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Effect of nitrogen and zinc fertilisers on yield and protein content of durum wheat (Triticum turgidum var. durum)

Ali Khourgami 1 and Ghobad Bour2

1 Assistant Professor, Azad Islamic University, Khoramabad Branch, Iran. Email ali_khorgamy@yahoo.com
2
Master of Agronomy. Email bour530@yahoo.com

Abstract

The effect of application of nitrogen and zinc fertilisers on durum wheat (Triticum turgidum var. durum) in dryland farming conditions was studied at the field station of Azad Islamic University, Branch Khoramabad, Lorestan, Iran during 2006-2007. A factorial design with 4 N treatments, 3 Zn treatments and 2 cultivars was used, with the N treatments as a split application at sowing and at the jointing stage and Zn was applied to the soil at sowing. N treatments had a significant effect on plant height, thousand seed weight, seed yield, biological yield, harvest index and protein content. Zn treatments had a significant effect on thousand seed weight and protein content. Cultivar Mn.a-1 was superior to 4321-Karaj for seed yield, biological yield and protein content. The interactions between N and Zn for thousand seed weight, protein content, plant height, seed yield and harvest index were significant. N fertiliser increased yield and yield components and is suitable for dryland farming under Iranian conditions, while the application of Zn also had a positive effect on grain size and composition.

Key Words

Dry farming, durum wheat, nitrogen, zinc

Introduction

Durum wheat (Triticum turgidum var. durum) accounts for approximately 10 % of world wheat production. The protein content of durum wheat grain is generally higher than bread wheat. In dry regions durum grows rapidly and matures early to escape water stress. Production under dryland farming systems in Iran is limited by moisture deficiency and lack of plant available nutrients in the soil. Sayadian and Khoshfetrat (1996) observed that the minimum concentration of total N in soil for western regions of Iran is 0.12 %, and the maximum yield of wheat followed the application of 30 to 90 kg/ha N fertilisers. In addition, cultivar, climatic factors, moisture and nitrate levels of soil also affected yield (Feyzi and Esmaeli 2002, Sayadian 1993, Sadri and Malacoti 2000). Erosion, high pH and low soil organic matter reduce root absorption and cause Zn deficiency in all dry regions of the world (Malacoti 1994, Bernan 1992). Research on the optimum level of N and Zn fertilisers in dry regions of Iran is essential especially in cereals.

Methods

The experiment was conducted at the field station of Azad Islamic University (Khoramabad Branch) during 2006-2007. The climate is temperate with a warm summer, effective rainfall in the period November to May and average annual rainfall of 500 mm. Treatments were arranged as a factorial design with 4 replications and consisted of 4 N treatments (0, 30, 60 and 90 kgN/ha), 3 Zn treatments (0, 10 and 20kg Zn/ha) and 2 cultivars (4321-Karaj and Mn.a1) (Table 1). N was applied as Urea in a split application with 50% applied at sowing and 50% when plants were at the jointing stage. Zn fertilizer was applied as ZnSO4 at sowing. Plots were 1.2 m x 6 m and the sowing rate was 400 seeds/m2.Weeds were controlled by the application of the herbicides Granstar (15-20 g/ha) and Tapic (0.6 – 0.8 l/ha). The flag leaf was used for determination of plant Zn and N concentration. After physiological maturity, plot borders were removed and seed yield, biological yield, thousand seed weight, plant height, protein content and harvest index were measured. MSTATE software program was used for analysis of variance and Duncan's test applied for comparison of means.

Results

Nitrogen fertiliser had a significant effect on plant height (Table 2) and N3 (90 kg/ha) produced taller plants than other treatments (96 cm). Interaction effects between cultivars and N, Zn and N, and cultivars and Zn were significant (Table 2). Cv. Mn.a-1 with 90 kg/ha N and 20 kg/ha Zn produced the tallest plants over all treatments (99 cm). These results are consistent with Feyzi and Emaeli (2002) and Sadry and Malacoti (2004) who also reported that environmental factors and plant nutrition affect height of wheat plants under Iranian conditions.

Table 1. Levels of treatments.

Cultivars

Zinc
(kg/ha)

Nitrogen
(kg/ha)

4321-Karaj

0

0

Mn.a-1

10

30

 

20

60

   

90

Grain weight was significantly affected by both N and Zn fertiliser treatments (Table 2). The greatest thousand seed weights were achieved at the highest treatment for both fertilisers. The N fertiliser treatment N3 (90 kg/ha) produced the greatest thousand seed weight (51 g), while Zn fertiliser treatment Zn2 (20 kg/ha) produced grain with a weight of 44g. Zn is required for the biosynthesis of the plant growth regulator (IAA) and for carbohydrate and N metabolism which leads to high yield and yield components. Interaction effects between cultivars and N, Zn and N, and cultivars and Zn were significant (Table 2). Mn.a-1 with 90 kg/ha nitrogen and 20 kg/ha zinc produced the highest thousand seed weight (52 g). Thousand seed weight is one of the most important yield components in cereals. Overcoming limitations to plant nutrient through the application of appropriate fertilisers increased assimilate production and photosynthesis efficiency at the seed filling stage (Calhor 2006, Yilmaz et al. 1997).

N fertiliser had a significant effect on seed yield (Table 2) and N3 (90 kg/ha) produced a greater yield than other treatments (4.11 t/ha). Interaction effects between cultivars and N, and Zn and N, were significant (Table 2). Cv. Mn.a-1 with 90 kg/ha N and 20 kg/ha Zn produced the highest overall seed yield (4.13 t/ha). Seed yield is derived from number of spikes per unit area, number of seeds per spike and thousand seed weight. In addition photosynthesis and remobilisation produce assimilate for seed formation at seed filling stage. In this study suitable rainfall at seed filling stage and good application of fertiliser (N at two times during growth and Zn applied to the soil at seeding) increased seed yield, consistent with other observations (Calhor 2006, Hajiboland et al. 2001).

N fertiliser had a significant effect on biological yield, but the effect of the Zn treatments was not significant (Table 2). Interaction effects between cultivars and N, and Zn and N were significant (Table 2). Mn.a-1 with 90 kg/ha N and 20 kg/ha Zn produced the highest biological yield (10.2 t/ha). Climatic factors such as temperature and moisture (rainfall or irrigation) and plant nutrition all have an influence on biological yield. N application at two times (sowing and jointing stage), as was the case in this experiment, can decrease N leaching and increase N use efficiency (Seyedin 2006, Lotfolahi et al. 2004).

Table 2. Analysis of variance (F values) of yield and yield components for two cultivars of wheat in response to N and Zn fertiliser treatments

Mean of square

       

Source of variation

Degrees of freedom

Plant height

Thousand seed weight

Seed yield

Biological yield

Harvest index

Protein content

Block

3

* 39.7

* 39.4

* 139.4

* 287.6

* 46.9

* 31. 8

Cultivar

1

ns 19.6

77.1 ns

* 82.8

* 217.8

ns 35.7

* 47. 1

Nitrogen

3

114.2*

* 55.6

* 87.5

* 243.6

* 54.0

* 66.9

Zinc

2

ns 30.4

61.2*

ns 31.0

ns 101.7

ns 38.1

* 59.9

Nitrogencultivar

3

217.4**

73.8 **

* 51.7

* 269. 8

** 70.4

** 90.9

Zinccultivar

2

* 64.8

* 60.7

ns 41.0

ns 138.7

** 87.2

* 61.2

NitrogenZinc

6

* 40.4

39.7 *

179.1**

397.5**

294.1**

84.4**

CultivarNitrogenZinc

6

79.7**

71.7**

218.4**

817.5**

** 687.7

111.7 **

Experimental error

69

13.8

17.1

21.7

38.2

15.9

9.2

Total

85

           

Coefficient of variation

-

13.1

9.7

11.4

14.1

12.8

12.3

ns, *,**: non significant, significant at the 5% and 1% levels of probability respectively

N fertiliser had a significant effect on harvest index (Table 2) and N3 (90 kg/ha) produced a higher harvest index than other treatments (40.2). Interaction effects between cultivars and N, Zn and N, and cultivars and Zn were significant (Table 2). Cv. Mn.a-1 with 90 kg/ha N and 20 kg/ha Zn produced the highest harvest index (40.3). High harvest index indicates a high seed yield (economic yield) relative to total biomass production. Zn fertiliser (ZnSO4) decreases pH of soil in dry lands and increases root absorption of minerals. Cv. Mn.a-1 has previously been reported to have a good response to fertilisers and environmental factors under dryland farming conditions (Khademi, 1998).

The application of both N and Zn fertilisers significantly increased the protein content of grain (Table 2). N fertiliser treatment N3 (90 kg/ha) produced the highest protein percentage in seed (16.1 %). Zn fertiliser treatment Zn2 (20 kg/ha) produced higher protein percentage in seed than other Zn treatments (15.8 %). Interaction effects between cultivars and N, Zn and N, and cultivars and Zn were significant (Table 2). Mn.a-1 with 90 kg/ha N and 20 kg/ha produced the highest protein content of all treatments (16.8 %). Correct management of N (both rate and type of application) improves soil fertility which can lead to high protein content in seed of wheat. Calhor (2006) and Sowers et al. (1994) reported that Zn deficiency caused low protein content in seed of wheat.

Conclusion

Production in dryland farming systems in Iran is limited by deficiency of both water and nutrients and durum wheat is considered to have good potential to increase production in these conditions. Research into plant nutrient in arid and semi-arid regions showed that application of N and Zn fertilisers had significant effects on yield and yield components of durum wheat. In this study, N fertiliser had a significant positive effect on plant height, thousand seed weight, seed yield, biological yield, harvest index and protein content. Zn, applied to the soil, had a significant effect on thousand seed weight and protein content. There was significant difference between the two cultivars tested and Mn.a-1 was superior to 4321-Karaj for seed yield, biological yield and protein content of grain. Mn.a-1 responded well to fertiliser treatments and environmental factors in dryland farming conditions. The interactions between N and Zn were significant for thousand seed weight, protein content, plant height, seed yield and harvest index therefore both nutrients should be applied for maximum production. The significant positive effect of N fertiliser on yield and yield components indicates that N can be effectively applied to dryland farming systems in Iran. Zn fertiliser (as ZnSO4) decreases pH of soil in dry areas and increases root absorption of minerals and improved Zn nutrition of plants improves biosynthesis of the plant growth regulator IAA and carbohydrate and N metabolism which lead to high yield and yield components. Enhanced plant nutrition increases assimilate production and photosynthesis efficiency at seed filling stage (Calhor 2006, Yilmaz et al. 1997). The application of N at two times (planting and jointing stage) decreased N leaching and increased N use efficiency (Seyedin 2006, Lotfolahi et al. 2004).

References

Calhor M (2006). Effect of Nitrogen and Zinc on yield of durum wheat in Khoramabad Region. Agricultural Research Institute (Lorestan, Iran).

Feyzi V and Esmaeli M (2001). Effect of Nitrogen on quality and quantity characteristics of wheat. Agronomy Journal of Iran 5, 4.

Hajiboland RB , Singh and Romheld V (2001). Retranslocation of Zinc from Leaves as important factor for Zinc-efficiency of rice genotypes. Plant Nutrition. Food Security and Sustainability of agro-ecosystem . pp. 226-227.

Khademi Z (1998). Effect of time and type of nitrogen consumption on wheat and protein content. Soil and Water Research institute. Tehran, Iran.

Lotfolahi M and Mehrvarz M (2004). Research about wheat cultivars for microelements adsorb efficiency. Agricultural Research Institute (Karaj, Iran).Malacoti M and Tehrani M (1999) Effect of microelement on agricultural yield (quantity & quality). Tarbiat Modares University. Iran.

Sadri M and Malacoti M (2000). Effect of Zn, Fe and Cu on quality and quantity of wheat. Wheat Nutrition. Kraj, Iran.

Sayadian K and Khoshfetrat G (1996). Final reports of soil science. Sararod Agricultural Research Institute. pp. 23-63.

Seyedin K (2006). Effect of microelement on wheat production. Maine Agricultural Research Institute. Final report.

Sowers K, Miller B and Pan W (1994). Optimizing yield and grain protein in soft winter wheat with split nitrogen application.Agronomy Journal 86, 1020-1025.

Yilmaz A , Ekiz A and Torun B (1997). Effect of different zinc application methods on grain yield and zinc concentration in wheat cultivars grown on zinc deficient calcareous soils. Plant Nutrition 20, 461-471.

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