In this study, we examined eight white inbred lines of maize and their F1 crosses under normal and drought stress conditions to estimate their combining ability for grain yield and associated traits. The results showed significant correlation (mean squares) of irrigation treatment with the studied traits. The effects of parents, crosses, and genotypes were all determined to be highly significant under both irrigation levels. Grain yield and other traits showed significant differences (mean squares) associated with both General combining ability (GCA) and Specific combining ability (SCA) under both irrigation regimes, demonstrating the importance of both additive and nonadditive genetic effects in the expression of performance traits. The parental line (P-86) had positive and highly significant GCA effects, as well as the crosses (P-17×P-96), (P-8×P-96), (P-8×P-171), (P-24×P-86), (P-86×P-96), (P-86×P-171), and (P-96×P-171) which then gave the highest specific combinations under both irrigation regimes for grain yield and some of the associated traits. The highest level of heterosis (heterobeltiosis) for grain yield was obtained in the crosses (P-8×P-96), (P-8×P-137), (P-8×P-171), (P-96×P137), and (P-96×P-171) under both irrigation regimes.

This experiment was implemented in the experimental farm of (Misr hytech seed co. Giza, Egypt) during winter growing seasons 2014 and 2015 to evaluate the inheritance of some cucumber vegetative and yielding traits using a complete diallel cross among five inbred lines. The results showed that the mean square of genotypes, parental inbred lines, crosses and parent vs crosses were significant for the studied traits. The hybrids P2xP4 and P2xP5 exhibited a useful heterosis relative to Mp and Bp for the fruit yield per plant and number of leaves per plant. The mean square of general and specific combining ability was significant for the studied traits. The higher GCA/SCA ratio than the unity of the studied traits indicating to the greatest role of the additive gene action in the expression of these traits. The inbred lines P1 and P 2 exhibited significant positive i g ˆ effects in the traits of number of fruit per plant and fruit yield per plant, so these inbred lines could be act as a good combiner for developing high yielding genotypes. The F1 hybrids P1xP3, P2xP4, P2xP5 and P4xP5 as well as the reciprocal hybrids P4xP1, P4xP2, P4xP3  and P5xP3 recorded a significant positive ij S ^  effect but the reciprocal hybrids recorded a significant rij effect. The results revealed to more than one hybrid distinct in some traits that could be utilized in the greenhouse cucumber cultivation and the future breeding programs.

Data on rabbits produced from a total number of 518 parities were analyzed to evaluate crossing effects among two breeds of rabbits. The breeds tested were Gabali (GAB) and Bouscat (B). sex effects on post weaning body weight were also studied. A total number of 80 rabbits at marketing age were slaughtered to evaluate effects of mating type and sex on some carcass traits. Mating type affected significantly (P ≤ 0.001) progeny weight from weaning up to marketing age and preslaughter, carcass, slaughter weight, hot carcass weight, fore legs weight and hind legs weight at marketing age. Meanwhile, the effects were not significant on loin weight and dressing percentages . Sex insignificantly affected body weight although body weights of female rabbits were slightly heavier than those of male rabbits. Effects of sex on carcass traits were not significant. Heterosis % and superiority % of body weight estimates were positive for all post weaning weights. Positive heterosis was shown for some carcass traits.

A 7x7 half diallel cross along with their parental wheat cultivars were evaluated under two sowing dates (19th Nov. and 17th Dec.).The results revealed that mean squares due to sowing dates, genotypes and genotypes x sowing dates interaction were significant for most of the studied traits. Delaying sowing date to Dec. reduced all studied characters compared to the normal sowing date except electrolyte leakage which increased by delaying sowing date. Heterosis over better parents showed that, the best hybrids under stress condition were Misr 2 X Giza 168 and Sids 1 X Giza 168   for grain yield / plant and some of other studied traits.  General and specific combining ability mean squares indicated the importance of both additive and non-additive gene effects in the inheritance of the studied traits with few exceptions. However, the additive effect was more important than the non-additive effects in the inheritance of days to 50% heading, plant height, No. of spikes/ plant,No. of kernels / spike and 1000-kernel weight while, the non-additive effects were more important than the additive effects in the inheritance of electrolyte leakage and flag leaf area. The best general combiner parents for grain yield / plant and some of other studied traits were Gemmeiza 11 and Giza 168under stress condition. The best hybrids for SCA effects were Sakha 93 X Sids 1, Gemmeiza 11 X Giza 168, Misr 2 X Giza 168 and Sids 1 X Giza 168 under stress condition for grain yield / plant and some of other studied traits. The crosses Gemmeiza 11 X Giza 168   (HSI 0.36), Gemmeiza 7 X Giza 168   (HSI 0.58) and Sakha 93 X Giza 168   (HSI 0.60) have recorded the lowest values of heat susceptibility index (HSI), indicating their tolerance to heat stress (late sowing date).

Twenty one wheat hybrids and their seven parental genotypes were evaluated in the research farm of the Faculty of Agriculture, Ain shams University, Shoubra El-khema, Cairo, Egypt, in 2016/2017 growing season. The genetic analysis was conducted using Griffing (1956), Method 2, model 1).                 Significant differences among parent genotypes and their 21 crosses for all the studied traits (days to 50% heading, days to maturity, flag leaf area, plant height, number of spikes/ plant, spike length, number of spikelets/ spike, number of kernels/ spike, 1000-kernel weight and grain yield/ plant) were detected. This indicated that, variability exists among these populations may increase the chance appearance of good new combination that can be isolated in the succeeding generations. Parents versus crosses mean squares as an indication for average heterosis over all crosses were significant for all studied traits.                 Mean squares of general (GCA) and specific (SCA) combining abilities were significant for all studied traits except spike length trait for SCA which was insignificant. GCA/SCA ratios were more than unity for all studied traits, which indicating that the additive type of gene action is of great importance in the inheritance of these traits. Heterosis over the better parents showed that, the best hybrids were Gemmiza 9xGiza 168, Sakha 93x Giza, 168, Sakha 94x Jawahir-14, Sakha 94x Bob white, Giza 168xAcsad 925 and Jawahir-14x Bob white for grain yield/ plant trait and some of the other studied traits. The best general combiner parents were Sakha 94, Jawahir-14 and Bob white for grain yield/ plant trait and some of the other studied traits. The best SCA hybrids were Gemmiza 9x Sakha 93, Gemmiza 9x Giza 168, Sakha 93x Jawahir-14, Sakha 94xJawahir-14, Sakha 94x Acsad 925, Sakha 94xBob white, Giza 168x Jawahir-14, Giza 168x Acsad 925, Jawahir-14x Bob white and Acsad 925x Bob white for grain yield/ plant trait and some of the other studied traits. These result could be used in wheat breeding programs.

Six population’s seeds of four yellow maize crosses were formed during 2001 and 2002 growing seasons. Their plants were evaluated during 2003 growing season under two planting dates (14th May and 29th June) for six agronomic traits at the Agric. Res. Stat. of Fac. of Agric., Ain Shams Univ., Shalakan, Kalubia Gover-norate, Egypt. The present work aimed to determine the genetic parameters and their interactions with planting dates for grain yield per plant, 100-kernel weight, number of kernels per row, ear length, ear diameter, and days to silking in the six popula-tions (P1, P2, F1, F2, BC1 and BC2). Mean values of the six populations for all studied traits in all crosses were higher under normal planting date than those under late one. Therefore, normal planting date seemed to be non-stress environment. The potence ratio for all traits in the four crosses exceeded (+1) except days to silking where it was less (-1). The highest heterosis percentage relative to mid and better parent reached 192.06% and 152.01% in cross 1 for grain yield per plant under late plant-ing date. Inbreeding depression values were not-significant in all studied traits ex-cept ear diameter and 100-kernel weight in crosses 1 and 3 as well as grain yield per plant in all crosses also, it was positive for most studied characters in the four cross-es except days to silking trait. Dominance occupied the first rank, additive or domi-nance type of epistasis occupied the second or the third contributor to the genetic ef-fects in order of importance according to cross with exception of days to silking, where additive and additive occupied the first and the second ranks. Narrow sense heritability was relatively high for yield attributes whereas it was low for grain yield per plant. Meantime, expected genetic advance was relatively moderate or low for all traits. Therefore, it could be suggested that selection for most studied traits in the subsequent generations will be relatively more effective than in the early genera-tions.

In this study, we examined eight white inbred lines of maize and their F1 crosses under normal and drought stress conditions to estimate their combining ability for grain yield and associated traits. The results showed significant correlation (mean squares) of irrigation treatment with the studied traits. The effects of parents, crosses, and genotypes were all determined to be highly significant under both irrigation levels. Grain yield and other traits showed significant differences (mean squares) associated with both General combining ability (GCA) and Specific combining ability (SCA) under both irrigation regimes, demonstrating the importance of both additive and nonadditive genetic effects in the expression of performance traits. The parental line (P-86) had positive and highly significant GCA effects, as well as the crosses (P-17×P-96), (P-8×P-96), (P-8×P-171), (P-24×P-86), (P-86×P-96), (P-86×P-171), and (P-96×P-171) which then gave the highest specific combinations under both irrigation regimes for grain yield and some of the associated traits. The highest level of heterosis (heterobeltiosis) for grain yield was obtained in the crosses (P-8×P-96), (P-8×P-137), (P-8×P-171), (P-96×P137), and (P-96×P-171) under both irrigation regimes.