Superior Yield Potential Research Articles

Effect of Chick Quality on Viability, Performance Traits and Meat Quality Characteristics of Broiler Chickens

The chick quality in broiler production is a major factor that has a direct impact on the profitability of both hatcheries and producers. In recent years, there has been considerable interest in the correlations between chick quality, which is measured by quantitative or qualitative methods, and yield characteristics. This study aims to compare the viability, performance traits, and meat quality characteristics of broiler chickens classified into two chick quality categories based on the Tona score method. In the study, broilers in the first-grade group had a lower mortality rate of 1.67%, while the average mortality rate of those with poor chick quality was 23.33% (P<0.05). There were no statistically significant correlations between post-hatch performance and chick quality characteristics such as Tona score, chick weight, chick length (all P>0.05). According to the Tona score, there were no differences between the mean values of body weight, feed efficiency, Gompertz growth curve parameters, slaughter carcass traits, and meat quality characteristics of first- and second-grade broiler chickens (all P>0.05). Although there is no difference between high and low quality chicks in terms of performance characteristics, it is possible that the use of low quality chicks in conventional broiler production will increase the general mortality of the flock. Due to their superior yield potential, it is recommended that low-quality chicks be utilized in more suitable production systems without culling, rather than in conventional broiler production.

Progress in hybrid wheat seed production technologies and implication of herbicide solutions in hybrid wheat purity improvement

<p indent="0mm">Hybrid wheat, potentially offering superior yield potential and yield stability, will play an important role in improving China’s food security. However, the high cost of hybrid seed production limits the adoption of hybrid wheat in China. Hybrid seed production cost is determined by several factors including the yield per unit of area, the purity of hybrid seed, and the seeding rate. Pilot studies have suggested that the seeding rate of hybrid wheat can be reduced by 20%–30% compared with that of traditional inbred varieties. However, the current growing practice in China makes it difficult to convince growers to embrace reduced seeding rate. Therefore, increasing hybrid seed yield and purity becomes more important for reducing the hybrid seed production cost; and particularly increasing the seed purity is a more feasible solution. In this review, hybrid seed production technologies, as well as herbicide solutions for seed purity improvement are summarized. In either a thermo-/photoperiod-sensitive genic male sterile (TGMS/PGMS) based 2-line seed production system or a cytoplasmic male sterility (CMS) based 3-line seed production system, male parents are always planted together with female parents in a certain ratio to provide pollen. Male parents can still produce inbred seeds through self-fertilization, which will reduce the purity of hybrid seeds. Herbicides can be used to terminate male parents or impair the inbred seed development after pollination, leading to an increased hybrid seed purity. However, not all herbicides fit this purpose; in this review, we suggest a set of criteria for selecting existing or developing new herbicides for hybrid seed purity improvement. Accordingly, ALS inhibitors and ACCase inhibitors are two major classes of herbicides that can be tested in wheat hybrid seed production. Glyphosate kills the whole plant when spray at 1 week or 2 weeks after pollination, but dead male plant still can produce few shrunken seeds. Compared to glyphosate treatment, imazethapyr and sethoxydim cannot kill male plants, but can limit selfed seed development. Shrunken seeds can be removed from hybrid seeds based on smaller size and lighter weight. Another novel angle is relying on chemicals/small molecules/ mycoherbicide to boost herbicide efficacy, such as Bobcat339, miR858 and <italic>Pyricularia setariae</italic>. The clues come from several studies, such as <italic>Atros1</italic> loss-of-function mutant is more sensitive to imazethapyr treatment, <italic>Pyricularia setariae</italic> can break sethoxydim resistance in foxtail, etc. Moreover, this review also provides an outlook into some of the new technologies, particularly the clonal seed (apomixis) technology which enables producing selfed hybrid seeds from hybrid seed parent without the need of a separate pollen parent, and thus maximize the yield and purity of hybrid seed production. <italic>SPO11</italic> (or <italic>PAIR1</italic>), <italic>REC8</italic> and <italic>OSD1</italic> are quite conserved among different crops, and <italic>Tamatl</italic>/<italic>pla1</italic>/<italic>nld</italic> mutant is already proved to induce maternal haloid in wheat.

BRS A502: an upland rice cultivar for intensive sustainable cropping systems in the Brazilian Cerrado

BRS A502 is an upland rice cultivar with a medium cycle, high resistance to lodging, superior yield potential and grains of excellent industrial and cooking quality. The cultivar is indicated for crop rotation and succession in areas under intensive agriculture in the main field crop regions of Brazil.

Studies on genetic variability, correlation and path coefficient analysis in fenugreek (Trigonella foenum graecum L.) genotypes

An experiment was carried out on fenugreek genotypes to study the genetic variability, and relationship among yield traits. Analysis of variance showed that the genotypes significantly differed in all the growth and yield parameters studied. The variability study indicated that PCV was higher than the GCV for all the traits and high genotypic and phenotypic coefficient of variation was recorded for the number of primary and secondary branches per plant, the number of pods per plant and seed yield per plant. High heritability was observed for all the studied characters. Correlation studies revealed that the seed yield was significantly and positively correlated both at the genotypic and phenotypic levels to pod length and the number of pods per plant. The highest positive direct effect on seed yield per plant was observed on the number of pods per plant (0.3467) followed by the number of secondary branches per plant (0.3259), the number of seeds per pod (0.2301) and pod length (0.1468). The information on these statistical parameters would be helpful to identify the genotypes having superior yield potential which can be utilized in the improvement of fenugreek. Key words: Genotypic variability, heritability, correlation, path coefficient analysis

Combining grain yield, protein content and protein quality by multi-trait genomic selection in bread wheat

Key messageSimultaneous genomic selection for grain yield, protein content and dough rheological traits enables the development of resource-use efficient varieties that combine superior yield potential with comparably high end-use quality.Selecting simultaneously for grain yield and baking quality is a major challenge in wheat breeding, and several concepts like grain protein deviations have been developed for shifting the undesirable negative correlation between both traits. The protein quality is, however, not considered in these concepts, although it is an important aspect and might facilitate the selection of genotypes that use available resources more efficiently with respect to the quantity and quality of the final end products. A population of 480 lines from an applied wheat breeding programme that was phenotyped for grain yield, protein content, protein yield and dough rheological traits was thus used to assess the potential of using integrated genomic selection indices to ease selection decisions with regard to the plethora of quality traits. Additionally, the feasibility of achieving a simultaneous genetic improvement in grain yield, protein content and protein quality was investigated to develop more resource-use efficient varieties. Dough rheological traits related to either gluten strength or viscosity were combined in two separate indices, both of which showed a substantially smaller negative trade-off with grain yield than the protein content. Genomic selection indices based on regression deviations for the two latter traits were subsequently extended by the gluten strength or viscosity indices. They revealed a large merit for identifying resource-use efficient genotypes that combine both superior yield potential with comparably high end-use quality. Hence, genomic selection opens up the opportunity for multi-trait selection in early generations, which will most likely increase the efficiency when developing new and improved varieties.

Morphological characterisation and evaluation of cacao (Theobroma cacao L.) in Trinidad to facilitate utilisation of Trinitario cacao globally

Cacao (Theobroma cacao L.) accessions conserved at the International Cocoa Genebank Trinidad (ICGT) are routinely characterised and evaluated in terms of traits of taxonomic and economic interest. The resulting data are crucial for selecting suitable candidates for future germplasm utilisation and breeding. In this study, the distribution of traits of taxonomic and economic interest was examined among Trinitario accession groups, represented by 260 accessions, and compared to what pertains for the 1900 genotypes characterised at the ICGT. Among the 1900 accessions studied, the Pod Index, an indicator of yield potential, ranged from 13.9 to 92.8. Twenty-three percent of the accessions with superior yield potential (Pod Index of 21 or lower) were ‘Trinitarios’, including the best. Despite a significantly negative correlation (r = − 0.162, P < 0.0001) between seed mass and seed number of the accessions studied, several Trinitarios combined large seed number (44 or more) with large seed (cotyledon) mass (1.2 g or more). The Trinitarios selected in Trinidad were observed to be phenotypically closely related. Trinitarios with high yield potential, large seed size and other favourable traits were identified. They are potentially useful sources of genes for introgression into Trinitario planting material in fine or flavour cocoa producing countries, which provide premium cocoa to an ever expanding global niche market. The resulting economic and social benefits of improvement in Trinitario cacao planting material should be significant.

Generation of a new thermo-sensitive genic male sterile rice line by targeted mutagenesis of TMS5 gene through CRISPR/Cas9 system

BackgroundTwo-line hybrid rice with high yield potential is increasingly popular and the photo- and temperature-sensitive male sterile line is one of the basic components for two-line hybrid rice breeding. The development of male sterile lines through conventional breeding is a lengthy and laborious process, whereas developing thermo-sensitive genic male sterile (TGMS) lines for two-line hybrid breeding by editing a temperature-sensitivity gene by CRISPR/Cas9 is efficient and convenient.ResultsHere, thermo-sensitive genic male sterility (TGMS) was induced by employing the CRISPR/Cas9 gene editing technology to modify the gene TMS5. Two TGMS mutants, tms5–1 and tms5–2, both lacking any residual T-DNA, were generated in the indica rice cultivar Zhongjiazao17 (cv. YK17) background. When grown at a sub-optimal temperature (22 °C), both mutants produced viable pollen and successfully produced grain through self-fertilization, but at temperatures 24 and 26 °C, their pollen was sterile and no grain was set. F1 hybrids derived from the crosses between YK17S (tms5–1) and three different restorer lines outperformed both parental lines with respect to grain yield and related traits.ConclusionThe YK17S generated by CRISPR/Cas9 system was proved to be a new TGMS line with superior yield potential and can be widely utilized in two-line hybrid breeding of indica rice.

Simultaneous selection for grain yield and protein content in genomics-assisted wheat breeding

Key messageLarge genetic improvement can be achieved by simultaneous genomic selection for grain yield and protein content when combining different breeding strategies in the form of selection indices.Genomic selection has been implemented in many national and international breeding programmes in recent years. Numerous studies have shown the potential of this new breeding tool; few have, however, taken the simultaneous selection for multiple traits into account that is though common practice in breeding programmes. The simultaneous improvement in grain yield and protein content is thereby a major challenge in wheat breeding due to a severe negative trade-off. Accordingly, the potential and limits of multi-trait selection for this particular trait complex utilizing the vast phenotypic and genomic data collected in an applied wheat breeding programme were investigated in this study. Two breeding strategies based on various genomic-selection indices were compared, which (1) aimed to select high-protein genotypes with acceptable yield potential and (2) develop high-yielding varieties, while maintaining protein content. The prediction accuracy of preliminary yield trials could be strongly improved when combining phenotypic and genomic information in a genomics-assisted selection approach, which surpassed both genomics-based and classical phenotypic selection methods both for single trait predictions and in genomic index selection across years. The employed genomic selection indices mitigated furthermore the negative trade-off between grain yield and protein content leading to a substantial selection response for protein yield, i.e. total seed nitrogen content, which suggested that it is feasible to develop varieties that combine a superior yield potential with comparably high protein content, thus utilizing available nitrogen resources more efficiently.

Non-destructive Phenotyping to Identify Brachiaria Hybrids Tolerant to Waterlogging Stress under Field Conditions.

Brachiaria grasses are sown in tropical regions around the world, especially in the Neotropics, to improve livestock production. Waterlogging is a major constraint to the productivity and persistence of Brachiaria grasses during the rainy season. While some Brachiaria cultivars are moderately tolerant to seasonal waterlogging, none of the commercial cultivars combines superior yield potential and nutritional quality with a high level of waterlogging tolerance. The Brachiaria breeding program at the International Center for Tropical Agriculture, has been using recurrent selection for the past two decades to combine forage yield with resistance to biotic and abiotic stress factors. The main objective of this study was to test the suitability of normalized difference vegetation index (NDVI) and image-based phenotyping as non-destructive approaches to identify Brachiaria hybrids tolerant to waterlogging stress under field conditions. Nineteen promising hybrid selections from the breeding program and three commercial checks were evaluated for their tolerance to waterlogging under field conditions. The waterlogging treatment was imposed by applying and maintaining water to 3 cm above soil surface. Plant performance was determined non-destructively using proximal sensing and image-based phenotyping and also destructively via harvesting for comparison. Image analysis of projected green and dead areas, NDVI and shoot biomass were positively correlated (r ≥ 0.8). Our results indicate that image analysis and NDVI can serve as non-destructive screening approaches for the identification of Brachiaria hybrids tolerant to waterlogging stress.

Trends in grain production and yield gaps in the high-rainfall zone of southern Australia

The high-rainfall zone (HRZ) of southern Australia is the arable areas where annual rainfall is between 450 and 800 mm in Western Australia and between 500 and 900 mm in south-eastern Australia, resulting in a growing-season length of 7–10 months. In the last decade, there has been a growing recognition of the potential to increase crop production in the HRZ. We combined (1) a survey of 15 agricultural consultants, each of whom have ~40–50 farmer clients across the HRZ, (2) 28 farm records of crop yields and area for 2000–2010, (3) 86 wheat and 54 canola yield observations from well managed experiments, and (4) long-term simulated crop yields at 13 HRZ locations, to investigate recent trends in crop production, quantify the gap between potential and actual crop yields, and consider the factors thought to limit on-farm crop yields in the HRZ. We found in the past 10 years a trend towards more cropping, particularly in WA, an increased use of canola, and advances in the adaptation of germplasm to HRZ environments using winter and longer-season spring types. Consultants and the farm survey data confirmed that the rate of future expansion of cropping in the HRZ will slow, especially when compared with the rapid changes seen in the 1990s. In Victoria, New South Wales and South Australia the long-term water-limited potential yield in HRZ areas, as measured by experimental yields, consultant estimates and simulations for slow developing spring cultivars of wheat and canola was 5–6 and 2–3 t/ha for a decile 5 season. For Western Australia it was 4–5 and 2–3 t/ha, where yields were less responsive to good seasons than in the other states. The top performing farmers were achieving close to the water-limited potential yield. There are yield advantages of ~2 t/ha for ‘winter’ over ‘spring’ types of both wheat and canola, and there is scope for better adapted germplasm to further raise potential yield in the HRZ. Consultants stated that there is scope for large gains in yield and productivity by encouraging the below-average cropping farmers to adopt the practices and behaviours of the above-average farmers. The scope for improvement between the below- and above-average farmers was 1–3 t/ha for wheat and 0.5–1.5 t/ha for canola in a decile 5 season. They also stated that a lack of up-to-date infrastructure (e.g. farm grain storage) and services is constraining the industry’s ability to adopt new technology. Priorities for future research, development and extension among consultants included: overcoming yield constraints where growing-season rainfall exceeds 350 mm; adaptation of winter and long-season spring types of cereals and canola and management of inputs required to express their superior yield potential; and overcoming barriers to improved planning and timeliness for crop operations and adoption of technology.

Genetic enhancement of Dubraj, a specialty rice through pedigree approach employing marker based selection for plant stature, aroma and grain quality

Grain quality is an important feature of the marketing strategies of the rice industry in both domestic and international markets as quality influences the market price. With the demand for aromatic rice increasing steadily, export of short grain aromatic rices having premium grain quality is a viable option as the cultivation of basmati rices is limited to a specific geographic region. However, these native premium native aromatic rices require significant improvements in yield, plant stature and response to fertilizer and as grain quality traits are complex, their retention in the recombinants is a major challenge. With the recent advances in molecular markers, selection of recombinants with desirable traits is feasible through precise tracking of the target traits. The present study reports the successful recovery of the premium grain quality traits of Dubraj in IET 21044 (L9), a derivative from Pusa 44/Dubraj cross combination using pedigree approach employing markers associated with plant stature, aroma and grain quality and stringent phenotypic selection. The validation of the superior yield potential and premium grain quality of IET 21044 in the multi location evaluation trials over a 4 year period resulted in its release thus making it the first semi dwarf, high yielding, short grain aromatic rice released in India at the national level. The study was a successful demonstration of the limitless potential of the marker technology in breeding specialty rices.

Enhancing Rice Productivity in West Africa through Genetic Improvement

ABSTRACTRice yields have stagnated in West Africa at 1 to 2 Mg ha−1 because of unfavorable rice environments and poor management practices. Interspecific rice cultivars, the New Rice for Africa (NERICA), were developed by crossing Asian rice (Oryza sativa L.) and African rice (O. glaberrima Steud.) to improve upland and lowland rice productivity in resource‐poor farmers’ fields. This paper provides an overview of recent studies, performed by the Africa Rice Center and its partners, on evaluation of growth and yield performance of upland and lowland NERICA cultivars and modern Asian rice cultivars including the improved upland indica cultivars often termed aerobic rice. Upland NERICA cultivars were found to lack the expected combination of superior yield potential with weed suppressive ability (WSA) and adaptation to low soil fertility, instead sharing similarity in these characteristics with their O. sativa parent WAB56‐104 but remaining inferior to their O. glaberrima parent CG 14 in terms of tillering ability and WSA. Some aerobic rice cultivars were identified for high yielding ability, strong WSA, and superior adaptation to low‐fertility uplands and water‐limited lowlands. Some lowland NERICA cultivars outyielded improved lowland O. sativa checks and aerobic rice cultivars in favorable lowlands, whereas they did not perform well in water‐limited lowlands. The implications of these findings for future challenges for genetic improvement in West Africa are discussed.

Differential Weed Suppression Ability in Upland Rice Cultivars

AbstractTwenty‐five upland rice (Oryza sativa L.) cultivars were evaluated in 2 yr of field experiments in the Philippines. The research was conducted with low and moderate levels of handweeding to determine the extent of cultivar differences in weed suppression ability. We sought the plant characters that may confer superior competitiveness, and determined their practical significance in contributing to weed management. A large significant variation was observed in the dry weight of weeds (0.84 to 3.89 Mg/ha) associated with the different cultivars. Several cultivars had consistently low weed weights in both weeding treatments across years. Weed weights for the five most competitive cultivars were 75% lower than for those of the five least competitive cultivars. Grain yields were negatively correlated with weed weights, in both weeding treatments in both years (r = −0.48** to −0.59**‐significant at P = 0.01). Plant height, which ranged from 0.73 to 1.35 m, was the character most strongly related to low weed weight, with negative correlations that varied from −0.76** to −0.88** among weeding levels and years. Leaf area index (determined at 60 d after seeding) was also negatively correlated with weed weight, but tiller number was not significantly related to weed weight. The minimum plant height necessary to adequately suppress weeds was approximately 1.00 to 1.15 m. Cultivars with superior yield potential were identified that had a minimum height of 1.0 m, with weed suppression ability similar to the tall traditional cultivars.

High‐ vs. Low‐Stress Yield Test Environments for Selecting Superior Soybean Lines

An important factor in cultivar development is the choice of yield testing sites that permit the best discrimination among breeding lines. The objectives of this study were to test the hypotheses that: (i) there are genotypes that have superior yield potential in both low‐ and high‐stress edaphic conditions, and (ii) yield tests conducted exclusively in low‐stress environments can be used effectively for selecting such genotypes. Forty‐eight random F4‐derived soybean [Glyciue max (L). Merr.] lines were evaluated for yield over 4 yr on a low soil acidity, high fertility site (low‐stress) and on a high soil acidity, low‐medium fertility site (high‐stress) at each of two locations (Crossville and Milan, TN). In addition, low‐stress yield tests were conducted at five other locations during each of the last 2 yr. The grand mean of low‐stress tests was 2.25 Mg ha−1 compared to 0.62 Mg ha−1 for high‐stress tests. The 16 lines (33% selection intensity), which had overall mean yields above the grand means of combined high‐ and combined low‐stress tests were designated as the superior lines. Simulated selections revealed that 32 to 54% of the superior lines would have been selected using either type of nursery at either the Crossville or Milan location each year. At least one of the top three lines would have been chosen in every case, regardless of type(s) of nursery environment, location(s), or year(s) used. These results indicate that the low‐stress environments commonly used in soybean breeding programs should provide high probabilities for selecting genotypes that have superior yield potential in both low‐ and high‐stress edaphic conditions. Regression coefficients for line mean yield regressed on site mean were generally highest for the superior lines (b ≥ 1.0), but the deviations from regression were similar to the non superiors. The ranges for maturity and plant height were similar for both groups indicating that selection for superior lines would not have led to extremes for either trait.

Modified Early Generation Testing Procedure for Yield Selection in Soybean

An early generation testing program to identify crosses with superior yield potential and F2 plants within these crosses which receive a superior complement of yield genes would be useful in soybean [Glycine max (L.) Merr.] breeding. Early generation testing is effective in identifying superior yielding pure lines, but requires extra yield testing. This paper describes a modified early generation testing procedure where the number of yield test plots required per cross has been reduced from 1860 to 175 plots, allowing a 10‐fold increase in the number of crosses that are evaluated per year. This was accomplished by reducing the number of F2‐derived lines per cross from 300 to 30 and by using single location, single replication data as a basis for selection in F2.3 through F2.4.6. This modified early generation testing procedure has been used in a soybean breeding program since 1972, resulting in the release of eight high‐yielding soybean cultivars.

Studies on protein content and yield levels in rice

Crosses between low and high protein varieties revealed the dominance of low protein over high protein content. The number of desirable segregants with the double combination of high protein and yield were scored in each generation. The increasing frequency of desirable segregants from the F2 to the F3 generation in all the crosses increase the chances of selecting desirable recombinants for propagating improved rice varieties. Hybridisation followed by selection may help in developing varieties with high protein content and superior yield potential.