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The effects of Zn and K fertilisers on agronomical characteristics and Zn, Fe and P accumulation in two wheat cultivars in calcareous soils

Mohammad Ali Bahmanyar1, Hemmatollah Piradshti2

1Associate Professor, Department of Soil Science, Email: mabahmaniar@yahoo.com
2
Assistant Professor, Department of Agronomy and Plant Breeding
Sari Agricultural Sciences and Natural Resources University, Sari, Iran

Abstract

In order to study the effects of zinc and potassium on growth traits and accumulation of nutrient elements in wheat leaves and grain, a pot experiment was conducted as a split plot factorial based on a complete randomized block design in 2006. There were two cultivars of wheat (Tajan and Nye60), four levels of K (0, 81.5, 163 and 244.5 kg K/ha), and four Zn treatments, consisting of Zn0 (without Zn fertiliser), Zn1 (5 kg Zn/ha in soil + 300 g Zn/ha as foliar application), Zn2 (10 kg Zn/ha in soil + 600 g Zn/ha as foliar application), Zn3 (15 kg Zn/ha in soil + 900 g Zn/ha as foliar application). Fertilisers were applied to the soil at planting and the foliar Zn applied at booting stage. Zn application increased the number of tillers, flag leaf length, grain yield, total dry matter, 1000 grain weight and Zn content in leaves, but P and phytic acid concentration in grain was decreased. K application increased the number of tillers, grain yield, K content and Zn content both in leaves and grain. The concentration of phytic acid in grain, K in leaves and grain and 1000 grain weight differed between the two cultivars. The interaction effects of Zn and K on growth traits, accumulation of nutrients and grain yield were not significant.

Key words

Potassium, zinc, phytic acid, nutrient accumulation

Introduction

Zinc (Zn) and potassium (K) deficiency are worldwide nutritional constraints for plant growth, particularly in calcareous soils (Takhar and Walker 1993). Zn deficiency is also a global micronutrient deficiency in humans and more than 2 billion people suffer from micronutrient deficiencies including Zn deficiency (Welch and Graham 1999). Biomass production, grain yield and concentration of Zn in grain increased with application of Zn to soil and leaves, and the application of Zn to both soil and foliage resulted in a greater increase in concentration than other methods of application (Yilmaz et al. 1997). Zn application has been reported to decrease the concentration of phosphorus and phytic acid in wheat kernel (Erdal et al. 2002).

K has a critical role in plant growth and development and in human nutrition. K application can increase the number of fertile tillers (Mehdi et al. 2001), biomass production (Ehsan Akhtar 2002), number of grains per spike (Evans and Riedell 2006), 1000 grain weight and wheat grain yield (Sharma et al. 2005; Evans and Riedell 2006). The present study was carried out to investigate the influence of Zn and K supply on plant growth and levels of Zn, Fe, K, P, protein and phytic acid in grains of two wheat cultivars growth in calcareous soil.

Materials and methods

The pot experiment was conducted at the Sari Agricultural Sciences and Natural Resources University, located in the North of Iran, in 2006. Two wheat cultivars, (Tajan and Nay 60) were selected. Four levels of K (0, 81.5, 163 and 244.5 kg K/ha, as K2SO4), and four Zn levels, consisting of Zn0 (without Zn fertiliser), Zn1 (5 kg Zn/ha in soil + 300 g Zn/ha as foliar application), Zn2 (10 kg Zn/ha in soil + 600 g Zn/ha as foliar application), Zn3 (15 kg Zn/ha in soil + 900 g Zn/ha as foliar application), were the treatments. The experimental soil was collected from the top layer of a calcareous soil and it contained considerable lime and low available Zn. A number of physical and chemical properties of this experimental soil are presented in Table 1.

Table 1. Some physico-chemical characteristics of the soil used in this study

pH

CaCO3
%

O M
%

Texture

Available P
g/g

Available K
g/g

Available Zn
g/g

7.62

19.8

2.06

SiCL

8.7

216

0.56

Ten seeds were sown per pot and thinned to five green plants after establishment. The K and basal Zn fertilisers were applied at seeding and the foliar Zn treatments were applied at the stem elongation stage. Samples were taken from flag leaves at heading to determine the leaf mineral content. The number of tillers, length and width of flag leaf, 1000 grain weight, biological dry matter and grain yield were determined. The concentration of protein in grain (Kjeldahl method) and accumulated Zn, K and Fe in the flag leaf and grain were determined. Zn, K and Fe concentrations in leaf and grain were determined by drying the samples at 60C and grinding, converting to ash at 550C for 18 h and then the ashes were dissolved in 3.3% HCl (v/v) to measure Zn and Fe by atomic absorption spectrometer (Varian specter AA-10) and K by flame photometer. Statistical analysis was conducted using MSTAT-C statistical software and means were compared by Duncan's multiple range test.

Results

Analysis of variance of the studied traits is summarized in Table 2. Application of K fertiliser had a significant effect on number of tillers, grain yield, biological dry matter, K concentration in leaf, protein in grain and P, Zn and K in grain. The Zn treatments had a significant effect on all studied traits except width of flag leaf and K concentration in leaf and grain (Table 2). The effect of Zn treatments was generally positive, with the exceptions of P and phytic acid in grain which decreased at the higher Zn treatments.

Yilmaz et al. (1997) reported that the application of Zn fertiliser increased biomass production and grain yield of wheat grown on calcareous soil. Despite the increase in yield, the concentration of K and phytic acid in grain decreased significantly (Torun et al. 2001; Erdal et al. 2002) (Table 3). K application has previously been reported to increase the number of fertile tillers (Mehdi et al. 2001), grain yield (Sharma et al. 2005; Evans and Riedell 2006) and biological dry matter (Ehsan Akhtar 2002) and similar responses were observed in this experiment.

Table 2. Significance of F values derived from analysis of variance of yield, yield components, Zn, Fe, P, protein and phytic acid.

Character

C

K

Zn

CK

CZn

KZn

CKZn

Number of tillers

ns

*

*

**

**

ns

ns

Length of flag leaf

ns

ns

**

ns

ns

ns

ns

Width of flag leaf

ns

ns

ns

ns

**

ns

ns

Grain yield

ns

**

**

ns

ns

ns

ns

Biological dry matter

ns

**

**

ns

ns

ns

ns

1000 grain weight

*

ns

**

ns

ns

ns

ns

Zn in leaf

ns

ns

**

ns

ns

ns

ns

K in leaf

**

**

ns

*

ns

ns

ns

Protein in grain

ns

*

**

ns

ns

ns

ns

P in grain

ns

*

**

ns

**

ns

ns

Phytic acid in grain

*

ns

**

ns

ns

ns

ns

Zn in grain

ns

*

**

ns

*

ns

ns

Fe in grain

ns

**

**

**

ns

ns

ns

K in grain

*

**

ns

ns

ns

ns

ns

C = cultivar K = potassium Zn = zinc
* and ** significant at P<0.05 and 0.01, respectively ns: not significant

The concentration of Zn, Fe and protein of grain in the control were 49, 36 ppm and 18.3% respectively. Application of Zn fertiliser increased the concentration of Zn in grain (Table 3) and this is in agreement with Yilmaz et al. (1997). Zn, Fe and protein in grain increased to 71, 42 ppm and 19.6% respectively. However, phytic acid content in grain decreased from 8.0 to 6.9 ppm with the application of Zn fertiliser (Table 3).

Conclusion

Zn and K application significantly affected the number of tillers, length of flag leaf, total dry matter, 1000 grain weight, protein content, Zn and K uptake in flag leaves, and Zn Fe and K in grain of wheat grown in a calcareous soil. Thus, the fertiliser treatments not only increased grain yield, but they also resulted in an improvement in grain quality through the effect on concentration of grain nutrients and protein. The higher application rates of Zn and K resulted in greater yield and growth characteristics than at the lower treatments demonstrating the benefit of application of Zn and K fertilisers to wheat cultivated in these calcareous soils. Further experiments are required to determine the appropriate application rates for field grown wheat crops. The two cultivars responded significantly differently and grain yield, 1000 grain weight, protein content and concentration of Zn, K and Fe in grain of cv. Tajan were greater than for cv. Nay 60, indicating that there is also potential to exploit genetic variation to improve the production of wheat on calcareous soils.

Table 3. The concentration of Zn, Fe, protein and phytic acid in wheat grain in response to Zn fertiliser treatments

Zn SO4 applied

Zn
(ppm)

Fe
(ppm)

Protein
(%)

Phytic acid
(ppm)

kg Zn/ha soil

Leaf g Zn/ha

       

0

0

49.2d

36.3c

18.3b

8.0a

5

300

55.1c

38.5bc

18.7b

7.8b

10

600

64.0b

40.4ab

18.6b

7.1bc

15

900

70.7a

42.4a

19.6a

6.9c

*Mean values within each column followed by different letter(s) are significantly different (P<0.05).

References

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Erdal I, Yilmaz A, Taban S, Eker S, Torun B, Cakmak I (2002) Phytic acid and phosphorous concentrations in seeds of wheat cultivars grown with and without zinc fertilization. Journal of Plant Nutrition 25(1), 113-127.

Evans KM and Riedell WE (2006). Response of spring wheat cultivars to nutrient solutions containing additional potassium chloride. Journal of Plant Nutrition 29, 497-504.

Mehdi SM, Ranjha AM, Sarfraz M and Hassan G (2001). Response of wheat to potassium application in six soil series of Pakistan. Journal of Biological Sciences 6, 429-431.

Sharma S, Duveiller E, Basnet R, Karki CB and Sharma RC (2005). Effects of potash fertilization on Helminthosporium leaf blight severity in wheat and associated increases in grain yield and kernel weight. Field Crops Research 93, 421-150.

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Yilmaz A, Ekiz H, Torun B, Gultekin I, Karanlik S, Bagei S A and Cakmak I (1997). Effect of different zinc application methods on grain and zinc concentration in wheat cultivars grown on zinc deficient calcareous soils. Journal of Plant Nutrition. 20 (4&5), 461-471.

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