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Abstract The selection of parents to originate promising base populations, as well as the knowledge of the gene effects controlling agronomic traits by means of diallel, are useful to drive genetic gains in Brazilian tropical wheat breeding programs. The goals of this study were to select tropical wheat parents with a high frequency of favorable alleles and segregating populations with high potential to originate superior progenies through partial diallel analysis. Thus, 14 parents were divided in two groups and crossed in a 7 × 7 partial diallel scheme to originate 49 F1 combinations. After obtaining F2 generation, the populations and the parents were evaluated in the field in the summer of 2021. Days for heading, plant height, rust and yellow spot resistance, and grain yield were evaluated. The data were subjected to partial diallel analysis. There were significant effects of general combining ability for all traits. The specific combining ability effect was significant for days for heading and plant height. The additive gene effects were predominant over the non-additive ones. The parents with the highest frequency of favorable alleles for the traits evaluated were selected in each group. Four populations with high genetic potential to originate superior progenies were selected.

Capsicum chinense Jacq. plays a pivotal role in imparting pungency and flavour to cuisines in the Caribbean. Despite its popularity, hot pepper production in the region has declined. A major constraint has been the low yields associated with cultivation of uncharacterised landraces, high cost of production and poor profitability. Although breeding high yielding varieties has been recognised as critical to expanding production and profitability, it has been impeded by the limited understanding of yield components and their genetics. The objective of the study was to understand the inheritance of yield, yield components and partitioning components. Progenies of a 9 - 9 half diallel mating design were evaluated in an open field experiment in a randomised complete block design with three replications. Considerable genetic variation was observed for all 12 yield components except for flowers per node. Diallel analysis revealed predominance of non-additive genetic effects for most yield components except fruits per cluster, clusters per plant and reproductive efficiency. The narrow sense heritability for clusters per plant, fruits per cluster, reproductive efficiency, harvest index and shoot dry weight was moderate to high, but was low for yield, fruit number and average fruit weight. Breeding methods to improve yield are discussed. [ABSTRACT FROM AUTHOR]

Straighthead is a physiological disorder of rice (Oryza sativa L.) that causes dramatic yield loss in susceptible cultivars. This disorder is found worldwide and is reported to increasingly occur in the southern United States. Genetic resistance breeding has been considered as one of the most efficient methods for straighthead prevention because the traditional prevention method wastes water and costs labor. In this study, we analyzed the genetic effects of five straighthead quantitative trait loci (QTLs), namely, AP3858-1 (qSH-8), RM225 (qSH-6), RM2 (qSH-7), RM206 (qSH-11), and RM282 (qSH-3), on the recombinant inbred lines (RILs) developed from Jing185/Cocodrie and Zhe733/R312 populations using our five previously identified markers linked to these QTLs. As a result, recombinant inbred lines (RILs) with four resistant alleles at the four loci (AP3858-1, RM225, RM2, and RM206) exhibited the highest straighthead resistance. This result suggests that the four markers could be efficiently used to select the straighthead-resistant recombinant inbred lines (RILs). Furthermore, by using AP3858-1, we successfully obtained five straighthead-resistant recombinant inbred lines (RILs) with more than 50% genetic similarity to Cocodrie. These markers and recombinant inbred lines (RILs) can be used for future straighthead resistance breeding through marker-assisted selection. [ABSTRACT FROM AUTHOR]

It is unknown what determines genetic diversity and how genetic diversity is associated with various biological traits. In this work, we provide insight into these issues. By comparing genetic variation of 14,671 mammalian gene trees with thousands of individual human, chimpanzee, gorilla, mouse, and dog/wolf genomes, we found that intraspecific genetic diversity can be predicted by long-term molecular evolutionary rates rather than de novo mutation rates. This relationship was established during the early stage of mammalian evolution. Moreover, we developed a method to detect fluctuations of species-specific selection on genes based on the deviations of intraspecific genetic diversity predicted from long-term rates. We showed that the evolution of epithelial cells, rather than connective tissue, mainly contributed to morphological evolution of different species. For humans, evolution of the immune system and selective sweeps caused by infectious diseases are the most representative examples of adaptive evolution. [ABSTRACT FROM AUTHOR]

The generation mean analysis was carried out to estimate nature and magnitude of gene effect for yield traits and oil content in two crosses RH 0749 × RLC-3 and RH 0749 × PDZ-1 of Indian mustard [Brassica juncea (L.) Czern & Coss]. Significance of scaling test as well as χ2 in joint scaling test showed the presence of digenic or higher order interactions for all characters except for days to maturity in cross RH 0749 × RLC-3. Additive gene effects (d) were important for days to maturity, number of secondary branches per plant, number of seeds per siliqua, 1000-seed weight and seed yield per plant. Both additive (d) and dominance (h) gene effect were important for plant height, number of primary branches per plant, main shoot length, number of siliquae on main shoot, siliqua length and oil content. The dominant × dominant (l) type of gene interaction and duplicate epistasis was observed for most of the character in two crosses except for seed yield per plant in cross RH0749 × PDZ-1 for which complementary epistasis was observed. These results suggested that substantial improvement in yield may be achieved through recurrent selection and heterosis breeding.

The use of rutabaga for increasing the level of heterosis in spring canola was investigated. For this, test hybrids were produced by crossing four inbred populations, derived from F2 and BC1 of two rutabaga × spring canola crosses, to their spring canola parent, and were tested in field‐plots for agronomic and seed quality traits. Average mid‐parent heterosis (MPH) in these test hybrid populations was about 5%‐15% for yield. Compared to the F2‐derived population, the BC1‐derived population exhibited 1.8‐times greater MPH for yield. No correlation was found between inbred and test hybrid for yield; however, a positive correlation of genetic diversity of the inbred lines was found with MPH (r =.58) and hybrid yield (r =.36) suggesting that non‐additive effect of the genes may play an important role for high yield in hybrids. About 2% negative MPH was found for days to flowering, while almost no heterosis was found for seed oil and protein contents. Thus, our study demonstrates the potential of the rutabaga gene pool for use in hybrid canola breeding. [ABSTRACT FROM AUTHOR]

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Two crosses of faba bean (Giza716xGiza40) and (Giza716xNubaria2), each represented by six population (P1, P2, F1, F2, BC1 and BC2) were tested for yield, yield components, growth attributes and two diseases (chocolate spot and rust). Heterosis in F1, which exhibited highly significant positive effects were detected for number of branches /plant, number of pod /plant, number of seed /plant, seed yield /plant and plant height in the two crosses over mid and better parents. Significant negative Heterosis effects were obtained for chocolate spot and rust diseases in the two crosses over mid parents. Highly significant positive values of inbreeding depression were detected for number of branches/ plant, number of pods/plant, number of seed /plant, seed yield /plant, 100-seed weight and plant height in both crosses. However, highly significant negative values of inbreeding depression were found for chocolate spot and rust diseases in the two crosses. Over dominance towards the higher parent were detected for number of branches/plant, number of pods/plant, number of seeds/plant, seed yield /plant and plant height in both crosses. It was also found that over dominance controls spot and rust diseases in the second cross. Additive gene effects were significant for all characters, excepted number of seed/plant and seed yield/plant in both crosses. Dominance effects were highly significant for all traits, excepted, seed yield/plant and plant height in both crosses and rust disease in second cross. Additive x additive, additive x dominance and dominance x dominance types of gene action were significant for most traits in both crosses, except, chocolate spot and rust disease. In both crosses, high heritability values in broad sense were detected for all traits which, ranged between 63.20 for rust disease and 85.32 % for reaction to chocolate spot and for cross (Giza 716 X Giza 40). However, cross (Giza 716 X Nubaria2) had values ranged from 60.7% for reaction to rust to 70.93% for seed yield/plant in (Giza 716 x Nubaria2). The values of heritability in narrow sense were detected for all traits which, ranged between 60.19 to 80.36% for resistance to rust and chocolate spot disease in first cross, respectively and between 59.36 and 68.42% for number of pods/plant and seed yield / plant in the cross (G.716 x Nubaria.2).The estimates of expected genetic advance from selection in F2 generation reflected low or moderate values for all studied traits in both crosses that ranged between 7.78 cm for plant height to 1.8 for rust disease in cross (Giza 716 X Giza 40) and between 8.13 cm for plant height to 1.84 for number of branches/plant in (Giza 716 X Nubaria2) cross. [ABSTRACT FROM AUTHOR]

The safflower (Carthamus tinctorius L.) is an oil seed crop from which the flowers is used as medicine and food colorants. The present investigation was undertaken to explore gene effects for safflower’s pigments in flower including carthamin and carthamidin. Six generation including P1, P2, F1, F2, BC1 and BC2 that derived from two different crosses (Mex. 2-138 (P2) × Wht-Esf (P1) and C111 (P2) × Wht-Esf (P1) were used for generation of mean analysis. The joint scaling test showed that additive [a], additive × additive [aa], and additive × dominance [ad] effects were significant for genetic control of carthamin and carthamidin in both crosses. The traits, including carthamidin and carthamin, had medium (48%) and low (17%) narrow-sense heritability, respectively. The results obtained here could be suitable for designing the breeding strategies based on selection to improve carthamin and carthamidin pigments in safflower. [ABSTRACT FROM AUTHOR]

Five two-row winter barley (Hordeum vulgare L.) cultivars divergent in spike traits were crossed in all possible combinations excluding reciprocals to produce 10 F1 and F2 hybrids for analysis of combining abilities. The analysis of variance of combining abilities showed significant differences for GCA and SCA in F1 hybrids and F2 generation, suggesting additive and non-additive gene action. The GCA/SCA ratio in F1 and F2 indicated the prevalence of the additive component of genetic variance for spike length, grain weight per spike and spike harvest index. By contrast, the SCA variance for grain weight per spike was higher than the GCA variance, indicating the dominance of non-additive gene action. Good GCAs were found in parents having high values for spike length (Djerdap, NS-293), grain number per spike (Vada, Jagodinac), grain weight per spike (Vada, NS-293) and spike harvest index (Djerdap, Jagodinac). None of the parents had good GCA for all traits, suggesting a potential increase in combining abilities for spike traits. The best SCA were obtained mostly from crosses between parents having high x low, high x high or average x low GCA values. Parents having high GCA values may be used to produce improved lines in hybridisation programmes. Combinations with high SCA values may yield good segregating lines in further selection programmes.

In red pepper cultivation for spice production, harvesting the fruits is time consuming and high cost requiring process. Also all the cultivated pepper (Capsicum spp.) fruits for processing have to be separated from the pedicel after or before drying. The pedicel is tightly attached with the calyx to the fruit pod in most pepper cultivar. For this reason fruit detachment force (FDF) is an important trait to improve pepper cultivars suitable for mechanical harvesting. Gene action for FDF was calculated using inter-specific crosses between four C. annuum L. (3.860 to 7.340 N FDF) genotypes and C. chacoense Hunz. (0.199 N FDF), C. annuum variety 'Totolapa' (0.173 N FDF). FDF values obtained from parents and F1 generation indicated that gene effects for this trait were mostly displayed dominance and additive. No differences were calculated with respect to heterosis both Capsicum species related FDF. Parents could generate hybrids with high degree of negative heterosis varying between 86.56% and 94.50% related with FDF. Except K7 x CC hybrid easily detached from the fruit with 0.153 N, all the hybrids have fruit detachment force over 'Totolapa'. [ABSTRACT FROM AUTHOR]

The present study was performed to assess the nature of gene action governing inheritance of agronomic traits in eggplant genotypes and extent of mid parent heterosis (MPH) and better parent heterosis (BPH) in six eggplant hybrids generated from four superior and optimally divergent genotypes of eggplant namely 'Yalo', 'Uyo', 'K3' and 'Iyoyo' selected from the germplasm and were crossed in 4×4 half diallel mating design. The six hybrids were found to show a significant (p< 0.05) positive MPH in yield traits and the highest was obtained in the hybrid 'Yalo' × 'K3' for number of fruits per plant (158.90%) and 'K3' × 'Iyoyo' for fruit yield per plant (63.14%) and fruit yield per hectare (62.20 %). The hybrid combinations 'Yalo' × 'K3' and 'K3' × 'Iyoyo' had significant positive BPH for the number of fruits per plant, 104.08% and 42.43%, respectively. For fruit yield per plant, the hybrid combination 'Yalo'× 'K3' (7.93%), 'Uyo' × 'K3'(8.48%) and 'K3' × 'Iyoyo' (12.26%) had significant positive BPH. However, the hybrid 'K3' × 'Iyoyo' (11.51%) showed significant positive BPH in fruit yield per hectare. Dominance and dominance × dominance gene effect were found to be positively higher in magnitude in all crosses for number of fruits per plant, fruit yield per plant and fruit yield per hectare. The prevalence of dominance and dominance × dominance gene effect in the yield traits indicate heterosis breeding as the best breeding method to improve the productivity of eggplant. [ABSTRACT FROM AUTHOR]

A study was conducted for estimating combining ability and standard heterosis for grain yield and various agromorphological traits involving 10 parents and their 45 F1s (half diallel) during 2012-13 and 2013-14. The results of present investigation revealed that additive gene action played a predominant role in the inheritance of most of the traits under study. On the basis of general combining ability (GCA) effects and specific combining ability (SCA) effects, three parents (Vallabh Basmati 21, Pusa Basmati 1, CSR 13) and three crosses (Vallabh Basmati 21 x Pusa 1121, Pusa 1121 x CSR 13 and Pusa Basmati 1 x CSR 13) were found good general and specific combiners. The best combinations mostly involved good x good and good x poor parental GCA effects suggesting that there is additive x additive and additive x dominance type of gene action for yield and other component traits. The cross showing additive gene action can be improved by pedigree breeding and selection can be postponed to later generations. The most appropriate breeding method for the exploitation of non additive gene action will be heterosis breeding. The six best cross combinations (Vallabh Basmati 21 x CSR 30, CSR 30 x CSR 13, Vallabh Basmati 21 x CSR 13, CSR 30 x Pusa basmati 1, Pusa basmati 1 x CSR 13 and Vallabh Basmati 21 x Pusa basmati 1) had significant standard heterosis for grain yield and other component traits. The crosses which showed significant standard heterosis is highly suitable for commercial exploitation of heterosis in rice crop. [ABSTRACT FROM AUTHOR]

Line x tester analysis using a set of four females, ten males and their forty hybrids was carried out to estimate the general combining ability of parents and specific combining ability of hybrids for yield and ten other associated components in rice (Oryza sativa L.) in a Randomized Block Design during Kharif 2011. GCA variances for females (s2f) were significant at 0.1% level of significance for plant height (40.8), no. of grains per panicle (505.9), grain yield per plant (29.1), test weight(17.9), straw yield per plant (61.3) and kernel L/B ratio (0.2) whereas specific combining ability (SCA) variances for f x m interactions were highly significant for all the characters. Non-additive gene action was prevalent in all characters (Range: 0.03 in amylose content to 0.88 in kernel length breadth ratio) except plant height (1.33) as evident by low GCA to SCA ratio. None of the parents were good general combiner for all traits, however, female IR-28 and male AMT-119 and PNR-546 were good general combiners for a maximum number of traits i.e. five traits out of eleven.. The general combining ability for grain yield per plant for female parent Gurjari (6.19) and NVSR-178 (5.29); and male parents AMT 119 (2.73) and PNR 546 (2.44) makes them a good choice for improving yields in a hybridization programme as these female and male parents are also having significant GCA effects for maximum number of yield associated traits i.e. four and five traits out of eleven for female and male parents respectively. A vis-à-vis comparison of top three specific combining ability crosses with their mean performance showed correlation and these crosses were having at least one good general combining ability parent. [ABSTRACT FROM AUTHOR]

This study evaluated the types of gene action governing the inheritance of resistance to Phytophthora nicotianae necrosis in populations derived from two crosses involving two susceptible (Beldi and Nabeul II) and one resistant (CM334) cultivars of pepper (Capsicum annuum L.). Populations, composed of Pr, Ps, F1,F2,BC1Pr, and BC1Ps generations, were inoculated with six P. nicotianae isolates. Generation means analysis indicated that an additive-dominance model was appropriate for P. nicotianae isolates PnKo1,PnKo2 and PnKr1, which showed low aggressiveness in the two crosses. For the more aggressive isolates PnBz1,PnBz2 and PnKr2, epistasis was an integral component of resistance in the two crosses. The presence of epistasis in the resistance of pepper to P. nicotianae was dependent on the level of aggressiveness of the isolates. Selection in pepper with less aggressive isolates was efficient, but not with more aggressive isolates; on the other hand, selection with more aggressive isolates was more stable. The minimum number of genes controlling resistance was estimated at up to 2.71. In the majority of cases, the additive variance was significant and greater than the environmental and dominance variance.

Six rice cultivars were crossed in half diallel design to evaluate their GCA and SCA in 2005. In the following year, parents and their progenies were grown in a randomized complete block design with three replications, and 10 traits were measured. The analysis of variance showed significant differences (p≤0.01) between cultivars. Furthermore, general combining ability (GCA) and specific combining ability (SCA) for parents and hybrids were significant. Therefore, additive and non-additive gene effects on controlling traits were demonstrated. According to the analysis based on the second and fourth Griffing methods, additive gene effects were more than non-additive gene effects on controlling growth period, plant height, panicle length, number of panicles/plant and brown rice length, while other studied traits were more controlled by non-additive gene effects. Comparison of the second and fourth Griffing methods showed that the proportions of additive and non-additive variances in two methods were different. Moreover, GCA and SCA resulting from the two methods for several traits such as vegetative and productive growth period, plant height, number of filled grains/panicle and grain yield were significant. Therefore, it could be concluded that using parental generations in the second Griffing method may cause biased estimate of the GCA and SCA variances. Thus, using the fourth Griffing method is more suitable than the other methods in providing time, cost and facilities, and is recommended as an applicable method.

In the present study, generation mean analysis and chi-square test were undertaken to estimate the nature and magnitude of gene action for yield and its component traits; and inheritance pattern of seed colour and lustre in two crosses of mungbean viz Sona/ DMS 03-17-2 and Sona/ DMS 01-34-2. Scaling and joint scaling tests revealed the presence of one or more kinds of epistatic effects for almost all the agro-morphological traits. The selection of elite lines from delayed generations and subsequent inter mating might be useful approach to recover/ develop the high yielding mungbean lines. The elite lines recovered from crosses Sona/ DMS 03-17-2 and Sona/ DMS 01-34-2 might be superior in terms of early maturity with more number of branches, pods high seed index, biomass and yield. Likewise, crosses i.e. Sona/ DMS 03-17-2 for average intermodal length; Sona/ DMS 01-34-2 for NSP; may give opportunity to isolate transgressive segregants in advanced generations. There was also a possibility to recover the yellow and shiny seeded mungbean lines due to its monogenic inheritance of seed coat colour and lusture. [ABSTRACT FROM AUTHOR]

Rapeseed (Brassica napus L.) with purple-red leaf is a valuable resource for plant breeder. It was utilized in breeding program as a morphological marker, and the source of resistance gene to biotic or abiotic stress due to its anthocyanin content (AC). However, the inheritance of AC and the correlation with chlorophyll content (CC) in rapeseed leaf are still unknown. This study aimed to investigate the gene action and heritability of AC and CC in a 10- Zi006 x 10-4438 rapeseed cross using generation mean analysis. The results indicated that AC and CC were controlled by main gene effect and non-allelic interactions. The AC was mainly controlled by genetic effect. However, the genetic effect and non-genetic effect were both important for CC. In addition, the total fixable gene effects was higher than unfixable gene effects for AC, but opposite results was found for CC. Both negative and positive correlations between AC and CC were obtained in different generations. [ABSTRACT FROM AUTHOR]

Ten genotypes of eggplant (Solanum melongena L.) comprising of four genitors and six hybrids generated using diallel crosses were evaluated to estimate the magnitude of genetic variability, their general combing ability (GCA) and specific combining ability (SCA) for improved growth and yield of eggplant. The results obtained showed a significant (p ≤ 0.05) difference among the genotypes in all the traits studied. The highest fruit yield per plant and fruit yield per hectare was obtained in 'Yalo' x 'K3' combination, with 1.77 kg per plant and 50.50 tonnes per hectare, respectively. The cluster analysis grouped the studied genotypes into three and six clusters for genitors alone and genitors with first filial generation (F1s), respectively. Principal component analysis showed that number of leaves, number of fruits and number of branches per plant contributed more to the total variations observed in the eggplant populations. Significant GCA and SCA effect were obtained for most characters analyzed, indicating the importance of both additive and non-additive genetic components. The genotype 'Iyoyo' was the best general combiner in regard to days to flowering and number of fruits per plant. 'Yalo' was the best general combiner in fruits' circumference and diameter, fruit yield per plant and per hectare. The cross 'Uyo' x 'Iyoyo' was the best specific combiner in days to flowering, whereas 'K3' x 'Iyoyo' and 'Yalo' x 'K3' were the best specific combinations in number of fruits, fruit yield per plant and per hectare. [ABSTRACT FROM AUTHOR]

Cowpea [Vigna unguiculata (L.) Walp.] is one of the most widely adapted grain legumes in hot regions of Africa, Asia and the Americas. In the semiarid Northeast of Brazil, it is the main subsistence crop, an excellent protein source of low cost, for the poor population. The objective of this work was to estimate genetic parameters to understand the inheritance of seed sizes in cowpea. The parents P1 and P2 and the generations, F1, F2, BC1 and BC2 of the cross TVx5058-09C X Manteiguinha formed the genetic material for this study. These six generates (P1, P2, F1, F2, BC1 and BC) were evaluated in a completely randomized block-design with six replications, in Teresina - PI, Brazil, in 1998. The genetic parameters estimated were: phenotypic and total genetic variance, additive and dominance genetic components of variance and the variance attributed to the environment, heritability in the broad and narrow senses, average degree of dominance and the number of genes controlling the character. The additive - dominance model fitted the data for 100-seeds weight in as much as the midparental value and the additive effect were the more important genetic parameters for the determination of this character. The number of genes that control its expression is five. The occurrence of high values for narrow sense heritability indicates that the selection for seed size can be made in early generations.Caupi [Vigna unguiculata (L.) Walp.] é uma das leguminosas mais adaptadas às regiões quentes da África, Ásia e das Américas. No semi-árido do nordeste do Brasil é a principal cultura de subsistência, por ser uma excelente fonte de proteína de baixo custo para a população mais carente. O objetivo deste trabalho foi estimar parâmetros genéticos que podem explicar a herança do tamanho das sementes de caupi. Os genótipos parentais P1 e P2 e as gerações F1, F2, RC1 e RC2 do cruzamento TVx5058-09C X Manteiguinha, constituíram o material genético utilizado no estudo. As seis populações (P1, P2, F1, F2, RC1 e RC2) foram avaliadas num experimento em blocos casualizados com seis repetições, em Teresina - PI; o plantio foi realizado em março de 1998. Os parâmetros genéticos estimados foram variâncias fenotípica, genética total, genética aditiva e dos desvios de dominância e devido aos efeitos do ambiente, herdabilidades no sentido amplo e restrito, grau médio de dominância e número dos genes que controlam o caráter. O modelo aditivo - dominante ajustou-se aos dados do peso de 100 sementes, visto que a média e o efeito gênico aditivo foram os parâmetros genéticos mais importantes na determinação desse caráter. O número dos genes que controlam sua expressão é cinco. A ocorrência de alto valor para a herdabilidade no sentido restrito indicou que a seleção para o tamanho da semente pode ser realizada em gerações segregantes iniciais.

Diallel crosses, without reciprocals, among eight new yellow maize inbred lines derived from different maize populations were made in 2012 season at Experimental Farm, Faculty of Agriculture, Minufiya University at Shebin El- Kom. The resultant 28 crosses along with the check hybrid SC 166 were evaluated in a randomized complete block design with three replications conducted at two locations, i.e. Shebin El-Kom and Alexandria in 2013 season. The results indicated that mean squares due to crosses, G.C.A. and S.C.A. were highly significant for all studied traits indicating the importance of both additive and non-additive gene effects in the inheritance of these traits. The parental inbred lines P 1 , P 6 and P 7 had significant positive G.C.A. effects for grain yield. For other traits, the best general combiner were P 5 and P 7 for earliness and P4 for both shorter plants and lower ear placement. The best cross combinations for earliness were P 2 × P 4 and P 3 × P 6 . Concerning plant and ear heights, the crosses P 1 × P 2 , P 5 × P 7 and P 5 × P 8 had the shortest plants with the lowest ear placement. The crosses P 1 × P 6 , P 2 × P 4 , P 3 × P 6 and P 7 × P 8 had the best S.C.A. effects for grain yield. The crosses P 1 × P 6 and P 3 × P 6 significantly out yielded the check hybrid SC166. The crosses P 1 × P 6 and P 3 × P 6 observed the highest percentage of heterosis for yield over the check variety. Six crosses showed significant negative heterosis for days to 50% silking. For short plant and lower ear placement, the crosses P 1 × P 2 and P 3 × P 4 showed negative heterosis. These promising crosses may be released as commercial hybrids after further evaluation. [ABSTRACT FROM AUTHOR]

Six white maize (Zea mays L.) inbred lines were crossed in a half diallel mating scheme at Gemmeiza Agric. Res. Stn. in 2009 season. In 2010 season, the resulting lS crosses along with three check hybrids.; SC 10, SC 128 and SC 129 were evaluated at Gemmeiza and Mallawy Agric. Res. Stations. General combining ability (GCA) and specific combining ability (SCA) effects were estimated according to Griffing (19S6) model 1, method 4. Location mean squares were highly significant for ear diameter and 100-Kernel weight, while crosses and cross x location interaction mean squares were highly significant for all traits. Mean squares due to GCA and SCA were significant revealing that both additive and non-additive types of gene effect were involved in the inheritance of the studied traits. GCA/SCA mean square exceeded the unity for no. of rows ear-1 at Mallawy and combined data, no. of kernels row-1 at Gemmeiza and grain yield at Gemmeiza and combined data, indicated the predominance of additive (a) and (aa) gene effects in the genetic variance of these cases, while the same ratio mean squares were less than unity for the rest of the cases indicating that non-additive genes played an important role in the inheritance of these traits. 'P3' was considered as a good general combiner for 100-kernel weight at Gemmeiza. The cross; P2 x PS had significant inter-and intra-allelic interactions for no. of kernels row-1, 100-kernel weight and grain yield at both locations. The crosses; P2 x PS, P3 x P4 and P3 x P6 were superior to the three check hybridS'for 100-kernel weight and grain yield. [ABSTRACT FROM AUTHOR]

Six yellow maize (Zea mays L.) inbred lines were crossed in a half diallel mating scheme at Gemmeiza Agric. Res. Stn. in 2009. In 2010, the resulting lS crosses along with three check hybrids; SC 162, SC 164 and SC 166 were evaluated at Gemmeiza and Mallawy, where GCA and SCA effects were estimated'; Location and crosses mean squares were significant for all traits except for no. of rows ear-1, Significant cross x location interaction mean squares were recorded for all traits, except for ear diameter and no. of rows ear-1, The mean squares associated with GCA and SCA were significant for all traits at both locations and also in the combined analysis, indicating that both additive and non-additive gene effects were involved in the inheritance of the traits. The ratio of GCA/SCA mean squares exceeded the unity for no. of rows ear-1 and no. of kernels row-1 at the two locations, and their combir.ied analysis. However, the same ratio was less than unity for ear diameter, 100-kernel weight and grain yielq fed.-1 at the two locations and their combined analysis, indicating that additive (a) and (aa) gene effects play an important role in the inheritance of the traits in the first case and non-additive was predominant in the second one. The ratio of GCA x L/SCA x L mean squares was less than unity for ear diameter, 100-kwt·and grain yield fed.-1, indicating that nonadditive genes were more interacted with location than additive ones for the traits in question, while the same ratio exceeded the unity for no. of rows ear-1 and no. of kernels row-1, indicating that additive (a) and (aa) changed with changing the environments. The parental genotype (P2) was a good general combiner for no. of kernels row-1 and 100-kwt at Gemmeiza, while P4 was cpnsidered as a good general combiner for no. of rows ear-1 and 100-kernel weight at Mallawy and for no. of kernels row-1 at Gemmeiza. The ·same parental genotype performed as a good general combiner for ear diameter, no. of rows ear-1 and grain yield fed.-1 at Mallawy. The crosses; Pl x P3 and PS x P6 had significant inter-and intra-allelic interactions for ear diameter at both locations and their combined data, no. of kernels row-1 at Gemmeiza and combined data and grain yield fed.-1 at Mallawy. Moreover, the crosses; Pl x P2, P2 x P4, P3 x P6 and PS x P6 surpassed the three check hybrids with respect to grain yield. [ABSTRACT FROM AUTHOR]

Little information is available on the genetics of physiological traits for drought tolerance in Indian mustard. Generation mean analysis was performed using two crosses (Maya x BPR 543-2) and (BPR-543-2 x BPR-2) to study the nature and magnitude of gene effects on seed yield and physiological characters in Indian mustard. The F1, F2, BC1 and BC2 of these crosses, along with P1 and P2, were studied for eight physiological traits. As to the water use efficiency, the dominance (h) and dominance x dominance (l) non-allelic interactions were found to be the most important in BPR 543-2 x BPR-2 cross. In Maya x BPR-543-2, negative significant values of h and l were observed. Water use efficiency also showed duplicate-type epistasis in both crosses; indicating that l gene interaction effect or other types of digenic complementary gene interaction could be exploited effectively by selection for improvement of this character. The seed yield per plant in the cross Maya x BPR-543-2 showed d, h, and additive x additive (i) types of gene interaction, which means that this trait is under the control of fixable and non fixable gene effects. The i gene interaction and duplicate epistasis seen in this trait suggest possibilities of obtaining transgressive segregants in later generations. [ABSTRACT FROM AUTHOR]

The development of sunflower hybrids with high genetic potential for seed and oil yields requires information on the general combining ability (GCA) and specific combining ability (SCA) for plant height and head diameter in the F1 generation. Used in this study were thirteen new divergent cms inbred lines (A), three Rf restorers utilized as testers, and their F1 hybrids. The inbred A-lines, Rf-testers and F1 hybrids differed significantly in the mean values for plant height and head diameter. The mode of inheritance for plant height was superdominance of the better parent and for head diameter it was dominance and superdominance of the better parent. Highly significant positive values of GCA for both traits were found in cms inbred line NS-G-7 and restorer line RHA-N-49. Based on the GCA values chosen were lines with the best GCA for plant height (NS-G-9, NS-G-7) originating from PRA-RUN and head diameter (NS-G-13, NS-G-12) originating from DES. The greatest highly significant positive SCA value was found in NS-G-1xRHA-N-49 for plant height and in NS-G-8xRUS-RF-OL-168 for head diameter. Non-additive genetic variance played the main role in the inheritance of both traits as confirmed by the GCA/SCA ratios in the F1 generation, which were invariably smaller than unit. The female A lines had the highest contribution to the expression of head diameter and plant height. [ABSTRACT FROM AUTHOR]

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With 1 figure and 6 tables Abstract Heritability and gene effect estimates for components of partial resistance to grey leaf spot were evaluated in Eastern Tanzania, using three populations derived from grey leaf spot partial-resistant maize inbred lines K36 and P103 and susceptible inbred lines CML 395-5 and L37 by generation mean analysis. Populations included the resistant parents (P1), susceptible parents (P2), F1 and F2 generations and backcross BC1 and BC2 generations. Significant differences between generations, crosses and generation × cross and generation × location interactions were detected. Measurements for components conferring partial resistance to grey leaf spot behaved in a quantitative manner. The magnitude of additive, dominance and epistatic effects varied between crosses and components. Broad- and narrow-sense heritability estimates were high for disease severity, lesion length and lesion size but lower for incubation period. Results have shown that lesion size, lesion length, lesion numbers and disease severity could be used for selection of partial resistance to grey leaf spot based on field measurements. [ABSTRACT FROM AUTHOR]

The effects of genes are commonly estimated using random regression models based on test-day data and only give a general gene effect. Alternatively, lactation curve models can be used to estimate biological and environmental effects, or to predict missing test-day data and perform breeding value estimation. This study combines lactation curve models and estimation of gene effects to represent gene effects in different stages of lactation. The lactation curve models used were based on the Wood, Wilmink, and Ali and Schaeffer models. A random regression test-day model was used to compare estimated gene effects with the results of commonly used models. The well-characterized DGAT1 gene with known effects on milk yield, milk fat, and milk protein production was chosen to test this new approach in a Holstein-Friesian dairy cattle population. The K232A polymorphism and the promoter VNTR (variable number of tandem repeats) of the DGAT1 gene were used. All lactation curve models predicted the production curves sufficiently. Nevertheless, for predicting genotype effects, the Wilmink curve indicated the closest fit to the data. This study shows that the characteristic gene effects for DGAT1 genotypes occur after lactation d 40, which might be explained by a link to other genes affecting metabolic traits. Furthermore, allele substitution effects of allele K of the K232A locus showed that the typical effect of low milk and protein yield is due mainly to a lower overall production level, whereas the higher fat and protein content is reached by increased production toward its peak and fat yield is increased because of a higher production after this peak. Predicting gene effects with production curves gives better insight into the timeline of gene effects. This can be used to form genetic groups, in addition to feeding groups, for managing livestock populations in a more effective way. [ABSTRACT FROM AUTHOR]