Influence of Micronutrients Foliar Application and Nitrogen Fertilization on
Wheat Yield and Quality of Grain and Seed
The field experiment was conducted at Tag AL-Ezz, Agricultural Research Station Farm, Dakahlia Governorate, Agricultural Research Center, Egypt (+7 m altitude, 31° 36' latitude and 30° 57' longitude), during 2005/2006 and 2006/2007 seasons to study the effect of foliar application with micronutrients (untreated (control), spraying with water, Cu, Mn, Fe and Zn at the rate of 500 ppm of each as well as the mixture of these 4 micronutrients at the rate of 500 ppm of each) under nitrogen levels 50, 70 and 90 kg N fed-1, as well as, their interactions on yield and its components, grains quality and chemical composition of wheat cultivar Giza 168. Also, a laboratory experiment was conducted at Seed Technology Research Unit at Mansoura, Dakahlia Governorate, Field Crops Research Institute, Agricultural Research Center, Egypt, to determine germination percentage and seedling vigor tests (seed quality) of the resultant seed from field experiment. Results indicated that foliar application of the micronutrients mixture at the rate of 500 ppm produced the highest values of grain yield and its components, chemical composition as well as quality parameters of both grains and seed with significant differences compared with other foliar application treatments in both seasons. The second best treatment was the application of Zn followed by Mn in both seasons. Cu and Fe treatments were similar in their effects and the difference between them were insignificant in most traits. The highest values of both straw and grain yields and yield components as well as quality parameters of grains and seed were resulted from increasing nitrogen levels up to 90 kg N fed-1 as compared with other levels (50 and 70 kg N fed-1) in both seasons. The results under the present conditions of Tag El-Ezz show that foliar application with mixture of micronutrients in addition to fertilizing with 90 kg N fed-1 can be maximize wheat straw and grain yields and gave the best quality parameter of both grains and seed. Moreover, it can be recommended that spraying wheat plants with Cu or Mn or Fe or Zn or mixture (at the rate of 500 ppm) and adding 70 kg N fed-1, which surpassed grain yield over untreated (control) + 90 kg N fed-1.
Wheat (Triticum aestivum L.) is cultivated worldwide primarily as a food commodity. Because of its importance in the Egyptian diet, wheat is considered a strategic commodity. Calderini and Slafer (1998) noticed that only 3 of the 21 countries (Egypt, Germany and India) exhibited a clear continuous increase in wheat yield (per unit area) during the last decade. Cropping intensity in Egypt accompanied with shortage in fertilization led to a serious depletion of both macro and micro nutrients from soil.
Micronutrients, such as transition metals like Fe, Cu, Mn and Zn are essential
for growth and development of the living plants, as they are found in most redox
reactions fundamental for cellular processes and in proteins and enzymes for
structural and catalytic enzyme activities (Hall and Williams, 2003). These
nutrients are known to be required for all higher plants (Welch et al.,
1991) and shortage of them in culture media causes deficiency symptoms and reducing
growth (Marschner, 1995). Soil organic matter use led to a significant and direct
impact on the availability of Zn, Fe and Mn, but has little influence on the
availability of soil Cu (Zhang et al., 2001). In addition, the interaction
of other soil macro and micro nutrients also affected micronutrients uptake
by crops (Aulakh and Malhi, 2005). However, the soil application of micronutrients
fertilizers in the cultivation may not meet the crop requirement for growth
and nutrient use, thus the alternative effective approach is to apply these
micronutrients as a foliar spray (Arif et al., 2006). Foliar application
of wheat with different micronutrients could be equal or more effective than
soil applications and used effectively to overcome the problem of micronutrients
deficiency in subsoil (Modaihsh, 1997; Torun et al., 2001). Kassab et
al. (2004) concluded that the foliar application with a 2% solution from
each of Fe, Mn, Zn and Mg significantly increased wheat yield components, grain
and straw yields fed-1 as well as carbohydrates yield fed-1.
Karamanos et al. (2004) reported that maximum grain yield of wheat was
obtained by foliar Cu application.
Nitrogen is often the most important plant nutrients. Wheat is very sensitive to insufficient nitrogen and very responsive to nitrogen fertilization (David et al., 2005). The efficiency of nitrogen fertilizer depends, much, on the level of available soil nitrogen in the rooting zone. Until now, on a world-wide-scale the adjustment of nitrogen fertilizer rates to nitrogen soil tests is rare (Sieling et al., 2005). Many workers all over the world concluded that using nitrogen fertilizer in suitable needed rates could improve growth, yield and its components as well as quality of wheat i.e., Sayed et al. (2003), Tammam and Tawfils (2004), Allam (2005), Seadh and Badawi (2006), Ibrahim (2007) and Mekhemar (2008).
During parental development, nutritive status can be modify the grain size, elemental composition percentage and rate of germination and longevity of seeds (Roach and Wulff, 1987; Fenner, 1992). Ascher et al. (1994) concluded that seed nutrition combined with soil nutrition gave better yields and better seed quality of wheat. Rengel and Graham (1995) found that higher Zn content in wheat seeds gave plants with better root and shoot and accumulated more dry matter compared to those from the low Zn content in seeds. Generally, trace mineral content in seeds are essential to help seedling survive and accelerate initial growth (Bouis, 2003). Nylor (1993) showed that wheat seed produced from parent plant receiving greater amount of nitrogen had a higher and faster germination percentage compared to those received lower amount of nitrogen.
The present experiment was undertaken to investigate the response of wheat cultivar Giza 168 to foliar application with micronutrients and soil nitrogen fertilization on yields and its components as well as grains and seed quality under the environmental conditions of Dakahlia Governorate at Tag El-Ezz district.
MATERIALS AND METHODS
The field experiment was conducted at Tag AL-Ezz, Agricultural Research Station Farm, Dakahlia Governorate, Agricultural Research Center, Egypt, during 2005/2006 and 2006/2007 seasons to study the effect of foliar application with micronutrients and soil applied nitrogen levels on yield and its components, grain and seed quality of wheat cultivar Giza 168. In addition to, laboratory experiment was conducted at Seed Technology Research Unit at Mansoura, Dakahlia Governorate, Field Crops Research Institute, Agricultural Research Center, Egypt, to determine germination percentage, speed of germination and seedling vigor tests (seed quality) of seeds resultant from field trials.
Field experiment: A split -plot in CRB design with three replicates was used. The main plots were allocated to seven foliar nutrition treatments as follows: untreated control, spraying with water, spraying solution of: CuSO4, Mn-EDTA, Fe-EDTA and Zn-EDTA at the rate of 500 ppm of each as well as the mixture of the micronutrients together at the rate of 500 ppm of each element. The foliar solution volume was 200 Liter fed-1 and spraying was conducted by hand sprayer (for experimental plots) until saturation point twice after 30 and 50 days from sowing. The sub plots were assigned to three nitrogen level treatments of: 50, 70 and 90 kg N fed-1. The nitrogen fertilizer in the form of ammonium nitrate (33.0% N) was used in two equal doses prior to each of the first and the second irrigations.
Before planting, soil samples for both physical and chemical analysis for the experimental soil were undertaken according to Jackson (1973) and corresponding data are presented in Table 1. Each experimental unit was 10.5 m2 (3x3.5 m). The preceding summer crop was rice (Oryza sativa L.) in both seasons.
Potassium fertilizer in the form of potassium sulphate (48% K2O) at the rate of 50 kg fed-1 was applied in one dose before the first irrigation. Calcium super phosphate (15.5% P2O5) was applied during soil preparation at the rate of 150 kg fed-1. The planting dates were at November 23rd and 26th in the first and second seasons, respectively. Wheat grains at the rate of 60 kg fed-1 were broadcasted using (Afir) method. The other recommended agricultural practices for growing wheat were followed.
Yield components: At harvesting time, one square meter was randomly selected
from each experimental plot to estimate the following characters: plant height
(cm), number of spikes m-2, spike length (cm), number of spikelets/spike,
number of grains/spike and 1000 grain weight (g).
and chemical soil characteristics at the experimental sites during 2005/2006
Yield determination: Grain yield (ardab fed-1) was calculated
by harvesting whole plants in each plot and left to dry on air, then they were
threshed and the grains (which were at 13% moisture) were weighted (kg), then
converted to ardab per fed (one ardab = 150 kg). Straw yield (t fed-1):
The straw resulted from each experimental plot was weighted in kg, then it was
converted to tons per fed.
Wheat grain quality and chemical composition: Carbohydrates percentage in grains was determined by Hedge and Hofreiter (1962). Nitrogen in grains and straw was determined by microkjeldahl methods (Jackson, 1967). Crude protein percentage was calculated by multiplying the total nitrogen values in wheat flour by 5.17. Phosphorous in grains and straw was determined by the methods described by Cooper (1977). Potassium in grains and straw was determined using flamephotometer as described by Peterburgski (1968).
All data were statistically analyzed according to the technique of analysis of variance (ANOVA) for the split -plot design using MSTATC computer software package according to Gomez and Gomez (1984). Least Significant of Difference (LSD) method was used to test the differences between treatment means at 5% level of significance as described by Waller and Duncan (1969).
Laboratory experiment: The germination experiment consisted of four replications of 100 seeds from each treatment. 50 seeds were placed on two sheets of blotter paper in 14 cm diameter Petri-dishes. The blotter paper was moistened with adequate distilled water. The Petri-dishes were placed in a growth chamber at 20°C. Standard germination tests were followed according to AOSA (1993). Germination percentage was expressed as the percentage of seed germinating normally after 8 days. The four replications were also used to evaluate daily speed of germination (during germination test) according to Agrawal (1986). Shoot and root lengths (cm) were determined at random from 10 normal seedlings taken from each replicate at the end of standard germination test and dried in a forced air dry oven at 110°C for 17 h (Agrawal, 1986) to obtain seedlings dry weight in milligrams. Data were subjected to the statistical analysis according to the technique of Analysis of Variance (ANOVA) for the factorial completely randomized design as published by Gomez and Gomez (1984).
RESULTS AND DISCUSSION
Yield and yield components: Foliar application with the applied micronutrients had a significant effect on plant height, number of spikes m-2, spike length, number of spikelets/spike, number of grains/spike, 1000-grain weight, grain and straw yields in both seasons (Table 2, 3). The mixture of four micronutrients (Cu, Mn, Fe and Zn) at the rate of 500 ppm of each significantly ranked first and produced the highest values of grain and straw yields as well as all its components with significant differences compared with the other singular micronutrient foliar application treatments in both seasons. Foliar application treatment with Zn was in the second rank and followed by Mn treatment. Cu and Fe treatments were seemed equally in their effect and the difference between them were insignificant in most cases. The lowest values of grain and straw yields and yield components were resulted from the untreated treatment in the two growing seasons. Such effects of foliar application with micronutrients (Cu, Mn, Fe and Zn) might be due to its critical role in crop growth, involving in photosynthesis processes, N-fixation, respiration and other biochemical and physiological activates and thus their importance in achieving higher yields. Similar results were reported by Welch et al. (1991), Hall and Williams (2003) and Kassab et al. (2004).
Data presented in Table 2 and 3 reveal
that, grain yield and its components i.e., plant height, number of spikes m-2,
spike length, number of spikelets/spike, number of grains/spike, 1000 grain
weight, grain and straw yield fed-1 were significantly increased
by increasing nitrogen fertilizer level up to 90 kg N fed-1.
||Plant height, No. of spikes m-2, spike length,
number of spikelets/spike and number of grains/spike as affected by foliar
application with micronutrients and nitrogen fertilizer levels during 2005/2006
and 2006/2007 seasons
||1000-grain weight, grain and straw yields as well as crude
protein and carbohydrates percentages in grains as affected by foliar application
with micronutrients and nitrogen fertilizer levels during 2005/2006 and
These results were noticed in the two growing seasons. Wheat plants fertilized
with the highest level of nitrogen (90 kg N fed-1) had the highest
values of grain yield and its components, followed by plants fertilized with
70 then 50 kg N fed-1 in both seasons. Noteworthy, the percentage
of increasing values of most mentioned characters due to increasing nitrogen
levels from 50 to 70 kg N fed-1 was more than those of increasing
nitrogen levels from 70 to 90 kg N fed-1. This means that the response
of wheat to increase nitrogen levels from 70 to 90 kg N fed-1 was
less than that when nitrogen was increased from 50 to 70 kg N fed-1.
The most important role of nitrogen fertilizer in plant is mainly in its presences
in the nucleic acid and protein structure. In addition, nitrogen is also found
in chlorophyll molecule. Chlorophyll enables plant to transfer energy from sunlight
by photosynthesis to assimilates (chemical energy form). Therefore, the nitrogen
supply to the plant will influence the amount of protein, protoplasm and chlorophyll
formed. In turn, this influences cell size and number, photosynthetic activity
and growth, hence increasing all yield components as well as grain and straw
yield per unit area. These results are in agreement with those obtained by David
et al. (2005), Sieling et al. (2005) and Seadh and Badawi (2006).
Grain quality and chemical compositions: Quality parameters of grains
(protein and carbohydrates percentages) and chemical composition i.e., N, P
and K concentrations in grains and straw show significant response to micronutrients
foliar application treatments in both seasons as shown in Table
3 and 4. Application with mixture of Cu, Mn, Fe and Zn
at the rate of 500 ppm, resulted in the highest values of these traits with
significant differences compared with other foliar application treatments in
the two growing seasons.
||N, P and K percentages in wheat grains and straw as affected
by foliar application with micronutrients and nitrogen fertilizer levels
during 2005/2006 and 2006/2007 seasons
Generally, it was observed that the foliar application treatments with micronutrients
assorted as: Mixture>Zn > Mn>Fe>Cu>water> untreated in both
seasons. This improvement in grains quality and chemical composition may be
due to the role of microelements in maintaining balanced plant physiological
growth. Even though micronutrients are present in small amounts in plants, they
activate about 100 enzymes in plant. It is inferred that plant not to be able
to survive without adequate of sufficient micronutrients because they are essential
to the synthesis of DNA and RNA and to metabolizing carbohydrates, lipids and
proteins. Micronutrients also play a key role in the release of carbon dioxide
and in the function of vitamins (Marschner, 1995).
Data in Table 3 and 4 illustrate that crude protein and carbohydrates as well as N, P and K percentages in grains and straw were significantly increased by increasing nitrogen levels in both seasons, except K% in straw in both seasons. From the data, each increase in nitrogen associated with a significant increase in grain quality parameters, this observation was true in the two growing seasons. Generally, the highest values of these traits were obtained as a result of increasing nitrogen fertilization up to 90 kg N fed-1. This improvement in quality parameter due to increasing nitrogen levels may be reflected to the role of nitrogen fertilizer in improving growth and dry matter accumulation which led to increasing the uptake of most nutrients. The results achieved in this work are partially compatible with those obtained by Allam (2005) and Mekhemar (2008).
Seed quality: Foliar application treatments with micronutrients exhibited significant effect on seed quality parameters (germination percentage, speed of germination, shoot length, root length and 10 seedlings dry weight) in both seasons (Table 5). The mixture of Zn, Fe, Mn and Cu at the rate of 500 ppm produced the highest values of the above mentioned characters in both seasons. Foliar application with Zn alone ranked after the formerly mentioned treatments in both seasons. Other foliar application treatment exceeded untreated (control) and spraying with water, this observation was true in both seasons. The improvement in seed quality parameters may be reflected to the role of microelements in enhance accumulation of assimilate in the grains (during grain filling stage) and thus the resultant seeds had greater individual mass and germinated quickly (Baskin and Baskin, 1998). Also, high micronutrient accumulation in seeds particularly Zn and Mn may be produce more viable and vigorous seedlings, because they supplying the young seedlings with these trace elements until it has developed a large root system enough to take over this role (Bouis et al., 2000). Similar results were reported by Roach and Wulff (1987) and Fenner (1992).
Seed quality characters were significantly affected due to increasing nitrogen
fertilization rates from 50 up to 90 kg N fed-1 in both seasons (Table
5). Each increase in nitrogen rates from 50 to 70 and 90 kg N fed-1
associated with a significant increase in studied seed parameters in the two
growing seasons. The highest values of seed quality parameters were resulted
from those fertilized wheat plants with 90 kg N fed-1. This enhancement
in seed quality parameter due to increasing addition of nitrogen levels may
be ascribed to increase N content of seeds which positively correlated with
germination percentage and seedling size (Nylor, 1993).
||Germination percentage, speed of germination, shoot length,
root length and 10 seedlings dry weight as affected by foliar application
with micronutrients and nitrogen fertilizer levels during 2005/2006 and
||Number of spikes m-2, number of grains/spike, 1000
grain weight and grain yield as affected by the interaction between foliar
application with micronutrients and nitrogen fertilizer levels during 2005/2006
and 2006/2007 seasons
Interaction: Regarding the interactions between foliar application with
micronutrients and nitrogen levels on studied characters, there are many significant
effects. We have reported enough the significant interaction on number of spikes
m-2, number of grains/spike, 1000 grain weight and grain yield only
(Table 6). The best interaction treatment which produced the
highest values of grain yield and its components was foliar application with
the mixture of Cu, Mn, Fe and Zn (at the rate of 500 ppm) beside fertilization
with 90 kg N fed-1. Foliar spraying wheat plants with Cu or Mn or
Fe or Zn or mixture plus adding 70 kg N fed-1 exceeded treatment
of untreated + 90 kg N fed-1 in number of grains/spike, 1000 grain
weight and grain yield in both seasons, except treatment of Cu + 70 kg N fed-1
in 1000 grain weight in the second season only. Also, spraying wheat plants
with Zn or mixture +70 kg N fed-1 significantly surpassed treatment
of untreated + 90 kg N fed-1 in number of spikes m-2 in
both seasons. While, untreated +90 kg N fed-1 treatment exceeded
spraying wheat plants with Cu or Fe + 70 kg N fed-1 (in both season)
or Mn +70 kg N fed-1 (in the second season) in number of spikes m-2
without significant differences between them.
In general, the obtained results show that foliar application with mixture of studied micronutrients (Cu, Mn, Fe and Zn) at the rate of 500 ppm in addition to mineral fertilizing with the highest nitrogen level (90 kg N fed-1) produced the highest values of wheat straw and grain yields as well as grain quality in addition to improve germination of the resultant seeds and seedling growth. Moreover, it can be recommended that spraying wheat plants with Cu or Mn or Fe or Zn or mixture (at the rate of 500 ppm) and adding 70 kg N fed-1, which exceeded in grain yield upon untreated (control) + 90 kg N fed-1.
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