The main objective of this investigation was to determine the genetic parameters, heritability in both broad and narrow senses, combining abilities and correlation for yield and yield component traits in squash (Cucurbita pepo, L.). For this purpose, five squash varieties were used .These varieties were: Eskandrani (P1); Zucchino tondo di piacenza (P2); Black beouty (P3); Zucchino romanesco (P4) and Coppi (P5). During the summer season of 2011, acomplete diallel crosses mating design was made to evaluate the performances of the 20 F1 hybrids including the reciprocal will their five parental varieties in afield trial at the Experimental Station, Faculty of Agriculture, Mansoura University. Data were recorded on the following traits, number of fruitsper plant (No.F./P.), fruits yield per plant (F.Y./P.Kg), fruit length (F.L.cm), fruit diameter (F.D.cm) and fruit shape index (F.Sh.I). The results indicated that the mean squares for all genotypes were highly significant for all yield and yield component traits. The results of means showed that Eskandrani (P1) was the highest parent for Number of fruits per plant No.F./P. the parental variety Zucchino romanesco (P4) was the highest variety for F.L.cm and F.Sh.I. However, the highest F1 hybrid for fruit yield per plant was Eskandrani (P1) × Zucchino tondo di piacenza (P2) with the mean value of 11.24 kg. Whereas, the highest F1r hybrid was Zucchino romanesco (P4) × Eskandrani (P1) with the mean value of 10.51 kg. The results revealed that the GCA effects (gi) were highly significant for the two parents: Eskandrani (P1) and Zucchino romanesco (P4) for F.L.cm, F.D.cm and F.Sh.I traits. At the same time, the results also revealed that the GCA effects were highly significant for the parents: Zucchino tondo di Piacenza (P2) for F.L.cm and F.D.cm; Black beouty (P3) for F.D.cm and F.Sh.I and Coppi (P5) for F.Sh.I. The results indicated the importance of both (GCA) and (SCA) combining abilities. General combining abilities (GCA) were larger than specific combining abilities (SCA) for all yield and yield component traits except fruits yield per plant (F.Y./P.Kg). The estimates of heritability in broad sense (h 2 b) were larger in magnitudes than those of narrow sense (h 2 n) for all studied traits. The values of heritabilities in broad sense ranged from0.513 to 0.894 for yield and yield component traits.

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This study aimed to test the effect of Rhizobium recombinants on the vegetative growth and yield components of faba bean under biotic stress of Rhizoctonia solani. Tweleve transconjugants resulted from six crosses were evaluated for their antigonism against Rhizoctonia solani. The results showed variations in chitin hydrolysis after genome shortening. At the molecular level, the recipient strains of rhizobia showed more similarity with each other. However, the donar strains of Serratia and pseudomonas showed less similarity. Meanwhile , Rhizobium transconjugants genomes have a similar distribution of bands. Both transconjugants Tr 4 and Tr15 showed more genome size than the other ones due to high level of plasmid transfer. The same transconjugants recorded higher values of chitin hydrolysis zone due to higher expression of chitinase genes. Most transconjugants showed significant increase in nodulation above the uninoculated plants grown in the infected soil. Rhizobium inoculants improved the yield , chlorophyll concentration and NPK content of the plants grown in the soil infected with Rhizoctonia solani compared with uninoculated plants. The results indicated that Rhizobium inoculants improved the growth and yield of plants grown under biotic stress condition. In addition, improved rhizobia with chitinolytic enzymes producing genes could inhibit significantly the growth of pathogenic fungi.

Inter simple sequence repeats (ISSR) or microsatellite markers were applied to assess genetic diversity induced in Allium cepa L. by drainage water and genetic relationship among five water resources which reflected water quality. Genomic DNA was extracted from fresh onion roots treated with drainage water from five resources. Six ISSR primers were initially used for screening water quality. Polymorphisms became evident through the presence and / or absence of DNA fragments in treated roots compared with the control treated with Nile River water. There was a distinct distance between the band profiles of treated roots and the control samples. When the cluster analysis was applied. The total number of bands generated by ISSR-3 molecular marker quality. This marker can be considered as a best reproducible primer to be used for screening water quality. This marker disappeared some bands depending on drainage water carrying toxicants. Similarity coefficients between different water resources was ranged from 0.76 to 0.98. The highest similarity coefficient was obtained between the drainage water from chemical fertilizer industry and oils and soap effluents. The lowest similarity was shown Nile River water and oils and soap industrial effluents. Number of polymorphic bands detected through six primers ranged from 3 to 10, whereas the unique fragments were ranged from 0 to 3. Finally , comparison between Nile River water treatment and treated genomes with drainage water shows that ISSR analysis can be used to evaluate the modifications induced in DNA structure in living organisms by drainage water carrying environmental pollution.

This study aimed to investigate the cytogenetic effects of two plant plant growth regulator as, naphthalene acetic acid(NAA)and benzylaminopurine(BAP)in root meristematic cells of onion.The categories of mitotic index rate , as well as, chromosomal aberrations and types of metaphase disturbance were comparatively analyzed after germinated the onion in different concentrations of each hormone.Both hormones stimulated cell division and have aneugenic potential by acting as spindle posion via disturbed the correct separation of chromosomes to the opposite cell poles.The highest percentage of irregular cell shape was induced by five ppm of NAA.The treatments of BAP appeared a doseresponse for increasing the percentage of extended cells.All treatments increased the percentage of chromosomal abnormalities above the control group.The most dominant phenotypes of abnormalities were binucleate cells, ghost cells, vacuolated nuclei, necrosis and extended cells, which reflected the toxicity of phytohormones leading to cell death.The most dominant cytological irregularities were c-mitosis, diagonal cells, bridges at ana-telophase, chromosomal breaks and stickness which indicates clastogenic potential of these hormones.Abnormalities induced reflected the action of stimulators on the spindle apparatus such as c-metaphase, laggards chromosomes and multipolar of ana-telophases.All treatments changed the percentage of mitotic index such decreased by NAA or increased by BAP in relation to control.The decline in mitotic index reflected the inhibition of DNA synthesis. Prophase cells declined, meanwhile metaphase and anaphase cells were increased in relation to control.It can be concluded that phytohormones caused toxic effects on the eukaryotic cells via induced different types of irregular mitosis as shown in this study.