Grain Yield Of Lines Research Articles

Combining Ability of Certain Agronomic Traits in Quality Protein Maize under Stress and Nonstress Environments in Eastern and Southern Africa

ABSTRACTGrowing maize (Zea mays L.) hybrids tolerant to drought and low‐nitrogen (N) stress would significantly reduce yield losses occurring in Africa. This study evaluated the performance of quality protein maize (QPM) F1 hybrids, and general (GCA) and specific combining ability (SCA) of QPM inbred lines for grain yield and other agronomic traits under stress and nonstress environments. A diallel cross of 15 QPM inbred lines was evaluated under drought and low‐N stresses and optimal conditions in a total of 17 environments in Eastern and Southern Africa. Significant variations were observed among the hybrids for all measured traits. TZMI703 × (6207QB/6207QA), GQL5 × (6207QB/6207QA), and CML511 × (6207QB/6207QA) were identified as the best single crosses across environments. The GCA and SCA mean squares were significant for all measured traits, indicating that additive and nonadditive genetic effects were important in this set of genotypes under all test environments. The GCA effects were more important under drought stress, and SCA effects were more important under low‐N and optimal conditions for grain yield. There was preponderance of GCA effects for most agronomic traits tested in all environmental conditions. Inbred lines CML159SR, GQL5, CML159, and CML312SRQ exhibited favorable GCA effects for grain yield under stress and optimal conditions, indicating that the genetic systems controlling a given trait under different conditions are at least partially similar. Cross combinations with favorable SCA effects for grain yield and other traits were also identified. Generally, this study provided evidence that good performance can be achieved under stress and nonstress conditions in QPM germplasm.

Evaluation of special grains bean lines for grain yield, cooking time and mineral concentrations

Genetic variability of 32 inbred special grains bean lines was investigated for grain yield, mass of 100 grains, cooking time, and mineral concentrations in grains, and Z index was used for selection of superior lines in most of the characters. IAC Centauro, IAC Galante, Xamego, Ouro Branco, Montcalm, and Hooter lines presented high yield grain, short cooking time (less than 24 min), and high potassium (>14 g kg-1dry matter [DM]), calcium (>1.42 g kg-1DM), iron (>97.60 mg kg-1DM), zinc (>29.05 mg kg-1DM) and copper (>8.67 mg kg-1DM) concentrations, and their dietary use is therefore recommended. Cal-96 line presents higher Z index for grain yield and for the most of the minerals, and its use is recommended for crosses for the development of superior lines.

Diallel analysis of maize inbred lines for grain yield, oil and protein content

This study aimed to investigate the combining ability and heterotic effects on grain yield (GY), oil content (OC) and crude protein (CP) in tropical and temperate maize lines. Hybrids and inbred lines were evaluated in a complete diallel scheme without reciprocals, in two experiments in randomized blocks with three replications. The partitioning of the sum of squares for general (GCA) and specific (SCA) combining ability indicated that both additive and non-additive effects were involved in the genetic control of the studied traits. The estimates of the quadratic components showed predominance of non-additive genetic effects in the trait control. However, for OC and CP, the non-additive effect had a clearly negative influence on the hybrid combinations. The cross L6x L10was considered promising, because it associated RG positively with BP and OC.

Análise dialélica parcial em gerações avançadas para seleção de populações segregantes de trigo

O objetivo deste trabalho foi estimar, em gerações avançadas, os efeitos da capacidade geral e específica de combinação de genitores de trigo, bem como selecionar populações segregantes superiores. Doze genitores e suas 36 populações nas gerações F2 e F3, obtidas em arranjo de dialelo parcial, foram avaliados quanto à produtividade de grãos. Utilizou-se o delineamento em látice 7x7, com duas repetições, mais um tratamento para completar o látice. O efeito de capacidade geral de combinação foi significativo, nas duas gerações. Observou-se alta correlação (0,83) dos efeitos de capacidade geral de combinação entre gerações, mas inexpressiva influência dos efeitos de gerações e de anos na classificação dos cruzamentos. As populações provenientes do cruzamento entre os genitores BRS 254, BRS 264 e IAC 364 (Tucuruí III) e os genitores MGS 1 Aliança, VI 98053 e UFVT 1 Pioneiro apresentam maior potencial para obtenção de linhagens superiores, quanto à produtividade de grãos. O uso da análise dialélica parcial em gerações avançadas é promissor para programas de melhoramento de trigo por hibridação.

Combining Ability for Sixteen Promising White Maize Inbred Lines for Grain Yield and Yield Component Traits

Combining Ability for Sixteen Promising White Maize Inbred Lines for Grain Yield and Yield Component Traits

Comparison among direct, indirect and index selections on agronomic traits and nutritional quality traits in common bean

Selection indices are linear combinations that allow the selection of several characters simultaneously. The objective of this study was to verify the efficiency of direct selection, indirect selection and selection indices in the identification of higher inbred common bean lines for grain yield, morphological, phenological and nutritional traits. There is genetic variability for grain yield, lodging, general adaptation note, cycle, insertion of the first pod, calcium and iron concentrations in the seeds. Moderate phenotypic correlation coefficients were observed between grain yield and general adaptation note (r = -0.57) and cycle (r = -0.57). When direct selection was performed for grain yield, the insertion of the first pod, calcium and iron concentrations showed negative indirect selection gains. The classic index showed that the distribution of gains has become more balanced: grain yield (39.05%), calcium (8.29%) and iron concentration (1.64%). Direct selection and indirect selection are not efficient in the simultaneous selection of agronomic traits and nutritional quality in common bean. The classical, base and multiplicative indexes provide responses of gain balanced among traits and superior genetic progress in the selection of inbred common bean lines, and have a high coincidence between the lines selected.

Comparison of Conventional, Modified Single Seed Descent, and Doubled Haploid Breeding Methods for Maize Inbred Line Development Using Germplasm Enhancement of Maize Breeding Crosses

ABSTRACTBreeding crosses from the Germplasm Enhancement of Maize (GEM) project between exotic accessions and elite Corn Belt Dent inbreds provide a unique opportunity for broadening the genetic base of the U.S. maize (Zea mays L.) crop by incorporating favorable exotic alleles in elite genetic backgrounds. Genetic gains in the GEM program could be enhanced by identifying more efficient breeding procedures for this purpose. We compared four breeding methods, conventional Germplasm Enhancement of Maize (CG), conventional mass (CM), modified single seed descent (MSSD), and doubled haploid (DH) methods, for their relative capacity to produce superior maize inbred lines and hybrids from three GEM breeding crosses: (ANTIG01 × N16) × DE4, (AR16035 × S02) × S09, and (DKXL212 × S09) × S43b. Testcross evaluations of 50 selected lines from each combination of cross and breeding method were conducted across multiple environments, generally revealing no differences among breeding methods. The MSSD and CM methods had higher proportions of the top 10 lines for grain yield and yield:moisture ratio in the second year testcross reevaluations of about the top 28% of lines. Hybrids from MSSD lines tended to have higher grain moisture, but MSSD hybrids with high yield:moisture ratio could still be identified. The MSSD method may be an effective and efficient alternative to both pedigree and DH methods for developing high performing lines from the GEM breeding crosses as it requires relatively fewer resources.

Quality and Agronomic Effects of Three High‐Molecular‐Weight Glutenin Subunit Transgenic Events in Winter Wheat

ABSTRACTQuality and agronomic effects of three transgenic high molecular weight glutenin subunit (HMW‐GS) events were characterized in advanced‐generation breeding lines of hard winter wheat (Triticum aestivum L.) in three Nebraska crop years. Two of the transgenic events studied, Dy10‐E and B52a‐6, overexpress HMW‐GS 1Dy10, while the third event, Dx5 +Dy10‐H, overexpresses HMW‐GS 1Dx5 and, to a much lesser extent, 1Dy10. In addition, novel proteins possessing solubility characteristics defined as HMW‐GS were present in Dx5+Dy10‐H and B52a‐6. Average grain yield of lines derived from the three transgenic events was statistically lower than that of a group of control cultivars and advanced breeding lines, but not lower than the mean values of respective nontransgenic siblings. Grain hardness was influenced by one of the events. Dx5+Dy10‐H produced harder kernels than controls, its nontransgenic siblings, and the two additional transgenic events. All three events produced doughs with unusual mixing properties, although not likely to be directly useful in commercial applications. As a consequence, loaf volumes were depressed to variable degrees by the three events. The results indicated that over‐expression of HMW‐GS could eventually lead to improved breadmaking quality by optimizing the level of overexpression or by development and characterization of additional events.

Combining abilities of maize inbred lines for grain yield and yield components

Diallel mating design experiment with reciprocal crosses was used to determine combining abilities of five maize inbred lines and their hybrid combinations for grain yield, ear length, ear diameter, number of kernel rows per ear, number of kernels per row in 2005. and 2006. year. GCA and SCA significant values were observed for all traits under study in both years. GCA/SCA relation showed that dominant gene effect had prevalent influence in the inheritance of grain yield, ear length and ear diameter. Additive gene effect had larger importance in the inheritance of number of kernel rows per ear. NS-1445 inbred line showed best GCA effect for grain yield, ear length and number of kernels per row, but worst GCA effect for number of kernel rows per ear. Best GCA effect for ear diameter achieved inbred line F-7R. Line BL-47 showed best GCA effect for number of kernel rows per ear in both years, but also the worst GCA effect for grain yield and number of kernels per row. Hybrid combination NS-1445 x BL-47 showed largest SCA effect for grain yield in both years and also showed, like hybrid combination F-7R x NS-1445, significant SCA effects for all other traits, except ear diameter. This cross also proved that hybrid combinations that include one parent with good GCA effect and the other parent with bad GCA effect can have very successful performance. It will be useful during selection material testing, to keep also genotypes which show bad GCA effect, but have phenotypic favorable trait values. Reciprocity effect was significant for SCA effects of all traits but ear diameter. It is the conformation of involvement of plasmagenes in maize quantitative traits inheritance. The largest reciprocity effect for grain yield achieved F-7R x BL-47 in both years. Significantly higher grain yield in this hybrid combination was achieved when line F-7R was used as a female parent and significantly higher number of kernel rows per ear was achieved when line BL-47 was used as a female parent.

Interação genótipo x ambiente na produtividade de grãos de linhagens e cultivares de feijão

The objective of this work was to evaluate the effects of the genotype x environment interaction in the grain yield in lines and cultivars of common bean, as well as to give directions for breeding programs to develop superior cultivars. During the 2005/2006 agricultural year, an assay was conducted in the wet and dry cropping seasons, at three IAPAR Experimental Stations, totaling six environments. Complete randomized blocks, with 20 genotypes and three replications were used. Each plot had two lines of 5 m, 0.5 m between rows, and 15 plants m -1 . Number of days to flowering and physiological maturity of the grains and grain yield were assessed. The individual and combined analyses of variance indicated significant differences among genotypes, environments and for the G x A interaction, at 1 and 5% levels of probability, revealing that the evaluated genotypes performed differently according to the environment in which the tests were performed. The following lines were selected: LPSIA04-103, LPSIA04-104 LPSIA04-106 and LPSIA04-108. All lines showed precocity (shorter number of days to flowering and physiological maturity of the grains), high grain yield and wide adaptability.

Interação genótipo x ambiente na produtividade de grãos de linhagens e cultivares de feijão

The objective of this work was to evaluate the effects of the genotype x environment interaction in the grain yield in lines and cultivars of common bean, as well as to give directions for breeding programs to develop superior cultivars. During the 2005/2006 agricultural year, an assay was conducted in the wet and dry cropping seasons, at three IAPAR Experimental Stations, totaling six environments. Complete randomized blocks, with 20 genotypes and three replications were used. Each plot had two lines of 5 m, 0.5 m between rows, and 15 plants m-1. Number of days to flowering and physiological maturity of the grains and grain yield were assessed. The individual and combined analyses of variance indicated significant differences among genotypes, environments and for the G x A interaction, at 1 and 5% levels of probability, revealing that the evaluated genotypes performed differently according to the environment in which the tests were performed. The following lines were selected: LPSIA04-103, LPSIA04-104 LPSIA04-106 and LPSIA04-108. All lines showed precocity (shorter number of days to flowering and physiological maturity of the grains), high grain yield and wide adaptability.

Diallel analysis of grain yield and resistance to seven diseases of 12 African maize (Zea mays L.) inbred lines

Maize (Zea mays L.) is grown on 15 million ha in eastern and southern Africa. Several diseases are of common occurrence in the region and regularly result in significant yield losses. A collaborative regional disease nursery (REGNUR) project was initiated in 1998 to identify and increase access to disease resistant germplasm, generate and disseminate information on disease and insect resistance sources, and facilitate the development of resistant cultivars by project partners. A diallel among 12 elite inbred lines was formed with the specific objective of evaluating the combining ability of these inbred lines for grain yield and resistance to seven diseases. The trial was grown at six sites in 2001. Results showed that both general (GCA) and specific combining ability effects were significant for most diseases. On the average, GCA accounted for 69% of resistance to diseases and only 37% of variation for grain yield. Correlations between GCA effects for disease scores were generally non-significant, implying that it is possible to pyramid genes for disease resistance in inbred lines. This underscores the need for screening for resistance to prevailing diseases using artificial inoculation or reliable hot-spots. Based on GCA effects for grain yield and across diseases, P12 and P6 were the best inbred lines. The crosses P4 × P9 (6.7 t ha−1) and P4 × P12 (6.9 t ha−1) were the best hybrids in the earlier maturity group, while P3 × P9 (8.3 t ha−1) and P2 × P8 (7.4 t ha−1) were the best hybrids in the late maturity group.

The Combining Ability of Maize Inbred Lines for Grain Yield and Reaction to Grey Leaf Spot Disease

Considering the potential threat of grey leaf spot (GLS) to maize production, the national maize research program of Ethiopia has been screening local and exotic maize genotypes against the disease as the commercially available and advanced inbred lines susceptible to GLS. This experiment was, therefore, conducted to investigate the general (GCA) and specific (SCA) combining ability of selected maize inbred lines for grain yield and GLS disease resistance. Eight maize inbred lines with contrasting reactions to GLS were crossed in diallel mating to generate 28 hybrids. The parents and hybrids were evaluated in randomised complete block design with three replications at Bako, Ethiopia in 2001 and 2002. Significant differences were observed among entries for disease parameters, plant height, days to maturity and grain yield. GCA and SCA effects were significant for all traits. Mean squares due to GCA were higher than that of SCA for all traits, except for grain yield, indicating the predominance of non-additive gene effect for grain yield and additive gene effect for other traits. Some inbred lines with resistance reaction have been identified. Parental lines 143-5-i and CML-387 showed a better per se performance and GCA effects while A-7016 was the worst parent for GLS disease reaction. Inbred parent 143-5-i was the best general combiner for grain yield; but a poor general combiner for plant height and days to maturity. The information from this study will be useful for the development of high-yielding and GLS disease-resistant maize varieties.

Enhanced tolerance to boron toxicity in two-rowed barley by marker-assisted introgression of favourable alleles derived from Sahara 3771

Boron (B) is an essential micronutrient for higher plant, but toxic levels can seriously diminish grain yield in cereal crops by affecting root growth, and thus restricting water extraction from the subsoil. Amelioration of high concentrations in soils is expensive and not always feasible, so breeding for B tolerance is the most viable alternative. This article reports the marker-assisted (MAS) transfer of favourable alleles from an unadapted six-rowed barley (Hordeum vulgare L.) variety, Sahara 3771, into two-rowed lines adapted to southern Australia. During the backcrossing process, the SSR marker, EBmac679, located on chromosome 4H was used to control the target region in foreground selection, but no background selection was applied. Gene introgression was confirmed with 40 BC6F1-derived doubled haploid lines segregating for the SSR marker EBmac679. We used a combination of molecular and conventional assays to unequivocally classify the 40 BC6F1-derived DH lines as B tolerant or sensitive, and then compared their means for grain yield measured over 2 years and four locations. Results showed modest improvements in grain yield of lines carrying B tolerance genes at some B toxic environments, and negative impact at others. Our results also showed that malting quality profile was not adversely affected through the introgression of the B tolerance allele from Sahara 3771, allowing the newly developed material to be used by breeding programs without risk of a penalty on malt quality.

Relationship between hybrid performance and AFLP based genetic distance in highland maize inbred lines

The objectives of this study were to determine the crossing performance of highland maize inbred lines for grain yield, days to silk and plant height; estimate genetic distance (GD) among the inbred lines and in association with tester parents, and to investigate the relationship of GD with hybrid performance and midparent heterosis (MPH). A total of 26 inbred lines were crossed with six (population and line) testers in a factorial-mating scheme. The F1’s and the parents were evaluated at five locations in Ethiopia. Nine amplified fragment length polymorphism (AFLP) primer pairs were used to genotype all the parents. The F1’s were found to vary widely for grain yield and other traits measured. Yield superiority of more than 30% over the best hybrid check was obtained for some testcross hybrids. Midparent heterosis on average was moderate for grain yield and, plant height. And for days to silking, MPH values were mostly negative. Mean GD values determined from the inbred lines by population tester (0.680) and line tester (0.661) combinations were not significantly different. Cluster analysis separated the tester parents from the corresponding inbred lines. AFLP grouping of the inbred lines was in agreement with their pedigree records. Genetic distances derived from the inbred lines × all testers and from the population testers’ sub-group were not positively correlated with hybrid performance and MPH for most traits. In contrast, correlations of GDs involving the line testers’ sub-group with F1’s and MPH were significantly positive but with low magnitude to be of predictive value.

Relationship of grain yield with carbon isotope discrimination and ash content in lines derived from a bread wheat cultivar

The objective was to explore, in lines derived from a bread wheat (Triticum aestivum L.) cultivar, the association of grain yield with carbon isotope discrimination (Δ) and ash content (Ash) determined in both flag leaf and kernel. Divergent selection within the cv. Nestos, based on individual plant yield under very low density (11547 plants/ha), produced 20 lines. Progeny evaluation was conducted in two sites of Northern Hellas (Greece) at both low (11547 plants/ha) and high (5000000 plants/ha) density. The results showed significant differences between lines for grain yield, Δ and Ash. However, only the conclusions on grain yield were similar in low and high density, perhaps because the selection criterion under low density was grain yield. This, combined with the lack of any strong relationship of grain yield with either Δ or Ash, failed to confirm the usefulness of these physiological traits as indirect selection criteria, when the within-cultivar variation for grain yield is exploited. The possible association of grain yield with Δ and Ash appeared to be influenced by various factors such as drought, level of grain yield and altitude. Results also showed that less plant-to-plant variability, as expressed by the coefficients of variation (CV) of single-plant yields, was associated with decreased drought response and higher yield stability. The less stressed lines were those that used water more conservatively till anthesis and maintained a high photosynthetic rate during grain filling.

Identification of Maize Lines with Contrasting Responses to Applied Nitrogen

ABSTRACT A better understanding of how maize responds to nitrogen (N) supply is required for both economic and environmental purposes. Contrasting genotypes are indispensable for genetic and physiological studies of any trait, and the identification of the response of a range of lines of maize to two N level, was the aim of this work. One S4 and seven S5 lines, originating from two commercial hybrids, were studied for agronomic traits related to nitrogen-use efficiency (NUE). Two field experiments with two levels of N (10 and 110 Kg N/ha in 2000 and 10 and 130 Kg N/ha in 2001) were carried out. In the first experiment, in which the lines 2, 3, 4, 5, 6, 10, 13, and 17 were tested, the N supplied appeared to be excessive because the maize controls and most of the lines did not show an increase in grain yield at the high N level when compared with the low-N treatment in this experiment. The high N level increased the grain yield only in line 2, decreased grain yield in line 13, but increased the chlorophyll content in all lines except line 3. The second experiment, in which the lines 2, 3, 4, 5, 6, and 10 were tested, showed a severe N deficiency because the maize controls and most of the lines exhibited reduction in grain yield at the low N level when compared with the high-N treatment in this experiment. This severe N deficiency caused a reduction in grain yield in lines 2, 3, 5, and 10, prolificacy (ears plant− 1) in lines 2, 3, 4,and 5, grain N content in all lines (except line 10), and total plant N in lines 2, 3, and 5. On the other hand, this severe N deficiency also caused an increase in 100-kernel weight in line 2 and anthesis-silking in lines 3 and 5. The interactive behavior of all the traits cited indicates that they have different genetic controls at each N level. The existence of genotype-environment interaction may mean that the best genotype at a low N level is not the best at a high N level, and that the physiological mechanisms as well the genes required for high performance are to some extent different. These results also demonstrate that the response to N of these traits is under separate controls for each one, because they did not exhibit consistency in the lines tested. The correlations indicated that the anthesis-silking interval and prolificacy were associated more with grain yield at low-N availability, supporting the idea that these traits can be used to select maize tolerant to low-N soils. The contrasting responses to N availability indicate that these lines are important plant materials for use in further studies of NUE.

Genetic analysis of F6 and F6:7 soybean generations

For estimating genetic parameters and selecting superior lines for grain yield, forty-five soybean (Glycine max L.) crosses in F6 and F6:7 generations were evaluated. The soybean lines FT-Cristalina, EMGOPA-301, IAC-4, IAC-5, IAC-6, IAC-8, IAC-9, IAC-11, Santa Rosa, and OCEPAR-9-SS-1 were used in the crosses. The F6 progenies of 44 crosses (except EMGOPA-301 x IAC-5) and the ten parents were evaluated as well as the F6:7 progenies from all 45 crosses and the ten parents in the next crop. The number of days to maturity (NDM), plant height at maturity (PHM), agronomic value (AV) and grain yield (GY) were evaluated for both generations. There was some difficulty to select early top yield lines due to the high positive genotypic correlation between GY and NDM. The heritability estimates were high (> 0.70) and moderate (0.40 – 0.70) for NDM and PHM, respectively. The presence of transgressive segregates indicated the possibility of selecting lines with high grain yield.

Variation within a bread wheat cultivar for grain yield, protein content, carbon isotope discrimination and ash content

The study was undertaken to assess the variation within a bread wheat ( Triticum aestivum L.) cultivar, primarily for grain yield, and the implications for wheat breeding. During the 1998–1999 growing season, cv. Nestos was established in a non-replicated (NR-0) honeycomb experiment, in the absence of competition (11 547 plants ha −1). Ten high yielding (H) and 10 low yielding (L) plants were selected, the seeds of which were used to form the respective H and L lines. The 20 lines, along with their original cultivar, were evaluated in two locations either in the absence of competition (11 547 plants ha −1) during the 1999–2000 season or under competition (5 000 000 plants ha −1) during the 2000–2001 season. Results showed significant differentiation between lines for grain yield, determined both in the absence of competition at the single-plant level, i.e. yield per plant (YP), and under competition at the crop yield level, i.e. yield per plot (CY). Significant differences between lines were also found for grain protein content (PC), grain carbon isotope discrimination ( Δ), and grain ash content (ASH), either in the absence of competition or under competition. A positive relationship was found between YP and CY ( r=0.53, P<0.02). Results showed that selection within a bread wheat cultivar, under very low density and on the basis of individual plant grain yield, could be an effective way to either upgrade or maintain the cultivar, whereas the use of Δ or ASH as indirect selection criteria instead of grain yield was not supported by the study.

Secondary traits in parental inbreds and hybrids under stress and non-stress environments in tropical maize

Secondary traits other than grain yield (GY) have been successfully used to enhance the rate of genetic improvement for maize ( Zea mays L.) populations under abiotic stresses. With increasing trend towards the development of hybrids in the tropics there is a need to understand the genetics of these traits in inbred–hybrid breeding systems. The objectives of this study were to estimate the general combining abilities for secondary traits and their relationship with GY in a group of tropical white inbred lines and their hybrids under stress and non-stress environments. Traits were measured in inbred lines and their hybrid combinations across stress and non-stress subtropical and tropical environments in México. Hybrids showed earlier flowering, taller plants, more ears per plant (EPP), higher shelling percentage, slower leaf senescence, and higher leaf chlorophyll content than inbreds under all environments. La Posta Sequı́a (LP)-derived inbreds in general had desirable GCA for traits such as anthesis–silking interval (ASI), EPP, and leaf senescence but were more susceptible to foliar diseases. Conventionally bred maize lines had better standability, stay green, and resistance to diseases. Higher GY in lines and hybrids was associated with shorter ASI, earlier flowering, increased plant and ear height, increased EPP, increased shelling percentage, delayed senescence, and greater leaf chlorophyll concentrations. Under stress vs. non-stress conditions, we observed a higher variability for ASI and EPP, a higher inbred–hybrid correlation, and significant correlations between these traits and GY. Inbreds from LP appear to have high frequency of favorable dominant alleles for ASI and EPP.