Crop Science最新文献

Gibberella ear rot (GER) of maize, caused by Fusarium graminearum, poses a serious threat to human and animal safety as mycotoxins are deposited in the grain during fungal colonization and are hazardous to human and animal health. Currently, no completely resistant germplasm has been identified, and the underlying mechanisms of resistance remain unclear. In this study, we evaluated three near-isogenic line (NIL) populations for resistance to GER—NC344 × H100 (DRIL), B73 × Oh43 (nNIL), and B73 × teosinte (tNIL)—across multiple environments. The recurrent parents, H100 and B73, were moderately resistant to GER. NC344 is susceptible to GER. Oh43 is moderately resistant to GER. The teosinte donor parent, PI 384071, had unknown resistance to GER. We employed two inoculation methods—kernel injection and silk channel injection—to assess their impact on genotype response to F. graminearum. The inoculation method did not significantly affect genotype response, although kernel inoculations produced more consistent disease levels. We identified lines with significantly increased susceptibility to GER compared to their recurrent parent in each population. We employed quantitative trait locus (QTL) mapping to identify markers associated with GER in the NC344 × H100 population. We identified QTL on chromosomes 4, 5, and 9. We highlight a large region on chromosome 5 that may harbor important alleles for GER resistance and for resistance to other ear rots. This study underscores the utility of NILs in dissecting the genetic basis of GER resistance and provides valuable resources for future fine mapping, gene discovery, and resistance breeding.

Productivity in strip intercropping systems is influenced by interspecific competition. Most research focused on initial design factors such as species combinations, row ratios, and sowing times; the potential to enhance productivity by regulating interspecific competition through altering crop growth within the system has been underexplored. A 2-year field experiment compared sole wheat (Triticum aestivum L.), sole alfalfa (Medicago sativa L.), and wheat/alfalfa strip intercropping under different alfalfa cutting times and numbers of border rows cut. In this study, we defined the human active intervention targeting crop growth itself in the strip intercropping system as internal regulation. Results demonstrated that internal regulation significantly enhanced system productivity by altering interspecific competition, increasing yield by 21.2% in 2022 and 31.0% in 2023 compared with weighted monoculture yields. The land equivalent ratio for all internal regulation treatments was greater than 1. Internal regulation can change the border row effect of alfalfa and make wheat become the dominant crop in wheat/alfalfa strip intercropping system; the minimum competitive ratio values of alfalfa against wheat were 0.64 and 0.66 for 2022 and 2023, respectively. The treatment, which involved cutting the first border rows and the second border rows of alfalfa at 10 days before the first flowering stage, achieved the highest system yield and land use efficiency. Thus, internal regulation via suitable alfalfa cutting during the co-growth period in wheat/alfalfa strip intercropping can adjust the interspecific relationship and increase the system yield, providing a reasonable method to increase the strip intercropping yield and ensure food security.

Breeding bermudagrass (Cynodon spp.) involves creating progeny combining multiple desired traits from hybridization and ensuring their adaptation and performance to various environments through rigorous testing. Turfgrass breeding programs in the southern United States collaborated to breed new bermudagrass lines for drought resistance. Thus, the objectives of this study were to evaluate advanced bermudagrass lines and to characterize their genetic gain in performance traits, reliability, genotype-by-environment interaction (GEI), and stability. The study, encompassing 34 advanced lines and three standard cultivars planted in randomized complete block designs with three replications, was carried out at eight locations across the southern United States from 2020 to 2023. Experimental lines OSU2073, OSU2081, OSU2082, TifB20201, and TifB20205 showed improved drought response relative to the drought resistant cultivar TifTuf with significant genetic gain in the mega-environment (a group of locations that share similar environment conditions in which a crop has consistent performance across them) of Dallas, TX, and Stillwater, OK. Substantial GEIs were observed under drought stress across the southern United States. This study highlights the continuous genetic gain made in breeding efforts to improve drought resistance of bermudagrass and identifies new cultivar candidates for conserving irrigation water to the turf industry.

Preharvest sprouting (PHS), the initiation of mature grain germination on the mother plant when wheat (Triticum aestivum L.) gets wet before harvest, is a major cause of elevated post-harvest alpha-amylase in wheat grain. Alpha-amylase digests starch to support seedling growth during germination. However, excessive starch digestion by alpha-amylase reduces its pasting capacity in flour/water mixtures leading to collapsed cakes, sticky noodles, and bread with sticky crumb. Elevated alpha-amylase can also result from cool temperatures during grain filling, either due to a developmental problem called late maturity alpha-amylase (LMA) or premature germination under moist conditions termed vivipary. PHS tolerance was mapped to 53 quantitative trait loci (QTL), including 16 of high significance (logarithm of the odds > 7.5), in a spring wheat panel previously used for association mapping of LMA. When vivipary assays were performed on a panel subset, vivipary, LMA, and PHS were significantly correlated with each other. This is interesting given that the PHS and vivipary phenotypes assayed were visible germination, whereas the LMA phenotype assayed was alpha-amylase activity. While there are LMA susceptible lines that are PHS tolerant and vice versa, this suggests that overlapping genetic mechanisms may govern tolerance in this population. Indeed, Five PHS QTL had a significant effect of LMA phenotype in the same population Qs2-1A, Qs20-3B, Qs31-5A, Qs39-5D, and Qs42-6A. Breeding programs may be able to use such QTL to select for both PHS and LMA tolerance. The more significant and reproducible PHS QTL identified are good candidates for marker development and cloning efforts.

Cicer milkvetch (Astragalus cicer L.) (CMV) is a perennial, winter hardy forage legume for grazing in the temperate regions of world. Low seed germination and low seedling vigor of this species often reduce stand establishment success, limiting producer adoption. Objectives of this study were to identify the differentially expressed genes (DEGs) associated with seedling vigor in high-vigor (AC Veldt and PI440143) and low-vigor populations (PI206405) in CMV. Five, 7-day-old seedlings per population were randomly chosen for RNA extraction. Sequencing generated a total of 319 million clean reads, with 97.3% mapped to the de novo assembled transcriptome. A total of 3,322 DEGs were identified between the high and low seedling vigor populations. Of these, a total of 269 DEGs were mapped to the UniProt database, with 30 DEGs (11.2%) aligned to species in the Fabaceae family, and 146 DEGs (54.6%) with proteins associated with seedling vigor. A total of 427 significant gene ontology (GO) terms were identified in the high versus low seedling populations, with 366 terms successfully classified into three main GO categories: molecular function, biological process, and cellular component. Among these, 286 (70.0%) GO terms were associated with seedling vigor, which were mainly related to BPs related to seed size determination, energy provision, and the transport of energy and ion. Once validated, these candidate genes could be used to select plants with high seedling vigor in CMV genetic improvement.

Leaf area index is one of the important parameters to reflect the crop group structure and has a significant influence on the photosynthesis and transpiration of crops. The cotton surface waterlogging experience was conducted to characterize the changes in leaf area index under different durations of surface waterlogging (0, 3, 5, and 7 days). Based on the surface waterlogging depth and comprehensively considering the aftereffects of surface waterlogging, a surface waterlogging indicator was developed. The leaf area index under surface waterlogging was calculated by logistic equation using meteorological data and the constructed surface waterlogging indicator. The results indicate that the constructed model can accurately simulate the cotton leaf area index under different surface waterlogging degrees. During the calibration and validation periods, the coefficient of determination was >0.74, the normalized root mean square error ranged from 0.08 to 0.18, and the Nash–Sutcliffe efficiency coefficient was >0.70. The results of the sensitivity analysis indicate that the leaf area at emergence (L_g0) and the initial leaf area at senescence (L_s0) had relatively little impact on the simulation results, while the potential maximum values of leaf area expansion and senescence (a_g and a_s), the maximum rate of change in expanding leaf area (ΔL_gxmax), and the maximum rate of change in senescing leaf area (ΔL_sxmax) had a greater influence on the simulation results. The constructed surface waterlogging indicator can more accurately reflect the impact of surface waterlogging on cotton growth, thereby improving the simulation accuracy of cotton growth and yield under surface waterlogging conditions. The results provide a scientific basis for developing crop growth models and implementing precision management in farmland drainage.

The southern root-knot nematode [SRKN; Meloidogyne incognita (Kofoid & White) Chitwood] is one of the most damaging soybean (Glycine max [L.] Merr.) pathogens in the southern United States. Genetic resistance is the primary management strategy. A major quantitative trait locus (QTL) on chromosome 10 (QTL 10) is widely utilized in SRKN-resistant soybean, yet the extent of population suppression in infested fields remains unclear. This study aimed to evaluate the effectiveness of QTL 10 in reducing SRKN population density under naturally infested environments, with a secondary post hoc objective of assessing the impact of off-target dicamba exposure on host resistance. Seventy-six elite breeding lines, 38 carrying the resistant allele, were evaluated in replicated field trials with natural SRKN infestation over 2 years. Soil samples were collected at the R5 stage, and SRKN second-stage juveniles (J2s) were extracted and quantified. Resistant lines had 1620 SRKN-J2 per 100 cm³, while susceptible lines had 2126 per 100 cm³. In 2019, prolonged off-target dicamba exposure significantly increased nematode density across all lines. Dicamba-tolerant breeding lines had lower SRKN densities, while susceptible lines had higher densities, regardless of SRKN resistance. These findings suggest that prolonged off-target dicamba exposure imposes additional stress that compromises plant defense response and increases nematode reproduction. Variation in SRKN-J2 densities among resistant lines further indicates loci beyond QTL 10 may influence nematode infection and/or reproduction. Future genetic studies could identify additional resistance sources, leading to stronger and more durable SRKN resistance in soybean.

Kentucky bluegrass (KB) (Poa pratensis L.) is an excellent cool-season turfgrass sod option because of its rhizomatous growth habit. There are known growth and other characteristics differences among cultivars, but little is known about the differences in germination and establishment speed, as well as differences in rhizome and sod production for turfgrass practitioners. Therefore, the objectives were to investigate the influence of 19 KB cultivars on germination and establishment speed and sod production characteristics through replicated field and controlled-environment experiments at Kansas State University. Faster-germinating KB cultivars reached 50% germination and 50% establishment within <8 and <23 days, respectively, compared to slower cultivars reaching 50% germination and 50% establishment in ≥9 and ≥24 days, respectively. However, fast germination speed did not always predict fast field establishment speed. Greenhouse experiments revealed differences in the number of rhizomes and total rhizome length among cultivars. Field experiments measured sod strength (maximum tensile load to tear sod [Newtons] and required work to tear sod [N-m]) at three harvests of 9, 10, and 13 months after planting. There were sod strength differences among KB cultivars, which ranged from ∼22 to 38 N-m of required work to tear sod and 389 to 568 N of maximum tensile load to tear sod. While KB classification systems assist in describing other KB traits (i.e., color, density, growth, and stress tolerances), they were not consistent in predicting differences in germination or establishment speed, as well as rhizome characteristics in the greenhouse or sod production differences for sod producers.

False-green kyllinga (FGK; Kyllinga gracillima Miq.) is a warm-season perennial weed in the Cyperaceae family. Our objective was to determine the potential for FGK to establish from seed in turfgrass. Replicated field experiments were conducted in Kentucky bluegrass (Poa pratensis L.) mowed at 6 cm. FGK was seeded at 5 or 500 kg ha⁻¹, and smooth crabgrass [Digitaria ischaemum (Schreb.) Schreb. Ex Muhl.] was seeded at 500 kg ha⁻¹. Turf was managed under either low or high input programs to generate swards of different density. Low-input turfgrass received 25 kg N ha⁻¹ annually, while high-input turfgrass received 200 kg N ha⁻¹ annually along with preventative fungicide applications. FGK establishment from seed was reduced more by turfgrass inputs than smooth crabgrass. Smooth crabgrass cover in September of both experiments was >93% and not affected by turfgrass inputs. When FGK was seeded at 500 kg ha⁻¹, cover in September was higher in low input (57% in Run 1, 59% in Run 2) than in high input turf (36% in Run 1, 18% in Run 2). When FGK was seeded at the lower rate of 5 kg ha⁻¹, cover in Run 1 was higher in the low input (14%) than high input turf (2%), but FGK cover was similar between input levels in Run 2, with 4 and 1% cover in the low and high input plots, respectively. FGK successfully overwintered in this study, with cover increasing during the second summer of growth. Although FGK is less competitive as a seedling than smooth crabgrass, its perennial life cycle allows it to increase weed cover over time.

Timothy (Phleum pratense L.) is a cool-season perennial forage grass species widely utilized for animal feed and fodder in temperate regions of the world. Timothy is one of the main forage grass crops grown for seed in the Peace Region of western Canada. Timothy performs well under well-fertilized and high-moisture soils, but seed production fields are prone to lodging under such conditions. Lodging in grass crops reduces seed production through self-shading, which limits successful pollination, fertilization, and seed fill. In this study, we investigated the effects of two plant growth regulators (PGRs), chlormequat chloride (CCC) and trinexapac-ethyl (TE), on plant height, lodging, seed weight, and seed yield of timothy for 8 site-years. The study encompassed 5 years at one site with crop stands in their first to fifth year of seed production and 3 years at a second site with crop stands in their first to third year of seed production. The PGRs were applied alone (TE and CCC) and in a mix (TE + CCC) at the 2–3 node (Biologische Bundesanstalt, Bundessortenamt, and Chemische Industrie [BBCH] 32–33) and early heading (BBCH 51–52) growth stages. The application of PGRs (TE, CCC, and their mix) at two different growth stages showed a differential decrease in lodging and plant height and an increase in seed yield in all but 1 site year. Among the PGR treatments, CCC applied at the BBCH 32–33 was the most effective in increasing seed yield and economic returns of timothy.