African Journal of Biotechnology Vol. 8 (24), pp. 6795-6798, 15 December, 2009
Available online at http://www.academicjournals.org/AJB
ISSN 1684–5315 © 2009 Academic Journals
Full Length Research Paper
Effect of foliar application of Zn and Fe on wheat yield
Department of Plant Production, Moghan Junior College of Agriculture, University of Mohaghegh Ardabili, Ardabil, Iran.
E-mail: firstname.lastname@example.org, email@example.com. Tel.: 00989141548667. Fax: 00984527463417.
Accepted 15 October, 2009
Intensive and multiple cropping, cultivations of crop varieties with heavy nutrient requirement and
unbalanced use of chemical fertilizers especially nitrogen and phosphorus fertilizers reduced quality of
grain production and the appearance of micronutrient deficiency in crops. A field experiment was
conducted on clay-loam soil in Moghan region during 2007-2008 to investigate the effect of foliar
application of zinc and iron on wheat yield and quality at tillering and heading stage. The experimental
design was a randomized complete block design with three replicates. The SAS software package was
used to analyze all the data and means were separated by the least significant difference (LSD) test at
P< 0.01. The treatments were control (no Zn and Fe Application), 150 g Zn.ha-1 as ZnSO4, 150 g Fe.ha-1
as Fe2O3, and a combination of both Zn and Fe. In this study, parameters such as wheat grain yield,
seed-Zn and Fe concentration were evaluated. Results showed that foliar application of Zn and Fe
increased seed yield and its quality compared with control. Among treatments, application of (Fe + Zn)
obtained highest seed yield and quality.
Key words: Wheat, yield, Zn, Fe, fortification.
Increasing the Zn and Fe concentration of food crop
plants, resulting in better crop production and improved
human health, is an important global challenge. Among
micronutrients, Zn deficiency occurs in both crops and
humans (White and Zasoski, 1999; Hotz and Brown,
2004; Welch and Graham, 2004). Zinc deficiency is
currently listed as a major risk factor for human health
and causes of death globally. According to a WHO (2002)
report on the risk factors responsible for development of
illnesses and diseases, Zn deficiency ranks 11th among
the 20 most important factors in the world and 5th among
the 10 most important factors in developing countries. In
a comprehensive study, Hotz and Brown (2004) reported
that Zn deficiency affects, on average, one-third of
world’s population, ranging from 4 to 73% in different
countries. The regions with Zn-deficient soils are also the
regions where Zn deficiency in human beings is
widespread, for example in India, Pakistan, China, Iran
and Turkey (Cakmak et al. 1999; Alloway, 2004; Hotz
and Brown, 2004). Zinc deficiency in soils and plants is a
global micronutrient deficiency problem reported in many
countries (Sillanpaa, 1982; Bybordi and Malakouti, 2003;
Alloway, 2004; Seilsepour, 2007). Nearly 50% of the
cereal-grown areas in the world have soils with low plant
availability of Zn (Graham and Welch, 1996; Cakmak,
2002). Cereal crops represent a major source of minerals
and protein in developing world. For example, in most of
Central and West Asian countries, wheat provides nearly
50% of the daily calorie intake on average, likely
increasing to more than 70% in the rural regions
(Cakmak et al., 2004).
According to FAO reports, wheat plays a particular role
in covering daily caloric requirements of humans in
Tajikistan. According to a report published by Hotz and
Brown (2004), among all countries in the world, Tajikistan
has been listed as the country having the highest
percentage of population living under risk of Zn
deficiency. Bybordi and Malakouti (2003) reported that
wheat is sensitive to zinc deficiency, but less sensitive to
Iron and copper deficiencies. Wheat is inherently low in
concentrations of Zn in grain, particularly when grown on
Zn-deficient soils. Based on a range of reports and
survey studies, the average concentration of Zn in whole
grain of wheat in various countries is between 20 to
35 mg kg−1 (Rengel et al., 1999; Cakmak et al., 2004;
Seilsepour, 2007). Most of the seed-Zn is located in the
6796 Afr. J. Biotechnol.
embryo and aleurone layer, whereas the endosperm is
very low in Zn concentration (Ozturk et al., 2006). The
embryo and aleurone parts are also rich in protein and
phytate (Lott and Spitzer, 1980; Mazzolini et al., 1985),
indicating that protein and phytate in seeds could be
sinks for Zn. According to a Zn-staining study in wheat
seed, Zn concentrations were found to be around 150 mg
kg−1 in the embryo and aleurone layer and only 15 mg
kg−1 in the endosperm (Ozturk et al., 2006). The Zn-rich
parts of wheat seed are removed during milling, thus
resulting in a marked reduction in flour Zn concentrations.
Enrichment of cereal grains with Zn is, therefore, a high
priority area of research and will contribute to minimizing
Zn deficiency-related health problems in humans. Among
the interventions currently being used as major solution
to Zn deficiency in humans, food fortification and
supplementation are being widely applied in some
countries. However, these approaches appear to be
expensive and not easily accessible by those living in
developing countries (Bouis, 2003; Stein et al., 2007). For
example, to eliminate micronutrient deficiencies in a
nation with 50 million affected people using food
fortification program US$ 25 million is needed annually
(Bouis et al., 2000). There are several examples
demonstrating that applying Zn fertilizers to cereal crops
improve not only productivity, but also grain Zn
concentration of plants. Depending on the soil conditions
and application form, Zn fertilizers can increase grain Zn
concentration up to fourfold under field conditions (Bansal
et al., 1990; Sharmas and Lal, 1993; Gill et al., 1994;
Yilmaz et al., 1997; Seilsepour, 2007).
Cultivated wheat contains very low levels of Zn and
shows a narrow genetic variation for Zn. Compared to
cultivated wheat, wild and primitive wheat represent a
better and more promising genetic resource for high Zn
concentrations. Little information is, however, available
about the genetic control and molecular physiological
mechanisms contributing to high accumulation of Zn and
other micronutrients in grain of different genetic materials
(White and Broadley, 2005; Ghandilyan et al., 2006;
Lucca et al., 2006).
Fertilizer studies focusing specifically on increasing Zn
concentration of grain (or other edible parts) are,
however, very rare, although a large number of studies
are available on the role of soil and foliar applied Zn
fertilizers in correction of Zn deficiency and increasing
plant growth and yield (Martens and Westermann, 1991;
Mortvedt and Gilkes, 1993; Rengel et al., 1999; Bybordi
and Malakouti, 2003; Seilsepour, 2007). Depending on
the application method, Zn fertilizers can increase grain
Zn concentration up to three- or fourfold (Yilmaz et al.,
1997). The most effective method for increasing Zn in
grain was the soil + foliar application method that resulted
in about 3.5-fold increase in the grain Zn concentration.
The highest increase in grain yield was obtained with soil,
soil + foliar and seed + foliar applications (Yilmaz et al.,
Timing of foliar Zn application is an important factor
determining the effectiveness of the foliar applied Zn
fertilizers in increasing grain Zn concentration. It is expected
that large increases in loading of Zn into grain can be
achieved when foliar Zn fertilizers are applied to plants at
a late growth stage. Ozturk et al. (2006) studied changes
in grain concentration of Zn in wheat during the repro-
ductive stage and found that the highest concentration of
Zn in grain occurs during the milk stage of the grain
development. Results show a high potential of Zn fertili-
zer strategy for rapid improvement of grain Zn
concentrations, especially in the case of late foliar Zn
application. In practical agriculture, it is known that foliar
uptake of Zn is stimulated when Zn fertilizer is mixed with
urea (Mortvedt and Gilkes, 1993).
Results showed that grain yield is dependent to
available-Fe and available-Zn in soil. So use of Fe and
Zn had not any effects in soils which had available-Fe
and available-Zn more than 4.7 and 0.8 mg kg-1,
respectively. Maximum increasing of grain yield by Fe
application was 1100 kg.ha-1 in soils which contain 2 mg
kg-1 available Fe and by Zn application, grain yield
increase received to 1200 mg kg-1 in soils which contain
0.5 mg kg-1 available Zn. There was a positive correlation
between grain yield and available soil Fe or available soil
Zn. The average grain yield increased by using of Fe and
Zn were 317 and 330 mg kg-1, respectively. Yield
increased 868 mg kg-1 by using of Fe and Zn. So the
critical levels of Fe and Zn in soils were determined 4.7
and 0.8 mg kg-1, respectively. In this way, 54 and 46% of
soils under wheat cultivation had deficiency in Fe and Zn,
respectively. So the use of Zn and Fe fertilizers is highly
recommended for yield increase in these soils (El-Majid
et al., 2000; Seilsepour, 2007).
MATERIALS AND METHODS
This field experiment was conducted on clay-loam soil in Moghan
Agricultural and Natural Resource Research Center during 2007-
2008 to investigate the effect of foliar application of zinc and iron on
wheat (Darya cultivar) yield and quality at tillering and heading
stage. The experimental design was a randomized complete block
design with three replicates. Treatments were control (no Zn and Fe
application), 150 g Zn.ha-1 as ZnSO4, 150 g Fe.ha-1 as Fe2O3, and a
combination of both Zn and Fe. Parameters such as grain yield
(kg/ha), seed Zn and Fe concentration (mg/kg) were evaluated.
Moghan is located in the North-west of Iran (lat 39º, 39' N; long
47° , 49' E and elevation 50 m) with mean 30-year averages of 275
mm rainfall per year and 14.6ºC temperatures.
According to soil analysis carried out prior to sowing, the soil
texture is a clay-loam with EC=2.03 dsm-1, pH= 8.08, O.C (%) =
0.994, soil P2O5 = 4 ppm, K2O = 379 ppm N= 0.109, field capacity =
21% W/W, wilting point = 10% W/W and the volume weight of the
soil was 1.21 g.cm3.
Climate temperature and rainfall from sowing to harvest are
presented in Table 1.
The experiment field received 80 kg.ha-1 of P2O5. Nitrogen at a
rate of 150 kg/ha was applied, in the form of urea, the first half of
which during disk harrowing and the remaining half used when the
plants were at heading stage.
Table 1. Mean temperature (° C), rainfall (mm), relative humidity (%) and number of days below zero of site from sowing to
Month Oct. Nov. Dec.
Temp (° C) 17.6 9.1 4.7
Rainfall (mm) 30 41.2 31.5
Relative humidity (%) 76.3 81.5 82.8
No. of days below zero 0 4 14
Table 2. Effect of foliar application of Zn and Fe on wheat yield (kg ha-1), seed-Zn and Fe
Concentration (mg kg-1).
Yield ± SE
Fe 8185 ± 93.853
Zn 7919 ± 67.3
Fe+Zn 8954 ± 74.638
Control 7665 ± 97.994
LSD (?=0.01) 414.7
Zn ± SE
22.6 ± 1.493
20.27 ± 1.291
12.17 ± 1.317
Fe ± SE
146.7 ± 5.783
123.7 ± 4.667
84.93 ± 4.91
Plant density was 350 plants per m2 and plots were hand sown
on 10th March, 2008 using a template to produce 10 rows of plants
12 cm apart. Seeds were sown 4 cm deep and 3 cm apart within
rows. Two seeds were sown in each position and the plots thinned
to the desired plant population when the seedlings reached the first
leaf fully emerged stage. Weeds were removed by hand. Zn and Fe
concentration was determined by atomic absorption set.
Data given in percentages were subjected to arcsine transfor-
mation before statistical analysis. The SAS software package was
used to analyze all the data (SAS, 2001) and means were
separated by the least significant difference (LSD) test at P< 0.01.
RESULTS AND DISCUSSION
Results showed that foliar application of Zn and Fe (alone
or together) has significant effect (at 0.01 probability) on
wheat yield, grain-Zn and Fe concentration. Mean wheat
yield, Zn and Fe concentration is presented in Table 2.
According to Table 2, maximum seed yield was obtained
by using (Fe + Zn) and Zn treatments. Although seed
yield was affected by using Fe fertilizer (+187 kg.ha-1),
but foliar application of Fe did not increase seed yield
significantly compared to control. Similar results have
been reported by Yilmaz et al. (1997), Seilsepour (2007)
and El-Majid et al. (2000). Seilsepour (2007) found that
the average grain yield increase by using of Fe and Zn
were 317 and 330 mg kg-1, respectively. Yield increased
868 mg kg-1 by using a combination of Fe + Zn.
Seed-Zn concentration affected more than other
adjectives and increased in all treatments. The highest
Zn concentration obtained by using Zn treatment. Zn
application increased grain-Zn approximately up to
threefold comparison with control (from 18.7 to 50.9
mg.kg-1). Yilmaz et al. (1997) reported that fertilizers can
increase grain Zn concentration up to three- or fourfold.
Zn concentration affected by using Fe treatment
compared with control, but it was not considerable (from
18.7 to 22.6 mg.kg-1).
Foliar application of (Fe+Zn) at tillering and heading
stage increased Zn concentration up to 20.27 from 12.17
mg.kg-1. Fe concentration increased by using (Fe+Zn)
compared with control (from 84.93 to 139.6 mg.kg-1).
In order to eliminate Fe deficiency, adding chemical
compounds such as premix to wheat flour is common in
Iran. However, seed bio-fortification is a more excellent
method compared to other chemical fortification. Also, the
application of micronutrients can improve seed yield and
This study has been supported by University of
Mohaghegh Ardabili and Moghan Agricultural and Natural
Resource Research Center. I would like to thank Kamal
Shahbazi for support and helpful comments.
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