High-yielding Cultivars Research Articles

Genetic Improvement and Application Practices of Synthetic Hexaploid Wheat.

Synthetic hexaploid wheat (SHW) is a useful genetic resource that can be used to improve the performance of common wheat by transferring favorable genes from a wide range of tetraploid or diploid donors. From the perspectives of physiology, cultivation, and molecular genetics, the use of SHW has the potential to increase wheat yield. Moreover, genomic variation and recombination were enhanced in newly formed SHW, which could generate more genovariation or new gene combinations compared to ancestral genomes. Accordingly, we presented a breeding strategy for the application of SHW-the 'large population with limited backcrossing method'-and we pyramided stripe rust resistance and big-spike-related QTLs/genes from SHW into new high-yield cultivars, which represents an important genetic basis of big-spike wheat in southwestern China. For further breeding applications of SHW-derived cultivars, we used the 'recombinant inbred line-based breeding method' that combines both phenotypic and genotypic evaluations to pyramid multi-spike and pre-harvest sprouting resistance QTLs/genes from other germplasms to SHW-derived cultivars; consequently, we created record-breaking high-yield wheat in southwestern China. To meet upcoming environmental challenges and continuous global demand for wheat production, SHW with broad genetic resources from wild donor species will play a major role in wheat breeding.

Application of UAS-Based Remote Sensing in Estimating Winter Wheat Phenotypic Traits and Yield During the Growing Season

Phenotyping approaches have been considered as a vital component in crop breeding programs to improve crops and develop new high-yielding cultivars. However, traditional field-based monitoring methods are expensive, invasive, and time-intensive. Moreover, data collected using satellite and airborne platforms are either costly or limited by their spatial and temporal resolution. Here, we investigated whether low-cost unmanned/unoccupied aerial systems (UASs) data can be used to estimate winter wheat (Triticum aestivum L.) nitrogen (N) content, structural traits including plant height, fresh and dry biomass, and leaf area index (LAI) as well as yield during different winter wheat growing stages. To achieve this objective, UAS-based red–green–blue (RGB) and multispectral data were collected from winter wheat experimental plots during the winter wheat growing season. In addition, for each UAS flight mission, winter wheat traits and total yield (only at harvest) were measured through field sampling for model development and validation. We then used a set of vegetation indices (VIs), machine learning algorithms (MLAs), and structure-from-motion (SfM) to estimate winter wheat traits and yield. We found that using linear regression and MLAs, instead of using VIs, improved the capability of UAS-derived data in estimating winter wheat traits and yield. Further, considering the costly and time-intensive process of collecting in-situ data for developing MLAs, using SfM-derived elevation models and red-edge-based VIs, such as CIre and NDRE, are reliable alternatives for estimating key winter wheat traits. Our findings can potentially aid breeders through providing rapid and non-destructive proxies of winter wheat phenotypic traits.

Variations in phenological, physiological, plant architectural and yield-related traits, their associations with grain yield and genetic basis.

Physiological and morphological traits play essential roles in wheat (Triticum aestivum) growth and development. In particular, photosynthesis is a limitation to yield. Increasing photosynthesis in wheat has been identified as an important strategy to increase yield. However, the genotypic variations and the genomic regions governing morphological, architectural and photosynthesis traits remain unexplored. Here, we conducted a large-scale investigation of the phenological, physiological, plant architectural and yield-related traits, involving 32 traits for 166 wheat lines during 2018-2020 in four environments, and performed a genome-wide association study with wheat 90K and 660K single nucleotide polymorphism (SNP) arrays. These traits exhibited considerable genotypic variations in the wheat diversity panel. Higher yield was associated with higher net photosynthetic rate (r = 0.41, P < 0.01), thousand-grain weight (r = 0.36, P < 0.01) and truncated and lanceolate shape, but shorter plant height (r = -0.63, P < 0.01), flag leaf angle (r = -0.49, P < 0.01) and spike number per square metre (r = -0.22, P < 0.01). Genome-wide association mapping discovered 1236 significant stable loci detected in the four environments among the 32 traits using SNP markers. Trait values have a cumulative effect as the number of the favourable alleles increases, and significant progress has been made in determining phenotypic values and favourable alleles over the years. Eleven elite cultivars and 14 traits associated with grain yield per plot (GY) were identified as potential parental lines and as target traits to develop high-yielding cultivars. This study provides new insights into the phenotypic and genetic elucidation of physiological and morphological traits in wheat and their associations with GY, paving the way for discovering their underlying gene control and for developing enhanced ideotypes in wheat breeding.

Large investment of stored nitrogen and phosphorus in female cones is consistent with infrequent reproduction events of Pinus koraiensis, a high value woody oil crop in Northeast Asia.

Pinus koraiensis is famous for its high-quality timber production all the way and is much more famous for its high value health-care nut oil production potential since 1990's, but the less understanding of its reproduction biology seriously hindered its nut productivity increase. Exploring the effects of reproduction on nutrient uptake, allocation and storage help to understand and modify reproduction patterns in masting species and high nut yield cultivar selection and breeding. Here, we compared seasonality in growth and in nitrogen ([N]) and phosphorus ([P]) concentrations in needles, branches and cones of reproductive (cone-bearing) and vegetative branches (having no cones) of P. koraiensis during a masting year. The growth of one- and two-year-old reproductive branches was significantly higher than that of vegetative branches. Needle, phloem and xylem [N] and [P] were lower in reproductive branches than in vegetative branches, although the extent and significance of the differences between branch types varied across dates. [N] and [P] in most tissues were high in spring, decreased during summer, and then recovered by the end of the growing season. Overall, [N] and [P] were highest in needles, lowest in the xylem and intermediate in the phloem. More than half of the N (73.5%) and P (51.6%) content in reproductive branches were allocated to cones. There was a positive correlation between cone number and N and P content in needles (R2 = 0.64, R2 = 0.73) and twigs (R2 = 0.65, R2 = 0.62) of two-year-old reproductive branches. High nutrient sink strength of cones and vegetative tissues of reproductive branches suggested that customized fertilization practices can help improve crop yield in Pinus koraiensis.

Estimation of Genetic Diversity by Principal Component Analysis of Yield Attributing Traits in Katarni Derived Lines

Katarni is a non-basmati traditional aromatic rice cultivar being grown in the Bhagalpur, Banka, and Munger districts of Bihar. However, it is weak-strawed, tall, prone to lodging, and late maturing. Attempt was made to develop a semi-dwarf and early maturing lines of Katarni by crossing with three semi-dwarf high-yielding cultivars and was advanced to F5 generation. In this study, 54 derived lines of Katarni were studied on the basis of 14 morphological traits. Five principal components (PCs) were observed which contributed 70% of cumulative variability and exhibited Eigenvalues&gt; 1. The first PC (23.31%) and the second PC (35.59%) showed a cumulative variation of 63.90%. On the basis of genotype by trait biplot analysis, flag leaf length, plant height, and fragrance were found to be strongly positive. Genotypes biplot study revealed diverse genotypes like KIR-46 KIR-48, KRS-39, KRS-43, KRS-15, KRS-19, KRS-8, KRS-25, and KMTU-52 which can be further exploited for varietal development.

Sugarcane cultivar genetic gains for coastal agro-ecological regions of South Africa

Cultivar genetic gains quantify the increase in productivity from release of cultivars and measure genetic improvements from plant breeding. The objectives of this study were to evaluate the genetic gains from sugarcane coastal cultivars and evaluate their contribution to productivity. Data were derived from replicated plant breeding and post-release variety evaluation trials conducted by the South Africa Sugarcane Research Institute (SASRI) from 1996 to 2020. There were significant cultivar differences for cane yield, sucrose content, sugar yield, fibre % and purity %. Significant analyses of cultivar by location, cultivar by crop-year and cultivar by location by crop-year indicate further optimisation of cultivar disposition is needed to increase productivity. Cultivar genetic gains were found for cane yield (0.19–0.48 t ha−1), sucrose content (0.01–0.02%), sugar yield (0.03–0.07 t ha−1 per year), fibre % cane (0.04–0.06%) and purity % (0.02–0.04%), highlighting the increased yield and quality from genetic improvement. The best cultivars produced 8–22% higher sugar yields than popular cultivars indicating that planting high yield cultivars did increase yields. Sugar cane production declined at a slower rate than area planted, also showing the benefit of high yield cultivars. Increasing the area planted to new, higher yielding cultivars will increase sugar yields for coastal regions of South Africa.

Research and Control Techniques for Volunteer Rice

Recently, the Japanese government policy has recommended the cultivation of multipurpose high-yield paddy rice cultivars for animal feed (not only in the form of brown rice but also of whole crop silage (WCS) and others) in response to the decrease in demand on palatable rice for human consumption in Japan. However, when palatable cultivars are cropped in the following year of cultivations of high-yield cultivars for animal feed, the seeds of the high-yield cultivars are often left in the paddy field and grow as volunteer rice in the next crop season over winter, resulting in decrease in grain yield and lowering the quality of the palatable rice. Up to date, many ecological studies on overwintering ability of rice seeds have been carried out, and several key techniques on how to reduce volunteer rice were developed. This review summarizes ecological characteristics of volunteer rice, and describes effective countermeasures with cultural method, herbicides, lime nitrogen, and premature harvest (for only WCS).

Climate Resilient Varietal Development of Diverse Crops through Mutation Breeding in Bangladesh

The capability to quickly generate a considerable range of genetic variation in plants through mutation enables the mutagenesis approach extremely successful in developing climate-resistant cultivars across the entire world. In Bangladesh, plant breeders are confronted with a significant challenge in producing resilient and high-yielding cultivars rapidly capable of adapting to the changing environment in this densely populated region. Based on Mutant varieties data of Bangladesh which are available in the domain of FAO/IAEA Mutant Varieties Database (MVD), this review attempted to highlight the relevance of mutation breeding in crop variety development to adapt to changes occurring in diverse ecosystems of Bangladesh during this era of ongoing climate change. So far, seventy-eight mutant varieties of important crops have been released in Bangladesh, including rice, wheat, mustard, sesame, jute, rapeseed, tomato, black gram, chickpea, grass pea, lentil, mung bean, groundnut, and onion. Significant improvements in agronomic and botanical qualities have been made to maximize crop production. Salinity-tolerant varieties for southern coastal regions, drought-tolerant varieties for drought-prone locations, early mature varieties for flash flood escape in haor regions, submerged tolerant varieties for flooding regions and various major disease and insect resistant varieties have been generated through mutation breeding. These mutant varieties with climate-resilient traits are sustainable under different climatic circumstances, playing a key role in assuring food security in Bangladesh. Therefore, it is anticipated that mutant breeding will contribute significantly to meeting the challenges that food production will confront in the near future due to a changing climate.

IAC VR211 and IAC VM211: new high-yielding cultivars of mung bean and black mung bean

IAC VR211 and IAC VM211: new high-yielding cultivars of mung bean and black mung bean

RESPONSE OF HIGH-YIELDING PEANUT CULTIVARS TO VARIOUS SEED TREATMENTS UNDER MARGINAL FERTILITY SANDY SOIL CONDITIONS

Ameliorating peanut production is a requirement to cope with the abrupt climate change and burgeoning population. Seed treatment is vital for enhancing and sustaining peanut production, particularly in semiarid environments. The latest study aimed to evaluate the impact of different seed treatments on the agronomic and quality of three high-yielding peanut cultivars: Giza-6, North Carolina (N.C.), and Aramanch. The applied seed treatments include Rhizobium inoculation, moringa leaf extract, vitavax, and gypsum versus untreated control. The evaluated peanut cultivars significantly varied in their results for agronomic and quality traits. The cultivar Giza-6, followed by Aramanch, proved the best displaying the highest number of seeds per pod, number of pods per plant, 100-seed weight, number of branches per plant, shelling percentage, biological yield, pod yield, seed yield, oil yield, and protein yield. The applied seed treatments substantially enhanced peanut yield traits, oil, and protein content of peanuts with the superiority of Rhizobium inoculation, gypsum, and moringa extract. These treatments effectively reinforced peanut growth, positively reflected in the yield and quality traits. Subsequently, integrating the seed treatments, particularly Rhizobium inoculation, gypsum, and moringa extract, with high-yielding cultivars, such as Giza-6 and Aramanch, confirmed a helpful approach to enhancing and sustaining peanut production in arid environments.

DEVELOPMENT OF RICE GERMPLASM BASED ON GENETIC VARIABILITY IN F5 SEGREGATING POPULATIONS

Water scarcity is a global dilemma, and rice crop needs plenty of water for optimum growth and yield. In the current climate change scenario, developing a broad-based gene pool of rice to help the crop breeders develop high-yielding cultivars needs dire action. This study assessed the genetic variation among 10 diversified parents and their 15 F5 populations developed under limited water supply for various morphological traits. Parents and F5 populations showed significant differences at 5% and 1% for most of the studied maturity and yield traits. F5 population ‘Dokri-Basmati/DR-92’ exhibited earliest for days to heading (93) with the highest culm length (85.5 cm). Maximum flag leaf area (34.67 cm2) resulted for the F5 population ‘DR-83/NIAB-IRRI-8.’ On the other hand, the F5 population ‘DR-83/DR-92’ excelled in performance for the number of primary branches panicle-1 (11). F5 population ‘IR-8/NIAB-IRRI-9’ displayed the longest panicle (28.70 cm) with the highest number of secondary branches panicle-1 (38). Three of the F5 populations ‘DR-92/DR-83,’ ‘DR-83/NIAB-IRRI-8,’ and ‘NIAB-IRRI-9/IR-8,’ displayed maximum heritability for panicle length (0.82), the number of primary branches (0.80), and secondary branches panicle-1 (0.94), respectively, offering the prospects for development of potentially high-yielding variety. The highest genetic advance for panicle length (9.87%) emerged from the F5 population ‘DR-92/DR-83,’ which also had the highest heritability for this trait. F5 population ‘DR-83/DR-92’ manifested maximum genetic advance (3.32%) for primary branches panicle-1, while ‘NIAB-IRRI-9/IR-8’ revealed the highest genetic advance (6.26%) for secondary branches panicle-1. Both of these populations may be suitable for developing the spreading type of rice germplasm with the potential water stress. F5 populations displayed differential responses for the studied traits, with none of the segregating populations excelling for studied maturity and yield traits. However, the germplasm pool created can serve as a better collection for improving existing populations from a production traits perspective under water-stress conditions or developing new cultivars focusing these traits for the target water stress region(s).

The optimisation of rapeseed yield and growth duration through adaptive crop management in climate change: evidence from China

Crop yield is influenced by plant growth and development; both are affected by climatic variables and crop management practices. Therefore, understanding the effects of climate variables and management practices on rapeseed (Brassica napus L.) yield and growth duration (GD) is essential for developing strategies for agricultural systems based on changing climatic conditions. Thus, we quantified the respective contributions of climate change and crop management to rapeseed yield and GD between 2008 and 2019 in China using a first-difference multivariate regression model. Our results showed that: i) based on observed rapeseed yield and phenological data, the average planting date was delayed by –1.1 to 9.5 days decade–1, the average maturity date was advanced by 4.4 to 9.9 days decade–1, the average GD was shortened by 6.0 to 19.6 days decade–1 and the average yield increased by 12.82 to 61.5 kg ha–1 year–1; ii) the relative contributions of climate change and crop management to winter rapeseed yield were changed from –20% to +39% and from +61% to +80%, respectively, and the relative contributions to GD were changed from –10% to +15% and from –85% to +97%, respectively; iii) among the three climatic factors considered in this study, the climatic factor that caused the most remarkable change in winter rapeseed yield and GD was different in different regions. Overall, compared with cumulative temperature, cumulative sunshine hours may be the most critical climate factor limiting rapeseed yield in the Yangtze River Basin, especially in the upper reaches of the Yangtze River. Our results suggest that stakeholders select highyielding cultivars to optimise crop management and adaptation strategies in different agroecological zones. Highlights - The growth duration of winter rapeseed was shortened, and the yield increased in most stations. - Crop management to changes in GD and yield of winter rapeseed was greater than the impact of climate change. - Cumulative sunshine hours may be the most critical climate factor limiting rapeseed yield in the Yangtze River Basin.

Promising source material for winter triticale breeding under the conditions of the Middle Urals

Background. The northern border of cereal crop cultivation passes through the territory of Sverdlovsk Province. Cultivars of winter triticale developed in the regions of Russia located to the south are grown there, but they die under unfavorable winter conditions. The breeding of this crop in local climate is at an early stage, so a study of source material for breeding new highyielding cultivars adapted to local conditions seems quite pertinent.Materials and methods. In 2017–2020, the Ural Research Institute of Agriculture in Yekaterinburg conducted a study of 78 winter triticale genotypes from 10 regions of Russia and 7 foreign countries. The seeds were obtained from the VIR genebank and breeding centers of Russia. Sowing was carried out in clean fallow on August 20–25 on 1 m2 plots in 3-4 repetitions, with the reference ‘Bashkirskaya korotkostebelnaya’ sown on every 10th plot. Plants were assessed for winter hardiness, yield, density of productive stems, plant height, ear length, number of spikelets and grains per ear, weight of 1000 grains, and ear productivity in accordance with published guidelines.Results. Cvs. ‘Privada’, ‘Tsekad 90’ and ‘Nemchinovsky 58’ combined high winter hardiness (70–81%) with resistance to damage by snow mold (15–20%), high density of productive stems (324–425 pcs/m2), and high yield (562–616 g/m2). They had high 1000 grain weight (45.4–49.1 g) and ear productivity (2.63–2.68 g). High yield (571–670 g/m2) and density of productive stems (285–436 pcs/m2 ) with reduced winter hardiness (62–72%) and resistance to snow mold (30–35%) was observed in cvs. ‘Sirs 57’, ‘Sotnik’, ‘Germes’, ‘Antey’, ‘Beta’, ‘Don’, and lines 1/1 and 8003 from Sweden.

Morphological and agronomic characteristics of winter rye cultivars in connection with their resistance to lodging

Background. Lodging resistance of winter rye is associated with morphological features of the stem. Searching for source material to breed non-lodging high-yielding cultivars requires studying the varietal phenotypic diversity according to morphological characters of the stem that affect the resistance to lodging and the productivity of the ear.Materials and methods. Experiments were carried out in 2017–2020 at the Federal Agricultural Research Center of the North-East (FARC North-East), Kirov. Field resistance to lodging, morphological characteristics of the stem, yield, and ear productivity were evaluated in 16 winter rye cultivars. The study was based on the International COMECON List of Descriptors for the Genus Secale L., and Methodology for the State Variety Trials of Agricultural Crops. The weight of segments of the second lower internodes was measured in 10 plants of each cultivar under laboratory conditions.Results and conclusions. Negative correlations of lodging resistance with stem length (r= –0.55) and the weight of the second lower internode (r = –0.65) were revealed. Ear productivity of rye cultivars was significantly associated with the wall thickness (r = 0.52) and the length of the second lower internode (r = –0.52). According to the results of the path analysis, the main causes of a decrease in lodging resistance were the weight of the segment (P = –0.467) and the length of the second lower internode (P = –0.408), while an increase was connected with the wall thickness of the second lower internode (P = 0.424). The cultivars differed significantly in their resistance to lodging (LSD05 = 0.8). Cvs. ‘Moskovskaya 12’, ‘Tatyana’, ‘Bylina’ and ‘Yantarnaya’ were identified; they are recommended as source material for breeding for lodging resistance.

Adaptability of high-protein barley genotypes under the conditions of the Volga-Vyatka region

Background. Barley grain is unique raw material of versatile uses. More than 60% of the grain produced In the Volga-Vyatka region goes directly to fodder production purposes. One of the urgent tasks is to develop high-yielding cultivars with good grain quality, thus reducing protein deficiency in farm animal feeds and meeting the need for fodder grain that increases every year. Its successful solution requires a search for new high-yielding and high-protein source genotypes adapted to the conditions of the Volga-Vyatka region and their involvement in the breeding process.Materials and methods. Experimental work was carried out in 2018–2020 at the Federal Agricultural Research Center of the North-East named N.V. Rudnitsky, Kirov. Protein content in grain, yield, resistance to lodging, and duration of the growing season of 31 barley accessions were assessed. The barley collection was studied according to the International COMECON List of Descriptors for the Genus Hordeum L. and Methodological Guidelines. Protein content was measured using a universal rapid analyzer (INFRAMATIC 8620).Results and conclusions. Protein content had a strong correlation with Selyaninov’s hydrothermal coefficient in the interphase period from ear emergence to maturity (r = 0.85); the sum of effective temperatures during the entire growing season (r = 0.75); and precipitation in the period from seedling emergence to maturity (r = 0.67). Traits of breeding value (yield, lodging resistance, environmental plasticity, and stability) were observed in the following accessions: k-30574 (‘Filippa’, Sweden), k-30256 (‘Rodos’, Poland), ya-52 (‘Crusades’, Great Britain), k-35415 (NCL 95098, Argentina), k-30892 (‘Naran’, Russia), k-15619 (‘Polyarny 14’, Russia), ya-4 (752A, Switzerland), k-30349 (Landrace, Peru), k-5983 (Local, Afghanistan), k-3506 (Local, India), k-2929 (Local, China), k-2930 (Local, China), and k-5210 (‘Makbo’, Australia).

Genome-Wide Association Studies of Salt Tolerance at the Seed Germination Stage and Yield-Related Traits in Brassica napus L.

Salt stress severely affects crop growth and development and reduces the yield of Brassica napus. Exploring natural genetic variations for high salt tolerance in B. napus seedlings is an effective approach to improve productivity under salt stress. Using 10,658 high-quality single nucleotide polymorphic (SNP) markers developed by specific-locus amplified fragment sequencing (SLAF-seq) technology, genome-wide association studies (GWAS) were performed to investigate the genetic basis of salt tolerance and yield-related traits of B. napus. The results revealed that 77 and 497 SNPs were significantly associated with salt tolerance and yield-related traits, of which 40 and 58 SNPs were located in previously reported QTLs/SNPs, respectively. We identified nineteen candidate genes orthologous with Arabidopsis genes known to be associated with salt tolerance and seven potential candidates controlling both salt tolerance and yield. Our study provides a novel genetic resource for the breeding of high-yield cultivars resistant to salt stress.

STEVIA (STEVIA REBAUDIANA B.) GENOTYPES ASSESSMENT FOR LEAF YIELD STABILITY THROUGH GENOTYPE BY ENVIRONMENT INTERACTIONS, AMMI, AND GGE BIPLOT ANALYSES

Multilocation testing plays a vital role in the release of new high-yielding cultivars of stevia (Stevia rebaudiana B.) in Indonesia. In stevia, the leaf yield potential demonstrates an important characteristic for superior genotype selection. The study sought to identify the effects of genotype by environment interactions (GEI) on stevia yield and select the genotypes with stable yield resulting from radiation and hybridization through AMMI and GGE biplot analyses under three growing environments. The experiments took place in three locations, namely, Bandung, Sumedang, and Garut, West Java, Indonesia, consisting of a randomized complete block design (RCBD), with three replications. The combined analysis of variance (ANOVA) attained the genotype by environment interactions measurements. Calculating yield stability used the additive main effects and multiplicative interaction (AMMI), AMMI stability value (ASV), genotype stability index (GSI), and genotype plus genotype by environments (GGE) biplot measurements. The results revealed significant effects of environments (92.38%), followed by GEI (5.20%), and genotype effects (2.43%) of the total variation on stevia yield. The stevia genotypes viz., G11, G27, G2, and G5 gave a higher and more stable yield based on the AMMI-1 biplot. Based on the GGE biplot and the genotypes’ sustainable performances, the stevia genotypes, i.e., G27, G2, G11, G20, and G26, gained selection as stable. The three selected stevia genotypes displayed the highest yields and proved stable in three environments viz., G2 (Tamangwangu EMS mutant number A), G11 (Bogor mutant with gamma ray radiation 5 number C), and G27 (a hybrid from Garut × Bogor-3). These promising genotypes exhibit the potential for further development into new superior stevia genotypes.

Allelopathic potential and competitive traits of sweetpotato cultivars

Allelopathy and competition are components of plant-plant interactions, delimiting the level of interference. Understanding this interaction has practical applications in agriculture. Crop cultivars possessing high allelopathic ability and competitive traits are themselves tools for sustainable weed management, enabling reduced use of herbicides. Greenhouse and field experiments were conducted to assess the weed suppressive ability of selected sweetpotato (Ipomoea batatas L.) cultivars. The effect of nine cultivars on Palmer amaranth (Amaranthus palmeri S. Watson), junglerice (Echinochloa colona L.), and hemp sesbania (Sesbania hederacea P. Mill.) was first evaluated in the greenhouse. The experiment was set up in a completely randomized design with four replications and conducted twice. Sweetpotatoes were cultured in sand. The target weeds were seeded in pots filled with a 2:1 mix of field soil:potting mix and watered with 100-ml aliquot of sweetpotato root leachates once every 2 d. Weed height and shoot biomass were measured. ‘Heartogold’, ‘Centennial’, and ‘Stokes Purple’ were the most allelopathic cultivars. Junglerice was most inhibited by sweetpotato leachates. Nine cultivars were evaluated in the field. Experiments were conducted at Fayetteville and Kibler, Arkansas, USA, in a split-plot design, with weed infestation (broadleaf spp., grass spp., or weed-free) as whole plot and the cultivars as split-plot. Across locations, ‘Beauregard-14’ had the longest vines, whereas ‘Hatteras’ and ‘Heartogold’ had the tallest canopy. ‘Heartogold’ had the largest leaf area. This cultivar reduced weed biomass 2- to 4-fold in both locations. Yield was reduced on average 55 and 68% with grass and broadleaf weeds across locations, respectively. ‘Beauregard-14’ and ‘Bayou Belle-6’were the high-yielding cultivars in Kibler and Fayetteville. The highest yielding cultivars were not the most weed suppressive but did not incur the highest yield loss from weed competition, indicating the ability to withstand weed interference. Cultivar competitiveness, weed-suppressive ability, and weed tolerance are important factors that should be considered before making a cultivar selection.

GWAS, MWAS and mGWAS provide insights into precision agriculture based on genotype-dependent microbial effects in foxtail millet

Genetic and environmental factors collectively determine plant growth and yield. In the past 20 years, genome-wide association studies (GWAS) have been conducted on crops to decipher genetic loci that contribute to growth and yield, however, plant genotype appears to be insufficient to explain the trait variations. Here, we unravel the associations between genotypic, phenotypic, and rhizoplane microbiota variables of 827 foxtail millet cultivars by an integrated GWAS, microbiome-wide association studies (MWAS) and microbiome genome-wide association studies (mGWAS) method. We identify 257 rhizoplane microbial biomarkers associated with six key agronomic traits and validated the microbial-mediated growth effects on foxtail millet using marker strains isolated from the field. The rhizoplane microbiota composition is mainly driven by variations in plant genes related to immunity, metabolites, hormone signaling and nutrient uptake. Among these, the host immune gene FLS2 and transcription factor bHLH35 are widely associated with the microbial taxa of the rhizoplane. We further uncover a plant genotype-microbiota interaction network that contributes to phenotype plasticity. The microbial-mediated growth effects on foxtail millet are dependent on the host genotype, suggesting that precision microbiome management could be used to engineer high-yielding cultivars in agriculture systems.

VALIDATION OF MARKER-TRAIT ASSOCIATIONS IN SIX-ROWED BARLEY LINES BRED IN KAZAKHSTAN

Barley is an important cereal crop in Kazakhstan, mostly used for animal feeding, malting, and the food industry. The success of barley production is dependent on the genetic resources (cultivars) available, and local breeding programs that focus on the development of competitive cultivars. One way to develop new high-yielding cultivars and improve the efficiency of breeding programs is the application of modern molecular genetic and genomic tools. One such technology is genome-wide association study (GWAS), which has been successfully applied to identify the quantitative trait loci (QTL) associated with the valuable traits. The identified single nucleotide polymorphisms (SNPs) based on GWAS can be converted to flexible and cost-effective KASP (Kompetitive Allele Specific PCR) assays and validated for use in future marker-assisted breeding projects. The purpose of this study was to genotype eleven promising six-rowed barley lines using twenty-one KASP assays associated with agronomic traits reported in previous GWAS. The genotyping results suggested that only seven out of twenty-one KASP markers were polymorphic in this group of barley accessions. The t-test output suggested that six out of nine agronomic traits were significantly associated with seven KASPs. Notably, two assays (ipbb_hv_6, ipbb_hv_108) affected both vegetation period (VP) and yield per m2 (YM2) in conditions of Northern Kazakhstan, where barley is growing in more than 80% of total crop sowing areas of the country. The application of these highly informative KASP markers can help enhance the efficiency of local breeding projects in barley.