الفهرس 
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Abstract
This study was carried out at the Experimental Farm and Biotechnology laboratory of the Rice Research and Training Center (RRTC), Sakha, Egypt during the three growing seasons 2009, 2010 and 2011 and Plant Pathology and Biotechnology Lap. Faculty of Agriculture, Kafrelsheikh University. Two cytoplasmic male sterile lines wild abortive (WA) IR69625A, IR70368A and one cytoplasmic male sterile line K type; K17A with their maintainers were chosen and used as parental lines to determine the genetic purity, stability, genetic analysis for some morphological, yield and its component characters and some floral traits.
In 2010 season, F1 ( 1-50 ) populations for each line were produced from paired cross between A and B line in 2009 season and sown in the nursery during the first week for identification and after three weeks of May for multiplication. Then, they were transplanted after 30 days adopted a spacing of 20 x 20 cm under isolation plot. Five replications were grown in randomized complete block design, each replication consisted of one row for the maintainer (1-50) and one row for F1 (1-50) populations (A / B). Each row was 5 m long and contained 25 individual plants. The same method was adopted in 2011 season.
The obtained results can be summarized as follow:
1- A wide range of differences was found among the parental lines and their populations, and also, for each trait, the same differences were recorded. The mean values of the IR69625A/B (1-50) were (101.25, 143.41,56.52 15.99 and 30.03) for days to heading, duration of spikelet opening, stigma exsertion, grain yield plant-1 and seed set % in 2011. But the mean performances of IR69625B(1-50) were (100.00, 51.32, 53.70, 31.70 and 96.00) for the above mentioned characters, respectively.
2- For the IR70368A/B (1-50), the recorded mean values were (98.32, 177.70,58.25, 17.70 and 28.80) for days to heading, duration of spikelet opening, stigma exsertion %, grain yield plant-1 and seed set % in 2011. But the mean performances of IR70368B (1-50) were (95.15, 67.88, 67.34, 41.38 and 95.14) for the same traits, respectively.
3–Also, many differences among the parental lines and their populations and for each trait were found for the K17A/B (1-50). The mean values for this line were (85.60, 190.82, 72.29, 16.49, and 29.01) for days to heading, duration of spikelet opening, stigma exsertion %, grain yield per plant and seed set % in 2011. But the mean performances of K17B (1-50) were (84.04, 76.95, 67.34, 33.43 and 92.75) for the same traits, respectively.
4- from these data, it could be concluded that, the desirable value for panicle exertion % ranged between (35 and 75) and seed set % ranged between (25 and 40) for CMS lines. For the no. of bagged panicles, it was zero without spraying growth regulator and for seed set, it was also zero for the panicle pagged. These traits are very important to select the desirable populations under the field conditions on the basis of the visible investigation.
5- The results of summarized heritability in broad sense for IR69625A/B were for panicle exsertion % ( 97.02 ), for seed set % ( 97.51) and for grain yield plant -1 ( 96.7). These traits gave the highest values. The heritability for days to heading recorded the lowest value (94.89), indicating that the environmental effect was very low; and all these traits were controlled by additive and non additive genetic variances and could be selected in early generation.
6- On the other hand, the maximum impurity which was (2 %) in line IR70368A and (4 %) in line K17A were DROPped from 2010 to 2011 season after three paired – cross evaluation. The purity ratio of 99.99 % for IR69625A, IR70368A and 94% for K17A plants were used for nucleus seed multiplication through paired cross cycles every year to produce breeders seeds. This procedure was successful in improving the purity of the parental lines, because it achieves the maximum yield potential (99 % pure seed) of the A line.
7- The analysis of variance revealed highly significant differences among the three CMS lines with their maintainers and 50 populations of each line tested for all the studied characters. The parental lines and populations showed highly significant differences for some characters, indicating that the average improvement was significant in all populations for all studied characters.
8- For biochemical analysis: results appeared that, the CMS lines showed one band with molecular weight of 26 KD, but maintainer lines exhibited three bands with molecular weights of (123, 43 and 28KD) . from the above results, this analysis could be used to determine the genetic purity for CMS lines and their maintainer lines.
9- For PCR analysis, the results suggested that, the primers RMT6 and cms could be used to identify the genetic purity for CMS lines under multiplication experiment. Moreover, these results were confirmed with the field characters.
10- The PCR results for RMT6 primer showed that, one DNA fragment with size of 210 bp was found in the maintainer lines and another band with size of 200bp in the CMS lines. But, cms primer gave one band with size of 480 bp in the CMS lines and was absent in the maintainer lines. These fragments may be carry genes which play an important role in the maintaining ability in the hybrid rice.