Inheritance of yield attributes in bread wheat under irrigated and ...

Sarhad J. Agric. Vol.25, No.3, 2009

INHERITANCE OF YIELD ATTRIBUTES IN BREAD WHEAT UNDER IRRIGATED AND RAINFED CONDITIONS GHULAM RABBANI*, MUHAMMAD MUNIR*, SAIF ULLAH KHAN AJMAL*, FAYYAZ UL HASSAN*, GHULAM SHABBIR* and ABID MAHMOOD** * **

Department of Plant Breeding and Genetics, University of Arid Agriculture, Rawalpindi, Pakistan Barani Agricultural Research Institute, Chakwal, Pakistan

ABSTRACT This study was carried out at Barani Agricultural Research Institute, Chakwal to investigate the inheritance of gene action in wheat genotypes; viz., Inqilab-91, MAW-1, 2KC033, Saleem-2000, No.2495, 3C061, 3C062, and 3C066 in an 8 x 8 diallel combinations under two diverse environments (irrigated and rainfed conditions). Observations were recorded for flag leaf area, fertile tillers per plant, spike length, 1000 grain weight and grain yield per plant. Experiment was planted in RCB design with three replications. The wr/vr graphic representation showed that traits like flag leaf area, fertile tillers per plant, 1000-grain weight and grain yield per plant were controlled by over-dominance type of gene action under irrigated and rainfed conditions. While spike length exhibited over-dominance type of gene action under irrigated conditions and additive type of gene action under rainfed conditions. Key Words: Triticum aestivum L, Yield, Gene action, Diallel, Rainfed Citation: Rabbani, G., M. Munir, S.U.K. Ajmal, G. Shabbir and A. Mahmood. 2009. Inheritance of yield attributes in bread wheat under irrigated and rainfed conditions. Sarhad J. Agric. 25(3): 429-439. INTRODUCTION Wheat (Triticum aestivum L. em Thell.) is one of the most demanded cereals in the world. One sixth of the total arable land of the world is under wheat with an area of 217 million hectares and the production of 596 million tonnes (Anonymous, 2007). But average yield is quite variable, ranging from less than 1 to more than 7 tones per hectare. The differences in yield are due to differences in the level of inputs, agricultural sophistication and agroclimatic conditions. Major wheat producers among developing countries are China, India and Turkey. About forty percent of the bread wheat in developing countries is produced in irrigated environments. In South Asia, wheat is largely grown in irrigated rice-wheat cropping pattern covering about 12 million hectares. It is also grown on a large area under rainfed conditions. In developing countries about forty percent of 120 million hectares sown to wheat are rainfed and are prone to drought (Rajaram, 2001). Agriculture is the largest sector of Pakistan’s economy. Annual rainfall is uneven with erratic distribution. Rainfed agriculture is dependent on natural precipitation during the cropping season and on conserved moisture during the previous mainly fallow period. About 26 % of the arable land in the Punjab province is rainfed where crop production depends on rainfall. During the year 2006-2007, area under wheat crop in Pakistan was 8.447 million hectares, out of which 7.338 million hectares were irrigated and rest 1.109 million hectares were planted under rainfed conditions, producing 21.27 million tones of wheat grain. Average per hectare yield in Pakistan was 2592 kg from irrigated areas and 1266 kg from rainfed areas (Anonymous, 2007). This shows a big yield gap between the two production environments. In a diallel cross of wheat genotypes, Ajmal et al. (2003) and Dera and Yildirim (2006) reported the additive type of gene action for flag leaf area while Iqbal et al. (1991) and Chowdhry et al. (1992) found over-dominance type of gene action for flag leaf area. Siddique et al. (2004), Pareek and Garg (2004) and Lia and Wei (2006) reported additive type of gene action for fertile tillers per plant while Lonc (1989) and Alam et al.(1991) found over-dominance type of gene action for fertile tillers per plant. Evidence of over-dominance for spike length was, reported by Khan et al. (1984b) and Iqbal et al. (1991) while Sharma et al. (1986b) and Meena and Sastry (2003) found additive genetic control of spike length. The present study was, therefore, planned to screen genotypes for stress tolerance and to study inheritance mechanism of drought adaptive traits reflecting yield potential by making a comparative assessment of their performance under irrigated and rainfed conditions, in terms of the types of gene action. Eight varieties/lines were crossed in diallel fashion. Data recorded on various traits were analyzed and interpreted according to the models and procedures described by Hayman (1954) and Mather and Jinks (1982).

Ghulam Rabbani et al. Inheritance of yield attributes in bread wheat under irrigated and rainfed conditions 430

MATERIALS AND METHODS Eight contrasting wheat genotypes having sufficient genetic diversity i.e. Inqilab-91, MAW-1, 2KC03, Saleem-2000, No.2495, 3C061, 3C062, and 3C066 were selected. These selected genotypes were planted during 2005-06 at Barani Agricultural Research Institute (BARI), Chakwal. Crosses were made among these selected genotypes in all possible combinations. Necessary precautions were taken during the crossing operations to avoid contamination of the genetic material used. The female parents were hand emasculated and pollinated to produce enough seed for all the crosses. Seed of the crosses were planted under irrigated as well as under rainfed conditions during 2006-07. The parents along with fifty six F1’s including reciprocals were space planted in Randomized Complete Block Design with three replications. F1’s, their reciprocals and the eight parents were sown in four meter long single row. Two seeds per hill were sown, and later on thinned to one plant per hill by maintaining a distance of 30 centimetres between rows. Extra non-experimental lines were also raised at the start and ends of each replication to eliminate border effects. For two sets of experiments, the field was irrigated for seed bed preparation. After planting of experimental population, four irrigations were applied to normal experiment during the active growing period. Whereas the other experiment entirely depended on natural precipitation and no surface irrigation was applied to rainfed experiment for maintaining moisture stress conditions. Normal agronomic practices like fertilizer application and weed control were applied to both experiments. The amount of rainfall received during the experimental period (October to April, 2006-07) was 393.6 mm. Data on flag leaf area (cm2), fertile tillers per plant, spike length (cm), 1000 grain weight (g) and grain yield per plant (g) were recorded from ten randomly selected guarded plants from every entry and each replication. The analysis of variance was carried out for all the characters for each experiments (irrigated and rainfed conditions) according to method of Steel and Torrie (1980). Further analysis was done according to techniques developed by Mather and Jinks (1982). RESULTS AND DISCUSSION Results revealed that genotypic differences were highly significant for all the characters under both conditions (Table I - II). This exhibited the presence of sufficient variability in the material grown under irrigated and rainfed conditions. Results of diallel analysis for various traits are discussed as below. Components of variation for various traits are shown in Table III - IV. Flag Leaf Area The estimates of components of variation are presented in Table III. Under irrigated conditions, D component, the variance due to additive effects of genes was found significant, which indicated the importance of additive variation in the heridity of this character. H1 and H2 were also found significant showing their important role in the expression of this trait. H1 and H2 components of genetic variation exceed the additive component (D), supporting over-dominance for flag leaf area. In the presence of unequal gene frequencies the sign and magnitude of F determines the relative frequency of dominance to recessive alleles in the parental population and the variation level over loci. Components F and h2 were non-significant displaying their unimportant role of dominant genes. Expected environmental component of variation (E) was found non-significant under irrigated conditions. The value of (H1/D)1/2 is the measure of average degree of dominance (1.917) indicated dominance for increased flag leaf area was complete and offered a quantification of the level of over-dominance. Narrow sense heritability was estimated to be 25 percent. In the presence of additive effects controlling this trait, genetic manipulation to breed for a desirable flag leaf area in to new varieties seems to be straight forward matter under irrigated conditions. Under rainfed conditions (Table IV) D component, the variance due to additive effects of genes was found significant, which indicated the importance of additive variation in the heridity of this character. H1 and H2 were also found significant showing their important role in the expression of this trait. Component F was non-significant displaying their unimportant role of dominant genes. The significant effect obtained by h2 also revealed a substantial contribution of dominant genes toward determining the flag leaf area under drought conditions. Expected environmental component of variation (E) was found non-significant under irrigated conditions. The value of (H1/D)1/2 is the measure of average degree of dominance (2.916) indicated dominance for increased flag leaf area was complete and offered a quantification of the level of over-dominance. Narrow sense heritability was estimated to be 10 percent. In the presence of additive effects controlling this trait, genetic manipulation to breed for a desirable flag leaf area in to new varieties seems to be straight forward matter under rainfed conditions. The wr/vr graphic representation (Fig. 1a) for flag leaf area under irrigated conditions showed that the cultivar, MAW-1 had the maximum dominant genes for flag leaf area followed by No.2495 under irrigated conditions while the genotype containing the most recessive and the least dominant genes was Inqlab-91, followed by 3C061. Rest of genotypes had intermediary gene constitution. The regression line intercepted the Wr axis below the point of origin


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showing an over-dominance type of gene action. Under rainfed conditions graphical analysis of the data (Fig. 1b) also depicted an over-dominance type of gene action controlling the inheritance of flag leaf area with a line of unit slope and positive intercept of the regression line. Distribution of the array points in the graph represented the genic constitution of the parental genotypes. It was observed that the MAW-1 had the maximum dominant genes for flag leaf area followed by 3C062 while the genotype containing the most recessive and the least dominant genes was 3C061 followed by Inqlab-91. Rest of genotypes had intermediary gene constitution. Similar results were also reported by Iqbal et al. (1991), Chowdhry et al. (1992) who reported the over-dominance type of gene action for flag leaf area. Fertile Tillers per Plant The estimates of components of variation under irrigated and rainfed conditions are presented in Table III IV. Graphical representation (Fig. 2a) disclosed an over-dominance type of gene action controlling the inheritance of fertile tillers per plant with a line of unit slope and positive intercept of the regression line. Distribution of the array points in the graph represented the genic constitution of the parental genotypes. It was observed that the 3C062 had the maximum dominant genes for fertile tillers per plant followed by Saleem-2000 while the genotype containing the most recessive and the least dominant genes was 3C061 followed by No.2495. Rest of genotypes had intermediary gene constitution. Under rainfed conditions, average degree of dominance (1.268) and graphical representation (Fig. 2b) disclosed an over-dominance type of gene action controlling the inheritance of fertile tillers per plant with a line of unit slope and positive intercept of the regression line. Distribution of the array points in the graph represented the genic constitution of the parental genotypes. It was observed that the 3C062 had the maximum dominant genes for fertile tillers per plant followed by 3C066 while the genotype containing the most recessive and the least dominant genes was MAW-1 followed by 2KC033. Rest of genotypes had intermediary gene constitution. These findings are also in agreement with the findings of 'Sharma and Ahmad (1980), Lonts (1984), Sharma et al. (1986b), Lonc (1989) and Alam et al.(1991) who also found over-dominance type of gene action for fertile tillers per plant. Spike Length The estimates of components of variation under irrigated and rainfed conditions are presented in Table III - IV. Graphical analysis of the data (Fig. 3a) indicated an over-dominance type of gene action with a line of unit slope and positive intercept of the regression line. Distribution of the array points in the graph observed that the MAW-1 had the maximum dominant genes for spike length followed by 3C062 while the genotype containing the most recessive and the least dominant genes was Inqlab-91 followed by 3C061 under irrigated conditions. Rest of genotypes had intermediary gene constitution. Evidence of over-dominance for spike length was, however, reported by Khan et al. (1984b), Yadav et al. (1987) and Iqbal et al. (1991). In case of rainfed, average degree of dominance (0.804) and graphical analysis of the data (Fig. 3b) depicted an additive type of gene action controlling the inheritance of spike length with a line of unit slope and positive intercept of the regression line. Distribution of the array points in the graph represented the genic constitution of the parental genotypes. It was observed that the MAW-1 had the maximum dominant genes for spike length while the genotypes containing the most recessive and the least dominant genes was 3C062 under rainfed conditions. Rest of genotypes had intermediary gene constitution. These findings are in agreement with the findings of Gill et al. (1983) and Sharma et al. (1986b) who also found additive genetic control of spike length. Thousand Grain Weight The estimates of components of variation under irrigated and rainfed conditions are presented in Table IIIIV. Graphical analysis of the data (Fig. 4a) depicted an over-dominance type of gene action with a line of unit slope and positive intercept of the regression line. Distribution of the array points in the graph represented the genic constitution of the parental genotypes. It was observed that the 3C062 had the maximum dominant genes for 1000-grain weight under irrigated conditions and it was followed by No.2495. The parents containing the most recessive and the least dominant genes were Inqlab-91 and 2KC033 under irrigated conditions. Rest of genotypes had intermediary gene constitution. Under rainfed conditions, graphical analysis of the data (Fig. 4b) depicted an over-dominance type of gene action with a line of unit slope and positive intercept of the regression line. Distribution of the array points in the graph represented the genic constitution of the parental genotypes. It was observed that the 3C062 had the maximum dominant genes for 1000-grain weight under stress conditions and it was followed by No.2495. The parents containing the most recessive and the least dominant genes were Inqlab-91 and 2KC033 under rainfed conditions. Rest of genotypes had intermediary gene constitution. Present findings are


supported by the results of Lonts et al. (1984) and Alam et al. (1991) who also found over-dominance genetic control of 1000-grain weight, however, Khan et al. (1984b), Sinitsyna and Strizhova (1985), Lonc et al. (1989) and Chowdhry et al. (1992) observed the partial type gene action for this trait. Grain Yield per Plant The estimates of components of variation under irrigated and rainfed conditions are presented in Table IIIIV. Graphical representation of Vr/Wr values (Fig. 5b) indicated also an over-dominance type of gene action controlling the inheritance of grain yield per plant with a line of unit slope and positive intercept of the regression line. Distribution of the array points in the graph represented the genic constitution of the parental genotypes. It was observed that the 3C062 had the maximum dominant genes followed by MAW-1 while the genotypes containing the most recessive and the least dominant genes were Inqlab-91 and 3C061 under rainfed conditions. Rest of genotypes had intermediary gene constitution. Similar results were reported by Sharma and Ahmad (1980), Lonc and Zalewski (1991), Prodanovic (1993), Srivastava and Nema (1993) and Sheikh et al. (2000) who also found an over dominance genetic control of grain yield per plant. However, Lonc et al. (1989), Alam et al. (1991) and Chowdhry et al. (1999) observed a partial dominance gene action for this trait under rainfed conditions. Table I. S. No. 1 2 3 4 5 Table II. S.No. 1 2 3 4 5

Analysis of variance of eight bread wheat genotypes and their possible F1 hybrids under irrigated conditions Mean Squares Character Replications (df=2) Genotypes (df=63) Errors (df=126) Flag leaf area 7.390 97.045** 3.942 Tillers per plant 0.508 1.977** 1.162 Spike length 1.153 6.310** 0.539 2.631 17.899** 4.978 1000-grain weight Grain yield per plant 0.434 30.167** 2.208 Analysis of variance of eight bread wheat genotypes and their possible F1 hybrids under rainfed conditions Character Mean Squares Replications (df=2) Genotypes (df=63) Errors (df=126) Flag leaf area 4.552 73.405** 1.543 Tillers per plant 0.735 0.573** 0.338 Spike length 0.948 1.763** 0.439 6.284 25.229** 6.644 1000-grain weight 3.817 9.623** 1.332 Grain yield per plant

** Significant at 1 percent probability level Table III

Components of variation for various traits of bread wheat under irrigated conditions

Components D H1 H2 F h2 E (H1/D)1/2 Heritability (Narrow sense)

Table IV

Flag leaf area (cm2) 27.15* ±7.829 99.739* ±17.997 94.726* ±15.658 15.447NS ±18.497 -0.315NS ±10.501 0.999NS ±2.661 1.917

Fertile tillers/plant 0.788* ± 0.134 1.267* ± 0.308 0.689* ± 0.268 1.079* ± 0.317 -0.122NS ± 0.180 0.288* ± 0.046 1.268

Spike length (cm) 1.539* ± 0.381 7.056* ± 0.877 6.789* ± 0.763 0.863NS ± 0.901 0.308NS ± 0.512 0.137NS ± 0.130 2.141

1000 grain weight (g) 2.660* ±0.847 14.475* ±1.947 14.406* ±1.694 0.29 NS ±2.001 -0.469NS ±1.136 1.235* ±0.288 2.333

Grain yield (g) 6.742** ± 1.545 34.116** ± 3.552 32.320** ± 3.090 4.117 NS ± 3.650 -0.141NS ± 2.072 0.545 NS ± 0.525 2.250

0.253

0.238

0.204

0.201

0.204

Components of variation for various traits of bread wheat under rainfed conditions

Components D H1 H2 F h2 E (H1/D)1/2 Heritability (Narrow sense)

Flag leaf area (cm2) 11.355* ±3.871 96.568* ±8.898 90.859* ±7.741 11.794 NS ±9.145 10.375* ±5.191 0.397 NS ±1.316 2.916 0.102

Fertile tillers/plant 0.128* ± 0.037 0.447* ± 0.086 0.424* ± 0.074 0.113NS ± 0.088 0.304* ± 0.050 0.086* ± 0.013 1.867 0.089

Spike length (cm) 1.817* ±0.125 1.176* ±0.288 0.787* ±0.251 1.537* ±0.296 -0.040NS ±0.168 0.112* ±0.043 0.804 0.520

1000 grain weight (g) 6.128* ±1.471 26.815* ±3.382 24.357* ±2.943 6.161* ±3.476 6.792* ±1.973 1.660* ±0.500 2.092 0.135

Grain yield (g) 1.984* ±0.822 11.442*±1.889 10.679*±1.644 1.679NS ±1.942 0.706NS ±1.102 0.343NS ±0.279 2.401 0.151


Fig. 1. Wr/Vr graph for flag leaf area under (a) irrigated and (b) rainfed conditions

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Fig. 2.

Wr/Vr graph for number of fertile tillers per plant under (a) irrigated, and (b) rainfed conditions


Fig. 3. Wr/Vr graph for spike length under (a) irrigated, and (b) rainfed conditions

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Fig. 4.

Wr/Vr graph for 1000-grains weight under (a) irrigated, and (b) rainfed


Fig. 5.

Wr/Vr graph for grain yield per plant under (a) irrigated and (b) rainfed conditions

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