Scholarly article on topic 'Grain yield response index of bread wheat cultivars as influenced by nitrogen levels'

Grain yield response index of bread wheat cultivars as influenced by nitrogen levels Academic research paper on "Agriculture, forestry, and fisheries"

CC BY-NC-ND
0
0
Share paper
Academic journal
Annals of Agricultural Sciences
OECD Field of science
Keywords
{Wheat / Cultivars / "N level" / "Agronomic efficiency" / "Grain yield response index"}

Abstract of research paper on Agriculture, forestry, and fisheries, author of scientific article — Nemat A. Noureldin, H.S. Saudy, F. Ashmawy, H.M. Saed

Abstract Two field experiments were conducted at Giza Agric. Res. Station, Agric. Res. Centre during the two seasons of 2009/2010 and 2010/2011. The study aimed to investigate the productivity of four bread wheat cultivars, namely Giza-168, Sakha-94, Gemmeiza-10, and Sids-12 under different nitrogen levels i.e. 0, 25, 50, 75, 100, and 125kgN/fad. The strip-plot design in three replicates was used. The obtained results showed significant differences among the tested wheat cultivars in the two seasons for number of spikes/m2, spike length, kernels number/spike, kernels weight/spike, weight of 1000 kernels, and grain and straw yields/fad. Gemmeiza-10 along with Sids-12 produced the highest weight of 1000 kernels surpassing the other cultivars in the second season only. Gemmeiaza-10 was the superior cultivar for producing higher grain yield, but statistically leveled with Sakha-94 in the 1st season and with Sids-12 in the 2nd one. Moreover, straw yield of Giza-168 was higher than each of other cultivars in the 1st season, while Gemmeiza-10 along with Sids-12 gave the maximum straw yield in the 2nd season. Increasing N up to 75kg/fad increased yield and its attributes of wheat in both growing seasons. All yield attributes significantly influenced by the interaction between wheat cultivars and N levels in both growing seasons, except kernels number/spike in the 1st season and spike length in the 2nd one. The maximum agronomic efficiency (AE) was recorded with Gemmeiza-10 and with application of 50kgN/fad. Grain yield response index showed that each of Giza-168 in 2009/2010 and Sids-12 in 2010/2011 was belonging to efficient-responsive group.

Academic research paper on topic "Grain yield response index of bread wheat cultivars as influenced by nitrogen levels"

Annals of Agricultural Science (2013) 58(2), 147-152

Faculty of Agriculture, Ain Shams University Annals of Agricultural Science

www.elsevier.com/locate/aoas

ORIGINAL ARTICLE

Grain yield response index of bread wheat cultivars as influenced by nitrogen levels

Nemat A. Noureldin a, H.S. Saudy a'*, F. Ashmawy b, H.M. Saed

a Agron. Dept., Fac. Agric., Ain Shams Univ., Cairo, Egypt b Cent. Lab. For Design & Stat. Analysis Res, A.R.C., Giza, Egypt

Received 10 June 2013; accepted 13 June 2013 Available online 5 September 2013

KEYWORDS

Wheat; Cultivars; N level;

Agronomic efficiency; Grain yield response index

Abstract Two field experiments were conducted at Giza Agric. Res. Station, Agric. Res. Centre during the two seasons of 2009/2010 and 2010/2011. The study aimed to investigate the productivity of four bread wheat cultivars, namely Giza-168, Sakha-94, Gemmeiza-10, and Sids-12 under different nitrogen levels i.e. 0, 25, 50, 75, 100, and 125 kg N/fad. The strip-plot design in three replicates was used. The obtained results showed significant differences among the tested wheat cultivars in the two seasons for number of spikes/m2, spike length, kernels number/spike, kernels weight/spike, weight of 1000 kernels, and grain and straw yields/fad. Gemmeiza-10 along with Sids-12 produced the highest weight of 1000 kernels surpassing the other cultivars in the second season only. Gem-meiaza-10 was the superior cultivar for producing higher grain yield, but statistically leveled with Sakha-94 in the 1st season and with Sids-12 in the 2nd one. Moreover, straw yield of Giza-168 was higher than each of other cultivars in the 1st season, while Gemmeiza-10 along with Sids-12 gave the maximum straw yield in the 2nd season. Increasing N up to 75 kg/fad increased yield and its attributes of wheat in both growing seasons. All yield attributes significantly influenced by the interaction between wheat cultivars and N levels in both growing seasons, except kernels number/spike in the 1st season and spike length in the 2nd one. The maximum agronomic efficiency (AE) was recorded with Gemmeiza-10 and with application of 50 kg N/fad. Grain yield response index showed that each of Giza-168 in 2009/2010 and Sids-12 in 2010/2011 was belonging to efficient-responsive group.

© 2013 Production and hosting by Elsevier B.V. on behalf of Faculty of Agriculture, Ain Shams

University.

* Corresponding author. Tel.: +20 (202) 44441172. E-mail address: Journalaaru@yahoo.com (H.S. Saudy). Peer review under responsibility of Faculty of Agriculture, Ain Shams

Introduction

In agricultural systems, increasing N use efficiency is a central issue and goal of applied research. The current N strategies in wheat crop are extremely inefficient, where N use efficiency ranging from 14% to 59% (Melaj et al., 2003; Lpez-Bellido et al., 2005). Nitrogen use efficiency in cereal grain production may be low owing to losses of N by volatilization,

University.

Production and hosting by Elsevier

0570-1783 © 2013 Production and hosting by Elsevier B.V. on behalf of Faculty of Agriculture, Ain Shams University. http://dx.doi.org/10.1016/j.aoas.2013.07.012

Table 1 Wheat yield and its attributes as affected by cultivars and N levels in 2009/2010 (S1) and 2010/2011 (S2) seasons

Variables Spikes Spike Kernels Kernels Weight of Grain yield (kg/fad) Straw yield (ton/fad)

number/m2 length (cm) number/spike weight/spike (g) 1000-grain (g)

S1 S2 S1 S2 S1 S2 S1 S2 S1 S2 S1 S2 S1 S2

Cultivar

Giza-168 242.00 236.44 10.99 10.36 58.23 56.44 3.39 3.00 53.15 55.83 1773.33 1810.28 4.04 3.63

Sakha-94 218.00 234.00 10.35 10.78 58.82 56.80 3.11 3.16 52.96 57.89 1883.89 1897.22 4.09 3.66

Gemmeiza-10 227.56 249.00 11.04 12.36 56.02 69.61 3.34 3.84 52.96 62.89 1912.50 2058.33 3.92 4.11

Sids-12 238.44 266.22 9.86 12.77 58.73 69.72 3.53 4.04 52.96 62.78 1754.17 2055.57 3.63 4.06

LSD (0.05) 15.60 30.73 0.55 0.45 2.47 4.32 0.19 0.65 NS 1.67 96.80 103.50 0.32 0.35

N level (kg/fad)

0 175.33 183.00 8.88 9.62 45.60 49.42 2.98 2.85 43.06 45.50 1445.00 1429.17 3.09 2.86

25 202.67 219.00 9.97 10.78 49.25 52.17 3.25 3.28 51.39 49.00 1728.75 1908.33 3.60 3.88

50 248.00 274.33 10.46 12.65 56.17 77.33 3.38 4.03 53.33 70.58 2013.75 2477.92 4.02 4.87

75 303.33 321.17 11.87 13.10 89.04 81.50 4.25 4.28 63.03 75.67 2218.75 2575.00 4.88 5.25

100 253.00 251.00 10.93 11.92 57.93 67.50 2.99 3.45 60.00 65.50 1958.33 1958.33 4.31 3.74

125 206.67 230.00 11.27 11.34 49.70 51.08 3.19 3.18 42.22 52.83 1621.25 1383.33 3.61 2.59

LSD (0.05) 15.80 18.72 0.62 0.60 4.02 3.76 0.31 0.14 4.94 1.36 239.30 237.40 0.33 0.30

Table 2 Wheat yield and its attributes as affected by the interaction of cultivars and N levels in 2009/2010 (Sj) and 2010/2011 (S2) seasons.

Variables

Spikes number/m2

Spike Kernels Kernels Weight of Grain yield (kg/fad) Straw yield (ton/fad)

length (cm) number/spike weight/spike (g) 1000-grain (g)

Giza-168 0 201.33 205.33

25 224.00 220.00

50 277.33 252.00

75 292.00 309.33

100 258.67 228.00

125 198.67 204.00

Sakha-94 0 196.00 177.33

25 176.00 208.00

50 228.00 248.00

75 286.67 292.00

100 234.67 270.67

125 186.67 208.00

Gemmeiza-10 0 153.33 148.00

25 210.67 214.67

50 233.33 320.00

75 310.67 336.67

100 256.00 260.00

125 201.33 214.67

Sids-12 0 150.67 201.33

25 200.00 233.33

50 253.33 266.33

75 324.00 346.67

100 262.67 245.33

125 240.00 293.33

LSD (0.05) 33.96 35.49

10.34 9.33 11.59 11.27

11.86 11.89

11.10 11.05

11.36 9.90

48.23 55.37 92.00 56.43 50.13

10.97 10.70 47.40

12.24 90.37 9.47 11.01 65.07 11.12 10.44 51.20

10.53 42.07 10.74 49.77

11.27 12.97 11.54 12.21

13.40 14.10 12.84

58.47 85.07 52.90

12.58 47.83

10.74 49.70 12.35 51.60

14.23 14.06 12.76

55.40 88.73 57.33

12.46 49.63 NS NS

48.00 64.33 72.67 56.33 51.00

45.33 48.67 63.67 72.67 60.67 50.33

52.33 56.00 94.33 86.67 78.00 50.33

53.67 56.00 87.00 94.00 75.00 52.67 8.12

3.37 3.00 4.77 2.93 3.03

3.20 3.00 3.03 3.50 2.73 3.17

2.77 3.13 2.73 4.23 2.93 3.27

3.03 3.20 3.77 4.50 3.37 3.30 0.42

2.50 2.63 3.30 3.67 3.13 2.77

2.27 3.03 3.83 3.80 3.20 2.83

3.27 3.60 4.07 4.87 3.70 3.53

3.37 3.87 4.93 4.77 3.77 3.57 0.22

40.00 41.67 1616.67 1383.33 3.00

52.22 54.00

65.55 56.67 50.00

44.45 50.00 53.33 61.11 62.22 46.67

44.44 48.89

45.56 64.44 62.22 52.22

43.33 54.44 60.00 61.11 58.89 40.00 6.80

46.67 59.67 71.33 62.67 53.00

45.3 48.00 69.00 72.00 62.00 51.00

46.33 50.00 77.67 81.33 67.33 54.67

48.67 51.33 76.00 78.00 70.00 52.67 3.26

1673.33 2075.00 2405.00 1653.33 1213.67

1438.33 1588.33 2220.00 2153.33 2058.33 1845.00

1340.00 1836.67 1840.00 2116.67 2321.67 2020.00

1395.00 1816.67 1920.00 2200.00 1800.00 1403.33 396.79

1666.67 2395.00 2300.00 1750.00 1366.67

1400.00 1916.67 2500.00 2450.00 1766.67 1350.00

1383.33 2000.00 2616.67 2750.00 2216.67 1388.33

1550.00 2050.00 2400.00 2800.00 2100.00 1433.33 237.63

3.71 3.69 5.30 4.92 3.63

3.50 3.12 4.71 4.68 4.61 3.95

3.16 3.66 3.81 4.90 4.25 3.73

2.71 3.90 3.88 4.65 3.47 3.15 0.76

2.75 3.55 4.48

4.77 3.48 2.72

2.83 3.83 5.02 5.10 2.80 2.35

2.75 3.98 5.20 5.50 4.47

3.10 4.13 4.78 5.62 4.22 2.50 0.56

denitrification, and leaching (Ercoli et al., 2012). Leaching losses occur when rainfall exceeds crop evapotranspiration, and downward water movement through the soil profile takes place, which corresponds to the fall-winter period in humid Mediterranean climate (Arregui and Quemada, 2006). Leaching N-NO3 losses from wheat were estimated in central Italy

at 21-32 kg N ha-1 yr-1, corresponding to 12-22% of the total N applied (Ercoli et al., 2012). Thus, as a general rule, N leaching in Mediterranean climate can be regarded as the greatest source of N loss and the major determinant of low N utilization efficiency. To reduce leaching losses, fertilizer application should aim to match as much as possible the requirement of

■Ï - 14 u A

£ S? 12 о

о £ 10

о œ 6

Sakha-97 Gemmeiza-10

Wheat cultivars

Fig. 1 Wheat cultivar differences in agronomic efficiency (kg grains kg N-1) in 2009/2010 and 2010/2011 seasons.

E "<5 о ^

ai ' <t

-2009/2010 ■2010/2011

25 50 75 100

Nitrogen levels (kg/fed)

Fig. 2 Effect of N levels (kg/fad) on agronomic efficiency (kg grains kg N-1) in wheat in 2009/2010 and 2010/2011 seasons.

plant N with the available nitrogen in soil, minimizing the excess of N in soil useless to the plant. Thus, application should be the latest possible compatible with the stage of development that still permits rapid N uptake, in order to reduce the opportunities for N losses of unused N (Raun et al., 2008) with

19.5- Gemmeiza-10,

18- (NER) Sids-12 (ER)

15- Giza-168,

13.5- Sakha-94 (NENR)

12 -1 1 1 1 1 1 1

800 1000 1200 1400 1600 1800 2000 2200 2400 2600 2800 Wheat grain yield at zero level (kg/fad)

Fig. 4 Grain yield response index (GYRI) of some wheat cultivars in 2010/2011 season. (ER, efficient and responsive; NER, not efficient and responsive; NENR, not efficient and not responsive.)

avoiding the pollution of ecosystems. From another site, farmers are facing difficulties with increasing costs of fertilizers, especially in developing countries. An integrated fertilization-plant breeding approach seems likely to give more economically viable and practical results in the future. The possibility of exploiting genotypic differences in absorption and utilization of N to improve efficiency of N fertilizer use or to obtain higher productivity on N-deficient soils has received considerable attention in recent years. Expanding research on cultivars with high N absorption and with low fertilizer requirements would be appropriate to develop cultivars that absorb N more efficiently and that use it more efficiently in the grain production process (Le Gouis et al., 2000). Genetic variation has been reported on wheat for nitrogen use efficiency (Ortiz-Monaste-rio et al., 1997; Dhugga and Waines, 1989). Therefore, the present work was undertaken to determine the quantitative physiological requirements of different levels N for some wheat cultivars to establish maximum N fertilization limits in relation to yield and grain yield response index.

12.5 -

12 - Gemmeiza-10,

11.5 " Sids-12 Giza-168

11 - (NER) (ER)

E 10.5-

>- u 10-

9.5 - Sakha-94

9 - (NENR)

8.5 -8 -1

800 1000 1200 1400 1600 1800 2000 2200 2400 2600 2800 Wheat grain yield at zero level (kg/fad)

Fig. 3 Grain yield response index (GYRI) of some wheat cultivars in 2009/2010 season. (ER, efficient and responsive; NER, not efficient and responsive; NENR, not efficient and not responsive.)

Materials and methods

Two field experiments were conducted at the Agric. Res. Station, Agric. Res. Centre, Giza Governorate, Egypt during 2009/2010 and 2010/2011 seasons. Each experiment included 24 treatments, which were the combinations of four bread wheat cultivars, namely Giza-168 Sakha-94, Gemmiza-10, and Sids-12 (obtained from Wheat Dept., Agric. Res. Centre at Giza) as well as six N fertilization levels, i.e. 0, 25, 50, 75, 100, and 125 kg N/fad. Physical and chemical characteristics of the experimental soil before planting were determined according to Jackson (1973) and revealed that the soil was clay in texture containing 16.5 and 15.2 ppm total N with pH 7.5 and 7.6, in the 1st and 2nd seasons, respectively. Nitrogen fertilizer was applied as urea (46.5% N) into two equal portions, before the first and the second irrigations. The experimental design was strip-plot design in three replicates, where wheat cultivars were arranged in vertical strips and N fertilization levels were allocated in the horizontal ones. The experimental unit area was 8.4 m2 consisting of 12 rows each of 3.5 m in length and 20 cm apart. Sowing date was 8th December in

the two growing seasons. The preceding crop was maize in both seasons of the study. All agricultural practices were done as recommended.

Data recorded

Yield and its attributes

At harvest (at the end of May), a sample of plants from square meter was randomly chosen from each plot to measure spikes number/m2, spike length, kernels number/spike, kernels weight/spike, and weight of 1000 grains. Straw and grain yields/fad were calculated from the whole plants of each plot.

Agronomic efficiency

Agronomic efficiency (AE) as a nitrogen physiological parameter was calculated according to Delogu et al. (1998) using the following equation:

Grain yield at N treatment — Grain yield at zero N

Applied N at N treatment x(kg grains kg N—')

Grain yield response index

Grain yield response index (GYRI) was calculated for each cultivar, according to Fageria and Barbosa Filho (1981) using the following equation:

Grain yield under high N level — Grain yield under low N level

GYRI =

High N level — Low N level x(kg grains kg N 1)

where Low N level = 0 kg/fad and High N level = 75 kg/fad. Statistical analysis

The obtained data from each season were exposed to the proper statistical analysis of variance according to Gomez and Gomez (1984). LSD test at 0.05 level of probability was computed to detect the differences among the means.

Results and discussion

Wheat yield and its attributes

Available data in Tables 1 and 2 reveal the effect of cultivars, N fertilization, and their interactions on wheat yield and yield attributes, i.e. spikes number/m2, spike length, kernels number/spike, kernels weight/spike, weight of 1000 kernels, grain yield, and straw yield in 2009/2010 and 2010/2011 growing seasons.

Varietal differences

The trend of all studied traits of yield and its attributes varied among wheat cultivars in the 1st season compared to those of the 2nd one. In this respect, the maximum spike number/m2 was obtained with Giza-168 surpassing those of Sakha-94 (Table 1). In the 2nd season, Sids-12 was the potent cultivar for producing the highest spikes number/m2 exceeding Sa-kha-94 by 13.8%. Gemmeiza-10 in the 1st season and Sids-12 in the 2nd one were the effective cultivars for achieving

the maximum values of spike length. The differences between Gemmeiza-10 and Giza-168 in the 1st season as well as Sids-12 and Gemmeiza-10 in the 2nd one did not reach the 0.05 level of significance in this respect. Sakha-94 along with Sids-12 and Giza-168 recorded the maximum kernels number/spike, while Gemmeiza-10 was inferior in 2009/2010 season. Moreover, Sids-12 along with Gemmeiza-10 possessed the highest kernels number/spike in 2010/2011 surpassing each of Giza-168 and Sakha-94. The maximum kernel weight/spike was recorded with Sids-12 in both seasons surpassing each of Sakh-94 in the 1st season and Giza-168 in the 2nd one. Weight of 1000 kernels markedly differed among wheat cultivars in the 2nd season only. Herein, Gemmeiza-10 along with Sids-12 produced the highest weight of 1000 kernels. Concerning wheat yields, Gemmeiza-10 was the superior cultivar for producing higher grain yield, but statistically leveled with Sakha-94 in the 1st season and with Sids-12 in the 2nd one. Moreover, straw yield of Giza-168 was higher than each of other cultivars in the 1st season, while Gemmeiza-10 along with Sids-12 gave the maximum straw yield in the 2nd season. It is clear that the environmental factors are not consistent across years which ultimately affect the stability of yield and its components of tested wheat genotypes. Grain yield is the function of genotype, environment, and genotype x environment interaction (Hamam et al., 2009; Sial et al., 2007). Stability in yield of genotypes over a wide range of environments is of great concern to plant breeders. Genotypes x environment interaction studies provide a basis for selection of genotypes that suit for general cultivation and others for the specific area and under defined environments (Nachit et al., 1992; Peterson et al., 1997; Khan et al., 2007). Yang and Baker (1991) suggested that the inconsistency of yield among genotypes from one environment to another may arise due to the expression of different sets of genes in different environments or difference in responses of the same set of genes to different environments. Moreover, the discrepancy in yield and its attributes among wheat cultivars might be due to the genetic makeup reflecting on grain filling rate and translocation of biochemical assimilates from source to sink. Varietal differences in yield components among wheat cultivars were obtained by El-Metwally and Saudy (2009), El-Habbal et al. (2000), Hassan and GabAllah (2000).

Effect of N fertilization

Increasing N up to 75 kg/fad increased yield and its components of wheat in both growing seasons (Table 1). Therefore, adding 75 kg N/fad resulted in increases over than non-fertilization which reached 73.0% and 75.5% for spikes number/ m2, 33.7% and 36.2% for spike length, 95.3% and 64.9% for kernels number/spike, 42.6% and 50.2% for kernels weight/spike as well as 46.4% and 66.3% for weight of 1000 kernels in the 1st and 2nd seasons, respectively. Although adding 75 kg N/fad caused the highest values of grain and straw yields of wheat, but the difference in grain yield between 75 and 50 kg N/fad was not significant in both seasons. Con-trarily, there was an adverse effect on wheat yield due to decreasing or increasing nitrogen level less or more than 5075 kg N/fad. The increments in yield and its attributes of wheat with increasing N rates up to adequate N need might be attributed to the effective role of N as an essential constituent of chlorophyll on dry matter accumulation. N fertilizer

influences the production of carbohydrates by affecting the mean leaf area available to intercept solar radiation and absorb CO2, promoting the efficiency of photosynthesis process. The improvements in wheat yield and its components under the acceptable increasing of N rates were obtained by David et al. (1999), Sobh et al. (2000) and Saudy et al. (2009).

Effect of interaction

Generally, increasing N up to 75 kg/fad with each tested cultivar showed the maximum values of spikes number/m2, spike length, kernels number/spike, kernels weight/spike, weight of 1000 kernels, and grain and straw yields in 2009/2010 and 2010/2011 growing seasons (Table 2). All yield components traits were significantly influenced by the interaction between wheat cultivars and N fertilization in both growing seasons, except spike length in the 2nd season and kernels number in the 1st season. Gemmeiza-10 plots fertilized with 75 kg N/fad in the 1st season and with 50 kg N/fad in the 2nd season achieved the maximum values of spike length and kernels number/spike, respectively. The heaviest kernels weight/spike was recorded with Giza-168 x 75 kg N/fad in the 1st season and with Sids-12 x 50 kg N/fad in the 2nd one. In plots received 75 kg N/fad, the highest weight of 1000 kernels was produced with Giza-168 in the 1st season and with Gemmeiza-10 in the 2nd one. Giza-168 plants fertilized with 75 kg N/fad produced the best grain and straw yields in the 1st season, while Sids-12 x 75 kg N/fad was the effective combination for enhancing grain and straw yields in the 2nd season.

Agronomic efficiency

Variation in agronomic efficiency (AE) appeared to result from differences among cultivars (Fig. 1) and levels of N supplied (Fig. 2). The maximum AE was showed with Gemmeiza-10 referring that increasing one N unit enhanced grain yield by 12.5 and 18.9 kg grains kgN-1 in the 1st and 2nd seasons, respectively. On the other hand, supplying wheat plants by 50 kg N/fad produced the maximum grain yield/N unit increase being recorded the greatest AE which reached 11.3 and 20.9 kg grains kg N_1 in the 1st and 2nd seasons, respectively. There was low AE at high N levels, where AE reached 5.1 and 5.3 kg grains kg N_1 with adding 100 kg N/fad. Som-arin et al. (2010) showed that increased nitrogen intake reduced nitrogen use efficiency.

Grain yield response index

Grain yield response index (GYRI) was calculated at 0 and 75 N kg/fad as low and high N levels, respectively. GYRI is an indication to the efficient of wheat cultivars for producing higher grain yield at low nitrogen rate and their response to increase N fertilizer rates. Accordingly, it is possible to classify wheat cultivars into four groups: (i) efficient and responsive (ER) that produce high grain yield at low as well as high rates of N fertilizer; (ii) efficient and not responsive (ENR) that produce high grain yield at low N rate with lower response to increase N fertilizer than ER; (iii) not efficient but responsive (NER) that has low grain yield with response to increase N fertilizer; and (iv) neither efficient nor responsive (NENR) that has low grain yield with low response to increase N fertilizer. Herein, each of Giza-168 in 2009/2010 (Fig. 3) and

Sids-12 in 2010/2011 (Fig. 4) belongs to ER group being exceeded the averages of grain yield at zero rate and GYRI, while Gemmeiza-10 and Sids-12 in the 1st season and Gemme-iza-10 in the 2nd one were NER being gave lower grain yield at zero N rate and higher GYRI than the average. Sakha-94 in the 1st season as well as Sakha-94 and Giza-168 was NENR, where both grain yield at zero N rate and GYRI were lower than the averages. According to GYRI parameter, results indicated clearly considerable differences among wheat cultivars for absorbing and utilizing N from deficient soils. Giza-168 in 2009/2010 and Sids-12 in 2010/2011 exhibited less reduction in yield under low N fertilizer level indicating the significance of focusing on these two cultivars as an efficient gene pool to incorporate the adaptation for low N availability (in the soil) and with high efficiency in the utilization of N fertilizer applied. At low N supply, differences among cultivars for GYRI were largely due to variation in utilization of accumulated N, but with high N, they were largely due to variation in uptake efficiency. Sattelmacher et al. (1994) reported that genotypic variation in N efficiency could generally be attributed to high N uptake and/or high N utilization. It should be concluded that N level in the soil could be manipulated together with the genetic diversity of the crop as a breeding tool for wheat cultivars development through improving N uptake and/or utilization efficiency. These findings are in good agreement with those obtained by Abd El Ghani and Awad (1999) and Saudy et al. (2008).

According to the aforementioned results, it could be concluded that the application of nitrogen should aim to match as much as possible the requirement of each wheat cultivar with the available nitrogen in soil for minimizing the excess of N in soil useless to the plant and avoiding the ecosystem pollution.

References

Abd El Ghani, A.M., Awad, A.M., 1999. Adaptation of some wheat genotypes to nitrogen deficiency under new lands conditions. Egypt. J. Plant Breed. 3, 89-99. Arregui, L.M., Quemada, M., 2006. Drainage and nitrate leaching in a crop rotation under different N-fertilizer strategies: application of capacitance probes. Plant Soil 288, 57-69. David, M., Wallach, D., Maynard, J.M., 1999. Models of yield grain protein and residual mineral nitrogen responses to applied nitrogen for winter wheat. Agric. J. 91, 377-385. Delogu, G., Cattivelli, L., Pecchioni, N., De Falcis, D., Maggiore, T., Stanca, A.M., 1998. Uptake and agronomic efficiency of nitrogen in winter barley and winter wheat. Eur. J. Agron. 9, 11-20. Dhugga, K.S., Waines, J.G., 1989. Analysis of nitrogen accumulation

and use in bread and durum wheat. Crop Sci. 29, 1232-1239. El-Habbal, M.S., Nour eldin, N.A., Hanan, A.Z., 2000. Response of some wheat cultivars to transplanting. Annals Agric. Sci., Ain Shams Univ., Cairo 45, 189-199. El-Metwally, I.M., Saudy, H.S., 2009. Herbicide tank-mixtures efficiency on weeds and wheat productivity. Annals Agric. Sci., Moshtohor 47 (2), 95-109. Ercoli, L., Arduini, I., Mariotti, M., Lulli, L., Masoni, A., 2012. Management of sulphur fertilizer to improve durum wheat production and minimize S leaching. Eur. J. Agron. 38, 74-82. Fageria, N.K., Barbosa Filho, M.C., 1981. Screening rice cultivars for higher efficiency of phosphorus absorption. Pesq. Agropec. Bras. Brasilia 26, 777-782. Gomez, K.A., Gomez, A.A., 1984. Statistical Procedures for Agriculture Research. A Wiley-Inter Science Publication, John Wiley & Sons, Inc., New York, USA.

Hamam, K.A., Abdel-Sabour, Khaled, G.A., 2009. Stability of wheat genotypes under different environments and their evaluation under sowing dates and nitrogen fertilizer levels. Aust. J. Basic Appl. Sci. 3 (1), 206-217.

Hassan, A.A., GabAllah, A.B., 2000. Response of some wheat cultivars to different levels and sources of nitrogen fertilizers under new reclaimed sandy soil. Zagazig J. Agric. Res. 27, 13-29.

Jackson, M.L., 1973. Soil Chemical Analysis. Prentice hall, Inc., Englewood Cliffs., N.J. U.S.A..

Khan, A.J., Azam, F., Ali, A., Tariq, M., Amin, M., Muhammad, T., 2007. Wide and specific adaptation of bread wheat inbred lines for yield under rainfed conditions. Pak. J. Bot. 39, 67-71.

Le Gouis, J., Beghin, D., Heumez, E., Pluchard, P., 2000. Genetic differences for nitrogen uptake and nitrogen utilization efficiencies in winter wheat. Eur. J. Agron. 12, 163-173.

Lpez-Bellido, L., Lpez-Bellido, R.J., Redondo, R., 2005. Nitrogen efficiency in wheat under rainfed Mediterranean conditions as affected by split nitrogen application. Field Crops Res. 94, 86-97.

Melaj, M.A., Echeverr, H.E., Lopez, S.C., Studdert, G., Andrade, F., Brbaro, N.O., 2003. Timing of nitrogen fertilization in wheat under conventional and no-tillage system. Agron. J. 95, 1525-1531.

Nachit, M.M., Nachit, G., Ketata, H., Gauch Jr., H.G., Zobel, R.W., 1992. Use of AMMI and linear regression models to analyse genotype-environment interaction in durum wheat. Theor. Appl. Genet. 83, 597-601.

Ortiz-Monasterio, R., Sayre, K.D., Rajaram, S., McMahon, M., 1997. Genetic progress in wheat yield and nitrogen use efficiency under four N rates. Crop Sci. 37, 898-904.

Peterson, C.J., Moffatt, J.M., Erickson, J.R., 1997. Yield stability of hybrids vs. pure line hard winter wheat in regional performance trials. Crop Sci. 37, 116-120.

Raun, W.R., Solie, J.B., Taylor, R.K., Arnall, D.B., Mack, C.J., Edmonds, D.E., 2008. Ramp calibration strip technology for determining midseason nitrogen rates in corn and wheat. Agron. J. 100, 1088-1093.

Sattelmacher, B., Horst, W.J., Becker, H.C., 1994. Factors that contribute to genetic variation for nutrient efficiency of crop plants. Z. Pflanzen. Bodenk 157, 215-224.

Saudy, H.S., EI-Habbal, M.S., Ashmawy, F., Soliman, E.M., Abbas, Iman.Kh., 2008. Using chlorophyll meter for predicting wheat nitrogen requirements. Annals Agric. Sci., Moshtohor 46 (4), 299308.

Sial, M.A., Dahot, M.U., Mangrio, S.M., Nisa Mangan, B., Arain, M.A., Naqvi, M.H., Shabana, M., 2007. Genotype x environment interaction for grain yield of wheat genotypes tested under water stress conditions. Sci. Int. 19 (2), 133-137.

Sobh, M.M., Sharshar, M.S., Soad El-Said, A., 2000. Response of wheat plants to nitrogen and potassium application in salt affected soil. J. Product 5, 83-97.

Somarin, S.J., Mahmoodabad, R.Z., Yari, A., Khayatnezhad, M., Gholamin, R., 2010. Study of agronomical nitrogen use efficiency of durum wheat affected by nitrogen fertilizer and plant density. World Appl. Sci. J. 11 (6), 674-681.

Yang, R.C., Baker, R.J., 1991. Genotype-environment interactions in two wheat crosses. Crop Sci. 31, 83-87.