Stage Zadoks Research Articles

Correlação entre resistência à brusone em cultivares de trigo e taxa de esporulação de conídios de Pyricularia oryzae Triticum

ABSTRACT: The use of resistant wheat cultivars is a fundamental strategy to minimize the damages caused by blast, a disease caused by the fungus Pyricularia oryzae Triticum (PoT). The objetive of this stydy was to (a) evaluate the reaction to blast of Brazilian wheat cultivars and (b) determine whether there is correlation between severity of symptoms on wheat spikes and “sporulation rate of PoT conidia per gram of wheat spike rachis” (Rscon). Plants of 16 wheat cultivars were grown in greenhouse until flowering (Zadoks stage 65), when their spikes were inoculated with a suspension formed by mixing the conidia of three PoT isolates. The evaluated variables were blast severity on spikes at 5, 7 and 11 days after inoculation (dai) and Rscon. Rachis were evaluated individually to determine the Rscon. Correlation analyzes were carried out between blast severity means on spikes of cultivars at 5, 7 and 11 dai and Rscon. The cultivars TBIO Mestre, TBIO Aton, ORS 1401, ORS 1403, ORS Destak, ORS Feroz, and CD 116 stood out for being classified in the statistical groups with the highest resistance to blast for the four variables considered in the study. The correlation between blast severity on spikes at 5, 7 and 11 dai and Rscon is at most moderate.

Biological effectiveness of fungicides Rango, Tacora, Velficur and Opus for control of Karnal Bunt

Commercial fungicides Rango, Tacora, Velficur, and Opus were evaluated in the field, to determine their biological effectiveness to control karnal bunt (Tilletia indica) of wheat. A completely randomized design was used with four replications. Twenty heads of cultivar Tacupeto F2001 were inoculated during the boot stage with an allantoid sporidial suspension (10,000/mL). Commercial rates indicated in the containers of each product were followed. The first application was carried out ten days after inoculation (Zadoks stages 56-58), and the second one ten days later. Inoculated spikes were threshed by hand and the healthy and infected kernels were counted to determine the percentage of infection. Two hundred grains per treatment and per replication were weighed. The biological effectiveness of the products evaluated were Opus 91.6, Velficur 83.2, Tacora 80.2, and Rango 70.3%. The untreated inoculated check had a mean of 18.6% infection. There were no statistical differences for the products evaluated for level of infection after arcsin transformation (Tukey, p = 0.05) and the coefficient of variation was 16.2%. The average weight of 200 grains per treatment was 10.6, 10.5, 10.6, and 10.7 g, respectively, and 10.7 g for the untreated inoculated check. No phytotoxic effects of treatments applied to the wheat plant were observed.

Balanced phosphorus fertilization enhances soil bacterial network complexity to maintain multifunctionality and plant production in dryland agricultural systems

Long-term fertilization significantly affected the function, diversity, and structure of soil microbial communities, which performed an indispensable role in maintaining ecosystem multifunctionality. However, the mechanism of how balanced fertilization affects soil microbial composition, function, and ecosystem multifunctionality is still poorly understood, especially during the whole plant life cycle, which will hinder our understanding the consequences of reducing phosphorus (P) fertilizer inputs as required in sustainable agriculture. Herein, the soil samples from a P fertilization field (with 0, 70, and 120 kg P2O5 ha−1 yr−1) at different stages of wheat (greenup stage (GP: Zadoks stage 26), elongation stage (EP: Zadoks stage 31), and flowering stages (FP: Zadoks stage 64)) were collected to investigate the effects of P fertilizer input on soil bacterial community, assembly, bacterial functionality, and multifunctionality in the Loess plateau. The results showed that soil bacterial diversity and functional groups (microbial P limitation) increased as wheat developed, but the bacterial network complexity and multifunctionality decreased. The highest soil bacterial network complexity, ecosystem multifunctionality, and homogeneous selection (deterministic processes) were observed in the balanced P fertilization treatment (P70), but wheat P uptake, biomass, and grain yield were similar at P rates of 70 and 120 kg P2O5 ha−1. The microbial nutrient limitation was also altered by both P fertilization and wheat growth stages. Moreover, the changes in soil available P and bacterial network complexity were the major determining factors of different microbial C and P limitations and ecosystem multifunctionality. Our results also showed that the core microorganisms with special functions drive the ecosystem multifunctionality by altering the community structure and network complexity of the microbes. Therefore, our result highlights the importance of soil available P and bacterial network complexity in maintaining ecosystem multifunctionality under P fertilizer inputs and provides support for the use of balanced P fertilization in sustainable dryland wheat production from the aspect of ecosystem multifunctionality.

Using 77Se-Labelled Foliar Fertilisers to Determine How Se Transfers Within Wheat Over Time.

Foliar selenium (Se) fertilisation has been shown to be more efficient than soil-applied fertilisation, but the dynamics of absorption and translocation have not yet been explored. An experiment was undertaken to investigate time-dependent changes in the absorption, transformation, and distribution of Se in wheat when 77Se-enriched sodium selenate (Sefert) was applied to the leaves at a rate of 3.33 μg Se per kg soil (equivalent to 10 g ha−1) and two growth stages, namely stem elongation, Zadoks stage 31/32 (GS1), and heading stage, Zadoks stage 57 (GS2). The effect of urea inclusion in foliar Se fertilisers on the penetration rates of Se was also investigated. Wheat was harvested at 3, 10, and 17 days and 3, 10, and 34 days after Se applications at GS1 and GS2, respectively. Applying foliar Se, irrespective of the formulation, brought grain Se concentration to a level high enough to be considered adequate for biofortification. Inclusion of N in the foliar Se solution applied at an early growth stage increased recoveries in the plants, likely due to improved absorption of applied Se through the young leaves. At a later growth stage, the inclusion of N in foliar Se solutions was also beneficial as it improved the assimilation of applied inorganic Se into bioavailable selenomethionine, which was then rapidly translocated to the grain. The practical knowledge gained about the optimisation of Se fertiliser formulation, method, and timing of application will be of importance in refining biofortification programs across different climatic regimes.

Evaluating the performance of the CCCI-CNI index for estimating N status of winter wheat

Spectral vegetation indices have proved versatile for rapid, non-destructive estimation of different canopy parameters. A combination of the canopy chlorophyll content index (CCCI) and the canopy nitrogen index (CNI) was used in previous studies to predict the canopy nitrogen (N) status of wheat until the end of stem elongation (Zadoks stage 13–37). The objective of this study was to evaluate and extend the CCCI-CNI approach to the end of booting (Zadoks 49) for winter wheat grown in temperate, high-yielding regions of Austria, where growing conditions, management practices, and N fertilization windows differ from the semi-arid cropping systems where the indices were developed. A comprehensive data set consisting of a time series of crop biomass, N concentration (%N), and spectral reflection measurements from three field experiment conducted during the growing seasons 2017/18, 2018/2019, 2019/20 with four winter wheat cultivars grown under four different N fertilisation levels in Tulln, Austria, was used for this study. While prediction of crop %N and N content (Ncont) using the original parameter values was not satisfactory, modification of the regression model between CCCI and CNI resulted in a skilful prediction of a broad range of %N and Ncont, with R2 values of 0.81 (RMSE = 0.72 %) and 0.96 (RMSE = 0.83 g m−2) for %N and Ncont, respectively. The results indicate that CCCI-CNI is a promising index for estimating Ncont of winter wheat of Austrian winter wheat until Zadoks stage 49, i.e. the end of the time when farmers make decisions about top dress N fertilization.

Plant Volatiles and Oviposition Behavior in the Selection of Barley Cultivars by Wheat Stem Sawfly (Hymenoptera: Cephidae).

Wheat stem sawfly, [Cephus cinctus (Hymenoptera: Cephidae)], females display complex behaviors for host selection and oviposition. Susceptible hollow stem wheat (Triticum aestivum L.) cultivars release a greater amount of attractive compound, (Z)-3-hexenyl acetate and receive a greater number of eggs compared to resistant solid stem wheat cultivars. However, barley (Hordeum vulgare L.) is becoming a more common host for C. cinctus in Montana. Therefore, how do host selection and oviposition behaviors on barley cultivars compare to what happens when encountering wheat cultivars? To answer this question, we carried out greenhouse experiments using two barley cultivars: 'Hockett' and 'Craft'. Between these cultivars at Zadoks stages 34 and 49, we compared host selection decisions using a Y-tube olfactometer, compared oviposition behaviors on stems, and counted the number of eggs inside individual stems. In Y-tube bioassays, we found a greater number of C. cinctus females were attracted to the airstream passing over 'Hockett' than 'Craft' barley cultivars. Although the frequencies of oviposition behaviors were similar between these cultivars, the number of eggs was greater in 'Hockett'. Volatile profiles indicated that the amount of linalool was greater in the airstream from 'Craft' than in 'Hockett' at Zadoks 34 while the amount of (Z)-3-hexenyl acetate was greater in airstream from 'Hockett' at both Zadoks 34 and 49. These results suggest that volatiles of barley plants influenced host selection behavior of ovipositing C. cinctus females, while other discriminating behaviors do not differ between cultivars.

Investigating conditions that induce late maturity alpha-amylase (LMA) using Northwestern US spring wheat (Triticum aestivum L.)

AbstractThe wheat industry rejects grain with unacceptably high α-amylase enzyme levels due to the risk of poor endproduct quality. There are two main causes of elevated grain α-amylase: (1) preharvest sprouting in response to rain before harvest and (2) late maturity α-amylase (LMA) induction in response to a cool temperature shock during late grain development. LMA induction was detected in a panel of 24 Northwestern US spring wheat lines. Thus, this problem previously described in Australian and U.K. varieties also exists in U.S. varieties. Because LMA induction results were highly variable using published methods, a characterization of LMA-inducing conditions was conducted in an LMA-susceptible soft white spring wheat line, WA8124. Problems with elevated α-amylase in untreated controls were reduced by raising the temperature, 25°C day/18°C night versus 20°C day/10°C night. LMA induction was not improved by colder temperatures (15°C day/4°C night) versus moderately cold temperatures (18°C day/7.5°C night or 10°C day/10°C night). While previous studies observed LMA induction by heat stress, it failed to induce LMA in WA8124. Thus, not all LMA-susceptible cultivars respond to heat. The timing of LMA susceptibility varied between two cultivars and within a single cultivar grown at slightly different temperatures. Thus, variability in LMA induction likely results from variability in the timing of the grain developmental stage during which cold shock induces LMA. Thus, it was concluded that the visual inspection of grain is needed to correctly identify LMA-sensitive spikes at the soft dough stage of grain development (Zadok's stage 85).

UAV-Based Thermal, RGB Imaging and Gene Expression Analysis Allowed Detection of Fusarium Head Blight and Gave New Insights Into the Physiological Responses to the Disease in Durum Wheat.

Wheat is one of the world’s most economically important cereal crop, grown on 220 million hectares. Fusarium head blight (FHB) disease is considered a major threat to durum (Triticum turgidum subsp. durum (Desfontaines) Husnache) and bread wheat (T. aestivum L.) cultivars and is mainly managed by the application of fungicides at anthesis. However, fungicides are applied when FHB symptoms are clearly visible and the spikes are almost entirely bleached (% of diseased spikelets > 80%), by when it is too late to control FHB disease. For this reason, farmers often react by performing repeated fungicide treatments that, however, due to the advanced state of the infection, cause a waste of money and pose significant risks to the environment and non-target organisms. In the present study, we used unmanned aerial vehicle (UAV)-based thermal infrared (TIR) and red-green-blue (RGB) imaging for FHB detection in T. turgidum (cv. Marco Aurelio) under natural field conditions. TIR and RGB data coupled with ground-based measurements such as spike’s temperature, photosynthetic efficiency and molecular identification of FHB pathogens, detected FHB at anthesis half-way (Zadoks stage 65, ZS 65), when the percentage (%) of diseased spikelets ranged between 20% and 60%. Moreover, in greenhouse experiments the transcripts of the key genes involved in stomatal closure were mostly up-regulated in F. graminearum-inoculated plants, demonstrating that the physiological mechanism behind the spike’s temperature increase and photosynthetic efficiency decrease could be attributed to the closure of the guard cells in response to F. graminearum. In addition, preliminary analysis revealed that there is differential regulation of genes between drought-stressed and F. graminearum-inoculated plants, suggesting that there might be a possibility to discriminate between water stress and FHB infection. This study shows the potential of UAV-based TIR and RGB imaging for field phenotyping of wheat and other cereal crop species in response to environmental stresses. This is anticipated to have enormous promise for the detection of FHB disease and tremendous implications for optimizing the application of fungicides, since global food crop demand is to be met with minimal environmental impacts.

Genetic factors increasing barley grain yields under soil waterlogging

AbstractIn‐crop soil waterlogging can be caused by extreme rainfall events, high ground water tables, excessive irrigation, lateral ground water flow, either individually or in concert, and together these factors inhibit potential grain yields. However, the extent to which yield is influenced by the timing and duration of waterlogging relative to crop phenology is unknown. To investigate this, we conducted a range of waterlogging treatments on modern barley genotypes differing in their waterlogging tolerance, with tolerance conferred through aerenchyma formation under oxygen deficit conditions. Experiment 1 was conducted in a controlled environment using four waterlogging treatments: waterlogging at Zadoks stage (ZS) 12.5 for 1 or 2 months (WL1 and WL2, respectively), waterlogging at ZS 15 for 2 months (WL3), and waterlogging initiated 1 day before heading for 15 days (WL4). Experiment 2 was conducted in the field with WL2. Averaged across experiments, yield was reduced by 35% in W1 to 52% in WL3 due to fewer spikes/m2 and kernels/spike. WL4 had the greatest impact on yield (70% reduction) due to its effect on spikelet fertility and grain filling. Phenology was delayed 1–8 ZS at the end of waterlogging treatments, with the waterlogging‐susceptible cultivar Franklin showing the greatest delays, and waterlogging tolerant genotypes (Macquarie+, TAMF169) capable of aerenchyma formation under waterlogging having the least delays (0–4 ZS). Genotypes with aerenchyma formation QTL (Macquarie+) showed nonsignificant yield reduction compared with nonwaterlogged controls, preventing 23% yield loss under early phenological waterlogging stress. Late growth stage waterlogging substantially reduced average final grain yield by 70%.

Sensor based calibration study for in-season nitrogen management of winter wheat in Turkey

The aims of this study were to compare the responses of four winter wheat cultivars to nitrogen fertilization with vegetation indices calculated using spectral reflection (GreenSeeker hand-held sensor) and to estimate in-season yield (INSEY) using the vegetation indices. The field experiment was conducted at Transitional Zone Agricultural Research Institute of Eskisehir province, Turkey in 2007-2008, 2008-2009 and 2009-2010 growing seasons. The experimental layout was a 2factor factorial in the randomized complete block design. Nitrogen rates were 0, 40, 80, 120, 160 and 200 kg N ha-1. Vegetation Index (NDVI) was obtained at growth stages of Zadoks 24 (tillering stage), Zadoks stage 30 (stem elongation), Zadoks stage 31 (the first node is visible) and Zadoks stage 32 (the second node is visible). The results revealed that Zadoks stage 30 was the most realistic reading time. NDVI had the advantage of providing information on biomass, in addition to nitrogen nutrition status of crops, enabling in-season yield estimation possible. Therefore, NDVI based calibration equations were preferred for testing in the fields of actual farmers for the last year of study. A comparison of the system with traditional farmer applications indicated that yield estimation obtained by the new system was quite similar yields with 13.2 kg ha-1 less N in the spring (ZD 3.0), showing its economically promising value.
 Asian J. Med. Biol. Res. June 2020, 6(2): 204-211

Identification of chromosomes in Triticum aestivum possessing genes that confer tolerance to the synthetic auxin herbicide halauxifen-methyl

Natural tolerance in hexaploid bread wheat (Triticum aestivum L.) to synthetic auxin herbicides is primarily due to rapid metabolic detoxification, but genes encoding these herbicide-detoxifying enzymes have yet to be identified. Herbicide safeners are commonly applied in wheat to achieve herbicide tolerance by inducing the expression and activity of herbicide-detoxifying enzymes. While safeners have been utilized for decades, knowledge of mechanisms that induce gene expression is limited. Our objective was to identify wheat chromosomes possessing genes that endow natural or safener-induced tolerance to halauxifen-methyl (HM), a postemergence (POST) wheat-selective synthetic auxin herbicide, using alien substitution (the S genome of Aegilops searsii) and aneuploid lines. Two POST rates of HM were applied to seedlings with 1-2 leaves (Zadoks stages 11-12), and the highest HM rate was also applied with the safener cloquintocet-mexyl (CM). Wheat chromosomes possessing genes associated only with natural HM tolerance were identified because Ae. searsii is HM-sensitive but CM-responsive. Lines with substitutions for 5A and 5B displayed sensitivity to HM, and experiments with nullisomic-tetrasomic (NT) lines further indicated major genes associated with HM tolerance are present on 5A and 5B chromosomes. However, the genes on 5A appear to play a larger role because lines lacking 5A chromosomes displayed more sensitivity than lines lacking 5B. Overall, these results can be utilized to guide future transcriptome analyses to identify candidate genes that confer HM tolerance in wheat.

Interactive effects of nitrogen fertilization and irrigation on grain yield, canopy temperature, and nitrogen use efficiency in overhead sprinkler-irrigated durum wheat

Nitrogen and irrigation management are crucial in the production of high protein irrigated durum wheat (Triticum durum Desf.) in arid regions. However, as the availability of irrigation water decreases and potential costs and regulation of nitrogen (N) increase, there is a need to better understand how irrigation levels interacts with N fertilizer rates. A two-year field experiment was conducted in Maricopa, Arizona USA on a Casa Grande sandy loam to assess effects of N fertilizer and irrigation rates on grain yield, grain N, canopy temperatures yellow berry, and N use efficiency. Five rates of N fertilizer as urea ammonium nitrate (0, 84, 168, 252, and 336kgNha−1) were applied in three equal splits at Zadoks stages 30, 32, and 39. Ten un-randomized, sequential rates of irrigation ranging from 0.35 to 1.14 fraction of a non-deficit base irrigation treatment (maintained >45% soil water depletion) were applied by sequentially varying the nozzles in a gradient in an overhead sprinkler system. Irrigation plus rain ranged from 230 to 660mm in the first season, and 180 to 600mm in the second season. Grain yield was maximum in 2013 at the 252kgNha−1 fertilizer rate and at the 10th water level (1.14 irrigation), and between 168kg and 252kgNha−1at the 8th water level (1.0 irrigation) in 2014. The maximum grain yield of 7500kgha−1 in 2013 was reduced to 5000kgha−1 in 2014 due to a warmer, shorter growing season. Economic optimum N rate was at water level 8 both years (196 and 138kgNha−1 in 2013, and 2014, respectively). Recovery efficiency of added N was high in this system (i.e., >70%) at N fertilizer and water levels that maximized biomass and grain yields. Grain N was maximum at a lower water level (level 3 or 0.50–0.54 irrigation), was positively affected by N fertilizer rate, and was negatively related to yellow berry incidence. Canopy temperature minus air temperature values decreased linearly with increasing irrigation level. Nitrogen fertilizer applications reduced canopy temperature when water levels >0.54 and 0.69 irrigation fraction in 2013, and 2014, respectively. The study results suggested that canopy temperature and weather data that reflects the grain-filling period could be used to improve irrigation and N management, respectively. In short, irrigated durum wheat growers on this soil would achieve the economically optimum grain yield, with the least risk of yield or protein reduction, by applying 200kgNha−1 at the base irrigation level which maintains root zone soil moisture depletion below 45%.

Effect of supplemental irrigation on the relationships between leaf ABA concentrations, tiller development and photosynthate accumulation and remobilization in winter wheat

Drought after the jointing stage restricted the growth and yield formation in wheat. Supplemental irrigation (SI) at Z31 (Zadoks Stage 31) reduced the ABA concentrations in the leaves of the inferior tillers (T3 and T10) and improved the survival rate of the tillers. Additional SI at Z60 reduced the ABA concentrations in the flag leaves of ear-bearing stems after anthesis and increased the assimilate accumulation and the 1000-grain weight. These two SIs increased the yield by 16.7–32.2 % compared with a rainfed control (W0). Delaying the first SI from Z31 to Z34 or Z39 reduced the ABA concentrations in the leaves of the main stem and superior tillers (T1 and T2) but increased the ABA concentrations in the leaves of the inferior tillers at Z45 and reduced the survival rate of the tillers. Delaying SI from Z31 and Z60 (W1) to Z34 and Z69 (W2) increased the partitioning of the recent (14C-labelled) assimilate to the stems plus sheaths and stalk plus glume at anthesis and the grains at maturity and increased the 1000-grain weight and the grain yield significantly. However, if SI was applied too late, i.e., at Z39 and Z77 (W3), the redistribution of the recent assimilate from the vegetative organs to the grain after anthesis and the grain yield at maturity were reduced. These data suggested that: (1) a lower soil moisture at the early jointing stage elevated the ABA concentrations in the inferior tillers and inhibited their growth; (2) if SI was applied too late (W3) senescence of the inferior tillers could not be halted; and (3) low ABA concentrations in the leaves during the later grain filling following the late SI (W3) were correlated with a reduced transfer of assimilates from the vegetative organs to the grain, leading to a significant reduction in the grain weight at maturity.

Occurrence of, and yield response to, Russian wheat aphid, Diuraphis noxia (Hemiptera: Aphididae) in irrigated wheat in Ethiopia

The present study investigated the incidence and effect of the Russian wheat aphid (RWA) Diuraphis noxia (Kurdjumov) on irrigated wheat yield at Debre Zeit, Ethiopia. Wheat varieties were sown at the rate of 140 kg/ha on Vertisols on plots of 3 × 3m. Treatments were tested in a split plot with varieties as the subplot and insecticide as the main plot, and were replicated three times. RWA appeared first when the crop reached the four- to five-leaf stage (Zadoks stage 22). In 2012 season, the RWA population peaked in the last week of March, and at this peak infestation, the average number of RWA per tiller was 46.9 on Denbi, 59.6 on Kubsa, 63.6 on Millennium and 56.2 on Werer. However, there were less than three RWA per tiller on sprayed wheat. In 2013, at the peak population intensity, there were 10.1, 10.5, 9.6 and 10.2 RWA per tiller on Denbi, Kubsa, Millennium and Werer, respectively. However, on sprayed wheat, the average population was less than one per tiller. The pattern of population build-up observed in the 2014 season was similar to that in 2013. Natural enemies of RWAwere only a few generalist predators and were found at an extremely low density. In the 2012 season, avoidable loss in plant height, seed weight, grain number and grain yield ranged from 3 to 10%, 32 to 47%, 12 to 25%, and 69 to 93%, respectively. In the 2013 season, avoidable loss in seed weight and grain yield varied between 14 and 20%, and 15 and 41%, respectively. Similarly, in the 2014 season, avoidable loss in seed weight ranged between 9 and 24% and in grain yield between 35 and 49%.

The effect of supplemental irrigation after jointing on leaf senescence and grain filling in wheat

Food security in the Huang-Huai-Hai Plain of China is threatened by water shortages and the early senescence of wheat induced by water deficit. However, effective water-saving irrigation techniques based on the consideration of precipitation, soil water storage and crop requirements are rudimentary. Information on the responses of transpiration, photosynthesis and plant senescence to Supplemental Irrigation (SI) at different stages of crop development is urgently required. Field experiments were performed in 2007–2008 and 2008–2009 to provide this information. Four irrigation treatments were tested: rainfed (W0), SI at Zadoks stage 31 (Z31) and Z60 (W1), SI at Z34 and Z69 (W2), and SI at Z39 and Z77 (W3). The SI brought soil water content in the 0–140cm profile to 75% field capacity. Supplemental Irrigation increased grain yields and the scheduling of SI affected yield components. Delaying SI from Z31 and Z60 (W1) to Z34 and Z69 (W2) decreased the number of spikes, but increased the number of grains per spike, 1000-grain weight and crop yield. Activities of superoxide dismutase (SOD) and catalase (CAT) in flag leaves of plants from the W2 treatment were greater, and malondialdehyde (MDA) concentrations in flag leaves were lower, than those from the W3 treatment until 24 days after anthesis and those from the W1 and W0 treatments throughout anthesis. Although SI increased both photosynthetic rate (Pn) and transpiration rate (E), the net effect was greater instantaneous water use efficiency (WUEleaf=Pn/E). Supplemental Irrigation also increased agronomic Water Use Efficiency (grain yield/crop evapotranspiration). Delaying SI decreased the grain filling rate at the beginning of grain filling in 2007–2008, but increased the grain filling rate later in grain filling in both 2007–2008 and 2008–2009. An appropriate delay in SI (W2) increased grain yield substantially, but if SI was applied too late (W3), there was less effect on grain yield, probably because of an inhibition of assimilate remobilization to the grain due to delayed senescence.

Non-destructive staging of barley reproductive development for molecular analysis based upon external morphology

A prerequisite to study the molecular genetic pathways of pollen and anther development is an accurate staging system for reproductive development. However in barley, floret formation occurs mainly within the pseudostem, which makes the observation of floret development and access to the floret particularly difficult without dissecting the plant. Thus selecting stages for molecular analysis cannot be done non-destructively. A staging method has therefore been developed for barley in order to define the relationship between readily detectable growth points and reproductive development, to provide a clear key to enable accurate selection of reproductive material. Initial staging followed the traditional Zadoks decimal system, with minor adaptations to stages 31–34 and stage 37. The later stages, from 37 onward, were replaced by growth staging based upon the last flag elongation (LFE) and the position occupied by the spike within the pseudostem. Spike size could be readily predicted by using the staging system incorporating Zadoks stages 31–37, supplemented with substages and by LFE staging to improve accuracy. The different spike sizes, as well as the LFE stages, showed a clear relationship to events occurring within the anther, as confirmed by light microscopy of the anthers. The defined relationship between spike size and development to anther development now makes possible the accurate prediction of anther and pollen progression by external staging. This, therefore, provides a mechanism for non-destructive selection of material for analysis that is critical for the molecular characterization of genes in anther and pollen development.

Assessment of wheat ear insects in winter wheat varieties in central Germany

Population densities of wheat ear insects infesting different winter wheat varieties (n = 50) were estimated during 2008 and 2009 seasons near Halle, central Germany. The research was aimed at identifying wheat varieties most resistant to wheat ear insect pests. Two methods were used to evaluate the degree of insect infestations in different wheat ear varieties. Wheat ears were dissected when kernels were in Zadoks stage 73 and examined using a binocular microscope to count the number of spikelets and infested kernels, and to identify the insect pests present. In addition, white water traps were placed on the soil underneath each variety to collect mature larvae of wheat blossom midges (WBMs) as an indicator of potential crop risk for the next year. There were significant differences in the number of thrips and WBM infesting wheat ears among varieties in both years. Thrips numbers were the highest in Akratos, Limes and Ritmo varieties in 2008 and in Michigan Amber, Elegant and Kontrast in 2009. Thrips were the lowest in Thuareg in 2008 and Robigus varieties in 2009. The results showed that the highest WBM infestation level was observed in Michigan Amber in both years. The lowest WBM infestations were found in Turkis, Cubus, Capo, Welford and Robigus in both years. The number of infested kernels was positively correlated with WBM among varieties. In the water traps, the highest numbers of WBM larvae were recorded in Saladin and Bussard in 2008 and Orlando, Julius and Glasgow varieties in 2009. The lowest values were recorded in Victo, Enorm, Robigus and Welford varieties in both years. The results provide a guide for selecting winter wheat varieties with resistance to these wheat ear pests.

A Root‐Zone Soil Regime of Wheat: Physiological and Growth Responses to Furrow Irrigation in Raised Bed Planting in Northern China

Different irrigation methods in wheat (Triticum aestivum L.) result in different water and nutrient use efficiencies and, ultimately, plant growth. A field experiment was conducted during the 2006–2007 and 2007–2008 crop cycles to investigate the effects of furrow irrigated raised bed planting and the effects of flood irrigated conventional planting on growth and productivity in winter wheat. In Zadoks Stages 5–31, wheat that was grown in raised bed planting suffered from a lower soil temperature by producing fewer tillers per plant with much slower growth and development than wheat grown in conventional planting. Subsequent flood irrigation in conventional planting improved soil moisture status while increasing soil bulk density and caused a deep percolation of irrigation water and soil nutrients. In contrast, furrow irrigation in a raised bed planting system improved root‐zone soil moisture and nutrient regimes, decreased soil bulk density by 8.5 to 10.4%, increased soil respiration by 3.2 to 10.4%, root vitality by 4.8 to 8.9%, and root dry weight by 2.8 to 3.7%. Consequently, compared with the conventional planting, the furrow‐irrigated wheat in raised bed planting developed greater leaf photosynthetic capacity, Photosystem II (PSII) potential (Fv/Fm), and actual (ΦPSII) quantum yields of photochemical processes, leaf area index (LAI), and dry matter accumulation (DMA). Ultimately, wheat on raised beds produced a grain yield of 698.7 g m−2, 7.6% higher than that in conventional planting. Based on these data, we can conclude that furrow‐irrigated raised bed planting optimizes the root‐zone soil regime, promotes plant growth and development, and increases wheat productivity.

The expression of caffeic acid 3-O-methyltransferase in two wheat genotypes differing in lodging resistance

Stem lodging-resistance is an important phenotype in crop production. In the present study, the expression of the wheat COMT gene (TaCM) was determined in basal second internodes of lodging-resistant (H4564) and lodging-susceptible (C6001) cultivars at stem elongation, heading, and milky endosperm corresponding to Zadoks stages Z37, Z60, and Z75, respectively. The TaCM protein levels were analysed by protein gel blot and COMT enzyme activity was determined during the same stem developmental stages. TaCM mRNA levels were higher in H4546 from elongation to the milky stages and in C6001 the TaCM mRNA levels decreased markedly at the heading and milky stages. The TaCM protein levels and COMT activity were also higher in H4564 than that in C6001 at the heading and milky stages. These results corresponded to a higher lignin content measured by the Klason method and stem strength and a lower lodging index in H4564 than in C6001 at the heading and milky stages. Therefore, the TaCM mRNA levels, protein levels, and enzyme activity in developing wheat stems were associated with stem strength and lodging index in these two wheat cultivars. Southern analysis in a different population suggested that a TaCM locus was located in the distal region of chromosome 3BL, which has less investigated by QTL for lodging-resistant phenotype.

Differential responses of two types of winter wheat ( Triticum aestivum L.) to autumn- and spring-applied mesosulfuron-methyl

Field experiments were conducted in the 2005/2006 and 2006/2007 crop seasons to evaluate the tolerance of hard winter wheat (HWW) and soft winter wheat (SWW) varieties to post-emergence mesosulfuron-methyl treatment. The application of mesosulfuron-methyl at 11.25 g a.i. ha −1 plus a noninonic surfactant at 252 g a.i. ha −1 to three HWW and three SWW varieties in either autumn (Zadoks stage 14–15) or spring (Zadoks stage 24–25) resulted in visible injury, including chlorisis, stunting and leaf deformities. The greatest injury occurred at fourteen days after treatment (DAT) for all wheat varieties. All varieties showed the same initial sensitivity to herbicide treatment, but differed significantly in their recovery from plant damages. The HWW varieties recovered more successfully from spring-applied herbicide than the SWW varieties; conversely, the SWW varieties recovered more rapidly from damage caused by autumn-applied herbicide than the HWW varieties. Normalized Difference Vegetative Index (NDVI) values were severely affected by autumn herbicide application for HWW varieties and spring application for SWW varieties. Autumn herbicide application for SWW varieties and spring herbicide application for HWW varieties produced higher grain yields. Based on these data, we conclude that applying mesosulfuron-methyl plus a noninonic surfactant in autumn for SWW varieties and in spring for HWW varieties is optimal, and that application timing has profound implications for herbicide tolerance and production of wheat.