Search Results (35)

Soil organic carbon (SOC) stocks play an important role in ecosystem functioning and climate regulation. These stocks are declining in many tropical dry forests due to land-use change and degradation. Data on topsoil (0–300 mm) organic C stocks from six experiments conducted in the Dry Chaco region, the world’s largest dry tropical forest, were used to test the predictive performance of the Rothamsted Carbon Model (RothC) after its implementation in an object-oriented graphical programming language. RothC provided promising predictions (i.e., precise and accurate) of the SOC stocks under two representative land covers in the region, native forest and Rhodes grass [relative prediction error (RPE) < 10%, concordance correlation coefficient (CCC) > 0.9, modelling efficiency (MEF) > 0.7]. Comparatively, model predictions of the SOC stocks under degraded Rhodes grass swards were suboptimal. The predictions were sensitive to C inputs; under native forests and Rhodes grass, a high C input improved the predictive performance of the model by reducing the mean bias and increasing the MEF values, compared with mean and low C inputs. Larger datasets and revisiting some of the underlying assumptions in the SOC modelling will be required to improve the model’s performance, particularly under the degraded Rhodes grass land cover. Full article

This study assessed the effectiveness of four competitive pasture species—Premier digit grass (Digitaria eriantha Steud. var. Premier), Rhodes grass (Chloris gayana Kunth.), sabi grass (Urochloa mosambicensis Hack.), and buffel grass (Pennisetum ciliare L.) against the toxic annual riceflower (Pimelea trichostachya Lindl.) at varying planting densities and ratios. At six plants pot⁻¹, with a 66:33 grass-to-weed ratio, riceflower biomass decreased by 73.7%, 82.5%, 73.7%, and 60.6% when grown alongside Premier digit, Rhodes, sabi, and buffel grasses, respectively. Similarly, with four plants pot⁻¹ at a 75:25 ratio, reductions were 69.1%, 79.8%, 71.0%, and 44.5%, respectively. Annual riceflower experienced the greatest suppression when grown with Rhodes grass, showing aggressivity index (AI) values of −60.2 and −67.2 and relative crowding coefficient (RCC) values of 0.4 for both six and four plants pot⁻¹. Premier digit grass also suppressed riceflower effectively, with riceflower AI values of −35.6 and −36.7 and RCC values of 0.5 and 0.6. Buffel grass had the least impact, with riceflower AI values of −41.1 and −27.9 and RCC values of 0.9 and 2.0. Sabi grass also demonstrated good suppressive effects, though slightly less than the top two species. Higher planting densities generally resulted in stronger riceflower suppression. The results highlight the importance of considering planting density, arrangement, and key plant traits when selecting pasture species for successful weed control. Based on these findings, we conclude that Premier digit grass and Rhodes grass show promising potential for effective suppression of annual riceflower growth. Full article

Feathertop Rhodes grass (Chloris virgata Sw.) is a problematic weed in Australian summer crop fields that has recently expanded its presence into colder seasons. In this study, the phenology, growth, and seed production of four C. virgata populations were investigated across six different planting dates every other month from May to March between 2021 and 2022 and between 2022 and 2023. In both years, the shortest time (3 to 6 days) for C. virgata emergence was observed for January planting, while the longest time (10 to 17 days) was observed for July planting. In both years, C. virgata populations showed variations in growth and seed production in response to planting time. The highest aboveground biomass production in the first year was observed in November planting, and in the second year, it was observed in both November and January plantings. In the first year, all four populations produced the highest number of seeds when planted in January, averaging 133,000 seeds plant⁻¹. In the second year, among the different planting dates, the March planting with two populations resulted in the highest seed production, averaging 148,000 seeds plant⁻¹. In both years, there was a positive and significant correlation between aboveground biomass and seed production. The ability of this species to emerge, establish, survive, and consistently produce seeds year-round indicates its successful adaptation to the Queensland climate. Failure to manage this weed will result in its further spread to new areas. Full article

Organic fertilizers and microbial biofertilizers are now widely recognized to effectively complement traditional mineral fertilizers for plant growth. The present study shows that bio-organic fertilizers can be enhanced by the addition of functional plant-growth-promoting rhizobacteria (PGPR) that provide additional benefits to plants. We hypothesized that not all beneficial soil bacteria are functional in different farm soils and plant varieties; hence, the most effective PGPR that are suitable to each farm’s individual cropping conditions were selected. Five different field soils and their respective crops were tested for compatibility with six microbial biofertilizers (including three new bacterial strains) to supplement a commercially available bio-organic fertilizer. In pot trials with lucerne plants, four out of the six microbial treatments led to significant (p < 0.05) growth promotion benefits (up to 79.8% more leaves and dry weight) compared to mock-treated or bio-organic fertilizer-only-treated control plants. A trial with industrial hemp demonstrated that compatibility with PGPR occurs in a cultivar-specific manner, leading to growth promotion ranging from −3.4% to 68.9%, with each cultivar displaying a preference for a different PGPR. Finally, pot trials with Rhodes grass and two different soils demonstrated high yield increases compared to control plants, with Bacillus amyloliquefaciens 33YE being most effective for one soil and Bacillus velezensis UQ9000N/Pseudomonas lini SMX2 for the other soil. Yield advantages reduced after several cuts of grass, but a repeat biofertilizer treatment at 69 days after the initial treatment restored high yield advantages, with the same PGPR again being most effective. These results demonstrate the importance of customization of microbial inoculants to identify the most compatible PGPR–cultivar–soil interaction. The customization of microbial biofertilizers to soils and plant cultivars, combined with complementary fertilizer applications, can potentially lead to more reliable and more sustainable agricultural practices. Full article

Utilizing the potential of crops to suppress weeds is an important strategy for sustainable management. Feathertop Rhodes grass (FTR) (Chloris virgata Sw.) is a problematic warm-season weed in Australia that has recently expanded into colder seasons. This study investigated the growth and seed production of FTR at two planting times (May and July) and three wheat planting densities (0, 82, and 164 plants m⁻²) using a neighborhood design over two years. In both years, the plant height, tiller production, and panicle production of FTR were lower in the presence of wheat compared to when wheat was absent. Surrounding FTR with wheat delayed its pinnacle emergence, varying from 1 to 6 days in the first year and 4 to 21 days in the second year, depending on the planting date and wheat density. During both years and planting times, wheat’s presence caused approximately a 99% decrease in the dry matter and seed production of FTR compared to wheat’s absence. Additionally, the wheat height, an important competitive factor, was higher at both densities in the May planting compared to the July planting. The emergence, establishment, and continuous production of FTR seeds throughout the year indicate that inadequate management could result in the further spread of this weed. Our findings suggest that adjusting the date and density of wheat planting could be a viable strategy for sustainably managing this weed during colder seasons. Full article

The addition of methane-reducing compounds (MRCs) to livestock drinking water presents an alternative method for enteric methane mitigation in extensive systems where these compounds cannot be fed through the diet. This work evaluated several such compounds with the potential to be deployed in this manner. Methane-reducing compounds were selected based on the existing literature and likelihood of dissolution when combined with a commercially available water-based nutrient supplement (uPRO) (uPRO ORANGE^®, DIT AgTech, QLD, Australia). This, in turn, would demonstrate the capacity for MRCs to be administered through animal drinking water when such supplements are in use. This technique requires the analysis of MRC solubility and stability in solution, which was completed via Fourier transform infrared-attenuated total reflectance spectroscopy. The uPRO supplement is comprised of urea, urea phosphate, and ammonium sulfate, providing nitrogen, phosphorus, and sulfur—limiting nutrients for ruminants grazing extensive systems during drier periods of the year. Accordingly, medium-quality Rhodes grass hay was used in fermentation runs to simulate a basal diet during the dry season. Methane-reducing compounds were assessed in accordance with each variable measured (gas/methane production, dry matter digestibility, stability under different environmental conditions) along with existing research in the field to determine the most suitable compound for co-administration. Whilst most compounds examined in this study appeared to retain their structure in solution with uPRO, fermentation results varied in terms of successful methane mitigation. The additive Agolin Ruminant L emerged as the most promising compound for further in vivo investigation. Full article

Navua sedge (Cyperus aromaticus), a perennial plant native to Africa, poses a significant weed concern due to its capacity for seed and rhizome fragment dissemination. Infestations can diminish pasture carrying capacity, displacing desirable species. Despite the burgeoning interest in integrated weed management strategies, information regarding the efficacy of competitive interactions with other pasture species for Navua sedge management remains limited. A pot trial investigated the competitive abilities of 14 diverse broadleaf and grass pasture species. The results indicated a range of the reduction in Navua sedge dry biomass from 6% to 98% across these species. Subsequently, three broadleaf species—burgundy bean (Macroptilium bracteatum), cowpea (Vigna unguiculata), and lablab (Lablab purpureus), and three grass species—Gatton panic (Megathyrsus maximus), Rhodes grass (Chloris gayana), and signal grass (Urochloa decumbens) were chosen for a follow-up pot trial based on their superior dry biomass performance. These six species were planted at three varying densities (44, 88, and 176 plants/m²) surrounding a Navua sedge plant. Among the grass pasture species, Gatton panic and Rhodes grass exhibited high competitiveness, resulting in a minimum decrease of 86% and 99%, respectively, in Navua sedge dry biomass. Regarding the broadleaf species, lablab displayed the highest competitiveness, causing a minimum decrease of 99% in Navua sedge dry biomass. This study highlights the increasing efficacy of crop competition in suppressing weed growth and seed production, with the most significant suppression observed at a density of 176 plants/m². Full article

Minerals play a dynamic role in plant growth and development. However, most of these mineral nutrients are unavailable to plants due to their presence in fixed forms, which causes significant losses in crop production. An effective strategy to overcome this challenge is using mineral solubilizing bacteria, which can convert insoluble forms of minerals into soluble ones that plants can quickly assimilate, thus enhancing their availability in nutrient-depleted soils. The main objective of the present study was to isolate and characterize mineral solubilizing rhizobacteria and to assess their plant growth-promoting potential for Rhodes grass. Twenty-five rhizobacterial strains were isolated on a nutrient agar medium. They were characterized for solubilization of insoluble minerals (phosphate, potassium, zinc, and manganese), indole acetic acid production, enzymatic activities, and various morphological traits. The selected strains were also evaluated for their potential to promote the growth of Rhodes grass seedlings. Among tested strains, eight strains demonstrated strong qualitative and quantitative solubilization of insoluble phosphate. Strain MS2 reported the highest phosphate solubilization index, phosphate solubilization efficiency, available phosphorus concentration, and reduction in medium pH. Among tested strains, 75% were positive for zinc and manganese solubilization, and 37.5% were positive for potassium solubilization. Strain MS2 demonstrated the highest quantitative manganese solubilization, while strains MS7 and SM4 reported the highest solubilization of zinc and potassium through acidifying their respective media. The strain SM4 demonstrated the most increased IAA production in the presence and absence of L-tryptophan. The majority of strains were positive for various enzymes, including urease, catalase protease, and amylase activities. However, these strains were negative for coagulase activity except strains SM7 and MS7. Based on 16S rRNA gene sequencing, six strains, namely, SM2, SM4, SM5, MS1, MS2, and MS4, were identified as Bacillus cereus, while strains SM7 and MS7 were identified as Staphylococcus saprophyticus and Staphylococcus haemolyticus. These strains significantly improved growth attributes of Rhodes grass, such as root length, shoot length, and root and shoot fresh and dry biomasses compared to the uninoculated control group. The present study highlights the significance of mineral solubilizing and enzyme-producing rhizobacterial strains as potential bioinoculants to enhance Rhodes grass growth under mineral-deficient conditions sustainably. Full article

Summer annual weed species in northern Australian summer fallows are frequently present at low densities and, increasingly, are glyphosate-resistant, creating the need for alternative herbicides for site-specific weed control. Alternative non-selective herbicide treatments are effective on problematic summer fallow weeds; however, many are yet to be evaluated as site-specific (spot spraying) treatments. This study aimed to identify herbicides that could be used in place of glyphosate to control larger/mature Chloris virgata and Sonchus oleraceus plants. The response of these weed species to 12 herbicide treatments was evaluated in pot experiments conducted over summer/autumn 2022. Despite herbicide treatments not being consistently effective across both species, there were instances where control was achieved by some herbicide treatments. S. oleraceus was controlled (i.e., ≤10% plant survival) by glufosinate-ammonium, paraquat and also with protoporphyrinogen-oxidase (PPO)-inhibiting herbicides saflufenacil, tiafenacil and trifludimoxazin. However, these results were not consistent in repeated studies or for C. virgata. Glyphosate was the only herbicide that controlled C. virgata. A glyphosate replacement as a spot-spraying treatment was not identified, and until further studies are more successful, alternative approaches are needed to preserve the ongoing effectiveness of this herbicide. Full article

For more than two decades, glyphosate has been relied on to control summer annual weeds in fallow systems in Australia’s northern grains region. With numerous cases of glyphosate resistance reported in weed species collected from this region, there are concerns about the future viability of this herbicide. A random seed collection survey of summer weeds was conducted between 2016 and 2018 with the aim of determining the frequency and distribution of resistance to glyphosate and other herbicides commonly used for summer weed control. Glyphosate resistance was ubiquitous in fleabane, with all collected populations resistant to this herbicide. Glyphosate resistance was also prevalent in feathertop Rhodes grass, windmill grass, and awnless barnyard grass, with resistance detected in 68%, 58%, and 36% of populations, respectively. Only 14% of sowthistle populations collected between 2013 and 2108 were resistant to glyphosate. Resistance to haloxyfop was detected in feathertop Rhodes grass, albeit at a low frequency (2%). Other herbicides, such as 2,4-D amine, propaquizafop, and clethodim, provided good control of the broadleaf and grass weeds tested. The results from these surveys conducted between 2013 and 2017 provide a first glimpse of the state of herbicide resistance in key crop weeds for Queensland and the northern region of New South Wales. It is clear that farmers and agronomists need to consider incorporating non-chemical weed management tactics to promote the sustainability of current herbicides. Full article

The extent of the feathers covering a bird’s body and the condition of the plumage largely determine the bird’s well-being and aesthetic condition. This investigation aimed to compare changes in the plumage status of laying hens in dissimilar housing systems in the egg-laying period. The experiment was carried out with 1460 non-beak-trimmed laying hens, provided by Bábolna TETRA Ltd., representing a part of the Rhode-type elite lines (Rhode Island Red (RIR) and Rhode Island White (RIW)) used for breeding brown layer hybrids. Hens were kept in the closed experimental laying house of MATE University (Kaposvár Campus), where the RIR and RIW hens were placed into three types of housing systems: EU standard furnished cage (EU) (7560 cm²; 10 hens/cage; 756 cm²/hen); Alternative pen (A) (5.52 m², floor and litter combination, 53 hens/pen; 1040 cm²/hen); and Conventional cage (C) (3780 cm²; 6 hens/cage; 630 cm²/hen). The feathering status of the hens was examined at five body parts: neck, breast, wings, back and tail at 33, 45 and 61 weeks of age, which was evaluated on a four-grade scale by the same experienced scorer, and the cumulated plumage point (5–20) was calculated for each hen. The RIW genotype had a better plumage condition than RIR at each of the examined times (at the 33rd week: 19.0, 18.3; at the 45th week: 18.4, 17.4; at the 61st week: 17.2, 15.5). The status of the plumage of the RIR hens had deteriorated to a greater extent. As age progressed, the plumage condition of both genotypes significantly deteriorated in all the three housing technologies. The relatively high level of deterioration can be partly explained by the fact that the animals were non-beak-trimmed. At all test times, the total feather score of the birds in the alternative cage housing was significantly better (at the 33rd week: EU: 18.4, A: 19.1, C: 18.5; at the 45th week: EU: 17.6, A: 18.6, C: 17.4; at the 61st week: EU: 15.9, A: 16.9; C: 16.1). The condition of the neck plumage was better in group RIW than in RIR, and the best in the alternative housing at each test time. At the end, the high decomposition results were striking, since at the beginning there were values close to the maximum (3.98; 3.99). It can be concluded that the reason for the dominantly favorable aviary results is that the hens in this type of housing have to come into contact with fewer mechanical factors, their companions do not jump on their backs when changing places, they do not have to stick their heads out of the grid to collect feed, etc. In addition to all this, they also had a littered scratching area and a nest lined with artificial grass, where they could scratch and take a dust bath. Full article

Understanding the spatial pattern of soil chemical properties along with the topologic indicators is essential for site-specific agriculture management. A study was conducted on a 50 ha field to investigate the effect of selected topographic indicators, including elevation (DEM), slope (SL), flow accumulation (FA) and Topographic Wetness Index (TWI) on forage crop production. The soil samples and yield data were obtained from the field inventory. Topographical parameters of elevation and slope were estimated with the use of a real-time kinematic global positioning system (RTK-GPS), and then the DEM was generated. The collected soil samples were analyzed for pH, EC, nitrogen and soil organic carbon. Sentinel-2 images were for the creation of yield maps of alfalfa and Rhodes grass. Subsequently, on the basis of DEM, the generated elevation, slope and FA model were then compared with the yield and soil chemical properties. Statistical analysis revealed that the SL, FA and TWI, which are associated with water distribution, were significantly related to crop yields. The FA showed a medium-to-non-significant correlation with the productivity of both alfalfa (R² = 0.586; p = 0.015) and Rhodes grass (R² = 0.578; p = 0.01). A significant inverse correlation was recorded between the SL and the yield of both crops (R² = −0.591 to −0.617; p = 0.01). The yield map revealed that the majority of the area (37.56%) of the experimental field was occupied by the medium-yield class, followed by the high-yield class (33.03%). Full article

The objective of the present study was to evaluate the potential of the dietary addition of neem (Azadirachta indica) leaf powder (NLP) when compared to monensin (MON) on ruminal fermentation, feed intake, digestibility, and performance of growing lambs. Eighteen Omani lambs (22.8 ± 2.18 kg of body weight (BW)) were equally divided into three groups (n = 6 lambs/group) for 90 days. Animals were fed an ad lib basal diet consisting of Rhodes grass (Chloris gayana) hay (600 g/kg) and a concentrated mixture (400 g/kg) offered twice daily. Experimental treatments were control (basal diet without supplements); MON (control plus 35 mg/kg DM as a positive control); and NLP (control plus 40 g/kg DM). Lambs fed NLP had reduced ruminal ammonia nitrogen concentrations, protozoal counts, total volatile fatty acid, and blood urea nitrogen concentrations compared to the control. Compared to MON, lambs fed NLP had increased ruminal acetate and decreased propionate proportions. Inclusion of NLP in the diet increased blood total protein, globulin, and liver enzyme concentrations in comparison with the control, which was similar to MON. The lamb’s final BW and average BW gain were also increased with the NLP relative to the control. Further, adding NLP to the diet increased the digestibility of crude protein compared to the control diet. In conclusion, adding NLP to the diet with 40 g/kg DM could be used as a promising phytogenic supplement for growing lambs with no detrimental effects on the ruminal fermentation profile, nutrient intake, or digestibility. Full article

The false Rhodes grasses [Leptochloa crinita (Lag.) P.M. Peterson and N.W. Snow and Leptochloa pluriflora (E. Fourn.) P.M. Peterson and N.W. Snow] are considered valuable native forage resources for arid and semiarid rangelands in Argentina and the United States. Effectively using plant materials as forage under aridity conditions requires understanding their resource allocation under those conditions. In the present study, plant functional traits were evaluated in six populations of each false Rhodes grass species from different geographic origin in a humid and an arid region. The evaluation was focused on seed weight, due to the key role of this trait in plant survival. The implication of seed weight in germination under osmotic stress and trade-off relationships between functional traits were also analysed. A fixed ontogenetic variation was found in both species, since populations maintained a stable seed weight across environments. The tolerance to osmotic stress at germination stage was more related to seed weight than to population origin or maternal environment of seeds; heavier-seeded populations produced heavier seedlings instead of a higher number of germinated seeds or higher germination rates. Some traits varied between environments but other traits exhibited a fixed response. Variation patterns among populations were similar within environments and in some cases even for populations from the same geographic origin, revealing a fixed ontogenetic variation; this phenomenon was clearer in L. crinita than in L. pluriflora. Moreover, several different trade-off strategies were detected in both species. These results reinforce the knowledge about the key role of seed weight in survival and performance of seedlings at initial growth stages under arid conditions; however, at advanced stages, other traits would have an important function in growth and development of false Rhodes grasses. Full article

Climate models predict that plants will face extreme fluctuations in water availability in future global change scenarios. Then, forage production will be more frequently subjected to the destabilizing pressure of sequentially occurring waterlogging and drought events. While the isolated effects of drought (D) and waterlogging (WL) are well characterized, little is known about the consequences when both stresses occur sequentially. We hypothesized that plants sequentially subjected to opposite water scenarios (D followed by WL or vice versa) are less stress tolerant than plants experiencing repetitions of the same type of water stress (i.e., D + D or WL + WL) due to contrasting acclimation and allocation to either shoots (WL) or roots (D). Chloris gayana (a tropical forage grass capable of tolerating either D and WL) plants were randomly assigned to nine treatments (a sequence of two stress rounds—WL or D—each followed by a recovery phase at field capacity). Relative growth rates and allometric responses were measured after each stress round and recovery period. In the first round of stress, both WL and D reduced plant RGR similarly, despite their allocation being opposite—prioritizing shoots or roots under WL and D, respectively. The high recovery displayed after either WL or D overrode any possible acclimation of the plants facing a second round of water stress. We conclude that the tolerance of C. gayana to sequential water stress (either for WL or D) is likely to depend more heavily on its recovery ability than on its previous adjustment to any stress scenario that may evoke memory responses. Knowledge like this could help improve forage grass breeding and the selection of cultivars for poorly drained soils subject to sequential stress events. Full article