Composition ofAzospirillum species associated with wetland rice plant grown in different soils

Total aerobic heterotrophs and N₂-fixing putative azospirilla associated with rice plant grown in long-term unfertilized wetland rice field at 5 sites in the Philippines were enumerated. Several azospirilla isolates were identified based on cellular morphology, biochemical tests and reaction to immunodiffusion. Azospirilla constitute about one percent of the total aerobic heterotrophs. Most (85%) of the Azospirillum isolates belong toA. lipoferum indicating its preferential colonization to the rice plant.     

Aerobic methylotroph bacteria as phytosymbionts]

This paper deals with the physiological, biochemical, and molecular genetic aspects of the interaction of aerobic methylotrophic bacteria with plants by means of phytohormones (such as cytokinins and auxins) and other physiologically active substances (vitamins, exopolysaccharides, bioprotectants). The state of the art and the prospects of research in the field of bacteria-plant interactions and the application of aerobic methylotrophs in plant biotechnology is discussed.     

中国陆地自然植物有氧甲烷排放空间分布模拟及其气候效应

区域尺度陆地植物有氧条件下排放甲烷及其气候效应研究不仅对甲烷收支平衡研究具有重要意义,对于全球变化研究也具有重要推动作用。通过改进Keppler提出的公式,模拟了中国区域植物有氧甲烷排放的时空分布。利用IBIS模拟的NPP数据结合相关文献统计生物量与NPP的比值,计算得到中国区域自然植物叶片生物量,以及叶片甲烷排放。结果显示,2001年至2012年中国植物生物量与植物叶片甲烷排放量在Sres A2和Sres B1两种情景下差异不明显;但是气候变化模式差异的影响会随着时间的推移而扩大。在Sres A2情景下,中国地区年均植物生物量为10803.22Tg C,叶片生物量为1156.15Tg C。如果不考虑天气对光照的影响,植物叶片甲烷排放年均2.69Tg,约是全国年甲烷排放总量7.01%,是中国稻田甲烷排放总量的29.05%。在各植被类型中,草地叶片甲烷排放量最高,达到47.53%,其次是混交林。森林(针叶林、阔叶林、混交林)是主要的植物甲烷排放源,占中国区域植物甲烷排放总量的51.28%,其次是草地,占47.47%。中国区域植物叶片甲烷排放南高北低,东高西低的分布状态主要由地表植被覆盖类型决定,光照和温度也是重要影响因素。对Sres A2和Sres B1两种气候情景下中国植物甲烷排放预测分析,中国区域植物甲烷排放不断增加,在Sres A2情景下不同时期的平均增长率为9.73%,高于Sres B1情景的5.17%,且两种情景下的增长率都在降低。21世纪Sres A2和Sres B1变化情景下,年均植物排放的甲烷CO_2当量分别为83.18Tg和77.34Tg,约占中国年均CO_2排放总量的1.39%和1.29%。     

Alleviating soil sickness caused by aerobic monocropping: responses of aerobic rice to soil oven-heating

“Aerobic rice” system is the cultivation of nutrient-responsive cultivars in nonflooded and nonsaturated soil under supplemental irrigation. It is intended for lowland areas with water shortage and for favorable upland areas with access to supplementary irrigation. Yield decline caused by soil sickness has been reported with continuous monocropping of aerobic rice grown under nonflooded conditions. The objective of this study was to determine the growth response of rice plant to oven heating of soil with a monocropping history of aerobic rice. A series of pot experiments was conducted with soils from fields where rice has been grown continuously under aerobic or anaerobic (flooded) conditions. Soil was oven heated at different temperatures and for various durations. Plants of Apo, an upland variety that does relatively well under the aerobic conditions of lowland, were grown aerobically without fertilizer inputs in all six experiments. Plants were sampled during vegetative stage to determine stem number, plant height, leaf area, and total biomass. Heating of soil increased plant growth greatly in soils with an aerobic history but a relatively small increase was observed in soils with a flooded history as these plants nearly reached optimum growth. A growth increase with continuous aerobic soil was already observed with heating at 90°C for 12 h and at 120°C for as short as 3 h. Maximum plant growth response was observed with heating at 120°C for 12 h. Leaf area was most sensitive to soil heating, followed by total biomass and stem number. We conclude that soil heating provides a simple and quick test to determine whether a soil has any sign of sickness that is caused by continuous cropping of aerobic rice.     

Crop performance, nitrogen and water use in flooded and aerobic rice

Irrigated aerobic rice is a new system being developed for lowland areas with water shortage and for favorable upland areas with access to supplementary irrigation. It entails the cultivation of nutrient-responsive cultivars in nonsaturated soil with sufficient external inputs to reach yields of 70–80% of high-input flooded rice. To obtain insights into crop performance, water use, and N use of aerobic rice, a field experiment was conducted in the dry seasons of 2002 and 2003 in the Philippines. Cultivar Apo was grown under flooded and aerobic conditions at 0 and at 150 kg fertilizer N ha^–1. The aerobic fields were flush irrigated when the soil water potential at 15-cm depth reached –30 kPa. A ¹⁵N isotope study was carried out in microplots within the 150-N plots to determine the fate of applied N. The yield under aerobic conditions with 150 kg N ha^–1 was 6.3 t ha^–1 in 2002 and 4.2 t ha^–1 in 2003, and the irrigation water input was 778 mm in 2002 and 826 mm in 2003. Compared with flooded conditions, the yield was 15 and 39% lower, and the irrigation water use 36 and 41% lower in aerobic plots in 2002 and 2003, respectively. N content at 150 kg N ha^–1 in leaves and total plant was nearly the same for aerobic and flooded conditions, indicating that crop growth under aerobic conditions was limited by water deficit and not by N deficit. Under aerobic conditions, average fertilizer N recovery was 22% in both the main field and the microplot, whereas under flooded conditions, it was 49% in the main field and 36% in the microplot. Under both flooded and aerobic conditions, the fraction of ¹⁵N that was determined in the soil after the growing season was 23%. Since nitrate contents in leachate water were negligible, we hypothesized that the N unaccounted for were gaseous losses. The N unaccounted for was higher under aerobic conditions than under flooded conditions. For aerobic rice, trials are suggested for optimizing dose and timing of N fertilizer. Also further improvements in water regime should be made to reduce crop water stress.     

The ability of aquatic macrophytes to increase root porosity and radial oxygen loss determines their resistance to sediment anoxia

Radial oxygen loss (ROL) has been suggested to be a major process to protect plants exposed to root anaerobic stress. In the present study, we aimed to test the importance of root porosity and radial oxygen loss on the aquatic macrophyte resistance to sediment anoxia. We expected that species living in eutrophic environments characterized by anaerobic conditions in sediments exhibited higher root porosity and radial oxygen loss than species restrained to oligotrophic environments. In this way, we compared the responses to sediment anoxia of two hydrophyte species growing under meso-eutrophic conditions in the field (Myriophyllum spicatum L. and Vallisneria spiralis L.) and three species growing under oligotrophic conditions (Potamogeton coloratus Horne, Elodea canadensis Michx and Sparganium emersum Michx.). Under laboratory conditions, ROL, root porosity, plant metabolism (aerobic respiration, photosynthesis, root fermentative activity) and plant growth were analysed after 3?months of acclimation in anaerobic sediments and compared with control values obtained from aerobic sediments. The results showed that two meso-eutrophic species (M. spicatum and V. spiralis) survived in anaerobic sediments and maintained similar photosynthesis rates than those measured under aerobic conditions. In contrast, the three oligotrophic species (P. coloratus, E. canadensis and S. emersum) suffered net biomass loss and depressed their photosynthesis rates under anaerobic conditions. All variables associated with plant tolerance to anaerobic conditions (maintenance of photosynthesis, aerobic respiration and growth rate, and limitation of root fermentative activity) were positively linked to root porosity and ROL. According to our hypothesis, species that could survive to anaerobic conditions were the species able to increase their root porosity and ROL under these conditions. Thus, in ecological studies, it would be useful to use the root porosity and ROL plasticity as biological traits in order to model the distribution of macrophytes in river floodplains.     

Net P-removal deterioration in enriched PAO sludge subjected to permanent aerobic conditions

Recently, some research in the field of enhanced biological phosphorus removal (EBPR) has been focused on studying systems where the electron donor (substrate) and the electron acceptor (nitrate or oxygen) are present simultaneously. This can occur, for example, in a full scale wastewater treatment plant during heavy rainfall periods when the anaerobic hydraulic retention time is temporarily shortened. To study this situation that could induce EBPR failure, the operation of a sequencing batch reactor (SBR) working under alternating anaerobic-aerobic conditions with an enriched EBPR population (50% Candidatus Accumulibacter phosphatis and less than 1% Candidatus Competibacter phosphatis) was shifted to strict aerobic operation. Seven cycle studies were performed during the 11 days of aerobic operation. Net P-removal was observed in this aerobic SBR during the first 4 days of operation but the system could not achieve net-P removal after this period, although the microbial composition, in terms of percentage of Accumulibacter and Competibacter, did not change significantly. The observed changes in the different compounds analysed (phosphorus, acetate, glycogen and PHB) as well as in the OUR profile indicate that metabolic changes are produced for the adaptation of PAO to aerobic conditions.     

From Flooded to Aerobic Conditions in Rice Cultivation: Consequences for Zinc Uptake

Scarcity of water causes a shift from flooded to aerobic conditions for rice production in zinc deficient areas in Northern China. This shift alters soil conditions that affect zinc availability to the crop. This paper concerns the effect of aerobic compared to flooded conditions on crop biomass production, grain yield and zinc content. A field experiment was done with six rice genotypes (Oryza sativa L.) grown on a calcareous soil, both with (23 kg Zn ha⁻¹) and without Zn fertilization. Sampling was conducted at tillering and physiological mature stage. Zn concentration in the shoots was significantly lower at both stages in plants grown in the aerobic field. At maturity, Zn uptake, biomass production, grain yield and Zn-harvest index [grain Zn/(shoot + grain Zn)] were lower under aerobic cultivation. Rice genotypes including aerobic rice and lowland rice differ in degree of response to low Zn supply. A twofold difference was found among aerobic genotypes in grain yield and Zn uptake. Also Zn-harvest index varied significantly. Zn application affected neither grain yield nor grain Zn content, although it significantly improved biomass production in both systems in most genotypes. These results demonstrate that introduction of aerobic rice systems on calcareous soils may increase Zn deficiency problems.     

Diversity and functional traits of culturable microbiome members,including cyanobacteria in the rice phyllosphere

The diversity and abundance of culturable microbiome members of the rice phyllosphere was investigated using cv. Pusa Punjab Basmati 1509. Both diversity and species richness of bacteria were significantly higher in plants in pots in a semi‐controlled environment than those in fields. Application of fertilisers reduced both diversity and species richness in field‐grown plants under a conventional flooded system of rice intensification (SRI) and in dry‐seeded rice (DSR) modes. Sequence analyses of 16S rDNA of culturable bacteria, those selected after amplified ribosomal DNA restriction analysis (ARDRA), showed the dominance of α‐proteobacteria (35%) and actinobacteria (38%); Pantoea, Exiguobacterium and Bacillus were common among the culturable phyllospheric bacteria. About 34% of 83 culturable bacterial isolates had higher potential (>2 μg·ml^?1) for indole acetic acid production in the absence of tryptophan. Interestingly, the phyllosphere bacterial isolates from the pot experiment had significantly higher potential for nitrogen fixation than isolates from the field experiment. Enrichment for cyanobacteria showed both unicellular forms and non‐heterocystous filaments under aerobic as well as anaerobic conditions. PCR‐DGGE analysis of these showed that aerobic and anaerobic conditions as well as the three modes of cultivation of rice in the field strongly influenced the number and abundance of phylotypes. The adaptability and functional traits of these culturable microbiome members suggest enormous diversity in the phyllosphere, including potential for plant growth promotion, which was also significantly influenced by the different methods of growing rice.     

Phytotoxicity dynamics of decaying plant materials

Allelopathic effects of plant litter have been extensively studied, but less attention has been given to the dynamics of phytotoxicity during the decomposition processes. Decomposition experiments were carried out on above- and below-ground plant materials of 25 species of different functional groups (nitrogen fixer, forbs, woody and grasses-sedges) in aerobic and anaerobic conditions. The phytotoxicity of aqueous extracts of decomposing material was assessed by bioassay in 30 d of laboratory and 90 d of litterbag decomposition experiments. Phytotoxicity was widespread with c. 90% of the tested species showing significant phytotoxic releases. Phytotoxicity largely varied between different plant functional groups (nitrogen fixer>forbs=woody>grasses-sedges) and was higher for leaf compared with root materials. In all species tested during decomposition, phytotoxicity rapidly decreased in aerobic conditions but sharply increased and became stable in anaerobic conditions. The results demonstrate an unexpectedly widespread occurrence of phytotoxicity with clear dynamic patterns during the decomposition processes of plant materials. The ecological consequences of this might have been underestimated.     

Bacterial community dynamics in long‐term operation of a pilot plant using aerobic granular sludge to treat pig slurry

Aerobic granular sludge represents an interesting approach for simultaneous organic matter and nitrogen removal in wastewater treatment plants. However, the information about microbial communities in aerobic granular systems dealing with industrial wastewater like pig slurry is limited. Herein, bacterial diversity and dynamics were assessed in a pilot scale plant using aerobic granular sludge for organic matter and nitrogen elimination from swine slurry during more than 300 days. Results indicated that bacterial composition evolved throughout the operational period from flocculent activated sludge, used as inoculum, to mature aerobic granules. Bacterial diversity increased at the beginning of the granulation process and then declined due to the application of transient organic matter and nitrogen loads. The operational conditions of the pilot plant and the degree of granulation determined the microbial community of the aerobic granules. Brachymonas, Zoogloea and Thauera were attributed with structural function as they are able to produce extracellular polymeric substances to maintain the granular structure. Nitrogen removal was justified by partial nitrification (Nitrosomonas) and denitrification (Thauera and Zoogloea), while Comamonas was identified as the main organic matter oxidizing bacteria. Overall, clear links between bacterial dynamics and composition with process performance were found and will help to predict their biological functions in wastewater ecosystems improving the future control of the process. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 32:1212–1221, 2016     

有机物料发酵流体和堆肥对苹果连作土壤环境及平邑甜茶幼苗生物量的影响

为探讨不同有机物料的发酵流体(厌氧发酵产物)和堆肥(有氧发酵产物)对苹果连作土壤环境的影响,以盆栽平邑甜茶幼苗为试验材料,分别设置猪粪+秸秆、鸡粪+秸秆、羊粪+秸秆、猪粪+鸡粪+羊粪+秸秆4个不同有机物料组合并进行厌氧发酵和有氧发酵,并将发酵产物分别施入连作土中,研究其对平邑甜茶幼苗生物量、连作土壤中微生物、土壤酶活性、土壤酚酸等的影响。结果表明:与有机物料堆肥相比,各有机物料发酵流体处理的平邑甜茶幼苗干重、鲜重较高,其中猪粪发酵流体处理显著提高了幼苗干、鲜重,7月份为对照的1.57、1.26倍,9月份为CK的1.55、1.86倍;两类发酵产物均增加了土壤微生物的数量,且发酵流体处理显著增加了土壤中细菌和放线菌的数量,其中羊粪发酵流体效果最明显,分别为CK的2.95倍和2.37倍,在堆肥处理中,真菌数量显著增高;两类发酵产物也影响了土壤中酚酸总量,表现为猪粪、鸡粪发酵流体和猪粪堆肥处理含量下降,至9月份分别下降到CK的0.45、0.39倍和0.36倍。     

Bioremediation of MTBE: a review from a practical perspective

The addition of methyl tert-butyl ether (MTBE) to gasoline has resulted in public uncertainty regarding the continued reliance on biological processes for gasoline remediation. Despite this concern, researchers have shown that MTBE can be effectively degraded in the laboratory under aerobic conditions using pure and mixed cultures with half-lives ranging from 0.04 to 29 days. Ex-situ aerobic fixed-film and aerobic suspended growth bioreactor studies have demonstrated decreases in MTBE concentrations of 83% and 96% with hydraulic residence times of 0.3 hrs and 3 days, respectively. In microcosm and field studies, aerobic biodegradation half-lives range from 2 to 693 days. These half-lives have been shown to decrease with increasing dissolved oxygen concentrations and, in some cases, with the addition of exogenous MTBE-degraders. MTBE concentrations have also been observed to decrease under anaerobic conditions; however, these rates are not as well defined. Several detailed field case studies describing the use of ex-situ reactors, natural attenuation, and bioaugmentation are presented in this paper and demonstrate the potential for successful remediation of MTBE-contaminated aquifers. In conclusion, a substantial amount of literature is available which demonstratesthat the in-situ biodegradation of MTBE is contingent on achieving aerobic conditions in the contaminated aquifer.     

Airborne Microorganisms in Broiler Processing Plants

Concentrations of total aerobic bacteria, molds, yeasts, coliforms, enterococci, and psychrophiles were determined in the air of two poultry processing plants with Andersen samplers and a mobile power supply. Total aerobic bacterial counts were highest in the dressing room, with diminishing numbers in the shackling, eviscerating, and holding rooms, when sampling was carried out during plant operation. The average counts per ft³ of air in these four rooms were 2,200; 560; 230; and 62, respectively. (Each value is the average of 36 observations.) The number of organisms increased in the shackling and dressing rooms once processing was begun. Average total aerobic bacterial counts increased from 70 to 870 to 3,000 in the shackling room and from 310 to 4,900 to 7,000 in the dressing room when sampling was carried out at 5:00 am (before plant operations), 9:00 am, and 2:00 pm, respectively. (Each value is the mean of 12 observations.) Airborne molds might originate from a source other than the poultry being processed.     

Effects of Different Cropping Systems on the Occurrence of Fluorescent Pseudomonads

In field experiments, winter wheat was grown under different crop rotation regimes (monoculture; rotation with field beans) and differentiated intensity (cv.‘Jubilar’ with 120 kg N/ha and 1l CCC/ha; cv.‘Okapi’ with 180 kg N/ha and l CCC/ha). Plant, protection measures were carried out at three levels (no treatment; specific treatments under consideration of damage thresholds; routine spraying program). The occurrence of aerobic bacteria, fluorescent pseudomonads and strong siderophore-producers as well as the effect of the different cropping systems on the two groups of bacteria mentioned last were determined during the vegetation period at the beginning of shooting, at full bloom and after harvesting on the surface of the roots of wheat plants. In comparison to the total population of aerobic bacteria, the populations of fluorescent pseudomonads and of the strong siderophore-producing bacteria changed in a characteristic way: whereas at the beginning of shooting the highest and at full bloom the, lowest numbers were determined, a slight increase could be observed after harvest. On roots of wheat plants in monoculture, higher numbers of fluorescent pseudomonads and strong siderophore-producers were detected at the begining of shooting and at full bloom, than on those grown in rotation with field beans. The roots of cv. ‘Okapi’ (higher cropping intensity) were colonized to a higher degree by both groups of bacteria as compared to those of cv. ‘Jubilar’. After application of herbicides, a stimulation of these micro-organisms was observed at the beginning of shooting. The influences of different crop rotation schemes, intensities of cropping and plant protection measures on the occurrence of fluorescent pseudomonads were altogether less pronounced than the natural fluctuations of the population during the growth of the wheat. On the basis of morphological, physiological and biochemical properties, it could be shown that different biovars of the species Pseudomonas fluorescens dominated in the experimental field.     

Terrestrial plant methane production and emission

In this minireview, we evaluate all experimental work published on the phenomenon of aerobic methane (CH(4) ) generation in terrestrial plants and plant. Clearly, despite much uncertainty and skepticism, we conclude that the phenomenon is true. Four stimulating factors have been observed to induce aerobic plant CH(4) production, i.e. cutting injuries, increasing temperature, ultraviolet radiation and reactive oxygen species. Further, we analyze rates of measured emission of aerobically produced CH(4) in pectin and in plant tissues from different studies and argue that pectin is very far from the sole contributing precursor. In consequence, scaling up of aerobic CH(4) emission needs to take into consideration other potential sources than pectin. Due to the large uncertainties related to effects of stimulating factors, genotypic responses and type of precursors, we conclude that current attempts for upscaling aerobic CH(4) into a global budget is inadequate. Thus it is too early to draw the line under the aerobic methane emission in plants. Future work is needed for establishing the relative contribution of several proven potential CH(4) precursors in plant material.     

The ammonium nitrogen oxidation process in horizontal subsurface flow constructed wetlands

The ammonium nitrogen oxidation process (ANOP) is the first and most important step for nitrogen removal in constructed wetlands (CWs). The process was investigated by observing the products generated from the ANOP in on-site aerobic systems with selective inhibition of nitrite-oxidizing bacteria (NOB) through appropriate regulation of the pH, temperature and dissolved oxygen concentrations. The effects of season, plant type and density on ANOP were also studied to determine the optimal conditions for the ANOP. Nitrite accumulation was found in the aerobic experiments and greater ammonia-oxidizing bacteria than NOB numbers, showing that partial nitrification to nitrite was occurring in the studied CWs. The nitrogen removal rate was positively linearly correlated with the nitrite accumulation rate, and so the more NH₃-N removed by ANOP, the greater the resulting nitrogen removal. Season and plant density had a significant effect on the ANOP. However, there were no significant differences between the units planted with common reed and cattail.     

Bioremediation of tetryl-contaminated soil using sequencing batch soil slurry reactor

A laboratory study was conducted to determine whether tetryl (2,4,6-trinitrophenlymethylnitramine) contaminated soil could be bioremediated using a sequencing batch soil slurry reactor (SBR) operated under anoxic–aerobic sequence. The results indicated that tetryl was co-metabolically converted to aniline under anoxic conditions with molasses as the growth substrate. The gas chromatographic/mass spectrometric analysis of the soil slurry showed various metabolites, identified as trinitrobenzeneamine, dintrobenzenediamine, nitroaniline and aniline. Aniline was not metabolized further under anoxic conditions. When the soil slurry reactor was operated under aerobic conditions, the aniline concentration was reduced to below the detection limit (0.05 ppm). This metabolic conversion of tetryl is probably of value in the treatment of tetryl-contaminated soil and ground water, such as those found at the Joliet army ammunition plant site in Illinois and the Iowa army ammunition plant site in Burlington, Iowa.     

Field Tests for Evaluating the Aerobic Work Capacity of Firefighters

Working as a firefighter is physically strenuous, and a high level of physical fitness increases a firefighter’s ability to cope with the physical stress of their profession. Direct measurements of aerobic capacity, however, are often complicated, time consuming, and expensive. The first aim of the present study was to evaluate the correlations between direct (laboratory) and indirect (field) aerobic capacity tests with common and physically demanding firefighting tasks. The second aim was to give recommendations as to which field tests may be the most useful for evaluating firefighters’ aerobic work capacity. A total of 38 subjects (26 men and 12 women) were included. Two aerobic capacity tests, six field tests, and seven firefighting tasks were performed. Lactate threshold and onset of blood lactate accumulation were found to be correlated to the performance of one work task (r_s = −0.65 and −0.63, p<0.01, respectively). Absolute (mL·min⁻¹) and relative (mL·kg⁻¹·min⁻¹) maximal aerobic capacity was correlated to all but one of the work tasks (r_s = −0.79 to 0.55 and −0.74 to 0.47, p<0.01, respectively). Aerobic capacity is important for firefighters’ work performance, and we have concluded that the time to row 500 m, the time to run 3000 m relative to body weight (s·kg⁻¹), and the percent of maximal heart rate achieved during treadmill walking are the most valid field tests for evaluating a firefighter’s aerobic work capacity.     

Host response of rice genotypes to the rice root-knot nematode (Meloidogyne graminicola) under aerobic soil conditions

Aerobic rice is a production system where adapted rice varieties are established via direct seeding in non-puddled, non-flooded, non-saturated fields and grown under conditions similar to upland conditions. On land cultivated continuously with aerobic rice, a yield reduction has been observed. The rice root-knot nematode Meloidogyne graminicola is considered one of the possible causes of these yield reductions. Resistance to and tolerance for M. graminicola are essential traits for aerobic rice cultivars in alleviating this problem. In our study, the host response of nineteen aerobic, seven upland and four lowland rice genotypes which are either being used in the International Rice Research Institute’s aerobic rice breeding programme or already cultivated by farmers in Asia was evaluated under aerobic soil conditions in an outdoor raised-bed experiment. Our study showed a large variation in susceptibility and sensitivity to M. graminicola infection among the rice genotypes examined. Resistance comparable to the resistant reference genotypes included in the experiment (CG14, TOG5674, TOG7235) was not found but in terms of susceptibility, the upland genotype Morobereken may be an interesting less-susceptible genotype. Tolerance was found and in terms of sensitivity, the high yielding aerobic genotype IR78877-208-B-1-2 may be an interesting tolerant genotype. Our study also allowed the identification of rice genotypes that are either highly susceptible or sensitive to M. graminicola infection and of which the cultivation should be discouraged. On average, M. graminicola caused an almost 30% reduction in yield. Excluding the two susceptible and three resistant reference genotypes included in the experiment, most affected was dry-shoot biomass (23.6% reduction) followed by root length, which was more affected than fresh-root weight (19.8 vs. 8%) and grain filling (17.3%), while plant height and the number of spikelets/panicle were less affected (10.2 and 8.1%, respectively). Neither tillering nor the number of panicles/plant were affected.