Genetic parameters controlling the inheritance of glaucousness and yield traits in bread wheat / Parâmetros genéticos que controlam a herança de glaucosidade e características de produção em trigo mole

Wheat breeders frequently use generation mean analysis to obtain information on the type of gene action involved in inheriting a trait to choose the helpful breeding procedure for trait improvement. The present study was carried out to study the inter-allelic and intra-allelic gene action and inheritance of glaucousness, earliness and yield traits in a bread wheat cross between divergent parents in glaucousness and yield traits; namely Mut-2 (P1) and Sakha 93 (P2). The experimental material included six populations, i.e. P1, P2, F1, F2, BC1, and BC2 for this wheat cross. A randomized complete block design with three replications was used, and a six parameters model was applied. Additive effects were generally more critical than dominance for all studied traits, except for plant height (PH) and grain yield/plant (GYPP). The duplicate epistasis was observed in spike length; SL, spikes/plant; SPP and days to heading; DTH. All six types of allelic and non-allelic interaction effects controlled SL, GYPP, DTH and glaucousness. All three types of epistasis, i.e. additive x additive, additive x dominance, and dominance x dominance, are essential in determining the inheritance of four traits (SL, GYPP, DTH and glaucousness). Dominance × dominance effects were higher in magnitude than additive × dominance and additive × additive in most traits. The average degree of dominance was minor than unity in six traits (glaucousness, grains/spike, spike weight, days to maturity, 100-grain weight and SL), indicating partial dominance and selection for these traits might be more effective in early generations. Meanwhile, the remaining traits (PH, SPP, GYPP and DTH) had a degree of dominance more than unity, indicating that overdominance gene effects control such traits and it is preferable to postpone selection to later generations. The highest values of [...].

Os criadores de trigo frequentemente usam a análise da média de geração para obter informações sobre o tipo de ação do gene envolvida na herança de uma característica para escolher o procedimento de melhoramento útil para o aprimoramento da característica. O presente estudo foi conduzido para estudar a ação do gene interalélico e intraalélico e a herança de características de glaucosidade, precocidade e produção em um cruzamento de trigo mole entre pais divergentes em glaucosidade e características de produção; nomeadamente Mut-2 (P1) e Sakha 93 (P2). O material experimental incluiu seis populações, ou seja, P1, P2, F1, F2, BC1 e BC2 para este cruzamento de trigo. O delineamento experimental foi em blocos ao acaso com três repetições e aplicado um modelo de seis parâmetros. Os efeitos aditivos foram geralmente mais críticos do que a dominância para todas as características estudadas, exceto para altura da planta (AP) e rendimento de grãos / planta (GYPP). A epistasia duplicada foi observada no comprimento da ponta; SL, espigas / planta; SPP e dias para o cabeçalho; DTH. Todos os seis tipos de efeitos de interação alélica e não alélica controlaram SL, GYPP, DTH e glaucosidade. Todos os três tipos de epistasia, ou seja, aditivo x aditivo, aditivo x dominância e dominância x dominância, são essenciais na determinação da herança de quatro características (SL, GYPP, DTH e glaucosidade). Os efeitos de dominância × dominância foram maiores em magnitude do que aditivo × dominância e aditivo × aditivo na maioria das características. O grau médio de dominância foi menor do que a unidade em seis características (glaucosidade, grãos / espiga, peso da espiga, dias até a maturidade, peso de 100 grãos e SL), indicando dominância parcial, e a seleção para essas características pode ser mais eficaz nas gerações iniciais. Enquanto isso, os traços restantes (PH, SPP, GYPP e [...].

Genetic parameters controlling the inheritance of glaucousness and yield traits in bread wheat

Abstract Wheat breeders frequently use generation mean analysis to obtain information on the type of gene action involved in inheriting a trait to choose the helpful breeding procedure for trait improvement. The present study was carried out to study the inter-allelic and intra-allelic gene action and inheritance of glaucousness, earliness and yield traits in a bread wheat cross between divergent parents in glaucousness and yield traits; namely Mut-2 (P1) and Sakha 93 (P2). The experimental material included six populations, i.e. P1, P2, F1, F2, BC1, and BC2 for this wheat cross. A randomized complete block design with three replications was used, and a six parameters model was applied. Additive effects were generally more critical than dominance for all studied traits, except for plant height (PH) and grain yield/plant (GYPP). The duplicate epistasis was observed in spike length; SL, spikes/plant; SPP and days to heading; DTH. All six types of allelic and non-allelic interaction effects controlled SL, GYPP, DTH and glaucousness. All three types of epistasis, i.e. additive x additive, additive x dominance, and dominance x dominance, are essential in determining the inheritance of four traits (SL, GYPP, DTH and glaucousness). Dominance × dominance effects were higher in magnitude than additive × dominance and additive × additive in most traits. The average degree of dominance was minor than unity in six traits (glaucousness, grains/spike, spike weight, days to maturity, 100-grain weight and SL), indicating partial dominance and selection for these traits might be more effective in early generations. Meanwhile, the remaining traits (PH, SPP, GYPP and DTH) had a degree of dominance more than unity, indicating that overdominance gene effects control such traits and it is preferable to postpone selection to later generations. The highest values of narrow-sense heritability and genetic advance were recorded by glaucousness trait followed by SL and SPP, indicating that selection in segregating generations would be more effective than other traits.

Resumo Os criadores de trigo frequentemente usam a análise da média de geração para obter informações sobre o tipo de ação do gene envolvida na herança de uma característica para escolher o procedimento de melhoramento útil para o aprimoramento da característica. O presente estudo foi conduzido para estudar a ação do gene interalélico e intraalélico e a herança de características de glaucosidade, precocidade e produção em um cruzamento de trigo mole entre pais divergentes em glaucosidade e características de produção; nomeadamente Mut-2 (P1) e Sakha 93 (P2). O material experimental incluiu seis populações, ou seja, P1, P2, F1, F2, BC1 e BC2 para este cruzamento de trigo. O delineamento experimental foi em blocos ao acaso com três repetições e aplicado um modelo de seis parâmetros. Os efeitos aditivos foram geralmente mais críticos do que a dominância para todas as características estudadas, exceto para altura da planta (AP) e rendimento de grãos / planta (GYPP). A epistasia duplicada foi observada no comprimento da ponta; SL, espigas/planta; SPP e dias para o cabeçalho; DTH. Todos os seis tipos de efeitos de interação alélica e não alélica controlaram SL, GYPP, DTH e glaucosidade. Todos os três tipos de epistasia, ou seja, aditivo x aditivo, aditivo x dominância e dominância x dominância, são essenciais na determinação da herança de quatro características (SL, GYPP, DTH e glaucosidade). Os efeitos de dominância × dominância foram maiores em magnitude do que aditivo × dominância e aditivo × aditivo na maioria das características. O grau médio de dominância foi menor do que a unidade em seis características (glaucosidade, grãos / espiga, peso da espiga, dias até a maturidade, peso de 100 grãos e SL), indicando dominância parcial, e a seleção para essas características pode ser mais eficaz nas gerações iniciais. Enquanto isso, os traços restantes (PH, SPP, GYPP e DTH) tiveram um grau de dominância maior do que a unidade, indicando que os efeitos do gene de superdominância controlam tais traços e é preferível adiar a seleção para gerações posteriores. Os maiores valores de herdabilidade no sentido restrito e avanço genético foram registrados pelo traço de glaucosidade seguido por SL e SPP, indicando que a seleção em gerações segregadas seria mais eficaz do que outros caracteres.

Genetic parameters controlling the inheritance of glaucousness and yield traits in bread wheat / Parâmetros genéticos que controlam a herança de glaucosidade e características de produção em trigo mole

Wheat breeders frequently use generation mean analysis to obtain information on the type of gene action involved in inheriting a trait to choose the helpful breeding procedure for trait improvement. The present study was carried out to study the inter-allelic and intra-allelic gene action and inheritance of glaucousness, earliness and yield traits in a bread wheat cross between divergent parents in glaucousness and yield traits; namely Mut-2 (P1) and Sakha 93 (P2).The experimental material included six populations, i.e. P1, P2, F1, F2, BC1, and BC2 for this wheat cross. A randomized complete block design with three replications was used, and a six parameters model was applied. Additive effects were generally more critical than dominance for all studied traits, except for plant height (PH) and grain yield/plant (GYPP). The duplicate epistasis was observed in spike length; SL, spikes/plant; SPP and days to heading; DTH. All six types of allelic and non-allelic interaction effects controlled SL, GYPP, DTH and glaucousness. All three types of epistasis, i.e. additive x additive, additive x dominance, and dominance x dominance, are essential in determining the inheritance of four traits (SL, GYPP, DTH and glaucousness). Dominance × dominance effects were higher in magnitude than additive × dominance and additive × additive in most traits. The average degree of dominance was minor than unity in six traits (glaucousness, grains/spike, spike weight, days to maturity, 100-grain weight and SL), indicating partial dominance and selection for these traits might be more effective in early generations. Meanwhile, the remaining traits (PH, SPP, GYPP and DTH) had a degree of dominance more than unity, indicating that overdominance gene effects control such traits and it is preferable to postpone selection to later generations. The highest values of narrow-sense heritability and genetic advance were recorded by glaucousness trait followed by SL and SPP, indicating that selection in segregating generations would be more effective than other traits.

Os criadores de trigo frequentemente usam a análise da média de geração para obter informações sobre o tipo de ação do gene envolvida na herança de uma característica para escolher o procedimento de melhoramento útil para o aprimoramento da característica. O presente estudo foi conduzido para estudar a ação do gene interalélico e intraalélico e a herança de características de glaucosidade, precocidade e produção em um cruzamento de trigo mole entre pais divergentes em glaucosidade e características de produção; nomeadamente Mut-2 (P1) e Sakha 93 (P2). O material experimental incluiu seis populações, ou seja, P1, P2, F1, F2, BC1 e BC2 para este cruzamento de trigo. O delineamento experimental foi em blocos ao acaso com três repetições e aplicado um modelo de seis parâmetros. Os efeitos aditivos foram geralmente mais críticos do que a dominância para todas as características estudadas, exceto para altura da planta (AP) e rendimento de grãos / planta (GYPP). A epistasia duplicada foi observada no comprimento da ponta; SL, espigas/planta; SPP e dias para o cabeçalho; DTH. Todos os seis tipos de efeitos de interação alélica e não alélica controlaram SL, GYPP, DTH e glaucosidade. Todos os três tipos de epistasia, ou seja, aditivo x aditivo, aditivo x dominância e dominância x dominância, são essenciais na determinação da herança de quatro características (SL, GYPP, DTH e glaucosidade). Os efeitos de dominância × dominância foram maiores em magnitude do que aditivo × dominância e aditivo × aditivo na maioria das características. O grau médio de dominância foi menor do que a unidade em seis características (glaucosidade, grãos / espiga, peso da espiga, dias até a maturidade, peso de 100 grãos e SL), indicando dominância parcial, e a seleção para essas características pode ser mais eficaz nas gerações iniciais. Enquanto isso, os traços restantes (PH, SPP, GYPP e DTH) tiveram um grau de dominância maior do que a unidade, indicando que os efeitos do gene de superdominância controlam tais traços e é preferível adiar a seleção para gerações posteriores. Os maiores valores de herdabilidade no sentido restrito e avanço genético foram registrados pelo traço de glaucosidade seguido por SL e SPP, indicando que a seleção em gerações segregadas seria mais eficaz do que outros caracteres.

Putative Mechanisms of Drought Tolerance in Maize (Zea mays L.) via Root System Architecture Traits

Identifying maize genotypes with favorable root architecture traits for drought tolerance is prerequisite for initiating a successful breeding program for developing high yielding and drought tolerant varieties of maize. The aims of the present study were: (i) to identify drought tolerant genotypes of maize at flowering and grain filling, (ii) to interpret the correlations between the drought tolerance and root architecture traits and (iii) to identify the putative mechanisms of drought tolerance via root system traits. An experiment was carried out in two years using a split plot design with three replications. The main plots were assigned to three water stress levels, namely: well watering (WW), water stress at flowering (WSF) and water stress at grain filling (WSG), and sub-plots to 22 maize cultivars and populations. Drought tolerance index (DTI) had strong and positive associations with crown root length (CRL), root circumference (RC) and root dry weight (DRW) under both WSF and WSG, a negative correlation with brace root whorls (BW), and positive correlations with crown root number (CN) under WSF and brace root branching (BB) and crown root branching (CB) under WSG. These root traits are therefore considered as putative mechanisms of drought tolerance. The cultivars Pioneer-3444, SC-128, Egaseed-77, SC-10 and TWC-324 showed the most drought tolerant and the highest yielding in a descending order; each had a number of such drought tolerance mechanisms. Further investigation should be conducted to determine the underlying root mechanisms contributing to the selection of water-efficient hybrids of maize.

The Effects of Genotype, Soil Water Deficit and Their Interaction on Agronomic, Physiologic and Yield Traits of Zea mays L.

The presence of genotypic differences in performances under soil water deficit would help plant breeders in initiating successful breeding programs to improve drought tolerance. The objectives of the present study were: (i) to assess the effects of genotype, water stress and their interaction on maize agronomic, physiologic and yield traits and (ii) to identify drought tolerant genotypes for use in future breeding programs. Fifteen commercial hybrids and seven breeding populations were evaluated in the field for two seasons under water stress at flowering (WSF) and grain filling (WSG) compared to well watering (WW). A split plot design with three replications was used. Data analysed across seasons revealed a significant reduction in grain yield/plant (28.69 and 20.26%), grain yield/ha (35.53 and 25.51%), chlorophyll concentration index (30.18 and 44.07%) and 100-kernel weight (6.75 and 12.36%) due to water stress under WSF and WSG, respectively, a significant reduction in ears/plant (11.58%), kernels/row (14.23%), kernels/plant (24.85%) due to water stress under WSF and in upper stem diameter (18.46%) due to water stress under WSG, but a significant increase in days to silking (3.50%), anthesis silking interval (21.17%) and barren stalks (26.18%) due to water stress under WSF. Rank of genotypes differed from one irrigation regime to another for most studied traits. The highest yielding genotypes were Eg-77, P-3444, SC-128 and HT-2066 under WSF and P-3444, SC-128, TWC-324 and SC-166 under WSG, in a descending order. These genotypes could be offered to maize breeding programs for developing drought tolerant inbred and hybrids.

Agronomic and Yield Characteristics of Grain Sorghum as Influenced by Environment Factors and Genotype

Genotypes tested in different locations, years or planting dates often change in yield due to the response of genotypes to environmental factors such as temperature, soil fertility etc. The objectives of the present study were to evaluate the effects of environment factors on agronomic and yield characteristics of grain sorghum and to identify the most adapted B-line(s) to different environments in Egypt. Six environments with 25 sorghum B-lines were conducted at two locations (Giza and Shandaweel) in 2012 and 2013 years and two planting dates in Giza location. A randomised complete block design was used in each environment with three replications. Mean squares due to genotype × environment were significant for all studied traits. Increasing temperature from second planting date to first planting date in Giza across seasons caused the significant decrease in grain yield per plant (GYPP) by about 15.3%. This reduction in yield was associated with significant decreases in the number of grains/plant (GPP) (9.29%), plant height (PH) (7.31%) and days to 50% flowering (DTF) (6.92%). Moreover, higher temperature in 2012 than 2013 season in Shandaweel caused significant (p<0.01) reduction in GYPP by 18.04%, GPP (34.76%) and DTF (8.33%). Though the temperature was higher in Shandaweel than Giza, the increase in GYPP in Shandaweel than Giza could probably due to the better physical and chemical properties of the soil. Across all environments, the B-line BTX-TSC-20 followed by ICSB-88003 showed the highest GYPP. BTX-TSC-20 followed by ICSB-1808 under E1 and E3 environments (Giza, first planting date in 2012 and 2013), ICSB-14 and ICSB-88003 under E2 and E4 (Giza, second planting date in 2012 and 2013), ICSB-11 followed by BTX 2-1 under E5 (Shandaweel, 2012 season) and ICSB-88003 followed by ICSB-70 under E6 (Shandaweel, 2013 season) were the most adapted B-lines.

Yield Adaptability and Stability of Grain Sorghum Genotypes across Different Environments in Egypt using AMMI and GGE-biplot Models

Presence of G×E interaction reduces the correlation between genotypic and phenotypic parameters and complicates progress of selection. Among several methods proposed for evaluation of the GE interaction, the AMMI and GGE-biplot are the most informative models. The objective of this study was to estimate the G×E interaction in sorghum parental lines and to identify sorghum B-lines of stability and adaptability across different environments using the AMMI and GGE-biplot models. Six environments with 25 sorghum B-lines were conducted at two locations in Egypt (Giza and Shandaweel) in two years and two planting dates in one location (Giza). A randomized complete block design was used in each environment (yield trial) with three replications. The AMMI analysis of variance indicated that the genotype (G), environment (E) and GE interaction had significant influence (p≤0.01) on sorghum grain yield. Based on AMMI model, BTX TSC-20 followed by ICSB-1808 showed both high yielding and stability across the test environments. However, ICSB-8001 (G11) and BTX-407 (G21), showed maximum stability, but with moderate grain yield. Based on GGE-biplot method, BTX TSC-20 (G25) was the winning genotype for the mega-environment which consists of E1 and E3, ICSB-14 (G3) for the mega-environment (E2 and E4), while BTX 2-1 (G20) for E5 mega-environment, ICSB-88003 (G12) and ICSB-70 (G6) for the mega-environment E6. These genotypes are the most adapted to the respective environments.

Leaf Amino Acids and Anatomical Traits of Drought Tolerant vs Sensitive Genotypes of Quinoa (Chenopodium quinoa Willd.) under Elevated Levels of Water Stress

Many plants accumulate compatible osmolytes at high levels in plant cells such as amino acids and/or develop special epidermal cell bladders which may serve as external water reservoirs and having small and thick-walled cells in response to water deficit. The objectives of the present investigation were: (i) to study effects of water stress on the anatomical traits and accumulation of free amino acids in quinoa leaves and (ii) to describe differences among drought tolerant and sensitive genotypes in such traits following the imposition of water deficit. A field experiment was carried out in the growing season 2015/2016, using a split plot design with five replications. Main plots were allotted to three irrigation regimes, i.e. well watering (WW) [95% field capacity (FC)], moderate water stress (WS) [65% FC] and severe water stress (SWS) [35% FC] and sub plots to five genotypes. Mean squares due to genotypes, irrigation regimes and their interaction were significant (p≤0.01) for studied leaf free amino acids and anatomical traits. Water stress caused a significant decrease in leaf thickness under WS and SWS, upper and lower epidermis under WS, palisade and spongy layers under SWS, but caused a significant increase in palisade and spongy layers under WS and upper and lower epidermis under SWS. The genotype CICA-17 (tolerant) had the thickest leaf and upper epidermis and second thickest lower epidermis, palisade and spongy layers. Contents of each amino acid were significantly increased due to water stress, except Leucine. Increases in amino acid content increased by increasing severity of water stress. Maximum increase (109.6%) was shown by Threonine under SWS, but minimum (8.08%) was by Arginine under WS. Under SWS, the tolerant genotype CICA-17 showed the highest mean increase percentage (47.9%) in total amount of amino acids relative to WW; it showed the highest increase in all amino acids, especially Proline, Methionine and Phenylalanine.

Heterobeltiosis in Wheat (Triticum aestivum L.) F1 Diallel Crosses under Contrasting Soil-N Conditions.

Breeding wheat cultivars with improved adaptation to low soil-N, has gained importance worldwide in order to decrease N fertilizer consumption and overcome the ecological and economic problems of the misuse of this fertilizer. Identification of wheat crosses that show useful heterosis (heterobeltiosis) is an important issue in breeding programs. The main objective of the present investigation was to estimate heterobeltiosis for nitrogen use efficiency and other studied traits of F1 diallel crosses among six wheat parents in order to identify the superior ones for future use in breeding programs. Genetic materials were evaluated at two seasons (2007/2008 and 2008/2009) in a split-plot design with randomized complete block arrangement, using three replications. Main plots were assigned to N levels (0 and 75 kg N/fed), while sub plots were devoted to genotypes. Data combined across the two seasons were presented. In general, low N caused a significant reduction in 9 out of 14 studied traits. These reductions were relatively high in magnitude for number of spikes/ plant (SPP) for parents (23.65%) and F1's (23.99%). On the contrary, low–N caused increases in the averages of nitrogen use efficiency (NUE) by 89.5 and 97.60% for parents and F1's, respectively. Averages of heterobeltiosis for all studied characters were either nonsignificant or significant but non favorable, except for plant height under both low and high N, NUPE under high N and GPS under low N. However, some crosses for each trait showed significant and favorable heterobeltiosis. Under low–N, the highest favorable and significant heterobeltiosis estimate was shown by L27 x Gem 7 for GYPP (14.94%), NUTE (44.81%) and GPS (25.82%), L25 x L26 for 100 GW (13.87%), L 25 x L 27 for SPP (12.53%), L 27 x Gem 9 for GPS (26.19%) and Gem 7 x Gem 9 for BYPP (28.99%).

Morphological and SSR Assessment of Putative Drought Tolerant M3 and F3 Families of Wheat (Triticum aestivum L.).

In an attempt to develop drought tolerant genotypes of bread wheat, two procedures, i.e., mutation and hybridization were used to induce new genetic variation. Selection for high grain yield/plant (GYPP) and other desirable traits was practiced in the M2 populations of 7 gamma irradiated genotypes and F2 populations of 15 diallel crosses among 6 genotypes of wheat under well watering (WW) and water stress (WS) conditions. Progenies of these selections (53 M3 and 109 F3 families) and their seven parents were evaluated in the field under WW and WS. Significant yield superiority of twelve families (7 M3 ’s and 5 F2 ’s) over their original and better parents, respectively under WS reached 74.71% (SF9). These putative drought tolerant families were assessed on the DNA level using SSR analysis. Fifteen SSR primers were used for PCR amplification of the genomic DNA of these 12 selections and their parents. The SSR analysis proved that the 12 families are genetically different from their 7 parents, with an average polymorphism of 86.67%. The genetic similarities (Gs) ranged from 30% to 88%. Both mutants SF3 and SF4 exhibited very low Gs (42 and 40%, respectively) with their common parent (Giza-168), indicating that gamma rays were very effective in changing the genetic background of Giza-168 towards high GYPP under WS conditions. SSR assay permitted the identification of seven unique bands (5 positive and 2 negative) for three drought tolerant wheat genotypes (SF3, SF4 and Aseel-5). These bands might be considered useful as markers associated with drought tolerance in bread wheat breeding programs.