Selection under salt stress conditions in F3 and F4 generations of wheat (Triticum aestivum L.)

Selection under salt stress conditions in F3 and F4 generations of wheat (Triticum aestivum L.)

M. N. Khamees ^*, H. E. Yassien, M. A. Hager, and E. I. Zaazaa

Department of Agronomy, Faculty of Agriculture, Al-Azhar University, Cairo, Egypt

*Corresponding author E-mail: Mohamed.abdeltawab@azhar.edu.eg (M. Khamees)

ABSTRACT

This study was carried out during two winter successive seasons 2017/18 and 2018/19 to determine the effect of salinity stress on yield and yield components in F₃ and F₄ segregating populations of the two bread wheat crosses (Sakha 93 x Gemmaiza 9) Cross1 and (Sakha 93 x Giza 168) Cross II. The results showed highly significant differences between means of the two crosses and families for most the traits in F₃, and 100 grain weight in F₄ generations. The differences between salinity levels were highly significant for all traits in both F₃ and F₄ generations. The interaction between crosses × families was highly significant for all traits, except for number of grains/spikes in F₃, while it was highly significant for number of grains per spike and weight of 100 grain in F₄. The interaction between crosses × salinity levels was highly significant for all traits in F₃, while it was highly significant for weight of 100 grain in F₄. As for the interaction between families, salinity levels were highly significant for most traits in F₃, while F₄ were highly significant for weight of 100 grain. The interaction between crosses × families × salinity levels, were highly significant for most traits in F₃, while in F₄ were highly significant for weight of 100 grain. Highest values of H and GA were found for grain yield / plant and weight of 100 grain under salinity conditions in F₄ generation. These traits would be improved by direct selection under saline soil conditions.

Keywords: Genetical variability, Selection, Salinity, Wheat.

INTRODUCTION

Wheat (Triticum aestivum L.) is one of the most important and strategic cereal crops in Egypt and all over the world which belongs Poaceae family which is constituted by out-standing group of food plants. The wheat breeders are concentrating to improve the yield potential of wheat by developing new varieties. In Egypt, 3.00 million feddan of wheat are planted, this area produces 8.10 million tons and the consumption is about 16.768 million tons (CAPMAS2017). This indicates that wheat consumption in Egypt has exceeded domestic production, thus requiring the importation of about 8.66 million tonsannually. This constituted a high level of import, and food security becoming a serious problem. Therefore, it is necessary to increase wheat production to realize the food security.

Salinity is one of the major factors reducing plant growth and productivity worldwide, and affects about 7% of the world’s total land area (Flowers et al., 1997). Egypt is one of the countries that suffer from severe salinity problems. For example, 33% of the cultivated lands, which comprises only 3% of total land area in Egypt, is already salinized due to low precipitation (<25mM annual rainfall) and irrigation with saline water (Ghassemi et al., 1995). Wheat is the most important and widely adapted food cereal in Egypt. However, Egypt supplies only 40% of its annual domestic demand for wheat (Salam, 2002). Therefore, it is necessary to increase wheat production in Egypt by raising the wheat grain yield. Obviously, the most efficient way to increase wheat yield in Egypt is to improve the salt tolerance of wheat genotypes Epstein et al. (1980), Shannon. (1997) and Pervaiz et al., (2002).

Heritability plays a predictive role in breeding, expressing the reliability of phenotype as a guide to its breeding value. It is understood that only the phenotypical value can be measured directly, while breeding values of individuals are derived from appropriate analysis. It is the breeding value, which determines how much of the phenotype would be passed onto the next generation (Rehman and Alam 1994). High genetic advance coupled with high heritability estimates offers the most effective condition for selection (Larik, et al., 2000). Thus, genetic advance is yet another important selection parameter that aids breeder in a selection program (Shukla, et al., 2004). Phenotypic and genotypic variance, heritability and genetic advance have been used to assess the magnitude of variance in wheat breeding material (Bhutta, 2006). Kumar et al., (2003) reported high heritability coupled with high genetic advance for plant height, number of spikelets per spike, 1000 -grain weight and number of tillers per plant in wheat. The high heritability indicates that the characters were less influenced by environment. The similar results were also found by Yadav et al., (2003) and Gupta et al., (2004).

The main objectives of this study:

Studies the effects of salinity levels for two crosses populations (F₃ and F₄) for all the studied characters.

Estimate genetic parameters (σ²_g , σ² _ph , σ²_e , PCV, GCV, Hand GA %) for F₃ and F₄ populations.

MATERIALS AND METHODS

This experiment was conducted at the Experimental Farm of Agronomy Department, Faculty of Agriculture, Al-Azhar University Nasr City Cairo, Egypt during two successive seasons of 2017/18 and 2018/19.

The experimental materials comprised of two bread wheat crosses, (Sakha 93 × Gemmiza 9) and (Sakha 93 × Giza 168), which were installed in a previous study of three varieties of wheat. The plant materials (F₁ and F₂) were obtained from Khamees, (2016). Agronomy Dept., Fac.of Agric., Al-Azhar Univ. These materials were tested for salinity tolerance by grown under salinity levels (control, 6000, 9000 and 12000 ppm), which were farming in plastic pots of 30 cm diameter, 25 cm deep and the sand soil weight in each pot was 12 kg. Each plot contained of 8 plants. Salinity concentration setting throw determine (Leaching Requirement) according to the following equation:

L.R= EC (irrigation water) / (EC water drainage) ×100

In 2017/18 growing season, the seeds of tolerant and high yielding plants for the two crosses and their parents which selected under each salinity level in F₂ seeds were planted as families (a family for each plant) to obtain F₃ families.

In 2018/19 growing season, the selected plant seeds which were salinity tolerant for all salinity levels under study from F₃ generation of the two crosses and their parents. They were planted to obtain F₄ plants and evaluated as families under all salinity levels (a family for each plant). 

The crosses and their parents were evaluated in a randomized complete block design (RCBD) with three replicates for each salinity level.

Data were recorded on individual guarded plants for number of spikes/plant, number of grains/spike, 100- grain weight (g) and grain yield/plant (g).

Statistical analysis and genetical parameters:

Data were estimated analysis according to Snedecor and Cochran (1980) the means differences were tested against the least significant difference (L.S.D) at 5% level of probability according to Gomez and Gomez (1984).

Analysis variance and expectation of mean squares, for source of variation are shown in Table (1)

The variance components were estimated according to (Millar et al 1959) as follows:

Genotypes (б²_g) = (M5+M2-M3-M4)/rbc

Genotypes × families (б²_gb) = (M4-M2)/rc

Genotypes ×concentration (б²_gc) = (M3-M2)/rb

Genotypes × families × concentration (б²_gbc) = (M2-M1)/r

Error (б²_e ) = M1

The importance of genotypic component of variance in relation to phenotypic variance (б²_ph) is as follows:

б²_ph = б²g ₊ (б²gb/b) +(б²gc/c)+(б²gbc/bc)+(б²e/gbr)

Heritability

The estimates of broad-sense heritability were computed as suggested by Allard (1960).

H²_b = б²_g / б²_ph ×100

Phenotypic and genotypic coefficient of variation

Phenotypic (PCV) and genotypic (GCV) coefficient of variation were estimated using the formula suggested by Burton (1952) as follows:                                 

PCV = √ б²_ph / ^-x ×100

GCV = √б²_g / ^-x × 100

Genetic advance

Genetic advance (GA) (10 % selection intensity) as percent means and genetic advance as percentage of mean (GA %) by Lush (1949) and Johnson et al. (1955).

GA = K ×√ б²_ph × h²_b    GA % = GA / x^- × 100

RESULTS AND DISCUSSION

Analysis of variance and average performance.

Analysis of variance and average performance. Average performance for four characters treated by salinity levels.

Analysis of variance

Analysis of variance for all the traits in F₃ and F₄ families are shown in Table (2) revealed high significant differences between two crosses for all traits in F₃ and non-significant differences between crosses for all traits, except 100-grain weight (g) in F₄. Moreover, high significant differences are shown between families, except number of grains/spikes in F₃, while in F₄ families were non-significant differences between them except, for 100-grain weight (g). The differences between salinity levels were highly significant for all studied traits in F₃ and F₄ generations. On the other hand there were high significant differences for interaction (crosses× families) for all the studied traits, except number of grains/spike in F₃, and number of spikes/plant and grain yield /plant (g) in F₄ generation. Highly significant differences were shown for interaction AC (crosses× salinity levels) for all the studied traits in F₃, but they were non-significant differences for all the traits, except 100-grain weight (g) in F₄. Highly significant differences were observed for interaction BC (families× salinity levels) for all traits, except number of grains/spikes in F₃, while they were non-significant differences for all the traits, except 100-grain weight (g) in F₄. The interaction between ABC (crosses× families× salinity levels) were highly significant for all the traits, except number of grains/spikes in F₃, and non-significant for all the traits, except for 100-grain weight (g) in F₄. This indicated that these populations are highly diversified for their performance and selection can be performed for various traits.

Average performance:

Average performance was variable according to the incidence of crosses, families, salinity levels, and interaction between them.

Number of spikes/plant:

Thistrait is presented in Table (3). Results indicated highly significant differences between two crosses in F₃. while the differences between crosses in F₄ were non-significant.

As for the families, results indicated high significant differences between families in Table (2). Family No. 8 gave the highest mean value (1.680),while family No. 10 gave the lowest one (1.297) in F₃. The differences between families in F_4, were non-significant differences.

As for salinity levels, results revealed high significant differences between salinity levels, control gave the highest value (1.968) and no significant differences between 6000 and 9000 ppm (1.303) and (1.297) respectively, while the salinity level 12000 ppm recorded the lowest value (1.199) in F₃. In F₄ generation the differences between salinity levels were non-significant Table (2).

Furthermore, the interaction between crosses× families were high significant differences, the family No.8 gave the highest mean value (1.802) for cross І, while, family No. 1 recorded the lowest value (1.245) for cross П in F₃ generation, the interaction between crosses× families in F₄ was non-significant.

The interaction between crosses × salinity levels were highly significant in F₃, cross І recorded the highest mean value (2.298) under control, while cross І recorded the lowest value (1.184) under 12000 ppm. These results agreed with those reported by EL-Amin et al. (2011) and Aziza, M. Hassanein (2016). The interaction in F₄ was non-significant.

The interactions between families × salinity levels in F₃ were high significant. The family No. 8 gave the highest value (2.430) under control, while the family No.1 and No. 9 gave the lowest value (1.000) under salinity level 12000.

The family No. 1 for F₄ gave the highest mean value (1.733) under control, while all families under 12000 ppm recorded the lowest values (1.000).

The interaction between crosses × families × salinity in F₃ generation for number of spikes per plant were highly significant and recorded the highest mean values (3.260) for cross І in family No. 8 under control. The families No. 6, No. 8 and No. 9 in cross І recorded the lowest value (1.000) in F₃ generation, while, the average performance for families No. 1, No. 4, No. 5 and No. 9 under the salinity level 12000 ppm in cross П recorded the same value (1.000), the interaction between crosses × families × salinity levels were non-significant in F₄ generation.

Number of grains/spike:

This trait is presented in Table (4). Results indicated high significant differences between crosses in F₃. Cross П gave the highest mean value (39.136), while cross І gave the lowest one (34.014) and the differences between crosses in F₄ were non-significant

Concerning the families, results indicated non-significant differences between families in F₃ and F₄.

In F_3, results revealed high significant differences between salinity levels and the control gave the highest value (52.387). On the other hand, the salinity level 12000 ppm recorded the lowest value (28.527) and there were no significant differences between 6000, 9000 ppm (32.713) and (32.672). These results are in agreement with Ahmad et al. (2013). In F₄  generation, the differences between salinity levels were high and significant. The control level gave the highest value (50.328). On the other hand, the salinity level 12000 ppm recorded the lowest value (30.889).

Moreover, the interaction between crosses and families were non-significant in F_3, while, the interaction between crosses and families in F₄ were highly significant. Family No. 2 gave the highest mean value (41.948) for cross П, while family 1 in cross І recorded the lowest mean value (30.122).

The interaction between crosses and salinity levels was highly significant in F₃. Cross П recorded the highest mean value (52.713) under control. On the other hand, the cross І recorded the lowest value (25.710) under level 12000 ppm. These results are in agreement with EL-Amin et al. (2011) as he found that the interaction in F₄ was non-significant.

The interaction between families and salinity levels in F₃ were high significant.  The family No. 3 gave the highest mean value (55.267) under control, while family No. 9 recorded the lowest value (20.795) under level 12000 ppm in F₃, but in F₄ were non-significant.

The interaction between (crosses, families and salinity) were non-significant differences in F₃ and F₄.

100- grain weight:

It is presented in Table (5). Results showed, high significant differences between crosses in F₃. Cross П gave the highest mean value (2.214), while cross І gave the lowest one (2.026). The differences between crosses in F₄ were high significant.  Cross П gave the highest mean value (2.149), while, cross І gave the lowest mean value (1.954).

As for the families, results indicated high significant differences between families.  Families No. 2 and No. 3 gave the highest values (2.399 and 2.373), respectively, while Family No. 10 gave the lowest mean value (1.862) in F₃. In F₄, results indicated high significant differences between families. Family No. 2 gave the highest value (2.135), while Family No. 3 gave the lowest mean value (1.887).

As for the salinity levels, the results revealed high significant differences between salinity levels, the control gave the highest value (3.206), but the salinity level 6000 ppm recorded the lowest value (1.632) in F₃. F₄ generation showed high significant differences between salinity levels. The control gave the highest value (3.263), but the salinity level 12000 ppm recorded the lowest value (1.291).

The interaction between crosses and families was high and significant and the family No. 3 gave the highest mean value (2.642) for cross П in F₃. The interaction between crosses and families, in F₄ were highly significant. The family No. 1 gave the highest mean value for cross П.

The interactions between crosses and salinity levels were highly significant in F3, cross П recorded highest mean under control (3.209). On the other hand the cross І recorded the lowest value under levels 6000 ppm (1.589). These results are in agreement with El-Hendawy et al. (2005). In F₄ generation the interaction between crosses and salinity levels was highly significant. Cross П recorded the highest mean under control (3.402). On the other hand, the cross І recorded the lowest value (1.322) under level 12000 ppm.

The interactions between families and salinity levels were highly significant. Family No. 3 gave the highest mean value (3.518) for control in F₃, while family No. 6 recorded the lowest value (1.195) under level 9000 ppm in F₃. Family No. 4 gave the highest mean value (3.450) under control. Family No.3 recorded the lowest value (1.063) under level 12000 ppm in F₄ generation.

Furthermore, the interaction between (crosses, families and salinity) in F₃ were highly significant with the highest mean value (3.840) for family No. 7 in cross І under the control, while the lowest values were (1.067) for cross І in family No. 10 under level 12000 ppm. The interaction between (crosses, families and salinity) in F₄ were highly significant, with the highest mean value (3.553) for cross П in family No. 1 under the control, but the lowest value was (0.770) for cross П in family No. 3 under level 12000 ppm.

Grain yield/plant (gm.)

They are presented in Table (6). Results showed, high significant differences between crosses in F₃. The cross П gave the highest mean value (1.445), while, cross І gave the lowest mean value (1.221). In F₄ generation, the differences between crosses were non-significant.

As for the families, results indicated high significant differences between families. Family No. 2 gave the highest value (1.460 gm), while family No. 9 gave the lowest mean values (0.990 gm) in F₃.  The differences between families in F₄ were non-significant.

Additionally the salinity levels, results revealed high significant differences between salinity levels, the control gave the highest value (2.877 gm.), followed by (0.853gm) under salinity level 9000 ppm in F₃, on the other hand, the salinity level 12000 ppm recorded the lowest value (0.803gm). In F₄ generation, the differences between salinity levels were high significant. The control gave the highest value (2.352 gm.), but the salinity level 12000 ppm recorded the lowest value (0.443 gm.)

The interactions between crosses and families were high significant differences, the family No. 8 gave the highest mean value (1.693gm) for cross П in F₃, but the interaction between crosses and families in F₄ were non-significant.

The interactions between crosses and salinity levels were highly significant in F₃ generation. Cross П recorded the highest mean under levels control (2.892gm). On the other hand, the cross І recorded the lowest value (0.591gm) under level 9000 ppm. These results are in agreement with, Mresheh et al. (2009), EL-Amin et al. (2011). In F₄, the differences were non-significant.

The interactions between families and salinity levels in F₃ were highly significant. Family No. 8 under the control gave the highest mean value (3.632gm), while family No. 9 and No. 10 recorded the lowest values under 12000 ppm. The interaction between families and salinity levels in F₄ was non-significant.

In F₃ generation, the interactions between (crosses, families and salinity) were high significant. The highest mean value was (4.290 gm) for cross І in family No. 8 under the control, while, family No. 9 in cross І recorded the lowest value (0.170gm.) under salinity level 12000 ppm. The interaction between crosses, families and salinity levels was non-significant in F₄ generation.

These results indicated that most of investigated traits were sensitive to salinity stress. These results are in agreement with Aslam et al. (1989). The reduction in the values of the number of spikes/plant, number of grains/spike, 100- grains weight (g) and grain yield/plant (g) may be due to low uptake of water by plants as well as toxicity of Na and C1 because of their high concentration in the irrigation water. Also, salinity stress significantly reduced greatly values of the most investigated traits under study. The reduction in the value of these characters might be due to the toxic effect of salt on plant growth (Bhatti, 2004).

Genetical variability under salinity conditions

Genetic parameters i.e. σ²_g,σ²_ph,PCV,GCV, h² % and GA% for plant height    and yield and its component traits under salinity conditions are indicated in Table (7) for F₃ and F₄ families.

Table (7) showed that PCV values were higher than the GCV values for all the characters. These results are confirmed with those reported by (Ali et al. 2008), Ehdaiel and Waines (1987) and Moghaddam et al. (1997). The estimates of PCV and GCV gave the highest values for grain yield/ plant 69.76 and 65.26. Other traits showed low estimates ranged between 23.99 and 22.60 %, respectively for number of spikes per plant to 48.20 and 38.30 % for number of grains / spikes, respectively under salinity conditions in F₃ generation. The estimates of PCV and GCV gave the highest values for number of grains / spike11.03 and 9.12 %. Other traits showed low estimates ranged between 1.005 and .083 % for number of spikes per plant to 8.28 and 7.94 % 100 grain weight in F₄ generation. These results are in agreement with that reported by Pathak and Nema (1985).

The broad sense heritability (H %) estimates ranged from 79.46 to 94.21% for number of grains per spike and number of spikes per plant, respectively in F₃ generation. The broad sense heritability (H %) estimates ranged from 71.42 to 95.88 % for grain yield per plant and 100 grain weight in F₄ generation.Sachan and Singh (2003) found that high heritability estimates were also shown for the traits (plant height, grain yield, number of grains per spike, 100 grain weight and number of spike per plant). High heritability estimates indicate that, the selection for these traits will be effective, being less influenced by environmental effects (Maniee et al. 2009).

The estimates of the expected genetic advance (GA %), as percentage of the mean is shown in (Table 7). Genetic advance (GA %) ranged between 7.81% for number of grains per spike and 67.60 % for number of spikes per plant in F₃ generation. The estimates of the expected genetic advance (GA %), as percentage of the mean is shown in (Table 12). Genetic advance (GA %) ranged between 13.38 % for number of spikes per plant and 46.31 % for 100 grain weight in F₄ generation. Dwivedi et al. (2002) reported that100-grain weight recorded highest values for genetic advance %. High heritability accompanied with high genetic advance indicates predominance of additive gene action and in such cases selection will be effective Panse and Sukhatme (1967).

CONCLUSION

This result indicates the traits 100-grain weight and grain yield per plant had high estimates of heritabilityandGenetic advanceunder salinity conditions in F₄ generation. These traits would be improved by direct selection under saline soil conditions.

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Table 1. The outline of analysis of variance and expectation of mean squares.

Table 2. Mean squares for studied characters as affected by salinity levels in F₃ and F₄ families of wheat crosses during 2017/18 F₃ and 2018/19 F₄ season.