Oat Roots Research Articles

Response of oat morphologies, root exudates, and rhizosphere fungal communities to amendments in a saline-alkaline environment.

The application of organic amendments to saline-alkaline soil has been recommended as an agricultural strategy to improve crop productivity and soil health. However, there has been limited research on how organic soil amendment strategies affect the health of oats and their associated rhizosphere fungal communities in saline-alkaline conditions. Thus, the objectives of this study were to understand the effects of oat cultivars with contrasting saline-alkaline tolerances and different amendments on plant morphologies, root exudates (soluble sugars and organic acids), and rhizosphere fungal communities in a saline-alkaline environment. Experiments were conducted on a saline-alkaline tolerant cultivar, Baiyan2, and a saline-alkaline sensitive cultivar, Caoyou1, under four different organic amendment strategies: 1. control (no amendment application), 2. bio-fertilizer application, 3. rotten straw application, and 4. a co-application of bio-fertilizer and rotten straw. Results showed that plant morphological characters of Baiyan2 were better than Caoyou1, and that soluble sugar and organic acid levels in the rhizosphere of Baiyan2 were significantly lower than Caoyou1. Compared to the control, oat root and plant development was significantly improved by the combined bio-fertilizer and rotten straw amendment. Bio-fertilizer application promoted malic and citric acid levels, contributing to a higher total organic acid level, and significantly increased the abundance of Rhizopus arrhizus and decreased the abundance of the fungal pathogens Alternaria, Cladosporium, Sarocladium and Heydenia of Ascomycota in both oat cultivars. All amendment treatments containing rotten straw, except the combined amendment in Baiyan2, significantly increased the relative abundance of Ascomycota (specifically Gibberella, Talaromyces, Fusarium, and Bipolaris) and decreased the relative abundance of R. arrhizus by reducing soluble sugar and organic acid levels. For the combined amendment in Baiyan2, there were no significant changes in Gibberella and Rhizopus between the control and amendment treatment. Our results suggest that co-application of bio-fertilizer and rotten straw, combined with a tolerant oat cultivar, is an effective method to increase crop productivity and enhance soil health in a saline-alkaline environment.

Roots and aboveground carbon and nitrogen inputs by black oats (Avena strigosa Schreb.) as affected by grazing and nitrogen in integrated crop-livestock system in subtropical Brazil

Roots are important contributors to soil organic matter in pasturelands, yet in integrated crop-livestock systems (ICLs), the effects of grazing intensities are poorly understood. We investigated the effects of grazing intensities and nitrogen application to black oats pasture (Avena strigosa) on carbon and nitrogen additions, mainly by roots, into soil. The ICL experiment in southern Brazil comprised no, moderate and intensive grazing of black oats pasture receiving 0, 75 and 150 kg N ha−1. Root (0–30 cm) and aboveground biomass of black oats were assessed over two years, in a sequence of maize (Zea mays)–black oats–soybean (Glycine max)–black oats. Moderate grazing did not change the carbon and nitrogen additions by roots, but reduced the aboveground additions by 45–54%, compared to no grazing. Generally, the intensive grazing did not affect root or aboveground additions relative to moderate grazing, but in year of normal precipitation and supplied with 150 kg N ha−1, it reduced root carbon and nitrogen addition by 11–22%. Nitrogen application had no clear effect on root additions, but increased the aboveground additions. In ICL system, moderate grazing maintained carbon and nitrogen additions by roots of black oats, compared to no grazing, while nitrogen fertilization can be used to increase carbon and nitrogen aboveground additions.

Soil Fertility, Root and Aboveground Growth of Black Oat Under Gypsum and Urea Rates in No Till

The residual effects of gypsum rates and the interaction with N -fertilization on soil fertility, black oat root growth and aboveground biomass yield under no till lacks information. This study evaluated soil chemical attributes up to 0.8 m depth and aboveground biomass of black oat in a continuous no-till area as affected by gypsum rates (0, 3, 6, 9 and 12 Mg ha−1) and topdressing N -fertilization (0, 50 and 100 kg ha−1) to a Typic Hapludox in Southern Brazil. Black oat root growth was also evaluated for two gypsum rates (0 and 6 Mg ha−1) and all N treatments. Gypsum application increased Ca2+ and SO42−-S fraction and reduced Mg2+ levels in all soil layers, and N -fertilization increased NO3− and NH4+ levels in the soil. Gypsum increased root length, superficial area and volume up to 0.8 m depth, while N-fertilization reduced root growth attributes in soil layers between 0.4 and 0.8 m depth. Gypsum increased (quadratically) the aboveground biomass yield of black oats in the two growing seasons, as did N-fertilization, but no interaction between gypsum and N -fertilization was observed. Gypsum can be used to improve soil fertility attributes, black oat biomass and root growth under no till. The higher N -fertilization (100 kg ha−1) increased black oat yield and reduced root growth in depth. In the average of the growing seasons, the gypsum rate of 7.36 Mg ha−1 applied 54 months earlier, associated with a rate of at least 50 kg ha−1 of N (urea) applied at the beginning of black oat tillering achieved the higher aboveground biomass yield.

Allelopathic effect of buckwheat extract for seedlings of selected weed species

The influence of 1% aqueous extract obtained from a 14-day plants of common buckwheat (Fagopyrum esculentum Moench) on weed species was evaluated. Seedling roots of wild oat (Avena fatua L.), yellow foxtail (Setaria glauca L.), barnyardgrass (Echinochloa crus galli (L.) P. Beauv.), common windgrass (Apera spica-venti (L.) P. Beauv.), catchweed bedstraw (Galium aparine L.), scentless mayweed (Matricaria inodora L), gallant soldier (Galinsoga parviflora Cav.) and tiny vetch (Vicia hirsuta L.) were exposed to buckwheat extract and compared with control plants grown in water. The obtained results show that the buckwheat extract had lower influence on the growth of shoot than on roots of the evaluated weed species. The use of buckwheat extract in the medium caused the inhibition of root growth in all species except from tiny vetch. In the case of shoot of weeds, inhibition of growth by buckwheat extract occurred only in wild oat. Whereas in yellow foxtail, scentless mayweed and tiny vetch, the stimulation of shoot growth was demonstrated. These results may indicate that the buckwheat extracts act on directly exposed tissues. A different metabolic reaction of wild oat to buckwheat extract after 5 days of exposure than after 2 days may indicate a quick adaptation of wild oat seedlings to stressful conditions.

Performance of soybean grown in succession to black oat and wheat

Abstract: The objective of this work was to evaluate the influence of isolated or combined roots and straw of black oat and wheat, as previous crops in autumn/winter, on the performance of soybean in succession. The experiment was carried out in the 2017/2018 and 2018/2019 crop seasons in a randomized complete block design, with four replicates. The following seven treatments were applied in the autumn/winter of 2017 and 2018, before soybean planting: fallow; straw of black oat or wheat, distributed on plots kept under fallow during autumn/winter, without roots; plots only with roots of black oat or wheat, without straw; and plots with straw and roots of black oat or wheat. Soybean crop performance was estimated using the following variables: plant density, leaf area index, soil plant analysis development (SPAD) index, shoot dry matter, grain yield, and yield components. In comparison with fallow, the cultivation of black oat or wheat, as previous crops during the autumn/winter, increases soybean grain yield. The impact of the roots of black oat or wheat on soybean yield is similar to that of straw. Soybean agronomic performance is improved in the combined presence of roots and straw of black oat or wheat.

Lime soil conditioner based on soda production sludge for reclamation of industry-disturbed soils in the impact zone of an oil refinery

The paper presents the results of a study on the use of soda production sludge (SPS) as a lime soil conditioner. SPS with a less than 0.1 mm fraction is the most suitable in terms of physical, chemical, and toxicological properties and meets the requirements of GOST-14050-93 «Limestone (dolomite) dust. Specifications» on the content of the active substance, the mass fraction of calcium and magnesium carbonates. Reclamative properties of SPS were studied on soil samples taken in the territory removed from the sanitary protection zone of the oil refinery. It was found that all soil samples have a phytotoxic effect on pea seedlings. The introduction of SPS in amount of 1-3 g per kg of soil stimulates the development of the ground part and roots of oats and peas, and also increases the germination energy of oat and pea seeds in the initial soil samples by 2÷10 times. The introduction of SPS into the samples of the studied soils at a dose of 1-3 g/kg stimulates the development of colonies of Azotobacter bacteria and leads to an increase in the total number of soil microorganisms. The introduction of SPS in an amount of 3 g per kilo of soil leads to a slight increase in the environment reaction and an increase in the content of water-soluble salts in the soil up to 2 times. In view of this, it is necessary to control that the content of water-soluble salts does not exceed the established standards. Based on the results obtained, we consider it expedient to use soda production sludge as a lime soil conditioner and for the reclamation of industry-disturbed soils.

Oat rhizogenesis due to the effects of phytohormones

Purpose. Select the optimum concentration of phytohormones and investigate their effect on oat rooting and develop a nutrient medium for induction of rhizogenesis in vitro.Methods. For rooting, cloned material of different breeding samples of oats No. 493-27 was used; No. 477-5; No. 399-38; No. 425-19 and the varieties of Decameron and Gift. Clone rooting was performed on nutrient media according to Murasige and Skug and Hamburg and Eveleg with reduced macrosolids, which served as control variants, and for experimental variants used auxins (IOC, NOC, IMC) and cytokinins (6-BAP, zept, and gibberellins (HA) in concentrations of 0.1 to 1.5 mg/l. During the growth and development of oat plants recorded the beginning of root formation, the presence of callus formation, the percentage of rooted plants (%), the number of roots (pieces), the length of the root system (see), plant growth (see) and their overall condition.Results. In breeding variants, on average, at a concentration of IBC of 1.0 mg/l, the percentage of rooted oats was 72.9 %, and in the varieties of this indicator was slightly higher – 81.6 %. With the use of NOC in the specified concentration in the breeding samples, the rooting index was 88.6 % and in the varieties – 89.5 %. The highest percentage of rooting was established with the addition of IOC in varietal samples – 89.7 % and 92.3 % in varieties. In the varieties Decameron and Gift, the length of the oat root system was longer compared to the linear material compared to the linear material. КаDecameron for use of all auxins and the gift from IOC and IMC had a root system length – 7.0 cm and NOC – 5.0 cm. Linear materials had a root system length using NOC – 4.5 cm, and in IOC – 5.7 cm, IMC – 5,2 cm. The number of roots in oat plants with auxin addition varied from 2,0 pc. up to 3,8 pcs. At concentrations of gibberellic acid – 1.0 mg/l oat plants had a height of 18 to 26 cm, and the length of the root system ranged from 12 to 25 cm.Conclusions. A nutrient medium has been developed that allows to obtain 91.0 % of rooted oats for 14 days. Rhizogenesis is advisable to carry out on the environment of Hamburg and Eweleg with the addition of auxins. The addition of gibberellic acid to the nutrient medium, regardless of concentration, provided a significant lengthening of the oat root system and the extraction of leaves and internodes. The highest percentage of rooted plants was observed in the combination of IOC and NOC, and the lowest in the use of IBS in all variants. The use of auxin concentrations greater than 1.0 mg/l was inappropriate, since the inhibition of the external state of the plants and the increase in the percentage of rooted plants did not occur.

First Report of Oat (Avena sativa) Root Rot Caused by Fusarium proliferatum in China

HomePlant DiseaseVol. 104, No. 3First Report of Oat (Avena sativa) Root Rot Caused by Fusarium proliferatum in China PreviousNext DISEASE NOTES OPENOpen Access licenseFirst Report of Oat (Avena sativa) Root Rot Caused by Fusarium proliferatum in ChinaH. Chen, L. H. Xue, and C. J. LiH. ChenState Key Laboratory of Grassland Agro-Ecosystems; Key Laboratory of Grassland Livestock Industry Innovation, Ministry of Agriculture and Rural Affairs; Engineering Research Center of Grassland Industry, Ministry of Education; Gansu Tech Innovation Center of Western China Grassland Industry; College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou 730020, ChinaSearch for more papers by this author, L. H. Xuehttp://orcid.org/0000-0002-1158-2152State Key Laboratory of Grassland Agro-Ecosystems; Key Laboratory of Grassland Livestock Industry Innovation, Ministry of Agriculture and Rural Affairs; Engineering Research Center of Grassland Industry, Ministry of Education; Gansu Tech Innovation Center of Western China Grassland Industry; College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou 730020, ChinaSearch for more papers by this author, and C. J. Li†Corresponding author: C. J. Li; E-mail Address: chunjie@lzu.edu.cnhttp://orcid.org/0000-0002-3287-2140State Key Laboratory of Grassland Agro-Ecosystems; Key Laboratory of Grassland Livestock Industry Innovation, Ministry of Agriculture and Rural Affairs; Engineering Research Center of Grassland Industry, Ministry of Education; Gansu Tech Innovation Center of Western China Grassland Industry; College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou 730020, ChinaSearch for more papers by this author AffiliationsAuthors and Affiliations H. Chen L. H. Xue C. J. Li † State Key Laboratory of Grassland Agro-Ecosystems; Key Laboratory of Grassland Livestock Industry Innovation, Ministry of Agriculture and Rural Affairs; Engineering Research Center of Grassland Industry, Ministry of Education; Gansu Tech Innovation Center of Western China Grassland Industry; College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou 730020, China Published Online:30 Dec 2019https://doi.org/10.1094/PDIS-09-19-2000-PDNAboutSectionsSupplemental ToolsAdd to favoritesDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InRedditEmailWechat In north and northeast China, oat (Avena sativa L.) is an important crop for local farmers, accounting for over 80% of the country’s total planting area of oat (Wang et al. 2019). During July and August 2018, severe outbreaks of seedling wilt were observed on oat with an incidence of approximately 5% in the farmland of Shandan County (38.22° N, 101.22° E), Zhangye City, Gansu Province. Symptoms included leaf yellowing, plant stunting, rotting of roots, and vascular discoloration in roots. The symptomatic plants were uprooted and collected from several incidence areas in the field. Discolored root tissues were disinfested by immersion in 75% ethanol for 30 s and 1% NaClO for 90 s, rinsed three times in sterilized water, plated on potato dextrose agar (PDA) medium, incubated at 22°C in the dark, and isolates purified by single-spore cultures (Leslie and Summerell 2006). Four single-spore cultures were consistently isolated with similar phenotypes. The colonies grew regularly in shape; the colonies were white, with older colonies becoming violet to dark. On carnation leaf agar, the microconidia were abundant, oval shaped with a flat base, single celled, and measured 5.9 to 12.5 × 2.6 to 3.8 μm (7.4 × 3.1 μm on average) (n = 50), and macroconidia were sparse, slender, two to three septate, and measured 19.7 to 36.8 × 1.9 to 2.5 μm (25.2 × 2.2 μm on average) (n = 50). No chlamydospores were observed. These phenotypical characteristics were consistent with previous descriptions of Fusarium species in general (Mun et al. 2012). Total DNA was extracted from 7-day-old aerial mycelium grown on PDA. Species identity was confirmed by sequencing partial sequences of EF1-α gene (EF1 and EF2 primers) (O’Donnell et al. 1998) and RPB2 regions (RPB2-5f2 and RPB2-7cr) (O’Donnell et al. 2010). Sequences for one isolate were deposited in GenBank under accessions MN245721 (RPB2) and MN245720 (EF1-α). A nucleotide BLAST search revealed EF1-α and RPB2 sequences to be 99% similar to the corresponding sequences of Fusarium proliferatum accession numbers MH582345.1 and MH582193.1, respectively. For pathogenicity tests, millet-seed-based inoculum of F. proliferatum was prepared using a modified procedure (Fang et al. 2011). Healthy oat seedlings were transplanted into plastic pots containing pasteurized potting mix infested with millet-seed-based inoculum of F. proliferatum at a rate of 0.5%. Control seedlings for comparison were transplanted into pots containing potting mix without inoculum. Plants were maintained for 22 days under greenhouse conditions at 18 to 25°C with all the inoculated plants developing symptoms similar to those observed in the field, whereas control plants remained healthy. The fungus was reisolated from the roots of inoculated plants and confirmed phenotypically and molecularly as F. proliferatum. F. proliferatum has been reported associated with root rot in soybean in Canada (Chang et al. 2015) and in alfalfa in China (Cong et al. 2016). To our knowledge, this is the first report of F. proliferatum causing root rot in oat in China. This study provides a basis for identifying pathogens causing oat root rot and managing the disease.The author(s) declare no conflict of interest.

Content of macronutrients in oat (Avena sativa L.) after remediation of soil polluted with cobalt

The purpose of this study was to determine the remediation effect of various substances (manure, clay, charcoal, zeolite and calcium oxide) on limiting the influence of high cobalt doses (0, 20, 40, 80, 160 and 320 mg/kg of soil) on the content of macroelements in grain, straw and roots of oat. The doses of cobalt applied in this experiment as well as soil amendments such as manure, clay, charcoal, zeolite and calcium oxide had a significant effect on the content of the analysed macronutrients in grain, straw and roots of oat. In the series without any neutralising substances, the soil contamination with cobalt caused an increase in the content of nitrogen, phosphorus, sodium, calcium and, partly, potassium, in grain, straw and roots of oat. Among the neutralising substances tested, the most unambiguous effect was produced by manure, which raised the content of all macronutrients (except calcium and magnesium) in oat grain, straw and roots. The influence of the other substances on the content of macronutrients in oat plants was less equivocal. However, all of them, especially calcium oxide, tended to induce a decrease in the content of most macronutrients in grain, straw and roots of oat.

Remediation of cobalt-polluted soil after application of selected substances and using oat (Avena sativa L.)

The aim of the study was to determine the effectiveness of soil application of manure, clay, charcoal, zeolite, and calcium oxide in remediation of soil polluted with cobalt (0, 20, 40, 80, 160, 320 mg Co kg−1 of soil). The following were determined: weight of harvested plants as well as the content of cobalt in grain, straw, and roots of oat. In addition, tolerance index (Ti), cobalt bioconcentration (BCF), translocation (TF), and transfer (TFr) coefficients were derived. In the series without amendments, the increasing doses of cobalt had a significant effect by decreasing the yields of oat grain and straw and the mass of its roots. Also, lower tolerance index values were noted in the objects polluted with cobalt, especially with its highest dose. The application of manure had the strongest effect on increasing the mass of particular organs of the test plant, while the application of charcoal led to a significant decrease in this respect. The application of all substances to the soil, and especially manure and calcium oxide, resulted in higher tolerance index Ti values. The growing contamination of soil with cobalt caused a significant increase in the content of this element in oat and in the values of the translocation coefficient, in contrast to the effects noted with respect to the bioconcentration and transfer coefficients. All the substances applied to soil reduced the content of cobalt and its bioconcentration in oat straw, in opposition to grain and roots, limited its translocation, but elevated the transfer of this element from soil to plants. Soil contamination with cobalt promoted the accumulation of lead and copper in grain, cadmium, lead, nickel, zinc, manganese, and iron in straw, as well as cadmium, nickel, zinc, and manganese in oat roots. As the cobalt dose increased, the content of other trace elements in oat organs either decreased or did not show any unambiguous changes. Of all the tested substances, the strongest influence on the content of trace elements was produced by calcium oxide in straw and roots and by zeolite in roots, whereas the weakest effect was generated by manure in oat grain. Oat is not the best plant for phytoremediation of soils contaminated with cobalt.

Physiological and TMT-based proteomic analysis of oat early seedlings in response to alkali stress

Oats are an important cereal crop worldwide, and they also serve as a phytoremediation crop to ameliorate salinized and alkalized soils. However, the mechanism of the oat response to alkali remains unclear. Physiological and tandem mass tag (TMT)-based proteomic analyses were employed to elucidate the mechanism of the oat response to alkali stress. Physiological and phenotypic data showed that oat root growth was inhibited more severely than shoot growth after alkali stress. In total, 164 proteins were up-regulated and 241 proteins were down-regulated in roots, and 93 proteins were up-regulated and 139 proteins were down-regulated in shoots. Under high pH stress, transmembrane proton transporters were down-regulated; conversely, organic acid synthesis related enzymes were increased. Transporters of N, P, Fe, Cu and Ca in addition to N assimilation enzymes in the root were highly increased. This result revealed that higher efficiency of P, Fe, Cu and Ca transport, especially higher efficiency of N intake and assimilation, greatly promoted oat root resistance to alkali stress. Furthermore, many resistance proteins, such as late embryogenesis abundant (LEA) mainly in shoots, GDSL esterase lipase mainly in roots, and WD40-like beta propeller repeat families, greatly accumulated to contribute to oat resistance to alkali stress. SignificanceIn this study, physiological and tandem mass tag (TMT)-based proteomic analyses were employed to elucidate oats early seedlings in response to alkali stress. Many difference expression proteins were found involving in oats response to alkali stress. Also, higher efficiency transport of P, Fe, Cu, Ca and N greatly promoted oat resistance to alkali stress.

Rusle parameters for modeling the loss of a soil subjected to pig slurry application

Abstract: The objective of this work was to determine adjustment parameters for the revised universal soil loss equation (Rusle) of a soil subjected to pig slurry application. Treatments consisted of 0, 50, 100, and 200 m3 ha-1 pig slurry (PS), after the cultivation of black oat (Avena strigosa), besides the application of 50 m3 ha-1 PS for six times onto the soil surface in a temporal sequence, and a control treatment of soil without cultivation and without pig slurry application. The evaluations were performed for black oat shoot dry mass, root mass and crop residues semi-incorporated into the soil (RMR), soil losses by means of simulated rain, and the parameters for water erosion modeling. The pig slurry application onto soil surface caused a reduction in the values of the soil consolidation parameter (Cf), an increase in the mass of living and dead roots and cultural residues incorporated in the upper layer (0.0-0.1 m) of the soil (Bu), and a reduction in the subfactor prior land use (PLU) of the Rusle.

Improvement of petroleum hydrocarbon remediation using the oat plant in the soil treated by poultry manure

This greenhouse experiment aimed to investigate the effects of poultry manure (PM) on the growth of oat plant (Avena sativa) and removal of total petroleum hydrocarbons (TPHs) from soil. The treatments consisted of three TPH levels (4%, 6%, and 8% w/w) and two PM levels (zero and 1%) at three replications. According to the findings, shoot height, number of leaves, and the fresh and dry weight of the shoots and roots of oat decreased significantly with 6% and 8% TPHs compared to 4% contamination level. On the other hand, the removal of TPHs and microbial respiration rate significantly increased by 16.8% and 78.18%, respectively in the PM treatment compared to the non-PM treatment. The rate was estimated at 28.85% and 27.03% in the soil cultivated by oat compared to the unplanted soil, respectively. The highest and lowest removal rate of TPHs was observed in the soil cultivated with oats in the PM treatments containing 4% of the TPHs (45.25%) and unplanted treatments without manure containing 8% of TPHs (11.38%). Therefore, it could be concluded that the addition of PM to the soil cultivated with oat in the soils with TPH contamination could increase the microbial respiration rate of the soil, as well as the removal of TPHs.

Long-term effects of three different silver sulfide nanomaterials, silver nitrate and bulk silver sulfide on soil microorganisms and plants

Silver nanomaterials (AgNMs) are released into sewers and consequently find their way to sewage treatment plants (STPs). The AgNMs are transformed en route, mainly into silver sulfide (Ag2S), which is only sparingly soluble in water and therefore potentially less harmful than the original AgNMs. Here we investigated the toxicity and fate of different sulfidized AgNMs using an exposure scenario involving the application of five different test materials (NM-300K, AgNO3, Ag2S NM-300K, Ag2S NM and bulk Ag2S) into a simulated STP for 10 days. The sewage sludge from each treatment was either dewatered or anaerobically digested for 35 days and then mixed into soil. We then assessed the effect on soil microorganisms over the next 180 days. After 60 days, a subsample of each test soil was used to assess chronic toxicity in oat plants (Avena sativa L) and a potential uptake into the plants. The effect of each AgNM on the most sensitive test organism was also tested without the application of sewage sludge. Although Ag sulfidized species are considered poorly soluble and barely bioavailable, we observed toxic effects on soil microorganisms. Furthermore, whether or not the AgNM was sulfidized before or during the passage through the STP, comparable effects were observed on ammonium oxidizing bacteria after sewage sludge application and incubation for 180 days. We observed the uptake of Ag into oat roots following the application of all test substances, confirming their bioavailability. The oat shoots generally containing less Ag than the roots.

Plant-mycorrhizal fungi feedbacks: potential accomplices of Avena barbata’s high invasiveness

Alteration of the soil microbial communities can have important effects on plant invasion. The interdependence between plants and soil microbes could generate complex dynamics in which the composition of plant communities is regulated by the feedbacks of microbial communities on plant growth. In a greenhouse experiment we tested whether the soil microbes in roots of an invasive annual (Avena barbata, wild oat) and a native grass (Rytidosperma caespitosum, wallaby grass) can affect invasive and/or native plant performance. Individuals of each plant species were planted in sterilized soil to which pieces of roots of the same or the other species were added as a layer below the top soil. When plants were harvested after 10 weeks, the addition of roots of any species reduced the total biomass of wild oat. On the other hand, addition of roots of wild oat caused a much stronger reduction of the growth of wallaby grass, while roots of wallaby grass tended to increase its plant growth and shifted biomass allocation patterns. On balance, given the strength of the negative effects, our results indicated that invasion-induced changes in the soil microbial community could contribute to a displacement of the native grass. Thus, these changes might induce a positive feedback mechanism, contributing to the increased dominance of wild oat over wallaby grass in South Australian grasslands.

Transcriptome and metabolome analyses provide insights into root and root-released organic anion responses to phosphorus deficiency in oat.

Roots and root-released organic anions play important roles in uptake of phosphorus (P), an essential macronutrient for food production. Oat, ranking sixth in the world's cereal production, contains valuable nutritional compounds and can withstand poor soil conditions. Our aim was to investigate root transcriptional and metabolic responses of oat grown under P-deficient and P-sufficient conditions. We conducted a hydroponic experiment and measured root morphology and organic anion exudation, and analysed changes in the transcriptome and metabolome. Oat roots showed enhanced citrate and malate exudation after 4 weeks of P deficiency. After 10 d of P deficiency, we identified 9371 differentially expressed transcripts with a 2-fold or greater change (P<0.05): 48 sequences predicted to be involved in organic anion biosynthesis and efflux were consistently up-regulated; 24 up-regulated transcripts in oat were also found to be up-regulated upon P starvation in rice and wheat under similar conditions. Phosphorylated metabolites (i.e. glucose-6-phosphate, myo-inositol phosphate) were reduced dramatically, while citrate and malate, some sugars and amino acids increased slightly in P-deficient oat roots. Our data are consistent with a strategy of increased organic anion efflux and a shift in primary metabolism in response to P deficiency in oat.

Suppressive effect of black oat, Avena strigosa, KH1a on Meloidogyne spp.

Summary The suppressive effect of a black oat, Avena strigosa, breeding line KH1a on Meloidogyne spp. was examined in pot tests and on Meloidogyne incognita in pot and field tests. In pot tests, roots of black oats were examined 42-46 days after inoculation of 500 second-stage juveniles. There were significantly fewer egg masses on the roots of KH1a than on 12 black oat cultivars examined. KH1a was a poor host for four isolates of M. incognita, two isolates of M. arenaria and one isolate of M. javanica, and a non-host for one isolate of M. hapla. The effect of autumn and spring cropping of KH1a on soil nematode density was examined in M. incognita-infested fields. Nematode density after autumn cropping of KH1a was significantly lower than that after susceptible black oat, resulting in significantly lower Pf/Pi in KH1a (0.10 and 0.13) than in susceptible black oat (0.42 and 0.74). Damage indices of the succeeding crop, sweet potato, were significantly lower in KH1a plots than in susceptible black oat plots. In spring cropping, there were significantly fewer soil nematodes in KH1a plots than in susceptible black oat plots 3 weeks after cultivation. In both autumn and spring cropping, there was no significant difference in soil nematode density between KH1a and bare fallow. These results suggested that KH1a is a good alternative to current susceptible cultivars for the management of M. incognita.

Use of zeolite to neutralise nickel in a soil environment

Nickel is a heavy metal which is a stable soil pollutant which is difficult to remediate. An attempt to reduce its impact on the environment can be made by changing its solubility. The right level of hydrogen ions and the content of mineral and organic colloids are crucial in this regard. Therefore, methods to neutralise heavy metals in soil are sought. There are no reports in the literature on the possibility of using minerals in the detoxication of a soil environment contaminated with metals. It is important to fill the gap in research on the effect of zeolites on the microbiological, biochemical and physicochemical properties of soils under pressure from heavy metals. Therefore, a pot experiment was conducted on two soils which examined the effect of various levels of contamination of soil with nickel on the activity of soil enzymes, physical and chemical properties and growth and development of plants. An alleviating effect of zeolite Bio.Zeo.S.01 on the negative impact of nickel on the soil and a plant (oats) was examined. The enzyme activity and the oat yield were found to be significantly and negatively affected by an excess of nickel in the soil, regardless of the soil type. The metal was accumulated more in the oat roots than in the above-ground parts. An addition of zeolite decreased the level of accumulation of nickel in oats grown only on sandy-silty loam. Zeolite Bio.Zeo.S.01 used in the study only slightly alleviated the negative effect of nickel on the biochemical properties of soil. Therefore, its usability in the remediation of soil contaminated with nickel is small.

Developmental morphology of cover crop species exhibit contrasting behaviour to changes in soil bulk density, revealed by X-ray computed tomography.

Plant roots growing through soil typically encounter considerable structural heterogeneity, and local variations in soil dry bulk density. The way the in situ architecture of root systems of different species respond to such heterogeneity is poorly understood due to challenges in visualising roots growing in soil. The objective of this study was to visualise and quantify the impact of abrupt changes in soil bulk density on the roots of three cover crop species with contrasting inherent root morphologies, viz. tillage radish (Raphanus sativus), vetch (Vicia sativa) and black oat (Avena strigosa). The species were grown in soil columns containing a two-layer compaction treatment featuring a 1.2 g cm-3 (uncompacted) zone overlaying a 1.4 g cm-3 (compacted) zone. Three-dimensional visualisations of the root architecture were generated via X-ray computed tomography, and an automated root-segmentation imaging algorithm. Three classes of behaviour were manifest as a result of roots encountering the compacted interface, directly related to the species. For radish, there was switch from a single tap-root to multiple perpendicular roots which penetrated the compacted zone, whilst for vetch primary roots were diverted more horizontally with limited lateral growth at less acute angles. Black oat roots penetrated the compacted zone with no apparent deviation. Smaller root volume, surface area and lateral growth were consistently observed in the compacted zone in comparison to the uncompacted zone across all species. The rapid transition in soil bulk density had a large effect on root morphology that differed greatly between species, with major implications for how these cover crops will modify and interact with soil structure.

Host Recognition Responses of Western (Family: Chrysomelidae) Corn Rootworm Larvae to RNA Interference and Bt Corn.

Western corn rootworm Diabrotica virgifera virgifera LeConte is an important pest of corn whose larvae exhibit particular quantifiable patterns of locomotion after exposure to, and removal from, host roots and nonhost roots. Using EthoVision software, the behavior and locomotion of the western corn rootworm larvae was analyzed to determine the level of host recognition to germinated roots of differing corn hybrids containing either rootworm targeted Bt genes, RNA interference (RNAi) technology, the stack of both Bt and RNAi, or the isoline of these. The behavior of the rootworm larvae indicated a significant host preference response to all corn hybrids (with or without insecticidal traits) compared to the filter paper and oat roots. A weaker host response to the RNAi corn roots was observed in the susceptible larvae when compared to the resistant larvae, but not for the Bt + RNAi vector stack. Additionally, the resistant larvae demonstrated a weaker host response to the isoline corn roots when compared to the susceptible larvae. Although weaker, these host responses were significantly different from those observed in the negative controls, indicating that all hybrids tested do contain the contact cues necessary to elicit a host preference response by both Cry3Bb1-resistant and Cry3Bb1-susceptible larvae that would work to hinder resistance development in refuge in a bag fields.