaves present the first barrier to 
UV rays that reach the leaf surface (Klančnik & Ga -
berščik , 2016), and can affect their optical properties.
Statistically significant differences were also found 
on the 16
th
 day after the first silicon application when 
roots were longer in Si treated plants compared to con-
trol plants. The shoot fresh weight of silicon-treated 
plants was higher than in control plants (Figure 4), in-
dicating the positive effect of Si on plant growth. Simi-
larly, biomass significantly increased in non-stressed 
wheat with foliar application of sodium silicate at til-
lering or anthesis stage (Maghsoudi et al. 2016). On 
the contrary, Habibi (2016) found no differences in 
Figure 3: Reflectance in blue, UVA and UVB wavelengths for silicon-treated (Si+) and untreated plants (Si0). 
3 RESULTS AND DISCUSSION

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385 FOLIA BIOLOGICA ET GEOLOGICA 64/2 – 2023
Table 2: Analyzed parameters in the middle (day 16) and at the end (day 35) of the experiment for Si0 and Si+ 
treated plants.
Day Plant organ Parameter Unit Si0 Si+
Day 16
Root
Length cm 12.8 ± 2,8 b 14.3 ± 2.4 a
Fresh weight g 5.2 ± 0.5 a 5.2 ± 0.7 a
Dry weight g 0.4 ± 0.1 a 0.4 ± 0.0 a
Shoot
Length cm 40.5 ± 4.2 a 39.7 ± 2.0 a
Fresh weight g 6.9 ± 1.2 b 7.5 ± 0.9 a
Dry weight g 1.0 ± 0.2 a 1.1 ± 0.2 a
Root Length cm 11.5 ± 1.3 a 11.9 ± 1.9 a
Fresh weight g 24.3 ± 9.0 a 18.2 ± 6.7 a
Dry weight g 2.2 ± 0.5 a 1.8 ± 0.6 a
Shoot
Length cm 58.8 ± 3.2 a 59.3 ± 2.8 a
Fresh weight g 25.8 ± 4.8 a 26.6 ± 4.2 a
Dry weight g 3.6 ± 0.8 a 3.9 ± 0.9 a
Number of shoots no. per pot 12 ± 2 a 12 ± 2 a
Number of leaves no. per pot 16 ± 2 a 16 ± 2 a
Speficic leaf area cm^2 g^-1 13.5 ± 0.9 a 13.1 ± 2.0 a
Lipid peroxidation nmol MDA g^-1 37.2 ± 7.6 a 38.8 ± 7.2 a
Transmitance  
Figure 4: Fresh shoot weight and root length of silicon treated (Si+) and untreated plants (Si0) on day 16.
fresh and dry shoot mass after application of potassi-
um metasilicate on non-stressed maize. Foliar applica-
tion of silicon is important at drought stress, with Si 
application increases shoot fresh and dry weight of 
barley (Mahmoud et al. 2021). We found no differ-
ences in other analyzed characteristics of treated and 
untreated barley plants (Table 2). We confirmed in our 
experiment that additional foliar application with Si 
concentration 3.5 mM does not cause stress in the bar-
ley plants and not significantly affect plant growth.

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386 FOLIA BIOLOGICA ET GEOLOGICA 64/2 – 2023
UV-B / 0.04 ± 0.11 a 0.07 ± 0.27 a
UV-A / 0.05 ± 0.06 a 0.08 ± 0.15 a
Day 35 Blue / 0.26 ± 0.09 a 0.31 ± 0.14 a
Green / 6.98 ± 0.50 a 7.46 ± 0.52 a
Yellow / 6.31 ± 0.63 a 6.78 ± 0.44 a
Leaf Red / 14.12 ± 0.35 a 14.50 ± 0.59 a
NIR / 59.76 ± 1.29 a 58.83 ± 0.84 a
Reflectance  
UV-B / 8.79 ± 0.29 a 8.03 ± 0.34 b
UV-A / 7.66 ± 0.20 a 7.06 ± 0.27 b
Blue / 8.66 ± 0.32 a 8.07 ± 0.36 b
Green / 13.42 ± 0.66 a 12.50 ± 0.84 a
Yellow / 12.39 ± 0.67 a 11.54 ± 0.77 a
Red / 17.24 ± 0.64 a 16.68 ± 0.95 a
NIR / 45.09 ± 1.53 a 47.59 ± 8.09 a
Data are means ± SD. n= 5-60. Letters indicate statistically significant differences (p≤0.05, Duncan test).
Silicij je za rastline koristen element in rastline ga v 
svoja tkiva nalagajo v različnih koncentracijah. Pri-
vzemajo ga lahko le v obliki monosilicijeve kisline, 
katere koncentracija v tleh je odvisna od fizikalnih in 
kemijskih lastnosti tal (Katz et al., 2021). Rastline, ki 
rastejo na s silicijem revnih tleh, so bolj občutljive na 
različne bolezni ter stres, ki ga povzročajo abiostki 
dejavniki. Silicij je tudi pomemben strukturni ele-
ment, ki preprečuje poleganje in senčenje listov pri 
travah. Silicij se nalaga v različnih strukturah na po-
vršini listov, kar omeji objedanje rastlinojedcev in 
okužbe s patogeni ter poveča trdnost rastlinskih po-
ganjkov. Koristni učinki silicija na rastline so tesno 
povezani z ravnmi kopičenja silicija v rastlinah. Med 
akumulatorje silicija spada navadni ječmen (Horde-
um vulgare L.), ki je agronomsko pomembna rastlin-
ska vrsta. Nalaganje silicija v ječmenu zakasni stara-
nje listov zaradi osmotskega stresa (Hosseini et al., 
2017). Dodajanje silicija v obliki kalijevega silikata 
vpliva na elementno sestavo listov in korenin ječme-
na (Mavrič Čermelj et al., 2022). Namen naše razi-
skave je bil določiti vpliv foliarnega dodajanja silicija 
pri hidroponsko gojenem navadnem ječmenu na nje-
gove fiziološke in morfološke lastnosti.
Razkužena semena navadnega ječmena sorte 
Wilma smo nakalili v šotnem substratu ter kalice po 
devetih dneh presadili v plastične mrežaste hidro-
ponske lončke s kameno volno, ki je omogočala uko-
reninjenje rastlin ter jih postavili na plavajoč hidro-
ponski sistem. Povprečna temperatura v rastlinjaku 
je bila 15 °C podnevi in 10 °C ponoči ter režim osve-
tljenosti 16 ur (noč)/ 8 ur (dan). Vsakih 10 dni smo 
polovico rastlin (Si+) škropili po listih s kalijevim si-
likatom s koncentracijo 3,5 mM Si. Druge polovice 
rastlin nismo škropili s Si (Si0). Za vsak tretma smo 
imeli pet ponovitev. 
Med poskusom smo merili potencialno (Fv/Fm) 
fotokemično učinkovitost II. Rastline smo vzorčili 
4 CONCLUSIONS
Silicon did not have negative effects on the vitality of 
barley plants. The potential photochemical efficiency 
of photosystem II was close to the maximal value of 
plants, which are not exposed to stress conditions. 
Lower leaf reflectance for silicon-treated plants in 
UVA, UVB, and blue light wavelengths, is possibly the 
consequence of a layer of potassium silicate on leaves. 
We can conclude that additional foliar spraying of sili-
con did not negatively affect the barley plant.
5 POVZETEK

MAVRIČ ČERMELJ, GOLOB, KACJAN MARŠIĆ & GERM: FOLIAR APPLICATION OF SILICON HAS LITTLE EFFECT
387 FOLIA BIOLOGICA ET GEOLOGICA 64/2 – 2023
med poskusom (16. dan) in na koncu poskusa (35. 
dan). Pri obeh vzorčenjih smo izmerili dolžino poganj-
kov, dolžino korenin ter svežo in suho biomaso. Na 
koncu poskusa smo prešteli število listov in poganjkov, 
določili specifično listno površino, optične lastnosti 
listov in stopnjo lipidne peroksidacije.
Ugotovili smo, da škropljenje s silicijem ni imelo 
vpliva na potencialno fotokemično učinkovitost foto-
sistema II pri rastlinah. Vrednosti so bile blizu teore-
tičnega optimuma (0,78), kar kaže na to, da rastline 
niso bile podvržene stresu in fotosintezni aparat ni bil 
poškodovan. Odboj svetlobe od listov je bil pri Si+ ra-
stlinah  pri valovnih dolžinah UVA, UVB in modre 
svetlobe nižji od odboja pri ostalih skupinah. Razlike v 
odbojnosti bi lahko povzročila plast kalijevega silikata 
na površini listov. Pri vmesnem vzorčenju so imele Si+ 
rastline daljše korenine in višjo svežo maso poganjka 
kot rastline, ki jih nismo škopili s Si, kar nakazuje na 
pozitivni vpliv Si na rast rastlin. V ostalih izmerjenih 
lastnostih nismo našli statistično značilnih razlik med 
tretmajema. Ugotovili smo, da škropljenje rastlin s ka-
lijevim silikatom nima negativnega vpliva na vitalnost 
rastlin, vpliva pa na odbojnost svetlobe v določenih 
delih svetlobnega spektra.
ACKNOWLEDGEMENTS
The experiment was carried out as part of the young 
researcher grant (Anja Mavrič Čermelj, ARRS num-
ber: 54730), program group P1-0212 (Plant biology) 
and projects J4-3091 and BI-RS/20-21-008 all founded 
by Slovenian Research Agency (Javna agencija za razi-
skovalno dejavnost RS). The authors are thankful to 
Vid Žitko, who helped with the experiment set-up and 
work in the greenhouse.
REFERENCES – LITERATURA
Čermelj, A. M., E. Fideršek, A. Golob, N. Kacjan Maršić, K. Vogel Mikuš & M. Germ , 2022: Different con-
centrations of potassium silicate in nutrient solution affects selected growth characteristics and mineral compo-
sition of barley (Hordeum vulgare L.). Plants. 11. doi:10.3390/plants11111405
Dawson, I. K., J. Russell, W. Powell, B. Steffenson, W. T. B. Thomas & R. Waugh , 2015: Barley: a translational 
model for adaptation to climate change. New Phytologist. 206:913–931. doi:10.1111/nph.13266
Golob, A., J. Kavčič, V. Stibilj, A. Gaberščik, K. Vogel-Mikuš & M. Germ , 2017: The effect of selenium and UV 
radiation on leaf traits and biomass production in Triticum aestivum L. Ecotoxicology and Environmental 
Safety. 136:142–149. doi:10.1016/j.ecoenv.2016.11.007
Guntzer, F., C. Keller & J. D. Meunier , 2012: Benefits of plant silicon for crops: A review. Agronomy for Sustain-
able Development. 32:201–213. doi:10.1007/s13593-011-0039-8
Habibi, G. , 2016: Effect of foliar-applied silicon on photochemistry, antioxidant capacity and growth in maize plants 
subjected to chilling stress. Acta Agriculturae Slovenica. 107:33–43. doi:10.14720/aas.2016.107.1.04
Hodges, D. M., J. M. DeLong, C. F. Forney & R. K. Prange , 1999: Improving the thiobarbituric acid-reactive-
-substances assay for estimating lipid peroxidation in plant tissues containing anthocyanin and other interfering 
compounds. Planta. 207:604–611. doi:10.1007/s004250050524
Hodson, M. J., P. J. White, A. Mead & M. R. Broadley , 2005: Phylogenetic variation in the silicon composition of 
plants. Annals of Botany. 96:1027–1046. doi:10.1093/aob/mci255
Hosseini, S. A., A. Maillard, M. R. Hajirezaei, N. Ali, A. Schwarzenberg, F. Jamois & J.-C. Yvin , 2017: In-
duction of barley silicon transporter HvLsi1 and HvLsi2, increased silicon concentration in the shoot and regula-
ted Starch and ABA homeostasis under osmotic stress and concomitant potassium deficiency. Frontiers in Plant 
Science. 8. doi:10.3389/fpls.2017.01359
Katz, O., D. Puppe, D. Kaczorek, N. B. Prakash & J. Schaller , 2021: Silicon in the soil–plant continuum: Intri-
cate feedback mechanisms within ecosystems. 10
Klančnik, K. & A. Gaberščik , 2016: Leaf spectral signatures differ in plant species colonizing habitats along a hy-
drological gradient. Journal of Plant Ecology. 9:442–450. doi:10.1093/jpe/rtv068
Klančnik, K., M. Mlinar & A. Gaberščik , 2012: Heterophylly results in a variety of “spectral signatures” in aqua-
tic plant species. Aquatic Botany. 98:20–26. doi:10.1016/j.aquabot.2011.12.004

MAVRIČ ČERMELJ, GOLOB, KACJAN MARŠIĆ & GERM: FOLIAR APPLICATION OF SILICON HAS LITTLE EFFECT
388 FOLIA BIOLOGICA ET GEOLOGICA 64/2 – 2023
Maghsoudi, K., Y. Emam & M. Ashraf , 2016: Foliar application of silicon at different growth stages alters growth 
and yield of selected wheat cultivars. doi:10.1080/01904167.2015.1115876
Mahmoud, A. W. M., A. Z. A. Hassan, S. A. Mottaleb, M. M. Rowezak & A. M. Salama , 2021: The role of 
nano-silicon and other soil conditioners in improving physiology and yield of drought stressed barley crop.  Agri-
culture (Pol’nohospodarstvo). 67:124–143. doi:10.2478/agri-2021-0012
Newton, A. C., A. J. Flavell, T. S. George, P. Leat, B. Mullholland, L. Ramsay, C. Revoredo-Giha, J. Rus -
sell, B. J. Steffenson, J. S. Swanston, W. T. B. Thomas, R. Waugh, P. J. White & I. J. Bingham , 2011: Crops 
that feed the world 4. Barley: a resilient crop? Strengths and weaknesses in the context of food security. Food 
Security. 3:141–178. doi:10.1007/s12571-011-0126-3
Schoelynck, J., K. Bal, H. Backx, T. Okruszko, P. Meire & E. Struyf , 2010: Silica uptake in aquatic and wetland 
macrophytes: a strategic choice between silica, lignin and cellulose? New Phytologist. 186:385–391. doi:10.1111/
j.1469-8137.2009.03176.x
Schreiber, U., M. Kühl, I. Klimant & H. Reising , 1996: Measurement of chlorophyll fluorescence within leaves 
using a modified PAM Fluorometer with a fiber-optic microprobe. Photosynthesis Research. 47:103–109. 
doi:10.1007/BF00017758