Search Results (42)

Grassland degradation, exacerbated by climate change and anthropogenic disturbances, poses a substantial barrier to ecological restoration, largely due to the invasion of toxic weeds. In the degraded grasslands of the Ili River Valley, Xinjiang, Sophora alopecuroides has emerged as the dominant toxic species; yet, its expansion mechanisms and sensitivity to management interventions remain poorly understood. This study utilized a three-year (2023–2025) field experiment to evaluate the impacts of nitrogen addition (N), mowing (M), and their combination (NM) on the stoichiometric characteristics and homeostasis of the plant–soil system. The results demonstrated that while M suppressed aboveground biomass, it facilitated the accumulation of root carbon (RC) and phosphorus (RP). Nitrogen enrichment significantly lowered soil C:N and C:P ratios, thereby alleviating phosphorus limitation. Crucially, the NM treatment effectively counteracted N-induced weed proliferation and mitigated M-induced biomass reductions. Analysis of stoichiometric homeostasis revealed that NM optimized plant adaptive strategies, maintaining strict homeostasis for RC and RP (H > 4) while preserving the sensitivity of the root N:P ratio of S. alopecuroides (RN:P). Structural equation modeling further indicated that soil C:P and N:P indirectly regulated total biomass by modulating the root C:P ratio of S. alopecuroides (RC:P). Consequently, stoichiometric coupling within the plant–soil system is essential for maintaining ecosystem functions. Integrated management (NM) optimizes soil nutrient balance and harnesses compensatory growth to suppress weed expansion, providing a robust scientific framework for the restoration of S. alopecuroides-invaded grasslands. Full article

Weed stress remains a major limiting factor in cotton production, and glyphosate-tolerant varieties provide an effective solution for chemical weed control. However, achieving a balance between herbicide tolerance and agronomic physiological traits remains challenging. In this study, three hybrid combinations were generated by crossing a glyphosate-tolerant cotton line (GGK2) with conventional elite lines and were comprehensively evaluated. Gene expression analysis revealed that the classical detoxification gene GAT was significantly downregulated in all hybrid combinations, whereas the expression of GR79-EPSPS, a gene associated with glutathione metabolism and oxidative stress response, was markedly elevated, particularly in the GGK2 × Y4 combination. This differential expression pattern suggests that GR79-EPSPS may compensate for the reduced function of GAT by conferring oxidative protection under herbicide stress. Physiological determination indicated that hybrid combinations with enhanced GR79-EPSPS expression, especially GGK2 × Y5, exhibited superior photosynthetic pigment composition and photosystem II (PSII) efficiency, validating the role of GR79-EPSPS in maintaining photosynthetic stability. Agronomic trait assessment demonstrated that GGK2 × Y4 achieved significant biomass accumulation and yield improvement through heterosis, although fiber quality improvement was limited. This study effectively enhanced the herbicide resistance of conventional cotton through crossbreeding and revealed that the interaction between GR79-EPSPS and GAT can improve cotton tolerance to herbicides, thereby providing a breeding strategy for developing cotton varieties with both herbicide tolerance and superior agronomic traits. Full article

The long-term application of traditional chemical herbicides has caused a significant escalation in herbicide resistance of barnyard grass (Echinochloa crus-galli). As an eco-friendly alternative, biological herbicides demonstrate substantial application potential. Acknowledging the growing herbicide resistance of E. crus-galli, this study aimed to screen target bacteria with inhibitory effects on the growth for bio-herbicide development. By using ungerminated E. crus-galli seeds as the screening substrate, a bacterial strain (BFYBC-8) with potent inhibitory activity was isolated and identified as Brucella pseudorignonensis. Pot experiments revealed that inoculation with B. pseudorignonensis BFYBC-8 significantly suppressed E. crus-galli growth, reducing plant height by 16.7% and root length by 85.1%, while markedly inhibiting biomass accumulation. Fluorescent labeling with green fluorescent protein (GFP) showed that BFYBC-8 successfully colonized the root intercellular spaces of E. crus-galli and extended continuously along the tissue matrix. Additionally, the strain’s supernatant metabolic products exhibited exceptional thermostability: inhibitory activity against E. crus-galli was maintained after thermal treatment at 28 °C, 60 °C, 80 °C, and 100 °C. Crucially, the bacterium displayed no toxicity to agronomically important crops such as rice, wheat, and corn. This study highlights B. pseudorignonensis BFYBC-8 as a promising candidate for bioherbicide development and provides an important reference for applying seed-associated pathogenic bacteria in developing bioherbicides for sustainable weed management. Full article

Tolprocarb (TPC), a fungicide primarily used for controlling rice blast, was recently shown to stimulate disease resistance in rice. To elucidate the molecular basis of this immunostimulatory effect, we conducted transcriptomic, metabolic, and field-based analyses focusing on diterpenoid phytoalexins, key antimicrobial and allelopathic compounds in rice. Microarray analysis revealed that TPC treatment induced a broad transcriptional activation of genes involved in phytoalexin biosynthesis, including DPF, a master regulator of diterpenoid metabolism. Consistent with this, LC-MS/MS analyses confirmed the accumulation of momilactones A and B, as well as phytocassanes B, C, and E, in rice leaves after TPC application, a response not observed with conventional resistance inducers such as probenazole or carpropamid. In root tissues under controlled conditions, phytoalexin accumulation was limited, and exudation into the rhizosphere was minimal. However, field experiments showed that TPC treatment led to a transient increase in leaf momilactones around 14 days post-transplanting, followed by increased exudation into the rhizosphere at 21 days. Notably, this increase in root exudation coincided with a reduction in total weed biomass, although weed species composition remained unchanged. These findings suggest that TPC not only enhances rice immunity through phytoalexin induction but may also contribute to weed suppression via allelopathic root exudates in field settings. Our study highlights a dual role for TPC in rice cultivation, boosting disease resistance and suppressing weed growth, and underscores the potential of phytoalexin-focused strategies for integrated crop protection. Full article

Wheat (Triticum aestivum) is grown on more arable acreage than any other food crop and has been well documented to produce allelochemicals. Wheat allelochemicals include numerous benzoxazinoids and their microbially transformed metabolites that actively suppress growth of weed seedlings. Production and subsequent release of these metabolites by commercial wheat cultivars, however, has not yet been targeted by focussed breeding programmes seeking to develop more competitive crops. Recently, the Commonwealth Scientific and Industrial Organisation (CSIRO), through an extensive recurrent selection programme investment, released numerous early-vigour wheat genotypes for commercial use, but the physiological basis for their improved vigour is under investigation. In the current study, we evaluated several early-vigour genotypes alongside common commercial and heritage wheat cultivars to assess the impact of improved early vigour on the production and release of targeted benzoxazinoids by field-grown wheat roots over a two-year period. Using UPLC coupled with triple quadrupole mass spectrometry (LC-MS QQQ), we quantified common wheat benzoxazinoids and their microbially produced metabolites (aminophenoxazinones) in soil collected from the rhizosphere and rhizoplane of wheat plants over two growing seasons in the Riverina region of New South Wales, Australia. The benzoxazolinone MBOA and several aminophenoxazinones were readily detected in soil samples, but actual soil concentrations differed greatly between years and among genotypes. In contrast to 2019, the concentration of aminophenoxazinones in wheat rhizosphere soil was significantly elevated in 2020, a year receiving adequate rainfall for optimal wheat growth. Aminophenoxazinones were detected in the rhizosphere of early-vigour genotypes and also parental lines exhibiting weed suppression, suggesting that improved early vigour and subsequent weed competitiveness may be related to increased root exudation and production of microbial metabolites in addition to changes in canopy architecture or other root-related early-vigour traits. As previously reported, MBOA was detected frequently in both the rhizoplane and rhizosphere of wheat. Depending on the year and genotype, we also observed enhanced biotransformation of these metabolites to several microbially transformed aminophenoxazinones in the rhizosphere of many of the evaluated genotypes. We are now investigating the role of early-vigour traits, including early canopy closure and biomass accumulation upon improved competitive ability of wheat, which will eventually result in more cost-effective weed management. Full article

Successful seed germination and plant seedling growth often require association with endophytic bacteria. Barnyard grass (Echinochloa crus-galli (L.) P. Beauv.) is a main weed during rice cultivation and has frequently been found in drought-prone fields such as cornfields in recent years. To determine whether endophytic bacteria enhance the survival chances of barnyard grass in dryland conditions, endophytic bacteria were collected from barnyard grass seeds. An endophytic bacterial strain, BC-14, was selected and confirmed as Cronobacter dublinensis based on its morphology, physiology, biochemistry, and genomic information. Moreover, C. dublinensis BC-14 secreted IAA in the Luria–Bertani broth up to 28.44 mg/L after 5 days; it could colonize the roots of barnyard grass. After the inoculation with seeds or the well-mixed planting soil, the bacterium can significantly increase the root length and plant height of barnyard grass under drought conditions. When comparing with the control group on the 28th day, it can be seen that the bacterium can significantly increase the contents of chlorophyll b (up to 7.58 times) and proline (37.21%); improve the activities of superoxide dismutase, catalase, and peroxidase (36.90%, 51.51%, and 12.09%, respectively); and reduce the content of malondialdehyde around 25.92%, which are correlated to the drought tolerance. The bacterial genomic annotation revealed that it contains growth-promoting and drought-resistant functional genes. In a word, C. dublinensis BC-14 can help barnyard grass suppress drought stress, promote plant growth, and enhance biomass accumulation, which is helpful to interpret the mechanism of weed adaptability in dry environments. Full article

Soil residual herbicides are often applied at cover crop termination to extend the period of weed control and reduce the selection pressure for herbicide resistance. Previous studies indicate that one of the benefits of cover crop use is the increase in the activity of enzymes in the soil. Some enzymes are also responsible for breaking down herbicide molecules. The biodegradation of herbicides in the soil is a natural process that leads to a reduction in the concentration of the parent compound overtime. Although cover crop use can result in the increased activity of soil enzymes, to date, there is no evidence that such increased activity also leads to a reduced persistence of residual herbicides in the soil. However, cover crop use does alter the fate of residual herbicides by interception, with some studies reporting more than 90% interception. Without rainfall or irrigation during the days following its application, the herbicide remains on the plant surface and is ineffective as a weed control tool. Following the integrated weed management approach, the combination of cover crop and soil residual herbicides is a promising alternative to delay the development of new herbicide resistance cases. However, more research is needed to understand the impact of biomass accumulation on residual herbicide fate and to determine the best strategies to improve herbicide placement on cover cropping system. This paper reviews the impact of cover crop use on soil microbial activity and the further degradation of soil residual herbicides as well as the fate of residual herbicides when applied at cover crop termination. Full article

Purslane (Portulaca oleracea L.) is a common weed that attracts research and agricultural attention because of its significant nutritional value, and it is used commercially. The present work rated the effect of different nitrogen (N) concentrations, i.e., N50: 50 mg L⁻¹; N100: 100 mg L⁻¹; N200: 200 mg L⁻¹; and N300: 300 mg L⁻¹, on the growth, physiology, antioxidant capacity, and nutrient accumulation in the different plant parts of hydroponically grown purslane. Seedlings were transplanted to a Nutrient Film Technique (NFT) system and exposed to different N levels. The plants grown in high N levels of 300 mg L⁻¹ had decreased biomass production, leaf number, leaf stomatal conductance, and total flavonoid content because of the increased oxidative stress, as shown by the elevated lipid peroxidation levels. Several enzymatic (superoxide dismutase) and non-enzymatic (ascorbic acid, total phenolics) plant antioxidant activities were activated to counteract the oxidative factors. Plants grown in intermediate N levels in the NS (i.e., 100 mg L⁻¹) had decreased oxidative stress as several enzymatic antioxidant activities, i.e., peroxidases and catalases, were increased. Additionally, the water use efficiency and nitrogen uptake, as well as leaf stomatal conductance and leaf chlorophyll fluorescence, were increased in plants grown at a N level of 200 mg L⁻¹. The mineral accumulation in the leaves, stems, and roots fluctuated, with increased calcium, magnesium, and sodium content being observed in the plants grown at high N levels in the nutrient solution. The stems accumulated less N compared with the leaves, but the N content and accumulation rates in purslane leaves were not affected by the N levels in the nutrient solution. Therefore, to increase the yield, nutritional value, and water use efficiency of purslane that is grown hydroponically, a concentration of 200 mg L⁻¹ N in the nutrient solution is recommended. Full article

Purple soils are greatly representative of ecologically fragile soils in southern China, yet the impact of vegetation restoration processes on the nitrogen (N) availability in purple soil ecosystems is still unclear. In this study, the soil nutrient content, available N fractions (including microbial biomass N (MBN), ammonium N (NH₄⁺-N), nitrate N (NO₃⁻-N), and total dissolved N (TDN)), and enzyme activities (including urease (URE), nitrate reductase (NR), and nitrite reductase (NIR)) involved in N mineralization and immobilization were investigated across the three vegetation-restoration measures: Camellia oleifera monoculture, Camellia oleifera ryegrass intercropping, and Camellia oleifera intercropping with weeds. The results showed that the Camellia oleifera monoculture mode considerably enhanced the accumulation and availability of soil N and modified the proportion of available N fractions in arable land situated on purple soil slopes, compared to the intercropping mode, the physical, chemical, and microbiological properties of soil demonstrated more pronounced effects due to the Camellia oleifera monoculture vegetation-restoration measures. However, soil nutrient loss is faster on set-aside land and in crop monocultures, and intercropping restoration measures are more beneficial for soil and water conservation under timely fertilization conditions. The soil URE, NR, and NIR activities and MBN content in the Camellia oleifera monoculture model were significantly higher than in the control check sample. Soil N transformation occurs through the combined influence of chemical and biological processes. The relationships between the activities of the three soil enzymes studied and the contents of various components of soil nutrients and effective N displayed significant differences. Notably, URE had a highly significant positive correlation with TOC. There is a strong positive correlation between NR and TN, NIR and TDN, NO₃⁻-N, and NH₄⁺-N. Our findings suggest that vegetation restoration improved the soil N availability and its enzyme activities in purple soils, making an essential contribution to the restoration and sustainability of purple soil ecosystem functions. Full article

The ecosystem services a cover crop (CC) provides depend enormously on species choice and tillage system. Here, we evaluated the impact of (a) three winter CCs—rye (Secale cereale L.) and squarrose clover (Trifolium squarrosum L.) monocultures and their mixture, and (b) two tillage systems—roller-crimping of CC residue as dead mulch for no-till (NT) systems and incorporating CC residue into the soil as green manure for conventional tillage (CT) systems—on the performance of organic processing tomato, i.e., plant growth, nutrient accumulation, fruit yield, and weed biomass. The assessments took place over two years in field experiments conducted under Mediterranean conditions. At the termination time, rye and mixture were the most productive and the best weed-suppressive CCs. During tomato growing season, squarrose clover regardless of tillage system stimulated tomato growth, Nitrogen content and uptake, and the yield relative to the other cover crops. Nevertheless, NT generally impaired the tomato nutritional status and increased weed biomass compared to CT despite some potential weed control by cover crops. These two aspects caused a significant drop in tomato yield in all NT systems. The results suggested that, despite the multiple benefits the compared CCs can offer in Mediterranean agroecosystems, legume CCs could be the key to developing feasible organic vegetable no-till systems. Full article

Field studies were conducted in the northeastern part of the Republic of Croatia to determine the influence of the critical period of weed interference on sunflower (Helianthus annuus) yield, yield components, and oil content. For this purpose, different durations of competition were established, allowing weeds to infest the crop for increasing periods of time after planting or maintaining plots weed-free for increasing periods of time after planting. The beginning and the end of the critical period of weed control (CPWC), based on a 5% and 10% loss of sunflower yield, were determined by fitting the four-parameter log-logistic equations to the relative seed yield. The total weed biomass increased progressively in relation to the increase in the competition. The beginning of the CPWC period, based on a 5% acceptable yield loss, ranged from 141 to 234 growing degree days (GDD), which corresponded to the two-to-four true leaf development stage (the V2–V4 growth stages) across both sites and years. The crop had to be kept weed-free until a period when sunflower inflorescence began to open and flower (the R4–R5 growth stage) or from 1365 to 1932 GDD. The sunflower yield and yield components varied between the years and among locations. An increasing duration of weed interference negatively affected crop height, head diameter, and 1000-kernel weight, but not seed oil content. Full article

Orobanche cumama wallr. is the sunflower root parasitic weed with special life stage in which seed germination and parasitism take place in the soil. In practice, applying microbial agents and trapping crop rotation are utilized separately, or just one of them is selected to control O. cumana. The development of the sunflower industry is severely constrained on the farmland, where there is high density of O. cumana’s seed banks. In this study, two biological control methods were combined to solve the problem of O. cumana parasitism. The bioassay experiment showed that the high concentration fermentation filtrates of Streptomyces rochei D74 could effectively inhibit the germination and growth of the germ tube of O. cumana seeds. As the concentration was increased to 3.1 mg/mL, O. cumana was almost unable to sprout. A two-year pot experiment revealed that the use of D74 agents and sunflower–maize–sunflower rotation together promoted sunflower growth, as shown by the biomass accumulation, plant height, and denser root systems. The combined method resulted in a significant decrease in the number of O. cumana parasitism, compared to one method alone. Additionally, it affected the bacterial community composition of sunflower rhizosphere, mostly leading to an increase in Streptomyces and Brevibacterium and a decrease in Arthrobacter. This experiment, combined with multiple biological control, means significantly reducing the parasitism of O. cumana, which provides an effective foundation for practical application. Full article

Weed infestation is a major cause of the poor yield of soybeans (Glycine max (L.) Merr.); therefore, proper weed management represents one of the most important and expensive steps in soybean production. Field experiments were established in northeastern parts of Croatia, in the Vukovar-Syrmia county from 2014 to 2016, arranged in a split-plot design with four replications. Two different studies were conducted: the first study was to determine the weed interference, weed biomass accumulation, yield, and yield components of soybeans growing in three different rows spacing (25, 50, and 70 cm), and the second study aimed to simulate a risk analysis by building models of probabilities for generating profit as a result of weed control. The weed community in soybean during the study period comprised 34 dicot and grass species of a varied perennation. Compositional differences in the weed community tended to be affected most by the year (humid–arid environment), followed by row spacing. There were no differences in the weed biomass accumulation with a reduction in row spacing from 70 to 50 and 25 cm. The dominant weed species Amaranthus retroflexus, Ambrosia artemisiifolia, Chenopodium album, Datura stramonium, Setaria viridis, and Sorghum halepense formed the main biomass and were spread over all row spacings. There was a significant influence of row spacing, the duration of weed interference, and year on soybean yield and yield components. Weed infestation until the second trifoliate (V2) stage had no detrimental effect on soybean yield, regardless of the row spacing. The number of pods per plant significantly decreased at the same V2 stage in 25 and 50-cm rows, but in 70-cm soybean rows, this process started later, at four unfolded trifoliate leaves (V4 stage). A 1000 kernel weight was less sensitive to weed infestation and was significantly decreased at full flowering (R2 stage) in 25 and 70 cm rows, while it already decreased at the V4 stage in 50 cm rows. The probability distribution of achieving a profit showed the best results for soybeans growing in 70 cm rows, with preemergence herbicide application and two inter-row cultivation. Full article

Competitive ability of cereals against segetal weeds depends among other things, on soil properties and the weather. Concerning cornflower (Centaurea cyanus L.), this issue is poorly recognized, as there are no reports on the impact of environmental conditions on the competitiveness of wheat against susceptible and resistant biotypes. Our study aimed to evaluate the effects of site and weather conditions on the competitive effects between winter wheat (WW) and two cornflower biotypes, either florasulam and tribenuron-methyl resistant (R) or sensitive (S). The experiment was conducted in a replacement series model at six sites across Poland in three growing seasons. The competitive relations were determined on the basis of two indices, i.e., the relative biomass and the number of seeds produced by the tested plants. The relative yield of wheat and weed were plotted on graphs and fitted to one of five competition models. In addition, a competitive ratio (CR) was calculated on the basis of fresh plant biomass and the number of seeds. Correlation coefficients were determined between the length of the plant, yield, biomass, the number of seeds per plant, hydrothermal coefficient K, and soil texture. Biometric parameters of wheat for its competition with two cornflower biotypes were analyzed using canonical variate analysis (CVA). The number of days to WW emergence and the day-difference between WW and cornflower (B) emergence were also calculated. The environmental characteristics of the sites, i.e., hydrothermal coefficient K and soil texture, were used as categorizing variables. Drought generally favored the greater competitive ability of WW against B for both biomass accumulation and seed production. During the first season of the research (relatively dry), only in one case out of 12 cases cornflower was more competitive than wheat. In the second year of the experiment (dry season), the competition of WW against B for resources was lower. It depended more on the site than on the cornflower biotype or the proportion of plants in the mixture. Under high or optimal rainfalls (the third year of the experiment), the competitiveness of WW toward B was significantly lower than in years with rainfall deficiency. In addition, the ability of wheat competition against the weed may have been influenced by the earlier emergence of wheat than cornflower. Even though it was sown together with wheat, cornflower emerged 0–12 days later than the tested cereal. It was also noticed that wheat was more competitive on light soils against the herbicide-susceptible (S) biotype. In contrast, greater WW competitiveness was observed against herbicide-resistant (R) cornflower on heavy soils. In conclusion, winter wheat competitiveness against herbicide-resistant or herbicide-sensitive cornflower biotypes is significantly dependent on weather and soil conditions. It is therefore reasonable to study this phenomenon in more detail. It would also be interesting to learn more about the underground competition on varying soil types under different water availability. Full article

Ammonia (NH₃) emissions resulting from the field application of livestock slurry has both negative human health and environmental impacts. However, decreasing the exposed surface area (ESA) of slurry upon application can reduce NH₃ volatilization by limiting its atmospheric exposure. In the present study, three strategies for depositing slurry within a growing crop were studied, including: 1. standard trailing hoses (SA_hose), 2. trailing shoes (SA_shoes), and 3. the combination of rigid tines and trailing shoes (SA_tines+shoes). Application methods interact with the soil to varying degrees and were evaluated within the context of contemporary weed management practices, namely in cereals receiving inter-row hoeing. SA_hose, SA_shoes, and SA_tines+shoes were compared in three coinciding experiments that assessed slurry ESA, NH₃ emissions, and crop and weed effects. SA_tines+shoes resulted in smallest ESA, 70–72% and 61–66% less than SA_hose and SA_shoes, respectively. However, in only one of three site–years did SA_shoes and SA_tines+shoes reduce NH₃ emissions compared to SA_hose, by 46% and 29%, respectively. Crop yields, nitrogen (N) accumulation in crop biomass, and intra-row weed biomass were unaffected by the placement method. In heavily crusted soils, the SA_tines+shoes prototype worked well; however, the functional differences among placement strategies were not great enough to detect crop and NH₃ effects. Full article