This investigation was conducted to study the possibility of improving some tomato traits. In this respect, during successive early summer seasons of 2008-2010 at Zifta distract, Middle-Delta Region, a line x tester analysis was made in tomato (Lycopersicon esculentum Mill.) with eleven femal parents (breed lines) and three male parents (testers) to determine the components of genetic variance, gene action and combining ability effects for some growth and fruit characters. All studied traits, i.e., plant height, main stem length, number of primary branches and leaves, early and total yield, as well as, average fruit weight, firmness, total soluble solids (TSS%) and vitamin C content of fruit have closer values of σ 2 g and σ 2 p. The G.C.V. and V.C.V%, which was confirmed by the estimated of G.C.V./P.C.V. ratios (ranged from 0.91 to 0.99) and broad sense heritability (h 2 bs) values (ranged from 0.85 to 0.98), suggesting less effect of environmental and the large portion of σ 2 p was due to the σ 2 g on these traits. The magnitude of variance due to general and specific combining abilites were highly significant indicating the importance of the additive (σ 2 A) and non-additive (σ 2 D) gene actions. However, the ratios of σ 2 GCA/ σ 2 SCA (<1) and σ 2 A/σ 2 D (<1) revealed the preponderance of non-additive variance in the inheritance of all the studied traits. The estimated average degree of dominance (0.76 and 0.90) revealed partial and complete dominance for average fruit weight and TSS % content, respectively, while revealed over-dominance (>1) for the remaining traits. The parental lines G.16, S.65, G.30 and the tester G.19 were found to be the most desirable general combiner (they possessed dominant genes) for seven, six, five and six traits, respectively. The cross combinations S.60 x G.19, S.125 x G. 19, G.30 x SSB and G.30 x Peto 86 considered the best specific combinations since showed significant SCA values for five traits. The results also suggested the possibility of improvement of these tomato traits through recurrent selection and hybrid breeding program.

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During successive summer seasons of 2008 to 2011, this study was conducted at Middle Delta region. Eight sweet pepper breed lines were used in halfdiallel cross mating design to produce 28 F1 pepper hybrids. The extent of heterosis was estimated based on (MP), (BP), (TP) and commercial hybrid (CH) for some palnt and fruit traits. Analysis of variance showed a great diversity and significant differences among the studied genotypes (parents and hybrids). 13 hybrids gave better parent heterosis (heterobeltiosis) for plant height and total yield, while five F1's for number of branches and early yield. Relative to the top parent, seven hybrids (for plant height) and two ones (for number of branches and total yield) reflected top heterosis (TH%). None of the studied hybrids showed heterosis over MP, BP and TP for average fruit weight, fruit length and diameter, while standard heterosis (SH%) was obtained for all the studied traits. Additive and non-additive gene effects were found for number of branches and early yield. Non-additive effects were predominance for plant height and total yield, white fruit characters (weight, length and diameter) of the whole were controlled by additive effects. Based on the standard heterosis expressed by the hybrids, "B.23-5 x MAR-6" (Balady fruited type) and "L.S.5-14 x L.S.2-2" (Long fruited type) were found to be superior over the commercial hybrid and could be used for commercial production, which must be depended on its actual high productivity and not on its average degree of heterosis.

Sixteen new lines of tomato (F5) were selected from six F2 generations, which exhibited high homogeneity based on estimated CV % values for plant height, number of leaves/ plant, hardness, shape index, TSS% and Vitam. C content during successive four seasons from 2017/2018 to 2020/2021 in the Experimental Farm, Faculty of Environmental and Agriculture Sciences, Arish University, North Sinai under open field conditions. The experimental work was conducted using a randomized complete block design with three replications. A highly significant differences were observed among the selected lines for all studied characters. Lines that showed the most vigorous growth were DAN-2-2, DAN-3-4, DAN-3-5, 6130-1-1, 6130-3-2, 6130-3-4, 3017-2-1, 3017-2-6, 783N-1-4, TYG-1-3, TYG-2-1, TYG-2-1, TYG-4-1 and KIS-N-2-1. For Mean performance all plants in the lines 6130.1.1, 6130.3.4, 3017.2.1, 3017.2.6, TYG-1-3 and KIS-N-2-1 were resistance to Tomato yellow leaf curl virus. Two lines recorded highest values for total yield, 3017.2.1 and 3017.2.6, while 6130.3.2 and 6130.3.4 where the best for avrage fruit weight.

2, were crossed in 7×7 half diallel mating design. The study was conducted in the experimental farm of, Faculty of Environmental and Agriculture Science, Arish University, North Sinai, Egypt to produce superior hybrids tolerant to Tomato Yellow Leaf Curl Virus (TYLCV). For heterotic effect, heterosis over mid-parents, better parent and check hybrid were detected in many traits, q.e.; plant height, No. of leaves, Fruit set (%) in first three clusters, hardness, T.S.S., total yield/plant and average fruit weight. For plant height heterosis, 12 crosses exhibited significant positive values ranging from 5.83% in the cross (4x7) to 23.8% in the cross (1x5) over the check hybrid. For number of leaves/plant 15 ones reflected mid-parents heterosis with significant values ranging from 8.23% for 1x6 to 59.4% for 2x6, suggesting dominance toward the high number/plant. Hybrids with good hardness were (1x7,2x4,2x7,3x4, and 4x7), total yield (1x5, 2x6, 2x7,4x5,4x7,5x6,5x7, and 6x7), and they were also found to have tolerance to heat stress and TYLCV under North Sinai conditions.