Sensitive Growth Stages Research Articles

Baseline sensitivity and control efficacy of antibiosis fungicide tetramycin against Botrytis cinerea

Gray mold is a common disease of many crops worldwide. Tetramycin is a broad-spectrum biopesticide that may control gray mold disease. In the present study, in vitro biological activity of tetramycin was measured in three development stages of Botrytis cinerea, and the baseline sensitivity of B. cinerea to tetramycin was characterized with a set of 165 isolates that were obtained from different geographical regions in Shandong Province, China. Tetramycin’s protective and curative activity against the fungal pathogen was determined on strawberry fruit in laboratory trials, and the efficacy of tetramycin was also determined in field conditions. Spore germination was found to be the most sensitive growth stage that was inhibited by tetramycin, whereas the mycelial growth was the least sensitive growth stage. The baseline sensitivities showed that the frequency distributions of tetramycin were unimodal curves, with mean EC50 values of 0.35 ± 0.20 and 0.020 ± 0.009 μg mL−1 for the inhibition of mycelial growth and spore germination, respectively. Tetramycin had no cross-resistance with other fungicides tested, including carbendazim, iprodione, diethofencarb, pyrimethanil, pyrisoxazole and boscalid. In field trials performed in Tai’an city, Shandong province in 2014 and 2015, tetramycin was used at a concentration of 60 g a.i. ha−1, provided gray mold with an efficacy ranging from 70.73 % to 78.44 %, with no significant difference with other fungicide treatments. These results showed that tetramycin may serve as an alternative fungicide for the control of gray mold in strawberry fruits and cucumber.

Velocity of temperature and flowering time in wheat - assisting breeders to keep pace with climate change.

By accelerating crop development, warming climates may result in mismatches between key sensitive growth stages and extreme climate events, with severe consequences for crop yield and food security. Using recent estimates of gene responses to vernalization and photoperiod in wheat, we modelled the flowering times of all 'potential' genotypes as influenced by the velocity of climate change across the Australian wheatbelt. In the period 1957-2010, seasonal increases in temperature of 0.012 °C yr(-1) were recorded and changed flowering time of a mid-season wheat genotype by an average -0.074 day yr(-1) , with flowering 'velocity' of up to 0.95 km yr(-1) towards the coastal edges of the wheatbelt; this is an estimate of how quickly the given genotype would have to be 'moved' across the landscape to maintain its original flowering time. By 2030, these national changes are projected to accelerate by up to 3-fold for seasonal temperature and by up to 5-fold for flowering time between now and 2030, with average national shifts in flowering time of 0.33 and 0.41 day yr(-1) between baseline and the worst climate scenario tested for 2030 and 2050, respectively. Without new flowering alleles in commercial germplasm, the life cycle of wheat crops is predicted to shorten by 2 weeks by 2030 across the wheatbelt for the most pessimistic climate scenario. While current cultivars may be otherwise suitable for future conditions, they will flower earlier due to warmer temperatures. To allow earlier sowing to escape frost, heat and terminal drought, and to maintain current growing period of early-sown wheat crops in the future, breeders will need to develop and/or introduce new genetic sources for later flowering, more so in the eastern part of the wheatbelt.

The Evaporative Stress Index as an indicator of agricultural drought in Brazil: An assessment based on crop yield impacts

Abstract To effectively meet growing food demands, the global agronomic community will require a better understanding of factors that are currently limiting crop yields and where production can be viably expanded with minimal environmental consequences. Remote sensing can inform these analyses, providing valuable spatiotemporal information about yield-limiting moisture conditions and crop response under current climate conditions. In this paper we study correlations for the period 2003–2013 between yield estimates for major crops grown in Brazil and the Evaporative Stress Index (ESI) – an indicator of agricultural drought that describes anomalies in the actual/reference evapotranspiration (ET) ratio, retrieved using remotely sensed inputs of land surface temperature (LST) and leaf area index (LAI). The strength and timing of peak ESI-yield correlations are compared with results using remotely sensed anomalies in water supply (rainfall from the Tropical Rainfall Mapping Mission; TRMM) and biomass accumulation (LAI from the Moderate Resolution Imaging Spectroradiometer; MODIS). Correlation patterns were generally similar between all indices, both spatially and temporally, with the strongest correlations found in the south and northeast where severe flash droughts have occurred over the past decade, and where yield variability was the highest. Peak correlations tended to occur during sensitive crop growth stages. At the state scale, the ESI provided higher yield correlations for most crops and regions in comparison with TRMM and LAI anomalies. Using finer scale yield estimates reported at the municipality level, ESI correlations with soybean yields peaked higher and earlier by 10 to 25 days in comparison to TRMM and LAI, respectively. In most states, TRMM peak correlations were marginally higher on average with municipality-level annual corn yield estimates, although these estimates do not distinguish between primary and late season harvests. A notable exception occurred in the northeastern state of Bahia, where the ESI better captured effects of rapid cycling of moisture conditions on corn yields during a series of flash drought events. The results demonstrate that for monitoring agricultural drought in Brazil, value is added by combining LAI with LST indicators within a physically based model of crop water use.

Baseline sensitivity and efficacy of the sterol biosynthesis inhibitor triflumizole against Botrytis cinerea

Triflumizole is a broad-spectrum fungicide in the chemical group of imidazoles. In the present study, the biological activity of triflumizole on Botrytis cinerea was determined in vitro, and the protective and curative activity against the fungal pathogen was determined on cucumber true leaves. Moreover, the baseline sensitivity for mycelial growth of B. cinerea to triflumizole was determined in vitro with a set of 79 isolates obtained from different geographical regions in Shandong Province of China. Inhibition of mycelial growth was found to be the most sensitive growth stage affected by triflumizole, whereas spore germination of B. cinerea was the least sensitive growth stage. Triflumizole provided excellent curative activity against B. cinerea at concentrations of 100 and 200 μg mL−1 and also was highly protective against the fungus at 200 μg mL−1. However, the control efficacy of protective activity and curative activity were relatively low when the concentration decreased to 50 μg mL−1. The baseline sensitivities were distributed as a unimodal curve, with a mean EC50 value of 0.58 μg mL−1. The individual EC50 values for triflumizole ranged from 0.15 to 1.49 μg mL−1. Triflumizole had no cross-resistance with other botryticides, including carbendazim, iprodione, diethofencarb, pyrimethanil and boscalid. However, cross-resistance to SPY-Z048, which is also a sterol biosynthesis inhibitor, was observed. In field trials in 2014 and 2015, triflumizole used at a concentration of 150 g a.i. ha−1 provided control efficacy on leaf ranging from 80.76 to 86.32 %, and its control efficacy on fruit could reach 84.93 % ~89.06 %, which were higher than the control efficacy of other treatments. These results suggested that triflumizole will be a good alternative fungicide for control of grey mould.

English

Sunflower has become an important crop for both farmers and consumers in Sudan. It is a crop that fits well in the local cropping system and is considered one of the most important oil crops of the country. Regular irrigation intervals could be reduced in order to increase total yield and maximize water productivity. In contrast prolonged irrigation intervals during sensitive growth stages may result in reduction in total yield. The application of water below the evapotranspiration requirements is termed deficit irrigation (DI). The experiments were conducted at Gezira Research Station, WadMedani, Sudan, in a randomized complete block design with three replications. In this study irrigation intervals every week (W) during the whole growing period, 10 days interval (F1), 15 days interval (F2) and 20 days interval (F3) after flowering stage and 10 days interval (S1), 15 days interval (S2) and 20 days interval (S3) after seed filling stage were applied to study the effect of full and deficit irrigation on yield and yield components of sunflower crop during the two growing periods 2011/12 and 2012/13. Results showed that water stress decreased the number of filled seeds per head, weight of full seed and seed yield. The highest seed yield of (3130 and 3140 kg/ha) was obtained from full irrigation (W) and the lowest seed yield of (2082 and 2130 kg/ha) from irrigation every 20 days after flowering stage in the first and second season respectively. Results indicated that there were no-significant differences on head diameter, plant height and stem diameter when water deficit occurred after the flowering stages. Lower WP of 0.21 to 0.26 and 0.21 to 0.27 kg/m3 were obtained when sunflower irrigated every 20 days after flowering and seed filling stages in the first and second season respectively. Results revealed that water productivity was low under Gezira conditions.   Key words: Water productivity, deficit irrigation, sunflower, seed yield.

Sensitive growth stages and temperature thresholds in wheat (Triticum aestivum L.) for index-based crop insurance in the Indo-Gangetic Plains of India

SUMMARYHigh temperature stress at critical growth stages is a major risk factor for wheat in many wheat growing areas globally. Developing weather indices relating to yield reductions in wheat is an urgent requirement for weather-index-based crop insurance. The objectives of the present study were to: (i) identify critical phenological stage(s) for heat stress, (ii) quantify the impact of heat stress at critical growth stage(s) and (iii) work out thresholds of temperature for obtaining above average, average and below average yield of wheat. For achieving these objectives, 11 years’ experimental data for three cultivars (HD-2285, K-8804 and K-9107) under three sowing dates at the Kanpur Centre located in the Indo-Gangetic Plains of Uttar Pradesh, India were used. Among the eight phenological stages, the milk stage (growth stage 73) was identified as most sensitive for high maximum and minimum temperatures to adversely affect yield. The rate of yield reduction with unit increase in maximum and minimum temperatures (°C) was found to be highest in K-8804 and lowest in HD-2285. The optimum ranges of maximum temperature during anthesis, milk, dough and maturity stages are 19·7–21·9, 24·2–26·5, 26·1–28·8 and 29·5–30·8 °C, respectively and those for minimum temperature are 4·3–6·2, 8·3–9·7, 11·5–12·4 and 13·0–15·1 °C, respectively. The thresholds of temperature during critical stages and quantification of heat stress on yield will be of use in devising weather-index-based crop insurance products in wheat and also for breeding temperature-stress-resistant genotypes. This method of devising weather indices in the present study can be used in other crops and regions of the world as an adaptation strategy for climate change.

Intensity of heat stress in winter wheat—phenology compensates for the adverse effect of global warming

Higher temperatures during the growing season are likely to reduce crop yields with implications for crop production and food security. The negative impact of heat stress has also been predicted to increase even further for cereals such as wheat under climate change. Previous empirical modeling studies have focused on the magnitude and frequency of extreme events during the growth period but did not consider the effect of higher temperature on crop phenology. Based on an extensive set of climate and phenology observations for Germany and period 1951–2009, interpolated to 1 × 1 km resolution and provided as supplementary data to this article (available at stacks.iop.org/ERL/10/024012/mmedia), we demonstrate a strong relationship between the mean temperature in spring and the day of heading (DOH) of winter wheat. We show that the cooling effect due to the 14 days earlier DOH almost fully compensates for the adverse effect of global warming on frequency and magnitude of crop heat stress. Earlier heading caused by the warmer spring period can prevent exposure to extreme heat events around anthesis, which is the most sensitive growth stage to heat stress. Consequently, the intensity of heat stress around anthesis in winter crops cultivated in Germany may not increase under climate change even if the number and duration of extreme heat waves increase. However, this does not mean that global warning would not harm crop production because of other impacts, e.g. shortening of the grain filling period. Based on the trends for the last 34 years in Germany, heat stress (stress thermal time) around anthesis would be 59% higher in year 2009 if the effect of high temperatures on accelerating wheat phenology were ignored. We conclude that climate impact assessments need to consider both the effect of high temperature on grain set at anthesis but also on crop phenology.

A Novel Phenotyping Technique for Reproductive-stage Salinity Tolerance in Rice

Rice responds differentially at different stages of development for salinity tolerance. Seedling and reproductive stages are the most sensitive growth stages; however, association between tolerances at the two stages is very weak, suggesting their regulation through different processes and sets of genes/QTLs. There are numerous reports on seedling-stage salinity tolerance in rice, but hardly on reproductive-stage salinity tolerance mainly because of the lack of reliable reproductive-stage-specific phenotyping.There are two major challenges, first, how to stress plants at the reproductive stage without stressing them at the seedling or late vegetative stage. Second, how to impose the stress on different genotypes or mapping populations at equivalent growth stages of development as they may mature differently. We devised a methodology that allows salt translocation to the reproductive organs such as the flag leaf (the largest source for the sink) and panicle as quickly as possible just at the initiation of booting when the genotypes are at the same stage of tissue/organ development rather depending on age of the plant. Extra leaves were clipped, leaving only a minimum number of leaves needed by the rice plant that will not significantly affect grain yield and yield components. Salt stress equivalent to EC 10 dSm-1 was imposed on rice plants with trimmed leaves starting from boot leaf emergence up to 20 days in a pot experiment under controlled conditions. The stage-specific effect of salt stress was verified by observing salt-sensitive and salt-tolerant genotypes. Leaf cutting before the booting stage efficiently directed the salt concentration to the reproductive stage and helped in discriminating tolerant genotypes from sensitive ones as evidenced by the lower pollen viability and higher accumulation of toxic ions in the flag leaf of the sensitive genotype (IR64). The opposite was found true for the tolerant genotype (IR4630-22-2-5-1-3). Details will be discussed during presentation.

Sowing and irrigation strategies for improving rainfed tef (Eragrostis tef (Zucc.) Trotter) production in the water scarce Tigray region, Ethiopia

Field experiments conducted under rainfed agriculture for three consecutive years (2008–2010) revealed that water stress at the late season is the most limiting factor for the productivity of tef (Eragrostis tef (Zucc.) Trotter) in Tigray, Ethiopia. Early sowing and one irrigation application late in the growing season, were evaluated with the AquaCrop model as management strategies to improve productivity. Simulations were run for three dominant soil types, under different soil fertility levels, and for four different locations in the region each with 19 years of historical climatic data. Advancing the sowing date, two to three weeks earlier than the commonly practiced by the farmers, resulted in stable yields and reduced the risks on yield failure by 72 to 100%. Moderate to high yields could only be achieved when the recommended fertilizer dose was applied. The yields became moderate but remained stable, by applying only 50% of the recommended dose, which is an affordable soil fertility management practice for the farmers. Considering the limited capacity of most farmers for irrigation, a very limited irrigation with only rainwater harvested during the growing cycle, was assessed as a strategy to further boost the productivity of tef in the region. Depending on the soil fertility level, one irrigation application of only 45mm around flowering, increased the yield by 50–168% for late sowing and 16–75% for early sowing. In conclusions, this study revealed that optimal timing for sowing and one-time irrigation applied only during water sensitive growth stage are good strategies to improve the productivity of rainfed crops in a drought-prone areas.

Chemical polymorphism in defense secretions during ontogenetic development of the millipede Niponia nodulosa.

A mixture of defense compounds (benzaldehyde, benzoyl cyanide, benzoic acid, mandelonitrile, and mandelonitrile benzoate), found commonly in cyanogenic polydesmid millipedes, was identified in the non-cyanogenic millipede Niponia nodulosa. These compounds were major components in 1st-4th instars, but were absent in older instars and adults. Extracts of older instars and adults contained 1-octen-3-ol, 2-methyl-2-bornene, E-2-octen-1-ol, 2-methyl-isoborneol, and geosmin; these compounds were minor components in 1st-4th instars. This ontogenetic allomone shift may be explained by the high cost of biosynthesis of polydesmid compounds from L-phenylalanine being offset by their potency in protecting the insect during fragile and sensitive growth stages. However, as the cuticle hardens in older juveniles (5th, 6th, 7th instars) and adults, this allows for a switch in defense to using less effective and less costly volatile organic compounds (presumably microbial in origin) that are ubiquitous in the millipede's habitat or are produced by symbiotic microbes and may be readily available through food intake or aspiration.

Prediction of maize yield under future water availability scenarios using the AquaCrop model

SUMMARYThe water driven crop growth model AquaCrop was evaluated for predicting the yield of kharif maize (i.e. maize sown in the monsoon season) under future water availability scenarios. Future climatic data were generated using the climate data generator ClimGen, which was parameterized using 37 years (1972–2008) of historical data relating to the study area. The climatic data generated were used first in the CROPWAT model to estimate the irrigation schedule, which was then used in the validated AquaCrop model to predict grain yield for future years. Rainfall estimates generated by ClimGen for 2012 (739 mm) and 2014 (625 mm) resulted in yields of 1600 and 5670 kg/ha, respectively, under rainfed situation during these 2 years with full fertilization levels. This variation may be attributed to the depths of rainfall events and their distribution during the entire growing season in general and sensitive growth stages in particular pertaining to the same sowing date (22 July) in both years. Nonetheless, the use of ClimGen, CROPWAT and AquaCrop models can be standardized as a model-linking protocol to estimate future maize yield and irrigation water requirements for sustainable production and as an adaptation measure to climate change.

Performance of mungbean under deficit irrigation application in the semi-arid highlands of Ethiopia

Knowing the performance of short season crops under deficit irrigation has a paramount importance for arid and semi-arid regions with limited access to on-farm water harvesting or other irrigation infrastructure. In this research, the performance of mungbean, a newly introduced crop into the cropping systems in Ethiopia, to stage-wise and uniform deficit irrigation was tested at Sekota Dryland Agricultural Research Center, Northern Ethiopia. Eight treatments – four stage-wise deficit and four uniform deficit irrigation applications were evaluated during the 2010/2011 dry season. Plant phenological variables, grain yield and irrigation water use efficiency were used for performance evaluation. The results showed that a uniform water stress shortened the dates to 50% flowering and maturity, but with proportionate reduction in yield. The yield obtained varied between 1366kg/ha under 331mm optimal seasonal irrigation to 492kg/ha when one-fourth of ETc (102mm) was uniformly applied though out the growing season. The flowering/reproductive stage was noted as the most sensitive growth stage with a 24.9% yield reduction compared to the control treatment. In all other stages, yield is linearly associated (R2=0.93) with the amount of irrigation water applied, over the range tested. IWUE values ranged from 0.248 to 0.304kg/m3. It can therefore be concluded that provided stress at the midseason stage is avoided and depending on the volume of water available, different deficit irrigation arrangements using on-farm pond water is possible.

Deriving data mining and regression based water-salinity production functions for spring wheat (Triticum aestivum)

Production functions (PFs) are practical tools for not only irrigation scheduling but also in economic analysis as a mathematical relationship between relative grain yield and factors like evapotranspiration, irrigation water and salinity. This study was carried out in the Mashhad region of Iran during cropping years 2010 and 2011 to evaluate the performances of two data mining methods, decision tree and neural network, for deriving PFs of spring wheat under simultaneous drought and salinity stress compared with four well known regression-based PFs. The four well known PFs were: Jensen-PF (Jensen, 1968), Minhas-PF (Minhas et al., 1974), modified Stewart-PF (Stewart et al., 1977; Stegman et al., 1980), and Nairizi-PF (Nairizi and Rydzewski, 1977). Heading and flowering were the most sensitive growth stages followed by the stem elongation and booting. Salinity stress also affected grain yield and therefore was an important parameter for deriving PFs. In general, all the PFs were in agreement concerning the sensitivity of spring wheat to water stress. The neural network-based PF performed the best with a root mean square error equal to 44.27gm−2 while the decision tree-based PF ranked fourth out of six in terms of accuracy. The most important advantage of the neural network-based PF was the flexible number of input parameters.

Investigation of water deficit stress effects on yield and yield components of four soybean cultivars at different growth stages

In order to evaluate effects of water deficit stress on yield and yield components of four soybean cultivars (Sahar, Williams, Hobit and Harcor), an experiment was conducted in the Agricultural Research Station in Shirvan Chardavul, Ilam, Iran in 2010. The experiment was arranged as split plot based on randomized complete block design in three replicates. The stress conditions consisted of three different levels of water deficit stress: I1: irrigation during all growth stages as control treatment, I2: omit irrigation at the onset of flowering stage (R1) and I3: omit irrigation at the onset of grain filling stage (R6). Results showed that water deficit stress had significant effect on number of pod, number grain per pod, number of grain per plant, 100grain weight, grain yield and biological yield. Also all of agro-morphological traits except harvest index influenced significantly by cultivars. The highest reduce of traits were at I2 to I3. In general, grain yield and yield components decreased with increasing water deficit. Therefore, water deficit can reduce the grain yield and its components however, the most grain yield and yield components was belonged to ‘Sahar’ and ‘Harcor’ cultivars under stress and non-stress conditions. Thus, these cultivars can be the most tolerant than other cultivars and the grain filling stage was the most sensitive growth stage of soybean to water deficit stress in this region.

Moisture extraction pattern and ET-yield models in wheat under different management practices in central Punjab

Under water limiting conditions, evaluation of sensitivity of crop growth stages to evapotranspiration is indispensable for efficient and judicious use of irrigation water. The present investigation was carried out at the research farm, School of Climate Change and Agricultural Meteorology, Punjab Agricultural University, Ludhiana during rabi 2006-07 and 2007-08. The experiment was laid out in randomized block design with two planting methods i.e. flat planting (F) and planting on raised beds (B) and five irrigation levels. Flat planting method recorded higher soil moisture depletion / ET as compared to bed planting during both the years of investigation. During 2006-07, soil moisture depletion for rainfed and four post-sowing irrigation treatments was 256 and 376 mm for bed planted, whereas it was 285 and 402 mm for flat sown crop, respectively. Similarly during 2007-08, soil water depletion for the corresponding treatments was 286 and 437 mm for bed planted; whereas it was 337 and 467 mm for flat sown crop. Multiplicative and additive ET and yield models suggested reproductive growth to be the most sensitive crop growth stage to soil moisture.

Effects of time of water stress on flowering, seed yield and seed quality of common onion (Allium cepa L.) under the arid tropical conditions of Sudan

An experiment was conducted for two consecutive seasons to investigate the effect of water stress on seed yield and seed quality of onion (Allium cepa L.). Water stress was imposed on the plants at four stages of reproductive growth, namely, bolting, flowering, seed formation and seed maturation stage, respectively. Watering was withheld for an interval of 2 weeks only once for every treatment “growth stage” during the first season, while during the second season, the interval of watering was extended to 3 weeks. Numbers of leaves per plant, umbel diameter, number of florets per umbel, number of seeds per florets; number of seed stalks per plant, 1000 seed weight per plant and seed yield and seed quality were recorded. Water stress at any stage of reproductive growth significantly reduced seed yield and its effect was variable depending on plant growth stage. Based on 1000 seed weight per seed head, bolting followed by anthesis were the most sensitive growth stages during the first season. Water stress at the time of anthesis significantly decreased the diameter of seed head when compared to control. The average number of seeds per floret was significantly decreased by stressing at bolting compared to all treatments. In the second season, seed formation stage was the most critical only followed by anthesis stage. When seed yield per plant was measured, the most sensitive stage was bolting. Number of florets per umbel and umbel diameter were reduced by water stress. In the first season, 1000 seed weight was not affected, but in the second season, it was significantly reduced with water stress at seed formation stage. Seed germination and field emergence were not affected. However, water stress at bolting in the second season resulted in lower seed quality. Some stress treatments were observed to promote seed germination and seedling emergence.

Effect of Salt Stress in Different Stages of Growth on Qualitative and Quantitative Characteristics of Cumin (Cuminum Cyminum L.)

Abstract Cumin (Cuminum cyminum L.) is one of the most important pharmaceutical plants. As a considerable portion of existing agricultural lands in arid regions is exposed to aridity and finally to salinity, we need to study the effects of salinity on the growth and production of agronomical products. For this purpose, an agricultural experiment in the form of split plots with three replications was conducted in 2011 at the Islamic Azad University, Gonabad Branch, Iran, in the longitude of 58°, 50’, latitude of 34°, 54’, and altitude of 940 m from the sea level. At the main plot, four salinity levels (2,5,8 and 11ds/m) and at the sub plot, the growth stages of stress implementation (including stress in establishment, flowering, and seed filling stage), were located at random. The results showed that the salinity rate had significant impact on fresh weight, dry weight, height , percentage of essence, seed and biological yield. With the increase in salinity from 2 to 11ds/m, a significant decrease in all vegetative and reproductive characteristics were observed. The most sensitive growth stages of plant to salt stress, during vegetative and reproductive period were the stage of establishment and flowering, respectively. There was no interaction between the growth stage of plant and salinity rate, except for seed yield and harvest index.

How Early Can the Seeding Dates of Spring Wheat Be under Current and Future Climate in Saskatchewan, Canada?

BackgroundShorter growing season and water stress near wheat maturity are the main factors that presumably limit the yield potential of spring wheat due to late seeding in Saskatchewan, Canada. Advancing seeding dates can be a strategy to help producers mitigate the impact of climate change on spring wheat. It is unknown, however, how early farmers can seed while minimizing the risk of spring frost damage and the soil and machinery constraints.Methodology/principal findingsThis paper explores early seeding dates of spring wheat on the Canadian Prairies under current and projected future climate. To achieve this, (i) weather records from 1961 to 1990 were gathered at three sites with different soil and climate conditions in Saskatchewan, Canada; (ii) four climate databases that included a baseline (treated as historic weather climate during the period of 1961–1990) and three climate change scenarios (2040–2069) developed by the Canadian global climate model (GCM) with the forcing of three greenhouse gas (GHG) emission scenarios (A2, A1B and B1); (iii) seeding dates of spring wheat (Triticum aestivum L.) under baseline and projected future climate were predicted. Compared with the historical record of seeding dates, the predicted seeding dates were advanced under baseline climate for all sites using our seeding date model. Driven by the predicted temperature increase of the scenarios compared with baseline climate, all climate change scenarios projected significantly earlier seeding dates than those currently used. Compared to the baseline conditions, there is no reduction in grain yield because precipitation increases during sensitive growth stages of wheat, suggesting that there is potential to shift seeding to an earlier date. The average advancement of seeding dates varied among sites and chosen scenarios. The Swift Current (south-west) site has the highest potential for earlier seeding (7 to 11 days) whereas such advancement was small in the Melfort (north-east, 2 to 4 days) region.Conclusions/significanceThe extent of projected climate change in Saskatchewan indicates that growers in this region have the potential of earlier seeding. The results obtained in this study may be used for adaptation assessments of seeding dates under possible climate change to mitigate the impact of potential warming.

Biological activity of the succinate dehydrogenase inhibitor fluopyram against Botrytis cinerea and fungal baseline sensitivity

Succinate dehydrogenase inhibitors (SDHIs) constitute a fungicide class with increasing relevance in crop protection. These fungicides could play a crucial role in successful management of grey mould disease. In the present study the effect of fluopyram, a novel SDHI fungicide, on several developmental stages of Botrytis cinerea was determined in vitro, and the protective and curative activity against the pathogen was determined on strawberry fruit. Furthermore, fungal baseline sensitivity was determined in a set of 192 pathogen isolates. Inhibition of germ tube elongation was found to be the most sensitive growth stage affected by fluopyram, while mycelial growth was found to be the least sensitive growth stage. Fluopyram provided excellent protective activity against B. cinerea when applied at 100 µg mL(-1) 96, 48 or 24 h before the artificial inoculation of the strawberry fruit. Similarly, fluopyram showed a high curative activity when it was applied at 100 µg mL(-1) 24 h post-inoculation, but, when applications were conducted 48 or 96 h post-inoculation, disease control efficacy was modest or low. The measurement of baseline sensitivity showed that it was unimodal in all the populations tested. The individual EC(50) values for fluopyram ranged from 0.03 to 0.29 µg mL(-1). In addition, no correlation was found between sensitivity to fluopyram and sensitivity to other fungicides, including cyprodinil, fenhexamid, fludioxonil, iprodione, boscalid and pyraclostrobin. The obtained biological activity, baseline sensitivity and cross-resistance relationship data suggest that fluopyram could play a key role in grey mould management in the near future and encourage its introduction into spray programmes.

Effects of fixed partial root-zone drying irrigation and soil texture on water and solute dynamics in calcareous soils and corn yield

► In field evaluation FPRD proved that it is a cost effective irrigation method for row crops. ► Deep percolation under FPRD drip irrigation is limited. ► Salt built up in high levels in the soil surface of the non irrigated interrow positions and decreased with depth. ► Transport and distribution of soluble salts are affected by the soil textural class, the CaCO 3 content and possibly the dissolution and precipitation of salts. ► Corn yield reached the usual standards despite the fact that the salinity levels encountered during the sensitive growth stages exceeded the salt tolerance threshold of corn. Water dynamics and salt distribution in the soil were studied under Fixed Partial Root zone Drying irrigation (FPRD) conditions in corn fields in Northern Greece. FPRD irrigation technique was applied without deficit treatment in two calcareous soils, a sandy clay loam and a sandy loam. Soil water content was recorded in the vertical profile of 0.6 m with the use of capacitance sensors in the row and interrow positions of plants. Salt built-up was monitored to the depth of the root zone, bi-weekly, by measuring electrical conductivity (EC e ) and the concentrations of soluble cations Ca 2+ , Mg 2+ , Na + and K + of the saturation extract on irrigated and non irrigated interrow positions. Soil moisture distribution and salt built-up in soil were used to evaluate the potentials and constraints of FPRD efficiency to sustain plant growth and crop production as a low cost drip irrigation technique. The results indicated that FPRD application on both soils was capable of supplying sufficient amounts of water on plant row. Soil analyses showed that salts accumulated to high levels in the soil surface and decreased in depth at the non irrigated interrow positions. Spatial and temporal variability of salt movement and distribution in the soil profile of 0.6 m were ascribed to soil textural differences. The development and yield of corn plants for both soils reached the usual standards for the area with a minor decrease in the sandy loam soil.