Main Stem Node Number Research Articles

Identification of quantitative trait loci for lodging and related agronomic traits in soybean (Glycine max [L.] Merr.)

BackgroundLodging, a crucial agronomic trait linked to soybean yield, poses a significant challenge in soybean production. Nevertheless, there has been less research on soybean lodging compared to other important agronomic traits, hindering progress in breeding high-yield soybeans. Our goals were to investigate lodging, pinpoint quantitative trait loci (QTL) linked to lodging, and forecast potential candidate genes linked to this trait. To achieve this, we employed a recombinant inbred line (RIL) population derived from a cross between Guizao 1 and B13 (GB) across various environments.ResultsThe lodging score of the RIL population was found to be significantly positively correlated with flowering time, maturity time, plant height, number of main stem nodes, stem diameter, and internode length, with correlation coefficients ranging from 0.457 to 0.783. A total of 84 QTLs associated with soybean lodging and related traits were identified using the GB population. The contribution of phenotypic variance ranged from 1.26 to 66.87%, with LOD scores ranging from 2.52 to 69.22. Additionally, within these QTLs, a stable major QTL associated with lodging was newly discovered in the GB population. Out of the ten major QTLs associated with other related traits, nine of them were situated within the qLD-4-1 interval of the major lodging score locus, displaying phenotypic variations ranging from 12.10 to 66.87%. Specific alterations in gene expression were revealed through the analysis of resequencing data from the two parental lines, potentially indicating their significant roles in lodging. Subsequently, it was determined through qRT-PCR that four genes are likely to be the major genes controlling soybean lodging.ConclusionsThis study’s findings offer valuable insights into the genetic underpinnings of soybean lodging resistance traits. By comprehending the potential genetic factors associated with lodging, this research lays the groundwork for breeding high-yield soybeans with improved lodging resistance.

The effect of exogenous gibberellin and its synthesis inhibitor treatments for morphological and physiological characteristics of Tartary buckwheat

Gibberellin (GA3) is an important plant hormone involved in many physiological and developmental processes in plants. However, the physiological mechanism of GA3 on the regulation yield and grain shell thickness of Tartary buckwheat is still unclear. In this study, the thick-shelled cultivar “Jinqiao 2” and thin-shelled cultivar “Miku 18” were used to study the effects of different concentrations (0, 50, and 100 mg L−1) of exogenous GA3 and chlorocholine chloride (CCC, GA3 synthesis inhibitor) on the cellulose content, amylase, and sucrose synthase (SS) activity in grain shell and the yield of Tartary buckwheat. The application of exogenous GA3 can improve the cellulose content and the activity of amylase and SS in the grain shell of the two Tartary buckwheat varieties. It can also increase the main stem node number, main stem branch number, grains per plant, and yield. Compared with the control treatment (CK, 0 mg L−1), the 100 mg/L exogenous GA3 treatment increased the number of grains per plant, grain weight per plant, 1000-grain weight, and yield of Jinqiao 2 by 20.1%, 41.9%, 13%, and 34.7%, respectively. These items of Miku 18 were increased by 26%, 15.2%, 10.2%, and 23.8%. The application of CCC reduced the activity of amylase and SS and cellulose content in grain shell. In addition, it decreased the main stem node number, main stem branch number, grains per plant, and yield of Tartary buckwheat. In summary, exogenous GA3 treatment not only improved the yield of Tartary buckwheat but also increased the thickness of grain shell by enhancing the activity of amylase and SS and promoting the synthesis and accumulation of cellulose. The results can provide theoretical references for clarifying the physiological mechanism of the difference in shell thickness between Tartary buckwheat varieties.

Potassium fertilizer promotes the thin-shelled Tartary buckwheat yield by delaying senescence and promoting grain filling.

The application rate of potassium fertilizer is closely related to the yield of crops. Thin-shelled Tartary buckwheat is a new variety of Tartary buckwheat with the advantages of thin shell and easy shelling. However, little is known about application rate of potassium fertilizer on the yield formation of thin-shelled Tartary buckwheat. This study aimed to clarify the effect of potassium fertilizer on the growth and yield of thin-shelled Tartary buckwheat. A field experiment to investigate the characteristics was conducted across two years using thin-shelled Tartary buckwheat (Miku 18) with four potassium fertilizer applications including 0 (no potassium fertilizer, CK), 15 (low-concentration potassium fertilizer, LK), 30 (medium-concentration potassium fertilizer, MK), and 45 kg·ha-1 (high-concentration potassium fertilizer, HK). The maximum and average grain filling rates; starch synthase activity; superoxide dismutase and peroxidase activities in leaves; root morphological indices and activities; available nitrogen, phosphorus, and organic matter content in rhizosphere soil; urease and alkaline phosphatase activities in rhizosphere soil; plant height, main stem node number, main stem branch number, leaf number; grain number per plant, grain weight per plant, and 100-grain weight increased first and then decreased with the increase in potassium fertilizer application rate and reached the maximum at MK treatment. The content of malondialdehyde was significantly lower in MK treatment than in other three treatments. The yields of thin-shelled Tartary buckwheat treated with LK, MK, and HK were 1.22, 1.37, and 1.07 times that of CK, respectively. In summary, an appropriate potassium fertilizer treatment (30kg·ha-1) can delay the senescence, promote the grain filling, and increase the grain weight and final yield of thin-shelled Tartary buckwheat. This treatment is recommended to be used in production to achieve high-yield cultivation of thin-shelled Tartary buckwheat.

Quantifying High-Temperature and Drought Stress Effects on Soybean Growth and Yield in the Western Guanzhong Plain

High-temperature and drought events significantly impact crop growth and development. In the soybean-producing region of the Guanzhong Plain in China, understanding the dynamics of these climatic phenomena is vital for soybean yield preservation. Through a fixed-position observation experiment that analyzed four growth stages, nine agronomic traits, and soybean yield per unit area from 1998 to 2023, this research evaluated the characteristics of high-temperature and drought processes in various growth stages. It also examined the influence of high-temperature processes, drought processes, and their combined effects on agronomic traits and yield. The results indicate the following: (1) High temperature was a constant factor during the soybean growth period, with temperature-related indices markedly surpassing those related to drought. Notably, the occurrence of high-temperature and drought events was more prevalent during the flowering–podding stage than at the podding or grain-filling stages. (2) High temperature profoundly affected soybean yield components, primarily through a decrease in the number of grains per plant during the flowering–podding stage, subsequently impacting the grain weight per plant and yield. In years with extremely high temperatures, the soybean plant height was reduced by 6.1 to 15 cm, the main stem node number decreased by 0.1 to 2.9, the branch number decreased by 0.2 to 0.6, the number of pods per plant decreased by 4.8 to 13.7, the number of grains per pod decreased by 0.1 to 0.3, the number of grains per plant decreased by 13.5 to 32.6, the grain weight per plant decreased by 3.8 to 6.9 g, and the 100-grain weight decreased by 0.1 to 4.5 g. The common impact of high temperature combined with drought processes in different growth stages was reflected in the reduction in the number of branches by 0.1 to 1.4 and the reduction in the number of grains per pod by 0.02 to 13.7. This study underscores the importance of addressing the quantitative effects of climate change and extreme weather on soybean yield, which could help to develop effective adaptation and mitigation strategies.

Identification of candidate genes and development of KASP markers for soybean shade-tolerance using GWAS.

Shade has a direct impact on photosynthesis and production of plants. Exposure to shade significantly reduces crops yields. Identifying shade-tolerant genomic loci and soybean varieties is crucial for improving soybean yields. In this study, we applied a shade treatment (30% light reduction) to a natural soybean population consisting of 264 accessions, and measured several traits, including the first pod height, plant height, pod number per plant, grain weight per plant, branch number, and main stem node number. Additionally, we performed GWAS on these six traits with and without shade treatment, as well as on the shade tolerance coefficients (STCs) of the six traits. As a result, we identified five shade-tolerance varieties, 733 SNPs and four candidate genes over two years. Furthermore, we developed four kompetitive allele-specific PCR (KASP) makers for the STC of S18_1766721, S09_48870909, S19_49517336, S18_3429732. This study provides valuable genetic resources for breeding soybean shade tolerance and offers new insights into the theoretical research on soybean shade tolerance.

The Effect of Plant and Row Configuration on the Growth and Yield of Multiple Cropping of Soybeans in Southern Xinjiang, China

To study the optimal plant row configuration of the multiple cropping of soybeans that are suitable for planting in southern Xinjiang, a field experiment using soybean variety SN35 was carried out employing different plant row designs. Three row spacing treatments of 15 cm (H1), 30 cm (H2), and 45 cm (H3) and three density treatments of 52.56 million (M1), 55 million (M2), and 60 million (M3) plants per hectare were set up in this experiment to explore the effects of different plant row spacing configurations on agronomic traits, photosynthetic characteristics, dry matter accumulation, and the soybean yield of the multiple cropping of soybeans. The results showed that the soybeans’ plant height, diameter, main stem node number, leaf shape index, leaf area index (LAI), leaf area duration (LAD), and pod dry matter distribution ratio increased gradually with the growth process. In contrast, the stem dry matter distribution ratio decreased gradually, and the leaf dry matter distribution ratio first increased and then decreased. The plant height of the soybeans treated with H2M3 was the highest, reaching 67.38 cm. The number of primary stem nodes of the soybeans treated with H1M3 was the highest, reaching 12.7 nodes. The stem diameter of the soybeans treated with H1M1 was the highest, reaching 0.64 cm. The leaf shape index of the soybeans treated with H3M1 was the highest, reaching 2.72. Intercellular CO2 concentration closely affects the final yield; the correlation coefficients with the pod number per plant, seed number per plant, and yield reached 0.75, 0.78, and 0.87, respectively. The theoretical maximum hundred-grain weights under the H1M1 and H2M1 treatments were higher, reaching 20.33 g and 17.98 g, respectively. The H3M3 treatment had the most significant one-hundred-grain weight, reaching 21.27 g. The soybean yield of each density treatment was M3 > M1 > M2. With the increase in row spacing, the average pod number per plant, grain number per plant, grain weight per plant, and yield of soybeans decreased gradually, and the hundred-grain weight increased gradually. The yield of the density treatment with 60 million plants per hectare under 15 cm row spacing was the highest, reaching 6155.8 kg·hm−2, followed by the density treatment with 60 million plants per hectare under 30 cm row spacing, reaching 5850.6 kg·hm−2.

不同镇压方式对荞麦生长特性影响的试验研究

In order to fully explore the influence of different pressure methods on the growth characteristics of buckwheat, a pressure test device with adjustable press force, and easy to replace the press wheel was designed. Using the dry matter quality of buckwheat roots, stems, leaves at seedling stage, plant height, number of main stem nodes, number of main stem branches, grain number per plant, grain weight per plant, and yield as evaluation indexes, single factor test on press force was carried out, and three-factor and three-level orthogonal test was carried out too with press wheel outer diameter, press force and press wheel type as factors. The results showed that the index values of buckwheat showed a trend of first increasing and then decreasing with the increase of press force. When the press force was 450 N, the growth and development of buckwheat performed best. The effects of press wheel outer diameter, press force, and press wheel type on growth characteristics of buckwheat was different. The effects of press force and press wheel type on the indexes were greater than that of press wheel outer diameter. The optimal pressure methods of buckwheat sowing are as follows: the press wheel outer diameter is 300 mm, the press force is 450 N, and the press wheel type is conical combined wheel. The results of this study could provide reference for the improvement of high-yield mechanized sowing technology of buckwheat and the design of rational pressure device.

Genetic analysis of agronomic traits of inter-subspecific cross populations of Tartary buckwheat

To provide a good basis for breeding new varieties, 2 different Tartary buckwheat (Fagopyrum tataricum Gaertn. 2x = 16) lines belonging to different subspecies with large differences in plant height were crossed. The progeny was analyzed for the genetic pattern of each agronomic trait and correlation analysis between traits. In terms of their coefficients of variation, the node numbers on the main stem and the weights per thousand kernels were small, while the number/weight of seeds per plant was large, indicating that the former character is more stable while the latter has greater potential for improvement. The average degrees of the dominance of plant height, number of main stem nodes, and number/weight of seeds per plant were greater than 1, indicating that these traits were mainly controlled by dominant effects. The heritability of the thousand kernel weight was greater than for the other traits, indicating that this trait is suitable for single plant selection in early generations. Correlation analysis of each agronomic trait revealed that plant height was significantly and positively correlated with all other traits in the F3 population, indicating the difficulty of selecting strains with both dwarf stature and high-yield traits. Nevertheless, 13 strains with dwarf stems and high yields were screened in the F5 population. Our study shows that the thousand kernel weight can be improved by single plant selection, while other traits need to be considered together to achieve optimal selection when endeavoring to breed dwarf, high-yield Tartary buckwheat.

Performance New Entries of Broad Bean Under Supplementary Irrigation Conditions

In this study, (25) new entries of broad bean (Vicia faba L.) were used. Sourced from the International Center for Agricultural Research in the Dry Areas (ICARDA). The entries seeds (25) were planted in an experiment according to a completely randomized block design with three replications at Al-Tuwaitha Research Station / Plant Breeding and Improvement Center / Agricultural Research Department during the growing season 2021/2022,With the aim of evaluating the entries and selecting the best ones in traits of yield and its components. The results showed that there were significant differences between the averages of the Entries and for all the studied traits, where entry (3) was characterized by the highest number of main stem nodes and the length of the pod. The number of seeds per pod is (26.00, 13.50 and 4.00) respectively, and entry (6) has the highest dry pod yield (132) and the highest seed yield (262). The entry (15) has the highest weight of 100 seeds (285.00) through the variation in the averages of the traits. Its use in breeding programs for selection for high seed yield of broad bean.

The effect of pre-drought mepiquat chloride management on cotton sensitivity to drought during peak water demands

Drought can substantially limit yield in cotton, and water loss in any crop is closely associated with plant growth, but studies addressing the effects of growth management on drought sensitivity are limited in cotton. We tested the hypothesis that aggressive plant growth management would decrease cotton sensitivity to drought during flowering and boll development. Cotton was grown at a field site near Tifton, GA during the 2021 and 2022 growing seasons. Treatments included mepiquat chloride (MC) strategies (aggressive and untreated) and two water availability treatments (well-watered and drought-stressed). At approximately 2 weeks after first flower, water was withheld from the drought-stressed treatment for a three-week period, and well-watered plots were kept irrigated using a regionally accepted water balance approach. Measurements throughout the season included heights, nodes, length of the fourth internode below the plant terminal, nodes above white flower (NAWF), and soil moisture. End-of-season measurements included lint yield, fiber quality, and yield component assessments. MC treatment significantly affected plant height, mainstem node number, 4th internode length, and cutout date. Soil moisture was significantly reduced during the drought stress period. Aggressive MC treated plots showed less drought-induced yield reduction than untreated in response to drought, but did not reach the same lint yield, boll density, or uniformity as well-watered, untreated plots. Aggressive MC treatment produced greater seed surface area, seed number boll-1, and boll mass. Aggressive MC management may prevent drought-induced yield reductions but penalize yield under well-watered conditions. Among the potential components driving yield, boll number per unit land area was the most important contributor. Our findings highlight the potential for aggressive MC management to mitigate drought risk, but future efforts should evaluate this possibility in a broader range of cultivars adapted for production in the southeastern United States and with the inclusion of a moderate MC treatment.

Overexpression of GmNF-YA14 produced multiple phenotypes in soybean

Soybean is an important oil crop, and more and more soybean gene functions have been reported; however, one soybean gene with multiple functions is rarely seen. The NF-YA subfamily plays a broad regulatory role in plant growth and development, and GmNF-YA14 (Glyma.14G010000) is one of them. We found that the expression level of GmNF-YA14 in the root of soybean seedlings was significantly increased after a one-hour treatment with 200 mM salt. The transgenic soybean was obtained by Agrobacterium-mediated method, and all experiments were carried out using transgenic soybean homozygous lines. Under a 200 mM salt treatment, the leaf chlorophyll content of overexpressed GmNF-YA14 transgenic soybean seedlings was significantly decreased compared to the control. Moreover, the first flowering time of overexpressed GmNF-YA14 transgenic soybean was shortened by more than six days compared to the control, and the growth period structure changed significantly. Overexpressed GmNF-YA14 transgenic soybean plants had two or three branches, whereas control soybean plants had eight or nine branches. Compared to the control, the number of main stem nodes and plant height of overexpressed GmNF-YA14 transgenic soybean plants were significantly reduced. The 100-seed weight of GmNF-YA14 transgenic soybean line OE-8 was significantly higher than that of the control. Transcriptome analysis indicated that the multiple phenotypes of the overexpressed GmNF-YA14 transgenic soybean may be related to the mitogen-activated protein kinase (MAPK) signaling pathway. These results indicated that compared to the control, overexpressed GmNF-YA14 transgenic soybeans had changes in salt stress tolerance, growth period, plant type, and 100-seed weight, and these changes may be related to the MAPK signaling pathway.

RETRACTED: Response of intercropping coffee (Coffea arabica L.) with banana (Musa spp.) on yield, yield components, and quality of coffee

AbstractThe coffee plant (Coffea arabica L.) is thought to have begun as an understory tree species in Ethiopia's northeastern high rain forests. Bananas (Musa spp.) are commonly intercropped with coffee to provide shade as well as food and money. However, the effect of this practice on coffee production is little known, hence the present study was initiated with the objective of evaluating the effect of intercropping coffee with banana on the yield and quality of both crops. The experiment was carried out using mature coffee intercropped with banana (var. Butezua) in different ratios in Kalu district, northeastern Ethiopia between the 2018 and 2020 cropping seasons. It was conducted in a randomized complete block design with three replications of four intercropping ratios (4C:1B, 3C:1B, 2C:1B, and 1C:1B) and two sole cropped plots (sole coffee, C; and sole banana, B). Over years, analysis of variance showed that intercropping of coffee and banana highly significantly (p < .01) influenced yield and growth parameters, such as clean coffee (a coffee free of taints and defects) yield, total plant height, number of main stem nodes, main stem internode length, number and percent of bearing primary branches, number of fruiting nodes per branch, canopy diameter, leaf length, leaf width, and leaf area of coffee trees. Similarly, coffee bean length, bean width, bean thickness, height up to the first primary branch, and number of primary branches were significantly (p < .05) affected by the treatments. In general, the results revealed that among the intercropped treatments, the staggered planting pattern (4C:1B) gave the maximum clean coffee yield (1,357.3 kg ha−1) and fresh banana fruit yield (20,482 kg ha−1) followed by the 3C:1B treatment, which gave (1,346.5 and 21,321 kg ha−1) clean coffee and green banana yields, respectively. In addition, higher mean land equivalent ratios (LER) of 1.78 and 1.61 and maximum net benefits of 316,265.50 and 302,484.00 Ethiopian birr (ETB) ha−1 were obtained from 4C:1B and 3C:1B, respectively. Therefore, it can be concluded that farmers in the Kalu area and similar agro‐ecologies can use these two ratios when practicing coffee–banana intercropping. Further intercropping studies may be required to validate the present results over locations.

Evaluation of Rearing Factors Affecting Clanis bilineata tsingtauica Mell Larvae Fed by Susceptible Soybean Variety NN89-29 in Spring and Autumn Sowing.

Clanis bilineata tsingtauica Mell is a nutritious edible insect. In the present study, soybean variety NN89-29 susceptible to leaf-feeding insects was used as the experiment material to evaluate the rearing factors affecting the production of C. bilineata tsingtauica in spring and autumn sowing. We artificially inoculated C. bilineata tsingtauica eggs to soybean plants, and the relevant indexes of larvae and soybean plants were recorded. The main results from spring sowing were as follows: (1) Larval number, single larval weight and plot-larval weight were all higher in the V6 stage (sixth trifoliolate) than those in the R3 stage (beginning pod) of inoculated eggs. (2) Larval number, single larval weight and plot-larval weight significantly decreased under higher planting density. Meanwhile, the soybean plant height and internode length increased, while the main stem node number of soybean decreased under higher planting density. (3) Single larval weight and plot-larval weight were not significantly affected by different numbers of eggs inoculated, but the larval number was significantly affected. Under autumn sowing conditions: (1) The larvae production and soybean plant growth were not significantly affected by covering the top of the net house with plastic film to isolate rainwater. (2) More eggs inoculated were associated with higher plot-larval weight. Conversely, fewer eggs inoculated resulted in a higher proportion of single larvae weight more than or equal to 6 g (≥6 g). Compared to spring sowing, the low biomass of autumn-sown soybean plants did not provide sufficient food for C. bilineata tsingtauica growth, and competition for food resulted in lower larval number, single larval weight and plot-larval weight.

Identification of Quantitative Trait Locus and Candidate Genes for Drought Tolerance in a Soybean Recombinant Inbred Line Population.

With global warming and regional decreases in precipitation, drought has become a problem worldwide. As the number of arid regions in the world is increasing, drought has become a major factor leading to significant crop yield reductions and food crises. Soybean is a crop that is relatively sensitive to drought. It is also a crop that requires more water during growth and development. The aim of this study was to identify the quantitative trait locus (QTL) that affects drought tolerance in soybean by using a recombinant inbred line (RIL) population from a cross between the drought-tolerant cultivar ‘Jindou21’ and the drought-sensitive cultivar ‘Zhongdou33’. Nine agronomic and physiological traits were identified under drought and well-watered conditions. Genetic maps were constructed with 923,420 polymorphic single nucleotide polymorphism (SNP) markers distributed on 20 chromosomes at an average genetic distance of 0.57 centimorgan (cM) between markers. A total of five QTLs with a logarithm of odds (LOD) value of 4.035–8.681 were identified on five chromosomes. Under well-watered conditions and drought-stress conditions, one QTL related to the main stem node number was located on chromosome 16, accounting for 17.177% of the phenotypic variation. Nine candidate genes for drought resistance were screened from this QTL, namely Glyma.16G036700, Glyma.16G036400, Glyma.16G036600, Glyma.16G036800, Glyma.13G312700, Glyma.13G312800, Glyma.16G042900, Glyma.16G043200, and Glyma.15G100700. These genes were annotated as NAC transport factor, GATA transport factor, and BTB/POZ-MATH proteins. This result can be used for molecular marker-assisted selection and provide a reference for breeding for drought tolerance in soybean.

Nitrogen fertilization can mitigate cotton yield loss by temporary shading at early flowering

Cotton (Gossypium hirsutum L.) yield is decreased under low radiation, but there are few reports on possible interactions of N fertilizer application and light limitation on cotton production. The objective of this work was to evaluate growth, yield components, and boll distribution in cotton as affected by N rates under light restriction. Three experiments were conducted for two years in Central (Primavera do Leste and Chapadão do Sul) and Southeastern (Itapeva) Brazil. Cotton plants were shaded at early flowering to a 42 % reduction in global radiation for 16–25 days. Four N rates were used in Primavera do Leste and Itapeva; and three N rates and two genotypes, an early- (FM 906GLT) and a late-maturing (FM 983GLT) cultivar, were used in Chapadão do Sul. Shading decreased lint yield by 10 % in Primavera do Leste and by 12 % in Chapadão due to 24 % and 32 % reduction in boll number at the lower third of the plant, respectively. In Itapeva, the number of bolls at the lower fruiting branches was decreased 19% by shading, but a 10% lint yield reduction was observed only with 35 kg ha−1 of N. As to the main effects, lint yield and number of bolls increased with N rates up to 155, 142 and 105 kg ha−1, depending on the site. Lint yield of shaded plants was more responsive to higher N rates, which also increased plant height, number of bolls and the main stem node number of the last fruiting branch. Cotton cultivars had similar lint yields despite differences in boll distribution. At lower fruiting branches, the early-maturing cultivar showed an average boll number 59 % higher, but the late one produced 81 % and 63 % more bolls on the upper branches at 105 and 185 kg ha−1 of N, respectively. We concluded that N-deficiency inhibited the recovery of cotton from losses caused by shading, whereas a high-N availability minimizes damages after shading during blooming.

Effect of Weed Interference on Yield, Nutritional Value and Some Morphological Characteristics of Alfalfa (Medicago sativa L.)

Abstract Objective: This research was conducted to evaluate the effect of weed interference and non-interference in different densities of alfalfa on yield, nutritional value and some morphological traits of alfalfa as a forage crop. Materials and Methods:The experiment was performed as factorial and based on a randomized complete block design with three replications in two cuttings during 2018-2019 crop years. The experimental treatments were weed interference and non-interference in two levels (hand weeding and non-hand weeding) and plant density in four levels (20, 40, 60 and 80 stems per square meter). Results:Weeds identified in this Alfalfa field included: Carthamus tinctorius, Centaurea cyanus, Ceratocephalus falcatus, Convolvulus arvensis, Cuscuta sp., Cynodon dactylon, Descurainia sophia, Euphorbia maculate, Poa bulbous, Hordeum morinim, Lactuca scariola, Rumex acetosella, Salvia sclarea, Sisymbrium irio, Sorghum halepense, Taraxacum officinalis, Tragopogon graminifolius, Vaccaria hispanica. The results of each harvest in the third year of established alfalfa showed that the presence of weeds caused a decrease in the quantity and quality of alfalfa forage plant. Conclusion: The results obtained in two cuttings in the third year of established alfalfa showed that the weeds caused quantitative and qualitative reduction in alfalfa. Alfalfa in the second cutting had better growth compared to the first cutting, so that the plant produced the highest fresh and dry yield in the second cutting. Weed non-interference increased the levels of superior morphological traits of alfalfa, such as fresh and dry yield, plant height, and number of leaves per plant, number of main-stem nodes, leaf area and percentage of vegetation cover as well as increased the nutritional value of alfalfa in terms of nutrient elements, proteins and factors such as ADF, Ash, CF, NDF.

Development of a lucerne model in APSIM next generation: 1 phenology and morphology of genotypes with different fall dormancies

Prediction of lucerne phenological and morphological development is important for optimising the defoliation schedule and time of other management events. A challenge for any lucerne phenology module is to capture the seasonality of development processes in response to environment, management and genotype. To date, lucerne phenological modules have not been evaluated under different defoliation regimes or with genotypes of different fall dormancy (FD) classes. This research integrated data of lucerne phenological development into the Agricultural Production Systems sIMulator (APSIM) next generation (APSIM NextGen) model framework to develop and verify a phenology module. Relationships derived from the FD5 genotype, grown under a 42 day (LL) defoliation treatment were used for model development. These were further tested for two genotypes with contrasting FD (FD2 and FD10) under frequent (28 day: S) or long (84 day: H) defoliation regimes, all under irrigated conditions. Development was parameterized based on thermal time targets to reach specific phenological stages and modified by photoperiod responses. Development stage and node appearance were shown to be independent of defoliation treatment and FD class. Simulation results showed good agreement for prediction of development stages (NSE of 0.77 for days to buds visible and 0.67 for days to flowering stage) and number of main stem nodes (NSE values were ranged from 0.53 to 0.84). However, both defoliation management treatment and FD classes affected stem height. For FD5, there was good agreement for the 84 day treatment (NSE of 0.83) and the 42 day treatment (NSE of 0.66), but it was poor for the 28 day treatment (NSE of -0.08). This was probably due to reduced stem extension rates, limited by low C and N reserves in perennial organs under the frequent (28 day) defoliation regime. For FD2 and FD10, two separate sets of parameters were used to improve model prediction of height to account for their contrasting seasonal C partitioning patterns. These results show that the APSIM NextGen lucerne phenology module was able to simulate crops grown under unconstrained growing conditions. However, the reason for under estimation of stem height for the 28 day treatment needs further investigation.

QTL for Main Stem Node Number and Its Response to Plant Densities in 144 Soybean FW-RILs.

Although the main stem node number of soybean [Glycine max (L.) Merr. ] is an important yield-related trait, there have been limited studies on the effect of plant density on the identification of quantitative trait loci (QTL) for main stem node number (MSNN). To address this issue, here, 144 four-way recombinant inbred lines (FW-RILs) derived from Kenfeng 14, Kenfeng 15, Heinong 48, and Kenfeng 19 were used to identify QTL for MSNN with densities of 2.2 × 105 (D1) and 3 × 105 (D2) plants/ha in five environments by linkage and association studies. As a result, the linkage and association studies identified 40 and 28 QTL in D1 and D2, respectively, indicating the difference in QTL in various densities. Among these QTL, five were common in the two densities; 36 were singly identified for response to density; 12 were repeatedly identified by both response to density and phenotype of two densities. Thirty-one were repeatedly detected across various methods, densities, and environments in the linkage and association studies. Among the 24 common QTL in the linkage and association studies, 15 explained a phenotypic variation of more than 10%. Finally, Glyma.06G094400, Glyma.06G147600, Glyma.19G160800.1, and Glyma.19G161100 were predicted to be associated with MSNN. These findings will help to elucidate the genetic basis of MSNN and improve molecular assistant selection in high-yield soybean breeding.

QTL‐allele system of main stem node number in recombinant inbred lines of soybean (Glycine max) using association versus linkage mapping

AbstractMain stem node number (MSN) as a major plant architectural trait determines the plant canopy and seed yield potential in soybean. To identify the MSN QTL system, a recombinant inbred line (RIL) population consists of 427 lines derived from the cross of KF‐1 × NN1138–2 was tested at two locations in 2 years showing MSN ranging in 11.9–23.7, from which the MSN QTL system was explored using RTM‐GWAS (restricted two‐stage multi‐locus genome‐wide association study) compared with linkage mapping CIM (composite interval mapping). By RTM‐GWAS, 89 QTLs were detected with a phenotypic contribution of 84.50%, whereas by CIM, 24 QTLs detected, indicating the RTM‐GWAS more powerful than CIM. In the population, the best RIL genotypic value was ~24.5, whereas the predicted extreme potential was as high as 49.0. Of the 89 MSN QTLs, 31 ones overlap with those reported in literature, whereas the rest 58 ones are novel. From the QTLs, 74 candidate genes were annotated and GO‐grouped into six categories of biological processes. RTM‐GWAS is potential in exploration of MSN QTL/Gene system benefiting breeding for ideal canopy.

Manipulation of Seeding Rate to Compensate for Plant Stand Loss by Wireworms in Cotton

True wireworms (Coleoptera: Elateridae) and false wireworms (Coleoptera: Tenebrionidae) are common pests of cotton (Gosssypium hirsutum L.) on the Texas High Plains. Wireworms as larvae damage cotton by feeding on the roots, hypocotyl, and cotyledon and reducing plant stand. A field study was done with the objective to determine how seeding rate in the presence of wireworms affects plant stand and yield of cotton lint. Seeding rates evaluated per 0.3-m row were 1.5 seeds (48,433/ha), 2 seeds (64,583/ha), 3 seeds (96,865/ha), and 4 seeds (129,167/ha). Increasing seeding rate resulted in significantly greater plant density. The percentage of seeds that established into plants, however, did not vary significantly among seeding rates. In 2018 and 2019, 28-38 and 60-63% of seeds of all seeding rates established plants. Seeding rate did not significantly affect the plant height, number of main-stem nodes, position of 1st fruiting node on the main stem, or lint yield. Results of the study indicated increasing seeding rate in wireworm-infested fields might increase plant stand in cotton, but not necessarily the lint yield. Lint yirld ranged from 354.35 ± 29.65 to 398.46 ± 12.48 kg/ha in 2018 and 615.66 ± 33.70 to 735.05 ± 79.40 kg/ha in 2019.