Abstract: Genetically variation is of the most important tool in plant breeding, so making and investigating of the variation in genotypes can be a factor of success in selection of favorable traits in crop randomized complete block design with three replications was conducted using the 96 double haploid genotypes of resulted from wheat and corn hybridation with embryo rescue along with the four local controls in Ardabil, Iran, in 2007 and 2008 cropping season. During the season, agricultural and morphological traits as well as yield and yield components were measured. It was cleared that there were significant differences between the genotypes were placed in the first group and low yielding ones placed in the second group, which can be used to attain the more heterosis by hibridation of the genotypes in the both groups. Highly yielding genotypes generally are derived from the corn father lines of CMH81, CMH82 different mother lines.

INTRODUCTION

Present genetically variation among the under study genotypes is a very important statistical method and the basic tool in plant breeding works (Moghaddam et al., 1997). Investigations of genetical variations have been conducted using the morphological traits (Moghaddam et al., 1997) and biochemical and genetical markers (Smale and McBride, 1997).

Recently, integrated method of these methods named Genetical Recowces Information (GRIS), a distinct and definite manner based on the overall pattern of genes relations, is used to evaluate the variations to among the genotypes (Manifesto et al., 2001).

Wheat is a plant feed by the majority of the people around the world. So, study of the genetically variations especially in synthetic genotypes is of the first important steps to breed for the high yield and quality as well as the source of the different resistances. Pecetti and Damania (1996) reported that among the traits such as yield components.

Moghaddam et al. (1997) studying the 7 wheat cultirars and 53 lines found the remarkable variations in growth aspects and other quantitative ones and expressed that the local cultivars had the longer period of time to spike appearance, had the higher height but were lower in number of grain per spike, 1000 grain weight, grain yield and harvest index than the newer ones and some of local cultivars were similar to newer ones in yield.

Belay et al. (1993) evaluated 60 tetraploid local wheat genotypes derived from the central heights of the Ethiopia along with the one commercial variety (Boohai) for the yield and some other aspects and stated that genetically variation among the genotypes for the mentioned aspects was very significant.

Tesemma et al. (1998) illustrated that among the breeded cultivars ready to release, there were some variations for traits such as yield components that may use to select. Synthetics wheat derived from hybridation between wheat as mother parent and corn as father parent via organ culture (embryo rescue) and increase in chromo some number using the chemical mutagen substances are of high yielding and rather favorable quality wheat, so this research was carried out to study the important agricultural traits and variation among the genotypes to select and transfer the favorable traits and classifications to the later hybridations.

The aim of this project was the evaluation of genetically variations among the synthetic wheat varieties as a result of wheat x corn hybridation in Ardabil, Iran.

MATERIALS AND METHODS

In order to study genetically variation in wheat synthetic genotypes resulted from wheat x corn hybridation, an experiment based on randomized complete block design with three replications was carried out in agricultural research station of Islamic Azad University, Ardabil branch, Ardabil, Iran, during the 2007 and 2008 cropping year. Genotypes included 96 synthetic genotypes and 4 local genotypes (kaspard, kaskogen, MV₁₇ and Bezostaya).

Seeds were sown on 6th November with a plant density of 350 plant m^-2. Each experimental plot included 10 rows each 6 m in 12 m². To study the variation, after the ripening of plants at the end of the growing season, whole plants of the plots were harvested and transferred to the laboratory to measure the traits such as: grain weight, number of fertile tillers, number of total tiller, number of internodes, plant height, peduncle length, awn length, number of grains per main spike, number of grains per spike let, grain weight in main spike, total grain weight in tiller, total plant dry weight and weight of main spike. Resulted data were subjected to analysis by SPSS procedure and means of treatments were compared using Duncan’s multiple range test.

Then, resulted means were classified into the two group of high and low yielding genotypes by means of cluster method.

RESULTS AND DISCUSSION

Result of analysis of variance indicated that there were significant differences among the genotypes in the majority of traits. This illustrates the high potential of these genotypes to use them as the genetically source for breeding purposes.

Comparisons of means Table 1 showed that the most grain yield derived from 1, 4 and 81 genotypes, which had no significant differences with 64, 67, 62, 58, 32, 31, 28, 3, 2 and 71 genotypes. In these genotypes, higher yields pertained to the higher number of grain and higher grain weight, total grain weight in tillers and number of fertile tillers.

Existence of high genetically CV among the genotypes for the yield components indicates the variation caused by the synthetic hybridation between wheat and corn, however, this can be due to the effect of mutagen substances presented in the medium to rescue the embryo or duplication of number of chromosomes.

Table 1:	The means of yield components in genotypes

The most variation was belonged to the total weight of grain per tillers, grain weight and total plant weight (Table 2) that reveals the high potential of these genotypes in breeding plant.

These were significant differences in number of spikes, length of spikes and length of awns among the control genotypes but not in other traits. It is probably, because of the important of these genotypes for the yield component traits.

At present, there are little works performed on the study of genetically variation in the synthetic genotypes, however, Tesemma et al. (1998) have reported existence of the genetically variation for the morphological traits in wheat.

Classification of understudy genotypes for evaluation of similarity among the genotypes based on the 14 morphological and agricultural traits (Fig. 1) revealed that among the synthetic genotypes derived from the wheat and corn hybridation, two large clusters of these ones can be made.

The first and the second clusters included the two sub clusters. The first one contained the genotypes having the higher potentials than the other genotypes such as grain weight, grain number and the length of the spike.

In contrast, the second cluster included the genotypes with lowest grain weight and the highest number of tillers.

This indicates that we can use the hybridation among the genotypes of the two clusters to gain the most heterosis.

In general, it can be said that the hybridation method not only can be resulted in the high amounts of the variation, but may be led to the favorable traits even the highest yields, which is under the extensive researches.

Fig. 1:	Dendrogram based on 14 agronomical treats among genotypes study

Table 2:	Summary of means, range and SD of on measured treats in genotypes

CONCLUSION

Among the evaluated genotypes, results showed that the most grain yield derived from 1, 4 and 81 genotypes, which had no significant differences with 64, 67, 62, 58, 32, 31, 28, 3, 2 and 71 genotypes. In these genotypes, higher yields pertained to the higher number of grain and higher grain weight, total grain weight in tillers and number of fertile tillers. In general, it can be said that the hybridation method not only can be resulted in the high amounts of the variation, but may be led to the favorable traits even the highest yields, which is under the extensive researches.