Search Results (82)

Water stress is one of the main factors affecting the development of agricultural crops. An innovative alternative to improve tolerance to water stress is the application of biostimulants. In the present study, the efficacy and physiological and biochemical responses of different biostimulants were evaluated in beans under moderate and severe stress. The treatments consisted of three types of irrigation: FC100, without water stress; FC75, irrigation reduced by 25% (moderate water stress); and FC50, irrigation reduced by 50% (severe water stress). In the treatments with water deficits, foliar biostimulants were applied: zinc oxide nanoparticles plus chitosan, Codasil^®, Osmoplant^®, Stimplex^® and salicylic acid. Foliar application of ZnO + chitosan nanoparticles benefited biomass accumulation and yield under moderate water stress (FC75) and Codasil^® and Osmoplant^® under severe water stress (FC50). Proline, free sugars and gas exchange were higher with the application of ZnO + chitosan nanoparticles under moderate water stress and with Codasil^® and Osmoplant^® under severe water stress. Depending on the severity of water stress, ZnO + chitosan nanoparticles, Codasil^® and Osmoplant^® are viable products to increase tolerance in green bean cv. Strike plants. Full article

Stalk lodging contributes to significant crop yield losses. Therefore, understanding the biomechanical strength and structural rigidity of grain stalks can contribute to improving stalk lodging resistance in crops. From the structural constituents of the stalk, the rind provides the principal structure, supporting cells against tension and bending loads. In this work, the biomechanical and viscoelastic behavior of the rind from the internodes of two sweet sorghum varieties (Della and REDforGREEN (RG)), grown in two different growing seasons, were evaluated by three-point micro-bending tests using a dynamic mechanical analyzer (DMA). In addition, the chemical composition of rinds and the microfibril angle (MFA) of the cell wall were determined using XRD. The results revealed that the biomechanical behavior of Della varieties was stiffer and more resistant to loads than that of RG varieties. Two features of the rind biomechanical properties, flexural modulus (FM) and flexural strength (FS), showed a significant reduction for RG. Particularly, a reduction in FS of 16–37% and in FM of 22–41% were detected for RG1. Changes in the stalks’ rind biomechanical properties were attributed to cell wall components. Total lignin and glucan/cellulose contents were positively correlated with the FM and FS of the rind. Subsequently, an increase in the two cell wall components drove an increase in stiffness. Furthermore, the MFA of the rind was also found to influence the rind strength. Full article

In current markets, the primary uses for soybean seeds are in products derived from their oil or protein content. However, growers are compensated based on seed yield, so a more valuable crop is one that does not compromise on yield when compared with existing options, with an optimum combination of protein and oil. A negative correlation of seed protein with seed yield and oil makes the simultaneous improvement of these traits difficult but not impossible through conventional breeding. Selections of lines with exceptional yield and seed composition were made from two recombinant inbred line (RIL) soybean mapping populations to identify high protein and/or high oil lines with yields comparable to elite cultivars. The performance of these RILs was evaluated in multiple environments, and several genotypes were identified with yields comparable to those of high-yielding check cultivars with seed protein and/or oil content superior to the checks. These genotypes will provide breeders with additional sources of germplasm for continuing efforts to improve seed composition traits without compromising seed yield and provide growers with more profitable cultivars. Full article

Fusarium head blight (FHB) is a devastating fungal disease of hexaploid wheat (Triticum aestivum). Several genetic loci were previously identified that control FHB resistance in wheat, including Fhb1. Fhb7, a major QTL conferring resistance to FHB, controlling for mycotoxin deoxynivalenol (DON) production, has been introgressed into soft red winter wheat (SRWW). As an exotic QTL, Fhb7 is associated with linkage drag, affecting agronomic and end-use quality performance. This study outlines a breeding strategy for introducing and pyramiding Fhb7 into SRWW breeding populations that already possessed Fhb1 and harbored some additional disease-resistance genes. In addition to the Fhb1-Fhb7 pyramiding, we developed gene-based markers for both genes and examined them on 57 SRWW breeding lines. Our data showed that 15 out of 57 breeding lines possessed both Fhb1 and Fhb7 resistant alleles. Two years of phenotypic data from the inoculated and misted irrigation field showed that the combination of Fhb1-Fhb7 lowers mycotoxin DON accumulation in kernels, which provides protection for end-users and the milling industry. The Fhb gene-pyramided lines, with the additional regionally important disease resistance genes, produced in this breeding pipeline showed reasonable agronomic traits and can be used in crossing programs for the widespread introgression in elite wheat cultivars. Full article

Plants of the genus Physalis are of economic interest because of their fleshy edible fruits with high nutritional value. Some species have high medicinal value with a long history of ethno-medicinal use to treat diverse diseases. There is therefore a need to correctly discriminate the different species of Physalis for proper utilization. Although most Physalis species have unique morphologies, their vegetative stages are identical, making it difficult to accurately identify them based on morphological characteristics. DNA barcoding has the potential to discriminate species accurately. In this study, ribulose bisphosphate carboxylase large (rbcL) and internal transcribed spacer 2 (ITS2) regions were used to discriminate Physalis species and to reveal their phylogenetic relationships and genetic diversity. Physalis plant samples were collected from seven counties in Kenya based on the availability of the germplasm. The voucher specimens were identified using the botanical taxonomy method and were deposited in the University of Nairobi herbarium. Genomic DNA was isolated from leaf samples of 64 Physalis accessions and used for PCR amplification and the sequencing of rbcL and ITS2 barcode regions. The discriminatory ability of the barcodes was based on BLASTn comparison, phylogenetic reconstruction and cluster analysis, and the determination of inter- and intra-specific distances. The nucleotide polymorphism, genetic diversity and distance of the identified Physalis species were determined using DnaSP and MEGA 11.0 software. Species discrimination was more robust using ITS2 sequences. The species identified and discriminated by ITS2 sequences were Physalis purpurea, Physalis peruviana and Physalis cordata. The rbcL sequences were only able to identify Physalis to the genus level. There was high interspecific and low intraspecific divergence within the identified Physalis species based on ITS2 sequences. The ITS2 barcode is an ideal DNA barcode for use in the discrimination of species, as well as in genetic diversity studies of Physalis accessions in Kenya. Full article

Parthenium weed (Parthenium hysterophorus L.) is an emerging production constraint in many summer crops including sorghum (Sorghum bicolor L. Moench), but limited control options are available. In this field study, the efficacy of sole and sequential applications of a pre-emergence (pendimethalin) and a post-emergence (bromoxynil) herbicide was evaluated for parthenium weed control in grain sorghum over two years. Pendimethalin or bromoxynil alone could only provide 54% and 63% control, whereas their sequential application provided 86% control of parthenium weed over the weedy treatment. The sorghum plants in pendimethalin followed by bromoxynil treatment had the highest leaf fresh weight per plant, plant dry biomass, plant height, and the number of heads among the herbicide treatments. Sorghum fresh forage yield, dry fodder yield, 1000-grain weight, and grain yield were highest in the weed-free treatment followed by the pendimethalin followed by (fb) bromoxynil treatment. Overall, the herbicide treatment performance was in an order of pendimethalin fb bromoxynil > bromoxynil > pendimethalin for weed control and sorghum yield improvement. These results suggest that pendimethalin followed by bromoxynil may provide acceptable control (>85%) of parthenium weed and may improve sorghum grain yield (up to 23%). Full article

Amid a rapidly growing global population and increasing threats to crop yields, this review focuses on Speed Breeding (SB) in crop genetics. It traces SB’s development from carbon arc lamp experiments 150 years ago to its modern use with LED technology which significantly accelerates breeding cycles. SB has applications in genetic mapping, genetic modification, and trait stacking, enhancing crop resilience by leveraging allelic diversity. It aligns well with breeding methods like single plant selection and single seed descent. The integration of SB with gene editing, genotyping, and genomic selection holds great promise. However, SB faces challenges related to infrastructure, genotypic variations, and potential stress responses. In summary, SB is a powerful and promising approach to address food security concerns and advancing crop genetics. Full article

Pearl millet (Pennisetum glaucum (L.) R. Br.) and cowpea (Vigna unguiculata L. Walp.) are well-adapted to semiarid regions. A two-year study at New Mexico State University’s Rex E. Kirksey Agricultural Science Center at Tucumcari, NM, USA, compared monoculture pearl millet and cowpea with their mixtures in various row arrangements in four randomized complete blocks each year. Treatments included monoculture pearl millet (millet) and cowpea (cowpea), pearl millet and cowpea mixture planted in the same row (millet–cowpea), the species planted in alternate rows (millet–cowpea 1:1), the species planted in two adjacent rows alternating between species (millet–cowpea 2:2), and the species planted in four adjacent rows alternating between species (millet–cowpea 4:4), Mixture neutral detergent fiber (NDF) was reduced i millet–cowpea 1:1 and millet–cowpea 2:2 compared to millet (673, 662, 644, 646, and 666 g NDF kg⁻¹ for millet, millet–cowpea, millet–cowpea 1:1, millet–cowpea 2:2, and millet–cowpea 4:4, respectively, LSD = 18, p ≤ 0.05). Crude protein tended to be increased in millet–cowpea 2:2. Based on these results two rows of cowpea alternated with two rows of pearl millet, all spaced at 15 cm and harvesting for hay at the pearl millet boot stage likely optimizes the compromise of DM yield and the nutritive value of the mixture. Full article

Tomato (Solanum lycopersicum L.) had almost 190 million tonnes produced in 2021. Tomato fruit suffer losses of up to 50% during harvest and transport, which causes financial hardship, reduces the amount of food available and causes environmental harm. Calcium plays an important role in cell wall strength. This work assessed the use of a calcium transport stimulant (MCAS) to increase the firmness of tomato fruit in the laboratory and the foliar application to tomato plants. Then, handling damage was simulated. In the laboratory, the calcium with MCAS significantly increased the fruit firmness compared to the untreated and calcium without MCAS, which were not significantly different. When calcium with MCAS was applied to tomato plants foliarly before harvest, the calcium with MCAS-treated fruit were significantly firmer than the untreated or calcium without MCAS-treated fruit for up to 10 weeks after harvest, and this was achieved by applying only 0.91 kg ha⁻¹ calcium. Finally, when fruit were exposed to a simulated drop, the calcium with MCAS-treated fruit remained firmer than the undamaged fruit or dropped fruit with calcium without MCAS. Calcium with MCAS could significantly increase the fruit firmness and increase the shelf-life of tomatoes while applying less calcium. Full article

Post-flowering drought tolerance (stay-green) in grain sorghum (Sorghum bicolor (L.) Moench) is an important agronomic trait in many arid and semiarid environments throughout the world. Stay-green has been associated with increased grain yields, as well as resistance to lodging and charcoal rot disease. Nonetheless, the relative effects of genotype, environment, and genotype × environment interactions are not well understood for this trait; similarly, the relationship between various leaf sugars and stay-green has not been sufficiently evaluated in diverse germplasm. Thus, the goals of this study were to determine the genotype, environment, and genotype by environment (GxE) effects for leaf dhurrin, sugars, and stay-green in ten diverse grain sorghum breeding lines, to evaluate the Pearson’s correlation coefficients (r) between these traits, and to determine entry-mean repeatability (R) for each of these traits. Of the compositional traits studied, we determined that leaf dhurrin had the highest correlation with the stay-green phenotypes (r = −0.62). We found that stay-green sorghum lines contained approximately 2–3 times as much dhurrin as non-stay-green lines, with B1778 containing the highest concentration of dhurrin (84.8 µg/cm²) and Tx7000 containing the least (20.9 µg/cm²). The differences between the environments for several of the traits were high, and all the traits examined had high repeatability (R = 0.89–0.92). These data demonstrate a relationship between leaf dhurrin and the stay-green phenotypes in sorghum, and further study will allow researchers to determine the causal effect that dhurrin has on post-flowering drought tolerance in sorghum. Full article

Several biogeochemical models have been applied to understand the potential effects of management practices on soil organic carbon (SOC) sequestration, crop growth, and yield. In this study, the denitrification and decomposition (DNDC) model was used to simulate soil SOC dynamics and harvested C-biomass in rice–wheat rotation under organic/inorganic fertilization with conventional tillage (CT) and reduced tillage (RT). Before calibration, DNDC underpredicted harvestable grain C-biomass of rice where percent difference (PD) varied from 29.22% to 42.14%, and over-simulated grain C-biomass of wheat where PD was −55.01% with 50% nitrogen–phosphorus–potassium (NPK) and 50% animal manure applied under the CT treatment. However, after calibration by adjusting default values of soil and crop parameters, DNDC simulated harvestable grain C-biomass of both crops very close to observed values (e.g., average PD ranged from −2.81% to −6.17%). DNDC also predicted the effects of nutrient management practices on grain C-biomass of rice/wheat under CT/RT using d-index (0.76 to 0.96) and the calculated root mean squared error (RMSE of 165.36 to 494.18 kg C ha⁻¹). DNDC simulated SOC trends for rice–wheat using measured values of several statistical indices. Regression analysis between modeled and observed SOC dynamics was significant with R² ranging from 0.35 to 0.46 (p < 0.01), and intercept ranging from 0.30 to 1.34 (p < 0.65). DNDC demonstrated that combined inorganic and organic fertilization may result in higher C-biomass and more SOC sequestration in rice–wheat systems. Full article

Cassava fresh root yield and dry matter content constitute major determinants of demand by end-users. Increased demand for the seeds of improved varieties will facilitate the development of a sustainable seed system. However, for wide acceptability, there is a need to continuously evaluate candidate varieties for stability across different agroecological zones. Participatory Demand Creation Trials (DCTs) were established to evaluate cassava varieties with farmers and processors utilizing the best agronomic practices. The multi-year DCTs were conducted in 20 environments (7 locations) during the 2016–2017, 2017–2018, 2018–2019, and 2019/2020 cropping seasons with two replications. The plot sizes were 320 m² with a spacing of 1 m × 0.8 m. The traits evaluated were Plant Vigor (PV), root number, fresh yield, dry yield, Dry Matter Content (DMC), and bundle estimation. The traits were subjected to a GGE biplot in R software to identify high-yielding and stable genotypes. Results obtained from the 20 environments showed that genotype (G), environment (E), and GXE interaction effects were significant (p < 0.01) for all the traits but PV. The heritability ranged from 56% (PV) to 96% (DMC). The average fresh yield t/ha ranged from 25.5 (IBA30572) to 35.4 (IBA980505). The DMC ranged from CR36/5 (36.1%) to IBA010040 (30.7%). The dry yield ranged from 8.8% (IBA30572) to 11.4 (IBA980505). Estimated bundles ranged from 13.5 (CR36-5) to 15.7 (IBA950289). Three varieties, IBA961632, TMEB419, and CR36/5, were identified as the most promising high dry matter content varieties for cassava processors and farmers in Nigeria, and genotype IBA961632 was the most stable. The study revealed greater genotypic effects than from the environment and high genetic advances. Full article

Wheat, the world’s most widely cultivated crop, is highly susceptible to Take-all disease caused by the soil ascomycete fungus Gaeumannomyces tritici (Gt). Crop rotations using different wheat cultivars can influence Take-all build up (TAB) in the following year’s wheat crop. The exact mechanism for this is unknown, but there may be a bacterial biocontrol component associated with TAB control. We cultured and characterised Pseudomonas isolates from the rhizosphere and endosphere of second-year field-grown wheat, in plots which, in the previous season, had been used to culture High-TAB cultivar Hereward or Low-TAB cultivar Cadenza. Analysis of two bacterial loci, wsm and fecB, showed that these genes were significantly and differentially associated with first-year wheat-planting regime: wsm was more abundant within the High-TAB Hereward-derived isolates, while fecB was more prevalent within the Low-TAB Cadenza-derived isolates. These findings were supported by a gyrB phylogenetic analysis and an in vitro Gt antagonism assay. These data show that the wheat cultivar grown in the first year plays an especially important role in the selection of the associated Pseudomonas spp. found in the second-season wheat-root environment, emphasising the importance of understanding agronomic practice in improving plant health and food security. Full article

Transplanted rice cultivation has caused groundwater depletion in several regions globally. Direct-seeded rice under aerobic conditions is a water-saving alternative. However, under aerobic conditions, iron in the soil is oxidized from the ferrous to ferric forms, which are not easily available to rice crops, resulting in iron-deficiency-induced chlorosis (IDIC) and causing significant reductions in yield. Cultivated rice accessions have limited variations in IDIC tolerance, while the wild Oryza germplasm could be a potential source of IDIC tolerance. In this study, 313 Oryza accessions were evaluated for IDIC tolerance at the tillering stage under aerobic conditions and 20 IDIC-tolerant lines were identified. The twenty lines showed no signs of chlorosis and had high levels of iron content and SPAD values, while the eight cultivated controls exhibited varying degrees of chlorosis symptoms and low levels of SPAD and iron content. To confirm their tolerance, the selected lines were evaluated again in a subsequent year, and they showed comparable levels of tolerance, indicating that these lines were efficient in iron uptake and utilization, resulting in maintained high chlorophyll and leaf area index. These accessions may be useful for developing IDIC-tolerant cultivars for aerobic rice cultivation and future studies of the molecular basis of IDIC tolerance. Full article