Buckwheat Genotypes Research Articles

Superior Buckwheat Genotypes for the River-Basin Areas of Sudurpaschim Province

Buckwheat is considered one of the climates smart crops, and it can play a significant role in food security in Nepal's hills and mountainous regions. Field experiments were conducted to identify suitable buckwheat genotypes for general cultivation in the mid-hills of far-western Nepal. The experiment was laid out in a randomized complete block design with three replications in both years. The experiments were conducted in the research field of the Directorate of Agricultural Research, Sudurpaschim Province, Bhagetada, Doti, during the two consecutive winters of 2019 and 2020. Eleven elite buckwheat genotypes received from the Hill Crops Research Program, Kabre, Dolakha, Nepal, were evaluated. The only released variety of sweet-type buckwheat, Mithe Fapar-1, was used as a standard check. There was a significant difference among the genotypes in both years. In 2019, genotypes Acc#5670 (1390 kg ha-1), standard check - Mithe Fapar-1 (1250 kg ha-1), PL-30 (1240 kg ha-1), KLF-72-22-520 (1199 kg ha-1), and Acc#6529 (1190 kg ha-1) were identified as higher yielder. In 2020, Acc#5670 (1556 kg ha-1), GF-5283 (1,434 kg ha-1), Acc#2234 (1,399 kg ha-1), Acc#2213 (1361 kg ha-1), and Acc#6529 (1312 kg ha-1) were found superior among the tested genotypes. Likewise, combined over 2019 and 2020 data revealed that the genotypes Acc#5670 (1473 kg ha-1), Acc#2234 (1275 kg ha-1), Acc#2213 (1261 kg ha-1), Acc#6529 (1251 kg ha-1), and the genotype GF-5283 (1247 kg ha-1) were found, high yielder. Genotypes found superior in these field experiments are valuable resources for the buckwheat breeding program of Nepal (Hill Crops Research Program) and especially for the mid-hills of Sudurpaschim Province. The superior genotypes can further be evaluated to develop location-specific genotypes for the regions.

Аnalyzing buckwheat genotypes obtained on selective media with zinc in vitro using ISSR markers

The paper evaluates four ISSR-markers (М1, М2, М7, and М11) for their effectiveness in research on the genetic distances of regenerated Fagopyrum esculentum plants, which were obtained in vitro on selective media with high doses of ZnSO4×7 H2O (808–1313 mg/L). The level of polymorphism was determined to be high in the combined sample (74.4%). The obtained speciemens might be used in the breeding of new varieties with economically important traits.

Morphological, Physiological, and Photosynthetic Differences of Tartary Buckwheat Induced by Post-Anthesis Drought.

Tartary buckwheat (Fagopyrum tataricum (L.) Gaertn) is a crop of significant interest due to its nutritional value and resilience to drought conditions. However, drought, particularly following flowering, is a major factor contributing to yield reduction. This research employed two distinct Tartary buckwheat genotypes to investigate the effects of post-anthesis drought on growth and physicochemical characteristics. The study aimed to elucidate the response of Tartary buckwheat to drought stress. The findings indicated that post-anthesis drought adversely impacted the growth, morphology, and biomass accumulation of Tartary buckwheat. Drought stress enhanced the maximum photosynthetic capacity (Fv/Fm) and light protection ability (NPQ) of the 'Xiqiao-2' genotype. In response to drought stress, 'Dingku-1' and 'Xiqiao-2' maintained osmotic balance by accumulating soluble sugars and proline, respectively. Notably, 'Xiqiao-2' exhibited elevated levels of flavonoids and polyphenols in its leaves, which helped mitigate oxidative damage caused by drought. Furthermore, rewatering after a brief drought period significantly improved plant height, stem diameter, and biomass accumulation in 'Dingku-1'. Overall, 'Xiqiao-2' demonstrated greater long-term tolerance to post-anthesis drought, while 'Dingku-1' was less adversely affected by short-term post-anthesis drought.

Characterization of Genetic Variability of Common and Tartary Buckwheat Genotypes Using Microsatellite Markers.

Buckwheat is a highly nutritional pseudocereal with antioxidant potential. The aim of this study was to analyze the genetic variability of 21 varieties of common buckwheat (Fagopyrum esculentum Moench.) and 14 varieties of Tartary buckwheat (Fagopyrum tataricum Gaertn.) using microsatellite markers. By analyzing 21 SSR markers, an average of 11.6 alleles per locus were amplified and an average PIC value of 0.711 was determined. We determined the heterozygous status of the individuals and variability in the set using the SSR analysis on the basis of expected heterozygosity (He, 0.477), observed heterozygosity (Ho, 0.675), Shannon's index (I, 0.820), and fixation indices (FST, FIS, FIT). Based on the SSR analyses, the lower level of expected heterozygosity in the analyzed set of Tartary buckwheat genotypes was observed compared to common buckwheat. With the help of a hierarchical cluster analysis using the UPGMA algorithm, Structure analysis, and PCoA analysis for the SSR markers, we divided the buckwheat varieties in the dendrogram into two main clusters according to the species. The AMOVA analysis showed that genetic variability between the individuals prevails in the analyzed set. The SSR technique proved to be a suitable tool for the determination of intra- and inter-varietal genetic variability and for analysis of diversity.

Effects of Cadmium Stress on Tartary Buckwheat Seedlings.

Cadmium (Cd) is a naturally occurring toxic heavy metal that adversely affects plant germination, growth, and development. While the effects of Cd have been described on many crop species including rice, maize, wheat and barley, few studies are available on cadmium's effect on Tartary buckwheat which is a traditional grain in China. We examined nine genotypes and found that 30 µM of Cd reduced the root length in seedlings by between 4 and 44% and decreased the total biomass by 7 to 31%, compared with Cd-free controls. We identified a significant genotypic variation in sensitivity to Cd stress. Cd treatment decreased the total root length and the emergence and growth of lateral roots, and these changes were significantly greater in the Cd-sensitive genotypes than in tolerant genotypes. Cd resulted in greater wilting and discoloration in sensitive genotypes than in tolerant genotypes and caused more damage to the structure of root and leaf cells. Cd accumulated in the roots and shoots, but the concentrations in the sensitive genotypes were significantly greater than in the more tolerant genotypes. Cd treatment affected nutrient uptake, and the changes in the sensitive genotypes were greater than those in the tolerant genotypes, which could maintain their concentrations closer to the control levels. The induction of SOD, POD, and CAT activities in the roots and shoots was significantly greater in the tolerant genotypes than in the sensitive genotypes. We demonstrated that Cd stress reduced root and shoot growth, decreased plant biomass, disrupted nutrient uptake, altered cell structure, and managed Cd-induced oxidative stress differently in the sensitive and tolerant genotypes of Tartary buckwheat.

RAPD MARKERS ARE EFFECTIVE TOOL FOR THE DIFFERENTIATION OF COMMON AND TARTARY BUCKWHEAT GENOTYPES

Common and tartary buckwheat are important cultivated species of the genus Fagopyrum. Genetic polymorphism of thirty-five genotypes of common buckwheat (Fagopyrum esculentum Moench) and tartary buckwheat (Fagopyrum tataricum Gaertn.) was analyzed using 10 random amplified polymorphic DNA (RAPD) primers. A total of 119 DNA fragments were amplified using ten RAPD primers with an average of 11.9 fragments per primer. The number of amplified fragments ranged from 6 (OPB-08) to 16 (SIGMA-D-01). PIC values ranged from 0.782 (OPC-08) to 0.919 (SIGMA-D-01) with an average of 0.871 per primer. The marker index (10.364) and diversity detecting index (2.961) were high and presented the utility of used marker technique. To evaluate the genetic relationships among buckwheat genotypes a phylogenetic tree based on UPGMA algorithm was constructed. The genotypes of common and tartary buckwheat were separated independently into cluster I and II. Cluster I separated 14 genotypes of tartary buckwheat into two subclusters (Ia, Ib). Genotype 903016, which originated in Pakistan, was separated individually into the subcluster Ia. Cluster II included genotypes of common buckwheat and was further subdivided into subcluster IIa and IIb. Two genotypes of subcluster IIb (Bamby and Hruszowska) were genetically the closest. Bamby and Hruszowska reflected the maximum similarity value (0.605) according to Jaccard’s coefficient of similarity. Based on the presented data it is suggested that the RAPD technique is suitable for differentiation among genotypes of common and tartary buckwheat. RAPD primers have proven to be reliable and useful method for studying genetic variability of buckwheat genotypes.

Stability Analysis and Genetic Variability in Buckwheat (Fagopyrum esculentum Moench.)

Aims: To estimate the genetic variability and to identify the stable buckwheat genotype for growth and yield parameters. Study Design: Eberhart and Russell model. Place and Duration of Study: Department of Plantation, Spices, Medicinal and Aromatic Crops, College of Horticulture, Bagalkot, Karnataka during Jan-April 2021-2022. Methodology: Fifteen genotypes of buckwheat were assessed for stability parameters for 15 characters across three environments i.e, full dose of recommended fertilizer (RDF), 3/4th dose of RDF and 1/2nd dose of RDF. The pooled data of these environments were used for estimation of genetic variability. Results: The heritability estimates were moderate to high for all the characters. The genetic advance over mean was found highest for number of clusters per cyme (35.05%), seed yield per plot (32.68%) and seed yield per hectare (32.72%). The genotype EC-104035 was found stable for seed yield per plant, per plot and hectare, EC-386667, EC-3222, Nilgiri local, PRB-1 and Sangla B-460 for thousand seed weight, IC-313134 and EC-3222 for plant height at 45 days after sowing and at harvest, Shimla B-1 for plant height at 15 days after sowing, IC-49671, IC-274429 and Sangla B-460 for number of branches at 30 DAS, PRB-1 for days to first flowering and Nilgiri local for days to 50 percent flowering. Conclusion: The genotypes stable for more traits with high genetic variability, will be considered for future breeding program.

Growth and production potential of buckwheat genotypes under organic farming in the Eastern Himalayan region of India

Growth and production potential of buckwheat genotypes under organic farming in the Eastern Himalayan region of India

Enhanced Antioxidant Activity and Secondary Metabolite Production in Tartary Buckwheat under Polyethylene Glycol (PEG)-Induced Drought Stress during Germination

Drought stress is one of the key factors impeding agricultural productivity worldwide. This experiment aimed at investigating the polyethylene glycol (PEG)-induced drought stress effects on seed germination, physiology, and biochemical mechanisms in Tartary buckwheat genotypes. Four PEG-induced stress conditions (0%, 10%, 20%, and 30%) were applied to 14 selected genotypes at the germination stage to evaluate their stress tolerance capacity. Significant differences were obtained in germination percentage, relative water content (RWC), and all growth parameters among the studied 14 genotypes. Based on the stress tolerance index (STI), XiNong 9943, XiNong 9940, and QianKu-5 were found to be tolerant, and QuanKu-4 was susceptible. These cultivars were selected for further physiological and biochemical characterization. The results demonstrated that the activity of enzymes was significantly increased with the increase in PEG dose. SOD (superoxide dismutase), POD (peroxidase), CAT (catalase), and APX (ascorbate peroxidase) levels obtained at 30% PEG in the XiNong 9943 genotype were 2.01, 2.19, 4.92, and 4.46 times higher, respectively, than the normal growth condition (T0). Moreover, the secondary metabolite content also increased with the increase in PEG dose. At 30% PEG, the genotype XiNong 9943 yielded phenols, flavonoids, polyphenol oxidase (PPO), and phenylalanine ammonia lyase (PAL) levels that were higher by 131%, 95%, 154%, and 164%, respectively, than T0 condition. From both the findings of the activity of enzymes and the secondary metabolite content, the genotypic response to drought was ranked in the following order: XiNong 9943 > XiNong 9940 > QianKu-5 > QianKu-4, which supported the STI selection system. Assessing the overall performance, the genotype XiNong 9943 shows drought tolerance, which can be useful material for future buckwheat breeding programs.

Аnalyzing Buckwheat Genotypes Obtained on Selective Media with Zinc In Vitro Using ISSR Markers

Аnalyzing Buckwheat Genotypes Obtained on Selective Media with Zinc In Vitro Using ISSR Markers

Cultivating Resilience: Disease Resistance Screening of Buckwheat (Fagopyrum spp.) Genotypes in India's Semi-tropical Belt

Buckwheat (Fagopyrum spp.) is a major pseudo cereal, the comprehensive exploration of buckwheat genotypes in the semi-tropical climatic region of India, reveals significant genetic variability among the genotypes for a range of biometrical features, underlining the potential for genetic improvement in this crop. Notably, traits such as days to maturity, and economic yield demonstrate substantial genetic potential for enhancement through targeted breeding programs, exhibiting relatively high genetic advancement values, indicating their potential for effective improvement through breeding programs. Disease resistance, as assessed by the percentage disease index (PDI) of chlorotic leaf spot and brown leaf spot, also reveals noteworthy scope for improvement, crucial for sustaining buckwheat cultivation in disease-prone regions. A correlation analysis uncovers intricate relationships between agronomic traits and disease parameters, with the observed positive correlation between plant height (PH) and economic yield (EY) suggesting that taller buckwheat plants may have a slight advantage in terms of yield, and the negative correlation between test weight (TW) and disease severity, both for chlorotic leaf spot (PDI CL) and brown leaf spot (PDI BL), underscores the potential for selecting genotypes with higher test weights as a means to enhance disease resistance. Identification of genotypes with low disease susceptibility offers promising avenues for disease-resistant buckwheat cultivation. Understanding the genetic parameters and disease dynamics presented in this study would be proved invaluable in developing resilient buckwheat varieties, ensuring food security, and promoting sustainable agriculture in the region opening doors to effective disease management strategies and improved crop productivity in buckwheat cultivation.

Moringa leaf extract enhances the growth and yield characteristics of buckwheat genotypes by modulating the biochemical and physiological activities

Moringa leaf extract enhances the growth and yield characteristics of buckwheat genotypes by modulating the biochemical and physiological activities

Unravelling the Genetic Potential of Buckwheat Genotypes through Yield and Yield Attributing Parameters in Semi-tropical Climate of India

In this comprehensive study on buckwheat genotypes conducted in the semi-tropical region of Prayagraj, Uttar Pradesh, India during the rabi, 2021 growing season, a range of critical agronomic traits, including plant height, flowering time, days to maturity, test weight, and economic yield, were systematically analyzed. The analysis of variance highlighted the significance of both replicates and treatments in explaining variations across these traits. The genotypes exhibited remarkable diversity, with notable differences in plant height, with IC-26755 exhibiting the tallest plants at 99.75 cm, while IC-582972 displayed the shortest at 14.93 cm. Moreover, flowering time varied widely, with IC-582972 and IC-329201 being non-flowering genotypes. These variations in plant height and flowering time can have significant implications for crop management and breeding strategies. Assessment of genetic variability and genetic advancement underscored the substantial potential for improving traits such as economic yield and days to flowering through selective breeding efforts. Genetic coefficients of variation (GCV) and phenotypic coefficients of variation (PCV) were calculated, with "Economic yield" displaying the highest values, signifying significant inherent variability among genotypes for this trait.Phenotypic and genotypic correlation analyses unveiled intriguing relationships among traits, offering valuable insights for crop management and breeding strategies. There were strong positive correlations between days to 50% flowering and total weight, suggesting that genotypes taking more time to flower tend to produce greater total weight.Phenotypic and genotypic path analyses further elucidated the intricate interplay of traits, providing actionable insights for trait improvement through selective breeding. In the phenotypic path analysis, it was observed that total biomass fraction had a direct positive effect on days to 50% flowering and days to 80% maturity, suggesting that genotypes with higher biomass fractions tend to have later flowering and maturity.

Genetic variability of buckwheat (Fagopyrum spp.) genotypes for nutritional and nutraceutical traits

Genetic variability of buckwheat (Fagopyrum spp.) genotypes for nutritional and nutraceutical traits

Evaluating Tartary Buckwheat Genotypes with High Callus Induction Rates and the Transcriptomic Profiling during Callus Formation.

Due to their complex genotypes, low in vitro regeneration rates, and difficulty in obtaining transgenic plants, studies concerning basic biological research and molecular breeding in Tartary buckwheat (TB) are greatly limited. In this study, the hypocotyls of 60 genotypes of TB (TBC1~60) were used as explants. Of these, TBC14 was selected due to a high callus induction rate of 97.78% under dark and a proliferation coefficient (PC) of 28.2 when cultured on MS medium supplemented with 2.0 mg/L of 2,4-D and 1.5 mg/L of 6-BA. Subsequently, the samples of the calli obtained from TBC14 were collected at 0, 10, 20, and 30 d, and their transcriptomes were sequenced where identified. GO enrichment led to the detection of the most significant active gene set, which was the DNA binding transcription factor activity. The DEGs related to the pathways concerning metabolism, the biosynthesis of secondary metabolites, and hormone signal transduction were the most enriched in the KEGG database. The sets of MYB, AP2/ERF, and bHLH TFs exhibited the highest number of DEGs. Using this enrichment analysis, 421 genes encoding TFs, 47 auxin- and cytokinin-related genes, and 6 signal transduction-associated genes were screened that may play significant roles in callus formation (CF) in TB. Furthermore, FtPinG0008123200.01 (bZIP), a key gene promoting CF, was screened in terms of the weighted gene co-expression network associated with the various stages of CF. Our study not only provides valuable information about the molecular mechanism of CF but also reveals new genes involved in this process.

The yield of common buckwheat (Fagopyrum esculentum Moench) depends on the genotype but not on the Pin-to-Thrum ratio

Common buckwheat has a complicated flowering biology. It is characterized by a strong self-incompatibility resulting from heterostyly, i.e. the occurrence of two types of flowers: Pin and Thrum, differing in the length of pistils and stamens. Fertilization occurs only as a result of cross-pollination between these morphs. Suspicions exist that the disturbed ratio between plants producing Pin and Thrum flowers (with the latter type generating more seeds) causes low seed yield. The aim of the study was to analyze: (1) the ratio between plants with Pin and Thrum morphs, (2) flower and seed production, as well as abortion of flowers, (3) the composition of nectar collected at an early flowering stage and during full flowering. The study was performed under semi-controlled and field conditions on six Polish accessions. The results indicated that under semi-controlled conditions the Pin-to-Thrum ratio was indeed disproportionate; such a phenomenon is called anisoplethy. In the field, however, the Pin-to-Thrum ratio was well-balanced (isoplethy). The plants with both morphs aborted a similar percentage of flowers and produced a comparable number of empty seeds. The number of flowers, their abortion, and ripe seed production were independent of flower type, however, they were genotypically controlled. A strong correlation between the number of flowers produced by a plant, flower abortion and the number of empty seeds was found. The percentage of aborted flowers correlated positively with the weight of ripe seeds. Nectar composition was similar for all buckwheat genotypes, but we found some differences in the amount of individual sugars depending on the blooming stage. In the majority of accessions, the nectar produced at the early blooming stage was characterized by a greater mass and volume, and contained more individual sugars than at the full-flowering stage.

Different genotypes of tartary buckwheat can regulate the transformation of nitrogen through the secretion of organic acids under low nitrogen stress

Roots respond to nitrogen deficiency by altering their physiological and metabolic responses. Soil nitrogen invertase activity and the diversity of nitrifying microorganisms (AOA and AOB) significantly affect the nitrogen cycle in soil. As an important part of root exudates, organic acids can reflect the dynamic changes of plant roots in soil. However, it is not clear how the barren-tolerant genotype plant varieties show their stress resistance through organic acids regulating nitrogen transformation under low nitrogen environment. Here, we selected two Tartary buckwheat varieties: HeiFeng1 (HF, low nitrogen sensitive cultivar) and DiQing (DQ, low nitrogen tolerance cultivar) for a two-year experiment. The urea addition levels of 0, 80, and 160 mg kg−1 soil were respectively set as nitrogen sources, and ozone sterilization experiments were designed to completely remove microbial effects to distinguish the contribution of plant roots and microorganisms to nitrogen invertase and organic acids (400 ml 1 mol L−1 ozone water daily, 0 nitrogen fertilizer, O3). The results showed that malic acid and tartaric acid were the main organic acids secreted by tartary buckwheat. The total amount and richness of organic acids in Diqing were higher than those in Heifeng, and organic acids directly affected the diversity of ammonia-oxidizing microorganisms (AOA and AOB), changed the soil environment by affecting soil water content, and indirectly affected the activity of nitrogen invertase. At the same time, it was found that the increase of nitrogen application rate would increase the proportion of key bacteria such as Nirtrosomonas and Nitrosospira in AOB of tartary buckwheat soil. Finally, Diqing tartary buckwheat was proved to be more suitable for planting in the nitrogen-deficient Loess Plateau, but attention should be paid to the negative effects of AOB and organic acids.

Variations in chemical composition of common buckwheat (Fagopyrum esculentum Moench) as a result of different environmental conditions.

Common buckwheat (Fagopyrum esculentum Moench) is a pseudo cereal that is gaining interest in the world. The chemical profile of common buckwheat determines its high nutritional and health-promoting value. The accumulation of these valuable ingredients depends on many factors, such as: variety, location of cultivation and related weather and agrotechnical conditions. Due to the growing interest in common buckwheat as a natural plant material for food production, it is important to know the factors affecting the quantitative and qualitative composition of its grains. The aim of the research was to determine the effect of the genotype (G), environment (E) and G × E interaction on the content of nutrients (protein, starch, ash, lipids) and bioactive components [dietary fiber (DF), total phenolic content (TPC)] in the common buckwheat grains. The study covered four cultivars grown in three locations for three consecutive vegetation seasons (2016/2017, 2017/2018, 2018/2019). Based on the obtained results, a significant influence of the environment and G × E interaction on the content of the studied parameters was found. The greatest impact on the diversity of the content of nutrients had environmental conditions, which in the case of protein and ash determined these features in more than 80%, and in the case of starch, 70%. With regard to bioactive compounds, the greatest influence of the environment was observed for the amount of TPC (78%), lignin (51%) and the DF complex (56%). The obtained results are useful for breeders working on expanding the pool of common buckwheat genotypes, stable in changing environmental conditions. © 2023 Society of Chemical Industry.

Metabolic-GWAS provides insights into genetic architecture of seed metabolome in buckwheat

BackgroundBuckwheat (Fagopyrum spp.), belonging to the Polygonaceae family, is an ancient pseudo-cereal with high nutritional and nutraceutical properties. Buckwheat proteins are gluten-free and show balanced amino acid and micronutrient profiles, with higher content of health-promoting bioactive flavonoids that make it a golden crop of the future. Plant metabolome is increasingly gaining importance as a crucial component to understand the connection between plant physiology and environment and as a potential link between the genome and phenome. However, the genetic architecture governing the metabolome and thus, the phenome is not well understood. Here, we aim to obtain a deeper insight into the genetic architecture of seed metabolome in buckwheat by integrating high throughput metabolomics and genotyping-by-sequencing applying an array of bioinformatics tools for data analysis.ResultsHigh throughput metabolomic analysis identified 24 metabolites in seed endosperm of 130 diverse buckwheat genotypes. The genotyping-by-sequencing (GBS) of these genotypes revealed 3,728,028 SNPs. The Genome Association and Prediction Integrated Tool (GAPIT) assisted in the identification of 27 SNPs/QTLs linked to 18 metabolites. Candidate genes were identified near 100 Kb of QTLs, providing insights into several metabolic and biosynthetic pathways.ConclusionsWe established the metabolome inventory of 130 germplasm lines of buckwheat, identified QTLs through marker trait association and positions of potential candidate genes. This will pave the way for future dissection of complex economic traits in buckwheat.

Specialized Metabolites Accumulation Pattern in Buckwheat Is Strongly Influenced by Accession Choice and Co-Existing Weeds.

Screening suitable allelopathic crops and crop genotypes that are competitive with weeds can be a sustainable weed control strategy to reduce the massive use of herbicides. In this study, three accessions of common buckwheat Fagopyrum esculentum Moench. (Gema, Kora, and Eva) and one of Tartary buckwheat Fagopyrum tataricum Gaertn. (PI481671) were screened against the germination and growth of the herbicide-resistant weeds Lolium rigidum Gaud. and Portulaca oleracea L. The chemical profile of the four buckwheat accessions was characterised in their shoots, roots, and root exudates in order to know more about their ability to sustainably manage weeds and the relation of this ability with the polyphenol accumulation and exudation from buckwheat plants. Our results show that different buckwheat genotypes may have different capacities to produce and exude several types of specialized metabolites, which lead to a wide range of allelopathic and defence functions in the agroecosystem to sustainably manage the growing weeds in their vicinity. The ability of the different buckwheat accessions to suppress weeds was accession-dependent without differences between species, as the common (Eva, Gema, and Kora) and Tartary (PI481671) accessions did not show any species-dependent pattern in their ability to control the germination and growth of the target weeds. Finally, Gema appeared to be the most promising accession to be evaluated in organic farming due to its capacity to sustainably control target weeds while stimulating the root growth of buckwheat plants.