Rainfed Wheat Research Articles

Frost trends and their estimated impact on yield in the Australian wheatbelt.

Radiant spring frosts occurring during reproductive developmental stages can result in catastrophic yield loss for wheat producers. To better understand the spatial and temporal variability of frost, the occurrence and impact of frost events on rain-fed wheat production was estimated across the Australian wheatbelt for 1957-2013 using a 0.05 ° gridded weather data set. Simulated yield outcomes at 60 key locations were compared with those for virtual genotypes with different levels of frost tolerance. Over the last six decades, more frost events, later last frost day, and a significant increase in frost impact on yield were found in certain regions of the Australian wheatbelt, in particular in the South-East and West. Increasing trends in frost-related yield losses were simulated in regions where no significant trend of frost occurrence was observed, due to higher mean temperatures accelerating crop development and causing sensitive post-heading stages to occur earlier, during the frost risk period. Simulations indicated that with frost-tolerant lines the mean national yield could be improved by up to 20% through (i) reduced frost damage (~10% improvement) and (ii) the ability to use earlier sowing dates (adding a further 10% improvement). In the simulations, genotypes with an improved frost tolerance to temperatures 1 °C lower than the current 0 °C reference provided substantial benefit in most cropping regions, while greater tolerance (to 3 °C lower temperatures) brought further benefits in the East. The results indicate that breeding for improved reproductive frost tolerance should remain a priority for the Australian wheat industry, despite warming climates.

Soil organic carbon fractions as influenced by vegetation type and land management: A case study in semiarid rangelands of Hamedan, Iran

Soil is an environmental component permanently changing due to the often cyclic processes of litter supply and vegetation cover. To investigate the influence of vegetation type on soil carbon fractions, six vegetation types, including rainfed wheat (RW), grasses (G), Astragallus–Bromus (A-B), Astragallus–lactuca (A-L), Astragallus–Artemisi (A-A), Astragallus–Euphorbia (A-E) were studied in similar environmental conditions in terms of parent material and slope aspect in Gonbad watershed, Hamadan. Total organic carbon (TOC), active carbon (AC), soil carbohydrates (Ch) and basal respiration (BR) were measured in surface soils (0-15 cm) in fall and spring. TOC, CH, and BR were significantly greater in A-B and A-A than other covers. A-B and A-A showed higher vegetation cover and litter compared to other types. TOC and Ch in RW and G were significantly lower than other types. The highest (711.7 mg/kg) and lowest (262.6 mg/kg) AC were observed in A-B and RW, respectively. RW had lowest values of selected soil quality indicators due to tillage and cultivation. The content of TOC and AC were significantly higher in spring than autumn. Amount of BR and Ch showed no significant difference in the two seasons. Significant positive correlations were observed between soil quality indicators, these correlations were stronger in spring than in autumn. In autumn, the highest correlations were observed between AC and Ch (0.701), as well as AC and BR (0.441). In spring, significant correlations were observed between all soil quality indicators at 1% level. It was concluded that AC and Ch are the most sensitive soil quality indicators that reflect land use and vegetation type differences.

Performance of improved practices in farmers’ fields under rainfed and supplemental irrigation systems in a semi-arid area of Pakistan

In Pakistan, like many of the developing countries, crop yields under dryland agriculture are very low. This field research aimed at investigating improving land and water productivities and farmers’ incomes through improved water management, crop intensification and diversification under rainfed and supplemental irrigation (SI) conditions. With improved packages (e.g. high yielding varieties, appropriate seed rates, time of sowing, and use of fertilizers) an average of 31% higher yields of rainfed wheat (Triticum aestivum) were obtained by farmers compared to their traditional practices. The net income under the improved package was about Rs. 70,000/ha (1 US$=Rs. 72), almost double that under farmers’ current practices. The highest wheat yield of 5102kg/ha obtained in small plots was 28% higher than for farmers’ current practices; followed by the raised bed yield of 4776kg/ha. With only 20% extra cost for water used as SI for small plot sowing with improved practices, there was 47% higher wheat yield and over 60% higher net income obtained compared to farmers’ practices. Similarly, with about 10% additional cost for SI, groundnut (Arachis hypogea) yield and net income increased up to four times compared to farmers’ practices. It may be concluded that, in this environment, much of the yield gap between farmers and research may be closed by adopting simple and low cost integrated packages.

Potential Impact of Climate Change Trends on Wheat Production and Mitigation Strategies in Afghanistan

Climate change is here and continues unabated. It is expected to affect different biological processes differently. Afghanistan has a varied climate profile and depends heavily on wheat, the staple food of its 30 million people. The irrigated wheat occupying about 1.35 million hectare and contributes major chunk of wheat to national granaries compared to rainfed wheat which is more opportunistic with an unpredictable and uncertain share in national harvest. Previous decades have already seen a reduction of up to 100 mm wheat season rainfall and more reductions are estimated by 2050. Also, wheat which is a cool season crop and is also estimated to face higher temperatures by up to 5 degree Celsius across several provinces in the country. The study predicts variable impact of the estimated changes on the productivity of irrigated and rainfed wheat in Afghanistan.

Nitrogen management is the key for low-emission wheat production in Australia: A life cycle perspective

Farm management affects the global greenhouse gas (GHG) budget by changing not only soil organic carbon (SOC) stocks and nitrous oxide (N2O) emissions but also other pre-farm, on-farm and off-site emissions. The life cycle assessment (LCA) approach has been widely adopted to assess the “carbon footprint” of agricultural products, but rarely used as a tool to identify effective mitigation strategies. In this study, the global warming impacts of no-till (NT) vs. conventional till (CT), stubble retention (SR) vs. stubble burning (SB), and N fertilization (NF) vs. no N fertilization (N0) in an Australian wheat cropping system were assessed using in situ measurements of N2O fluxes over three years, SOC changes over forty years and including other supply chain GHG sources and sinks. The results demonstrated the importance of full GHG accounting compared to considering SOC changes or N2O emissions alone for assessing the global warming impacts of different management practices, and highlighted the significance of accurately accounting for SOC changes and N2O emissions in LCAs. The GHG footprints of wheat production were on averaged 475kg carbon dioxide equivalent (CO2-e) ha−1 (or 186kg CO2-e t−1 grain) higher under NF than N0. Where fertilizer N was applied (70kgNha−1), the life cycle emissions were 200kg CO2-e ha−1 (or 87t−1 grain) lower under NT than CT and 364kg CO2-e ha−1 (or 155t−1 grain) lower under SR than SB. Classification of the emission sources/sinks and re-calculation of published data indicated that under the common practices of SR combined with NT, N-related GHG emissions contributed 60–95% of the life cycle emissions in the predominantly rain-fed wheat production systems in Australia. Therefore, future mitigation efforts should aim to improve N use efficiency, explore non-synthetic N sources, and most importantly avoid excessive N fertilizer use whilst practising NT and SR.

Effects of Resource Conservation Practices on Productivity, Profitability and Energy Budgeting in Maize–Wheat Cropping System of Indian Sub-Himalayas

Resource conservation issues have drawn the attention of scientists to devise innovative tillage and crop establishment techniques for higher productivity in small holder farming systems in the tropics but relatively less attention has been given in rainfed sloping lands of the Indian sub-Himalayan (sub-temperate) regions. To investigate these issues, an experiment was conducted on resource conservation practices under rainfed conditions for 5 years (June 2007–May 2012) at Dehradun, Uttarakhand in the Indian Himalayan region. Four treatments, 1. 100:60:40 kg N:P2O5:K2O + conventional tillage (CT) + chemical weeding + PANICUM vegetation strip (T1); 2. FYM (5 t ha−1) + minimum tillage (MT) + 1 weed mulch (30 DAS) @ 0.52 t ha−1 + PALMAROSA vegetation strip (T2); 3. FYM (5 t ha−1) + vermi-compost (1.0 t ha−1) + MT + 2 weed mulch (25 and 50 DAS) @ 1.47 t ha−1 + PALMAROSA vegetation strip (T3) and 4. FYM (5 t ha−1) + vermi-compost (1.0 t ha−1) + poultry manure (2.5 t ha−1) + MT + 3 weed mulch (20, 40 and 60 DAS) @ 2.18 t ha−1 + PALMAROSA vegetation strip (T4). The results showed that resource conservation treatments (T4, T3 and T2) had significant (P ≤ 0.05) multiple benefits as compared to traditional agriculture treatments (T1). T1 gives the highest yield of maize whereas T4 gives highest yield of wheat. For the maize–wheat cropping system, mean wheat equivalent yield (WEY) was ~16 % higher in T4 than T1. Mean runoff was ~30 % lesser and mean soil loss was ~34 % lesser in T4 as compared with T1. Similarly, mean soil moisture conservation for rainfed wheat was ~31 % higher in T4 than T1. Mean carbon retention potential increased by ~53 % which subsequently increased mean soil quality index (SQI) by ~25 %. Mean energy productivity increased by ~70 % and mean energy intensiveness decreased by ~56 % in T4 than T1. Treatment T1 (2,560 MJ−1) emerged to be the most energy intensive system as compared to T4 (1,113 MJ Rs.−1). On an average, T4 had 7 % higher net returns than T1 and in terms of net returns per tonne of soil loss, T4 was the best treatment (Rs. 4,907). Therefore, resource conservation system (PALMAROSA as a vegetation strip along with organic amendments, FYM, vermi-compost, poultry manure and weed mulch under minimum tillage) had significant positive impact on yield, resource conservation and energy saving and may be introduced as a substitute of conventional system in the Indian sub-Himalayas and under similar climatic and edaphic conditions.

Depth of nitrogen fertiliser placement affects nitrogen accumulation, translocation and nitrate-nitrogen content in soil of rainfed wheat

A field experiment was conducted to examine the effects of different depths of nitrogen (N) fertiliser placements on N accumulation, remobilisation and NO3 − -N content in soil of rainfed wheat. Nitrogen was applied on the surface (D1) and in the 10 cm (D2), 20 cm (D3) and 30 cm (D4) soil layers from 2010 to 2012. Compared with D1 and D2, D3 and D4 treatments obtained significant higher N distribution amounts in grain and N accumulation amounts at maturity. D3 and D4 treatments increased the N accumulation amount of vegetative organs at anthesis and at maturity. D3 treatment resulted in significantly higher N translocation amounts from vegetative organs to grains compared with D1 and D2 treatments and had no significant difference with D4 treatment. Compared with the D1 and D2, D3 and D4 treatments obtained significant higher NO3 − -N contents in the 20 cm to 120 cm soil layer at anthesis from 2011 to 2012. However, D3 treatment showed no significant differences with D1 and D2 treatments at maturity in terms of the NO3 − -N contents in the 40 cm to 100 cm soil layer. D4 treatment produced the highest NO3 − -N contents in the 40 cm to 140 cm soil layer. Grain yield, N uptake efficiency, apparent N recovery efficiency, N agronomic efficiency and N partial factor productivity were significantly increased by D3 and D4 treatments. These results suggest that the D3 treatment facilitates the best wheat production and highest efficiency among all treatments.

Water use efficiency and crop water balance of rainfed wheat in a semi-arid environment: sensitivity of future changes to projected climate changes and soil type

Wheat production is expected to be affected by climate change through changing components of the crop water balance such as rainfall, evapotranspiration (ET), runoff and drainage. We used the Agricultural Production Systems Simulator (APSIM)-wheat model to simulate the potential impact of climate change on field water balance, ET and water use efficiency (WUE) under the SRES A2 emissions scenario. We ran APSIM with daily climate data statistically downscaled from 18 Global Circulation Models (GCMs). Twelve soil types of varying plant available water holding capacity (PAWC) at six sites across semi-arid southeastern Australia were considered. Biases in the GCM-simulated climate data were bias-corrected against observations for the 1961–1999 baseline period. However, biases in the APSIM output data relative to APSIM simulations forced with climate observations remained. A secondary bias correction was therefore performed on the APSIM outputs. Bias-corrected APSIM outputs for a future period (2021–2040) were compared with APSIM outputs generated using observations for the baseline period to obtain future changes. The results show that effective rainfall was decreased over all sites due to decreased growing season rainfall. ET was decreased through reduced soil evaporation and crop transpiration. There were no significant changes in runoff at any site. The variation in deep drainage between sites was much greater than for runoff, ranging from less than a few millimetres at the drier sites to over 100 mm at the wetter. However, in general, the averaged drainage over different soil types were not significantly different between the baseline (1961–1999) and future period of 2021–2040 (P > 0.05). For the wetter sites, the variations in the future changes in drainage and runoff between the 18 GCMs were larger than those of the drier sites. At the dry sites, the variation in drainage decreased as PAWC increased. Overall, water use efficiency based on transpiration (WUE_T) and ET (WUE_ET) increased by 1.1 to 1.6 and 0.7 to 1.3 kg ha−1 mm−1, respectively, over the baseline historical climate. Significant relationships between changes in wheat yield and PAWC were only seen at three sites. At the dry sites, the impact of a future climate under a soil of high PAWC was less than that under one of low PAWC. Conversely, the opposite response was seen at two wetter sites, highlighting the importance of PAWC and rainfall in determining the interactive response of crops to primary components of the water balance.

The effect of vegetation type on selected soil quality indicators in a semiarid rangeland in Hamedan, Iran

Soil quality approach can be used to describe soil health changes caused by different land use managements and vegetation types. Our objective was to assess the response of some soil quality indicators to different vegetation types including rainfed wheat (RW), grasses (G), Astragallus-Bromus (A-B), Astragallus-Lactuca (A-L), Astragallus-Artimisia (A-A) and Astragallus-Euphorbia (A-E) in a semiarid experimental rangeland in Hamedan, where environmental conditions in terms of slope aspect and soil parent material were similar., Substrate-induced microbial respiration (MR I ) and the activity of phosphomonoesterase enzyme (PMEase) were determined in surface soil (0-15 cm) in spring and autumn. Morover, bioavailable phosphorus (P) and potassium (K) were measured in autumn. No significant disparity was detected in P content of different vegetation types. Bioavailable K between was highest in A-E, and lowest in G and RW sites. MR I was significantly higher in spring irrespective of vegetation type. This index was significantly highest in A-B site in both seasons. As for PMEase, A-A and A-B showed the highest values in autumn in spring, A-B, A-A and A-L demonstrated the highest phosphatase activity. PMEase in A-L and A-A sites was significantly higher in spring than autumn. Strongly significant positive correlation was found between PMEase and MR I . Overall, soil quality is highest under vegetation types composed of perennial shrubs, irrespective of season.

Effects of conservation tillage practices on ammonia emissions from Loess Plateau rain-fed winter wheat fields

Ammonia emissions from agricultural activities contribute to air pollution. For the rain-fed winter wheat system in the Loess Plateau there is a lack of information about ammonia emissions. Current study aimed to provide field data on ammonia emissions affected by conservation tillage practices and nitrogen applications. A two-year field experiment was conducted during 2011–2013 wheat growing seasons followed a split-plot design. Main plots consisted of one conventional tillage (CT, as the control) and five conservation tillage systems, i.e., stalk mulching (SM), film mulching (FM), ridge tillage (RT), ridge tillage with film mulch on the ridge (RTfm), and ridge tillage with film mulch on the ridge and stalk mulch in the furrow (RTfmsm); while subplots consisted of two nitrogen application rates, i.e., 0 and 180 kg Nha−1. Ammonia emissions were measured using an acid trapping method with vented chambers. Results showed ammonia fluxes peaked during the first 10 days after fertilization. On average, nitrogen application increased ammonia emissions by 26.5% (1.31 kg Nha−1) compared with treatments without nitrogen application (P < 0.05). Ammonia fluxes were strongly dependent on soil ammonium, moisture, and temperature. Tillage systems had significant effects on ammonia emissions. On average, conservation tillage practices reduced ammonia emissions by 7.7% (0.46 kg Nha−1) compared with conventional tillage (P < 0.05), with FM most effective. Deep-band application of nitrogen fertilizer, stalk mulches, and film mulches were responsible for reductions in ammonia emissions from nitrogen fertilization in conservation tillage systems, thus they were recommended to reduce ammonia emissions from winter wheat production regions in the southern Loess Plateau.

Lalmi 04 - A New Rainfed Wheat Variety for Afghanistan

A new rainfed wheat variety Lalmi 04 has been released in Afghan from out of the genotypes introduced through 14 th Semi-Arid Wheat Yield Trial of CIMMYT in 2006. The variety was tested in a total of eight yield evaluation trials over a period of four years and gave more than 10% higher yield than the check variety Lalmi 02. The released variety showed a yield potential of 6836 kg/ha and an average yield of 3826 kg/ha. Lalmi 04 had an average 1000 grain weight of 44 grams and matured in 179 days. The variety has an erect flag leaf and grew to a height of 88 cm. The variety was resistant to all the rusts in Afghanistan under natural conditions.

Performance of rainfed wheat under different fertility levels and sowing methods in the mid hills of north-western Himalayas

A field experiment was conducted during winter (rabi) seasons of 2012-13 and 2013-14 at the experimental farm of the ICAR–Vivekananda Parvatiya Krishi Anusandhan Sansthan located at Hawalbagh, Almora. The experiment was laid out in split plot design with four replications. The treatments consisted of two fertility levels viz., unfertilized control (F 0 ) and recommended dose of fertilizers–60 : 30 : 20 kg NPK/ha (F 1 ) in main plots, while three sowing methods viz., broadcasting/farmer’s practice (S 1 ), line sowing –manual (S 2 ) and line sowing with multi-crop planter (S 3 ) in sub-plots. Under poor residual soil moisture, fertilizer application resulted in higher effective tillers/m 2 , plant height, yield attributes, yield and B : C ratio than control. Among sowing methods, multi-crop planter recorded the highest seedling emergence, number of tillers/m 2 , plant height, yield attributes, yield and B : C ratio. Sowing of wheat with recommended dose of fertilizer with multi-crop planter, which provides simultaneous placement of seed and fertilizer, was very effective under extremely low residual soil moisture conditions which are basic features during sowing of rabi crops in the region.

Applying the CSM-CERES-Wheat model for rainfed wheat with specified soil characteristic in undulating area in Iran

Models can provide researchers with an opportunity to understand the multidimensional relationships among factors affecting crop growth. All such factors, including field condition, must be tested using models. The main objective of this study was to apply the Cropping System Model (CSM)-Crop-Environment Resource Synthesis (CERES)-Wheat model to uneven areas for simulating rainfed wheat. First, the model was calibrated at a field cultivated with wheat variety Sardari. The model was then applied to different points at a ‘hummocky’ evaluation site. At this site, 69 sample points from 5 different slope positions (summit, shoulder, backslope, footslope, and toeslope) were specified and physical and chemical soil properties as well as final grain and total aboveground wheat biomass at each of 69 points were measured. The overall results showed that the normalized root-mean-square error varied between 15% and 34% for the top weight; this was considered to be good enough for undulating areas. The model efficiency (EF) also ranged from 0.35 to 0.26 both in simulation of final grain and in top weight. It can be concluded that CSM-CERES-Wheat model can be effectively applied for yield prediction in hills. It should be noted that use of the CSM-CERES-Wheat model is not recommended for estimation of grain yield in individual slope positions unless more detailed water and fertilizer data are also available.

Quantification of agricultural drought occurrence as an estimate for insurance programs

Temporal irregularities of rainfall and drought have major impacts on rainfed cropping systems. The main goal of this study was to develop an approach for realizing drought occurrence based on local winter wheat yield loss and rainfall. The domain study included 11 counties in the state of Washington that actively grow rainfed winter wheat and an uncertainty rainfall evaluation model using daily rainfall values from 1985 to 2007. An application was developed that calculates a rainfall index for insurance that was then used to determine the drought intensity for each study year and for each study site. Evaluation of the drought intensity showed that both the 1999–2000 and 2000–2001 growing seasons were stressful years for most of the study locations, while the 2005–2006 and the 2006–2007 growing seasons experienced the lowest drought intensity for all locations. Our results are consistent with local extension reports of drought occurrences. Quantification of drought intensity based on this application could provide a convenient index for insurance companies for determining the effect of rainfall and drought on crop yield loss under the varying weather conditions of semi-arid regions.

Early Estimation of Drought Impacts on Rainfed Wheat Yield in Mediterranean Climate

Drought events can cause severe damages to agriculture and in particular to rainfed agriculture. The problems can be more evident in semi-arid regions of the Mediterranean. It is of great importance to assess the impacts of drought on the yield at an early stage, in order to be able to take measures on time for mitigating the anticipated losses, supporting the farmers, and enhancing food security. The aim of the paper is to formulate a simple methodology for estimating the impacts of drought on rainfed agriculture, and especially on wheat yield, prior to the harvest. The Reconnaissance Drought Index (RDI) is used as the main independent variable in linear regression models for the assessment of drought effects on wheat yield. To test the proposed methodology, data from two rural areas of Greece are used and the wheat yield is simulated using the AquaCrop model. Multiple regression models with variables that include RDI and the minimum temperature for winter months are tested and evaluated through a cross-validation process. The performance of the models is assessed by various criteria. Indicatively, the correlation coefficients at each study area reach 0.87 and 0.91 for predictions 1 month before harvest, 0.84 and 0.82 for 2 months and 0.67 and 0.77 for 3 months before harvest. The results show that the RDI, for reference periods that represent the critical development stages of the crop, is highly correlated with the wheat yield. A satisfactory prediction of the drought impacts on wheat yield 2 to 3 months before the harvest can be achieved. The proposed methodology can be useful to the authorities, stakeholders and insurance services for facing drought events and mitigating losses in rainfed agriculture.

Demand for multi-scale weather data for regional crop modeling

A spatial resolution needs to be determined prior to using models to simulate crop yields at a regional scale, but a dilemma exists in compromising between different demands. A fine spatial resolution demands extensive computation load for input data assembly, model runs, and output analysis. A coarse spatial resolution could result in loss of spatial detail in variability. This paper studied the impact of spatial resolution, data aggregation and spatial heterogeneity of weather data on simulations of crop yields, thus providing guidelines for choosing a proper spatial resolution for simulations of crop yields at regional scale. Using a process-based crop model SIMPLACE 〈LINTUL2〉 and daily weather data at 1km resolution we simulated a continuous rainfed winter wheat cropping system at the national scale of Germany. Then we aggregated the weather data to four resolutions from 10 to 100km, repeated the simulation, compared them with the 1km results, and correlated the difference with the intra-pixel heterogeneity quantified by an ensemble of four semivariogram models. Aggregation of weather data had small effects over regions with a flat terrain located in northern Germany, but large effects over southern regions with a complex topography. The spatial distribution of yield bias at different spatial resolutions was consistent with the intra-pixel spatial heterogeneity of the terrain and a log–log linear relationship between them was established. By using this relationship we demonstrated the way to optimize the model resolution to minimize both the number of simulation runs and the expected loss of spatial detail in variability due to aggregation effects. We concluded that a high spatial resolution is desired for regions with high spatial environmental heterogeneity, and vice versa. This calls for the development of multi-scale approaches in regional and global crop modeling. The obtained results require substantiation for other production situations, crops, output variables and for different crop models.

A comparison between the Example Reference Biosphere model ERB 2B and a process-based model: simulation of a natural release scenario

The BIOMASS methodology was developed with the objective of constructing defensible assessment biospheres for assessing potential radiological impacts of radioactive waste repositories. To this end, a set of Example Reference Biospheres were developed to demonstrate the use of the methodology and to provide an international point of reference.In this paper, the performance of the Example Reference Biosphere model ERB 2B associated with the natural release scenario, discharge of contaminated groundwater to the surface environment, was evaluated by comparing its long-term projections of radionuclide dynamics and distribution in a soil-plant system to those of a process-based, transient advection-dispersion model (AD). The models were parametrised with data characteristic of a typical rainfed winter wheat crop grown on a sandy loam soil under temperate climate conditions. Three safety-relevant radionuclides, 99Tc, 129I and 237Np with different degree of sorption were selected for the study.Although the models were driven by the same hydraulic (soil moisture content and water fluxes) and radiological (Kds) input data, their projections were remarkably different. On one hand, both models were able to capture short and long-term variation in activity concentration in the subsoil compartment. On the other hand, the Reference Biosphere model did not project any radionuclide accumulation in the topsoil and crop compartments. This behaviour would underestimate the radiological exposure under natural release scenarios.The results highlight the potential role deep roots play in soil-to-plant transfer under a natural release scenario where radionuclides are released into the subsoil. When considering the relative activity and root depth profiles within the soil column, much of the radioactivity was taken up into the crop from the subsoil compartment.Further improvements were suggested to address the limitations of the Reference Biosphere model presented in this paper.

Physiological responses of the co-cultivation of PGPR with two wheat cultivars in vitro under stress conditions

Wheat (Triticum aestivum L.) may be exposed to different stress conditions that influence its productivity. In southern Brazil the rainfed wheat crop is limited by dry spells consisting of short periods of drought during rainy periods. One way to confer tolerance to the drought´s effects and stimulate plant productivity is the action of a group of bacteria capable of making association with plants, known as Plant Growth Promoter Bacteria (PGPB), as Herbaspirillum seropedicae and Azospirillum brasilense, both diazotrophic. It was demostrated that the PGPB can benefit the plants in several ways: synthesizing some phytohormones, siderophores, biological nitrogen fixation, inducing systemic resistance etc. The strain H. seropedicae SmR1 unlike A. brasilense AbV5, presents a gene encoding the 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase, which breaks ACC, the ethylene precursor in alpha-keto-butyric acid (AKB) and ammonium ion. The indole-3-acetic acid (IAA) is a phytohormone, produced by PGPB that modulates the synthesis of plant ethylene, and it is known as stress and senescence promoter. The IAA can stimulate the synthesis of ACC by increasing the activity of ACC synthase and inhibit the transformation of ACC into ethylene by decreasing the activity of ACC oxidase. The aim of this work was study the in vitro interactions of two varieties of wheat, CD120 and an ancestor cultivar Frontana, with the H. seropedicae SmR1 and A. brasilense AbV5 to verify the physiological changes in the culture medium under osmotic stress imposed by polyethylene glycol (PEG 6000). Wheat plantlets were obtained throughout mature embryos cultured on solid MS medium, aseptically transferred after 28 days to 10 mL of 1/10 MS liquid medium with or without PEG and inoculated with H. seropedicae and/or A. brasilense. The controls consisted of wheat plantlets with and without PEG in the same condition. After 5 days, plantlets and bacteria were harvested and the co-culture medium was taken to determine the concentrations of IAA (Glickmann & Dessaux, 1995) [1], AKB (Penrose and Glick, 2003) [2], and total protein (Hartree, 1972) [3]. The treatments of CD120 without PEG and with H. seropedicae showed the highest IAA concentration. In Frontana the amounts of IAA are lower as compared to CD120, however, treatments under the stress condition (with PEG) and A. brasilense stood out. Treatments with PEG and both bacteria showed similar performances associated with CD120. The amounts of AKB increased in the presence of PEG and H. seropedicae for both cultivars, probably by action of ACC deaminase activity. The total protein increased in the presence of PEG comparing the two controls for both cultivars. The total protein in CD120 was greater only when bacteria were present compared to their controls indicating a plant cell death for CD120 and Frontana. It is possible to conclude that the association of H. seropedicae is more effective with CD120 and indicated the reduction of ethylene. Frontana associates better with A. brasilense Possibly PEG causes cell death in the system or exudation of proteins by the cultivars tested. These data corroborate with the literature where plant vs. bacteria interaction is genotype and strain dependent.

Best Management Practices for Summer Fallow in the World's Driest Rainfed Wheat Region

CSA NewsVolume 59, Issue 10 p. 12-12 Science Best Management Practices for Summer Fallow in the World's Driest Rainfed Wheat Region First published: 07 October 2014 https://doi.org/10.2134/csa2014-59-10-2Citations: 1Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article.Citing Literature Volume59, Issue10October 2014Pages 12-12 RelatedInformation

P.1.c.002 Inducible rescue of NMDA receptor deficiency to measure the plasticity of neural networks

Weather variables such as maximum and minimum temperatures and precipitation influence crop production especially under rainfed conditions. The goal of this study was to determine the optimum planting date of rainfed wheat based on crop evapotranspiration under water stress conditions (ETc adj), using modeled precipitation uncertainty. This analysis was conducted for 5 locations in the Khorasan province (Mashhad, Sabzevar, Birjand, Bojnourd and Torbat-heydarye) in Iran, using five planting dates at 15 day interval (23 Sep to 23 Nov). The climate data for each location ranged from 29 years to 44 years containing daily values of maximum temperature, minimum temperature, and precipitation. Evapotranspiration was calculated using the FAO (Food and Agricultural Organization of the United Nations) modified form of the Penman–Monteith equation (FAO 56). Cumulative values of ETc adj for all locations except Sabzevar showed the highest values for the final planting date with a sharp increase at the end of the growth period. However, there was no difference among the different planting dates of rainfed wheat for Sabzevar. Rainfed wheat experienced extreme and medium drought conditions based on the calculated Dry Days Since Last Rain (DDSLR) index which represents the number of drought days (DDN) during the growing season. Rainfed wheat planted at the final planting date was exposed to the lowest drought intensity during the growth period for all study locations. Planting a rainfed crop based on the occurrence of the first precipitation is not always a suitable strategy for drought avoidance. The approach introduced here will improve the appropriate selection of representative planting dates that will produce highest potential yield under rainfed conditions.