Differential Selection on Rhynchosporium secalis During Parasitic and Saprophytic Phases in the Barley Scald Disease Cycle

Competition among eight Rhynchosporium secalis isolates was assessed during parasitic and saprophytic phases of the disease cycle in field experiments conducted at two locations and over two growing seasons. The eight isolates were inoculated onto six barley populations exhibiting varying degrees of resistance. Microsatellite analysis of 2,866 isolates recovered from the field experiments showed significant, and sometimes opposite, changes in the frequencies of R. secalis genotypes during the growing season (parasitic phase) and between growing seasons (saprophytic phase). Isolates that showed the most complex virulence in greenhouse seedling assays had the lowest fitness in the field experiment. Significant differences in isolate fitness were found on different host populations and in different environments. Selection coefficients were large, indicating that evolution can occur rapidly in field populations. Although inoculated isolates had the lowest overall fitness on the moderately resistant landrace cv. Arabi Aswad, some isolates were more virulent and consistently increased in frequency on this landrace, suggesting a risk of directional selection and possible erosion of the resistance following its widespread deployment in monoculture. These results provide the first direct evidence that R. secalis pathogen genotypes differ in their saprophytic ability and parasitic fitness under field conditions.

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Rattail fescue (Vulpia myuros) interference and seed production as affected by sowing time and crop density in winter wheat

Weed Science ◽

10.1017/wsc.2020.84 ◽

2020 ◽

pp. 1-10

Author(s):

Muhammad Javaid Akhter ◽

Per Kudsk ◽

Solvejg Kopp Mathiassen ◽

Bo Melander

Keyword(s):

Winter Wheat ◽

Grain Yield ◽

Seed Production ◽

Yield Components ◽

Field Experiments ◽

Growing Season ◽

Sowing Time ◽

Growing Seasons ◽

Crop Density ◽

Wide Range

Abstract Field experiments were conducted in the growing seasons of 2017 to 2018 and 2018 to 2019 to evaluate the competitive effects of rattail fescue [Vulpia myuros (L.) C.C. Gmel.] in winter wheat (Triticum aestivum L.) and to assess whether delayed crop sowing and increased crop density influence the emergence, competitiveness, and fecundity of V. myuros. Cumulative emergence showed the potential of V. myuros to emerge rapidly and under a wide range of climatic conditions with no effect of crop density and variable effects of sowing time between the two experiments. Grain yield and yield components were negatively affected by increasing V. myuros density. The relationship between grain yield and V. myuros density was not influenced by sowing time or by crop density, but crop–weed competition was strongly influenced by growing conditions. Due to very different weather conditions, grain yield reductions were lower in the growing season of 2017 to 2018 than in 2018 to 2019, with maximum grain yield losses of 22% and 50% in the two growing seasons, respectively. The yield components, number of crop ears per square meter, and 1,000-kernel weight were affected almost equally, reflecting that V. myuros’s competition with winter wheat occurred both early and late in the growing season. Seed production of V. myuros was suppressed by delaying sowing and increasing crop density. The impacts of delayed sowing and increasing crop density on seed production of V. myuros highlight the potential of these cultural weed control tactics in the long-term management programs of this species.

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Relationship between lodging, morphological characters and yield of varieties of maize (Zea mays L.)

The Journal of Agricultural Science ◽

10.1017/s0021859600060019 ◽

1978 ◽

Vol 91 (3) ◽

pp. 633-638 ◽

Cited By ~ 22

Author(s):

S. U. Remison ◽

Dele Akinleye

Keyword(s):

Zea Mays ◽

Field Experiments ◽

Zea Mays L ◽

Growing Season ◽

Morphological Characters ◽

Growing Seasons ◽

Basal Internode ◽

Ear Height ◽

The Relationship ◽

Rainforest Zone

SummaryField experiments were carried out in the early and late growing seasons in the rainforest zone of Nigeria to find out the relationship between lodging, morphological characters and yield of maize.Morphological characters associated with lodging were plant height, ear height and length of basal internode. There was a negative correlation between lodging and yield. Much of the lodging recorded, especially in the early growing season, was due to weak stems. Earliness, diameter of stem and leaf area had no relationship with lodging.

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Impact of sowing time, hybrid and environmental conditions on the contamination of maize by emerging mycotoxins and fungal metabolites

Italian Journal of Agronomy ◽

10.4081/ija.2017.928 ◽

2017 ◽

Cited By ~ 4

Author(s):

Massimo Blandino ◽

Valentina Scarpino ◽

Debora Giordano ◽

Michael Sulyok ◽

Rudolf Krska ◽

...

Keyword(s):

Environmental Conditions ◽

Field Experiments ◽

Fusarium Species ◽

Growing Season ◽

Fungal Metabolites ◽

Fusarium Spp ◽

Sowing Time ◽

Agronomic Practices ◽

Growing Seasons ◽

Late Sowing

Mycotoxins and other fungal metabolites represent the most insidious safety risks to cereal food and the feed chain. Optimising agronomic practices is one of the main strategies adopted to minimise the contents of these undesirable substances in grain-based commodities. The aim of this study was to investigate the effect of the combination of sowing times and hybrids on the occurrence of emerging mycotoxins and fungal metabolites in maize. Field experiments were carried out in 2 sowing times (early vs late) and 3 maize hybrids were compared in the 2014 and 2015 growing seasons. Overall, 37 fungal metabolites produced by Fusarium and Alternaria species were detected. Apart from fumonisins type B (FBs), other metabolites produced by Fusarium verticillioides and F. proliferatum, such as fumonisins type A, fusaric acid, bikaverin and fusaproliferin, were also detected in all of the samples. Fusarin C was found in 61% of the samples. Deoxynivalenol (DON), deoxynivalenol-3-glucoside, culmorin and zearalenone, all of which are produced prevalently by Fusarium graminearum and F. culmorum, were found in all the samples. Their contents were clearly affected by the meteorological trend: the highest contamination was detected in the 2014 growing season, which was characterised by abundant rainfall and lower temperatures from flowering to maize ripening. Among the mycotoxins produced by other Fusarium species, aurofusarin was found to clearly be associated with DON, while moniliformin and beauvericin followed the same behaviour as the FBs. A late sowing time significantly increased the FBs and fumonisin- associated mycotoxins in both growing seasons. The increase in contamination with the delay of sowing was more pronounced in the 2015 growing season, as the environmental conditions were less favourable to the infection of other Fusarium species. The effect of sowing time on DON and DON-associated mycotoxins produced conflicting results for the two growing seasons, because contamination by these metabolites depends more on the conditions that occur during maize flowering than those that occur during ripening. A clearer hybrid susceptibility was observed for these compounds. Other metabolites, such as enniatins, equisetin, T-2 and HT-2 toxins and Alternaria toxins, were always found in traces. The occurrence of these metabolites seems to be influenced less by the considered agronomic practices. The results, obtained under naturally-infected field conditions, underline the key role that the sowing date and hybrid susceptibility play in influencing, in a variable way, the contamination of mycotoxins produced by different Fusarium species in maize subjected to different meteorological conditions. The content of mycotoxins produced by Fusarium spp. section Liseola is more directly and steadily related to late sowing time, while the contamination of mycotoxins associated to Fusarium spp. section Discolor depend more strongly on the environmental conditions at maize flowering and on hybrid susceptibility.

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Seed dispersal and dormancy patterns in northern willows: ecological and evolutionary significance

Canadian Journal of Botany ◽

10.1139/b83-358 ◽

1983 ◽

Vol 61 (12) ◽

pp. 3207-3216 ◽

Cited By ~ 46

Author(s):

Roseann Densmore ◽

John Zasada

Keyword(s):

Seed Dispersal ◽

Boreal Forest ◽

High Temperatures ◽

Field Experiments ◽

Growing Season ◽

Evolutionary Significance ◽

Cold Stratification ◽

Cold Climates ◽

Growing Seasons ◽

Soil Temperatures

Seeds of the 24 common Salix species of the Alaskan boreal forest and tundra were set to germinate in laboratory and field experiments, and seed dispersal times were observed. During the growing season, 16 species disperse short-lived, nondormant seeds. At the end of the growing season, eight other species, all tundra willows, disperse conditionally dormant seeds. These fall-dispersed seeds are fully developed in the same length of time as summer-dispersed seeds, but they develop dormancy while being held on the plant until the leaves senesce. At the time of dispersal, some seeds are capable of germinating at high temperatures, but no seeds can germinate at the low soil temperatures occurring then. Cold stratification gradually widens the range of temperatures at which seeds can germinate, and seeds germinate at low soil temperatures in the spring shortly after snowmelt. Salix species dispersing dormant seeds during the fall appear to have evolved, as an adaptation to short growing seasons in cold climates, from taxa dispersing nondormant seeds during the summer.

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New Formulation of Clethodim/Adjuvant at Control of Grass Weeds for Soybean Crops

Journal of Agricultural Studies ◽

10.5296/jas.v8i4.17036 ◽

2020 ◽

Vol 8 (4) ◽

pp. 19

Author(s):

Alan Serafini Betto ◽

Rafael Dysarz ◽

Rafaela Cinelli ◽

Rubens Antonio Polito ◽

Tamara Heck ◽

...

Keyword(s):

Weed Control ◽

Field Experiments ◽

Crop Yields ◽

Block Design ◽

Growing Season ◽

Growing Seasons ◽

Randomized Block Design ◽

High Control ◽

New Formulation

The use of ACCase-inhibiting herbicides without the correct addition of an adjuvant is a major cause of inefficient poaceous weed control. As such, this study aimed to assess the efficiency of a new clethodim/adjuvant formulated mixture in postemergence weed control for soybean crops. Two field experiments were conducted in the 2015/16 and 2016/17 growing seasons. A randomized block design, consisting of ten treatments with four repetitions, was used. The treatments and doses were: clethodim (108 g a.i. ha-1) + Lanzar® (0.5%), clethodim (108 g a.i. ha-1) + Nimbus® (0.5%), clethodim/adjuvant formulation at doses of (84 g a.i. ha-1), (96 g a.i. ha-1), (108 g a.i. ha-1), (120 g a.i. ha-1), (132 g a.i. ha-1), and (144 g a.i. ha-1), and a control with and without weeding. The formulated clethodim/adjuvant mixture showed high control at 7 days after application (DAA) in the 2015/16 growing season. At 28 DAA, formulation doses of 108 g a.i. ha-1 and higher exhibited superior weed control and the highest crop yields. Therefore, the use of correct adjuvant or formulated mixture is essential to increase the efficiency of clethodim herbicide.

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Growth Responses of Boreal Scots Pine, Norway Spruce and Silver Birch Seedlings to Simulated Climate Warming over Three Growing Seasons in a Controlled Field Experiment

Forests ◽

10.3390/f11090943 ◽

2020 ◽

Vol 11 (9) ◽

pp. 943

Author(s):

Katri Nissinen ◽

Virpi Virjamo ◽

Antti Kilpeläinen ◽

Veli-Pekka Ikonen ◽

Laura Pikkarainen ◽

...

Keyword(s):

Norway Spruce ◽

Scots Pine ◽

Root Biomass ◽

Growing Season ◽

Silver Birch ◽

Shoot Biomass ◽

Growth Responses ◽

Growing Seasons ◽

Simulated Climate ◽

Shoot And Root Biomass

We studied the growth responses of boreal Scots pine (Pinus sylvestris L.), Norway spruce (Picea abies L. Karst.) and silver birch (Betula pendula Roth) seedlings to simulated climate warming of an average of 1.3 °C over the growing season in a controlled field experiment in central Finland. We had six replicate plots for elevated and ambient temperature for each tree species. The warming treatment lasted for the conifers for three growing seasons and for the birch two growing seasons. We measured the height and diameter growth of all the seedlings weekly during the growing season. The shoot and root biomass and their ratios were measured annually in one-third of seedlings harvested from each plot in autumn. After two growing seasons, the height, diameter and shoot biomass were 45%, 19% and 41% larger in silver birch seedlings under the warming treatment, but the root biomass was clearly less affected. After three growing seasons, the height, diameter, shoot and root biomass were under a warming treatment 39, 47, 189 and 113% greater in Scots pine, but the root:shoot ratio 29% lower, respectively. The corresponding responses of Norway spruce to warming were clearly smaller (e.g., shoot biomass 46% higher under a warming treatment). As a comparison, the relative response of height growth in silver birch was after two growing seasons equal to that measured in Scots pine after three growing seasons. Based on our findings, especially silver birch seedlings, but also Scots pine seedlings benefitted from warming, which should be taken into account in forest regeneration in the future.

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Estimating the Leaf Nitrogen Content with a New Feature Extracted from the Ultra-High Spectral and Spatial Resolution Images in Wheat

Remote Sensing ◽

10.3390/rs13040739 ◽

2021 ◽

Vol 13 (4) ◽

pp. 739

Author(s):

Jiale Jiang ◽

Jie Zhu ◽

Xue Wang ◽

Tao Cheng ◽

Yongchao Tian ◽

...

Keyword(s):

Nitrogen Content ◽

Precision Agriculture ◽

Field Experiments ◽

Mean Squared Error ◽

Growing Season ◽

Leaf Nitrogen ◽

Textural Analysis ◽

Hyperspectral Images ◽

Leaf Nitrogen Content ◽

New Feature

Real-time and accurate monitoring of nitrogen content in crops is crucial for precision agriculture. Proximal sensing is the most common technique for monitoring crop traits, but it is often influenced by soil background and shadow effects. However, few studies have investigated the classification of different components of crop canopy, and the performance of spectral and textural indices from different components on estimating leaf nitrogen content (LNC) of wheat remains unexplored. This study aims to investigate a new feature extracted from near-ground hyperspectral imaging data to estimate precisely the LNC of wheat. In field experiments conducted over two years, we collected hyperspectral images at different rates of nitrogen and planting densities for several varieties of wheat throughout the growing season. We used traditional methods of classification (one unsupervised and one supervised method), spectral analysis (SA), textural analysis (TA), and integrated spectral and textural analysis (S-TA) to classify the images obtained as those of soil, panicles, sunlit leaves (SL), and shadowed leaves (SHL). The results show that the S-TA can provide a reasonable compromise between accuracy and efficiency (overall accuracy = 97.8%, Kappa coefficient = 0.971, and run time = 14 min), so the comparative results from S-TA were used to generate four target objects: the whole image (WI), all leaves (AL), SL, and SHL. Then, those objects were used to determine the relationships between the LNC and three types of indices: spectral indices (SIs), textural indices (TIs), and spectral and textural indices (STIs). All AL-derived indices achieved more stable relationships with the LNC than the WI-, SL-, and SHL-derived indices, and the AL-derived STI was the best index for estimating the LNC in terms of both calibration (Rc2 = 0.78, relative root mean-squared error (RRMSEc) = 13.5%) and validation (Rv2 = 0.83, RRMSEv = 10.9%). It suggests that extracting the spectral and textural features of all leaves from near-ground hyperspectral images can precisely estimate the LNC of wheat throughout the growing season. The workflow is promising for the LNC estimation of other crops and could be helpful for precision agriculture.

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Smallseed Falseflax (Camelina microcarpa) Management in Oklahoma Winter Wheat

Weed Technology ◽

10.1017/wet.2021.51 ◽

2021 ◽

pp. 1-14

Author(s):

Jodie A. Crose ◽

Misha R. Manuchehri ◽

Todd A. Baughman

Keyword(s):

Winter Wheat ◽

Weed Control ◽

Herbicide Resistance ◽

Wheat Yield ◽

Acetolactate Synthase ◽

Growing Season ◽

Time Of Application ◽

Adequate Control ◽

Growing Seasons

Abstract Three herbicide premixes have recently been introduced for weed control in wheat. These include: halauxifen + florasulam, thifensulfuron + fluroxypyr, and bromoxynil + bicyclopyrone. The objective of this study was to evaluate these herbicides along with older products for their control of smallseed falseflax in winter wheat in Oklahoma. Studies took place during the 2017, 2018, and 2020 winter wheat growing seasons. Weed control was visually estimated every two weeks throughout the growing season and wheat yield was collected in all three years. Smallseed falseflax size was approximately six cm in diameter at time of application in all years. Control ranged from 96 to 99% following all treatments with the exception of bicyclopyrone + bromoxynil and dicamba alone, which controlled falseflax 90%. All treatments containing an acetolactate synthase (ALS)-inhibiting herbicide achieved adequate control; therefore, resistance is not suspected in this population. Halauxifen + florasulam and thifensulfuron + fluroxypyr effectively controlled smallseed falseflax similarly to other standards recommended for broadleaf weed control in wheat in Oklahoma. Rotational use of these products allows producers flexibility in controlling smallseed falseflax and reduces the potential for development of herbicide resistance in this species.

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Red spruce seedling gas exchange in response to elevated CO2, water stress, and soil fertility treatments

Canadian Journal of Forest Research ◽

10.1139/x94-125 ◽

1994 ◽

Vol 24 (5) ◽

pp. 954-959 ◽

Cited By ~ 13

Author(s):

L.J. Samuelson ◽

J.R. Seiler

Keyword(s):

Water Stress ◽

Gas Exchange ◽

Soil Fertility ◽

Net Photosynthesis ◽

Growing Season ◽

Red Spruce ◽

Fertility Treatment ◽

Sink Strength ◽

Growth Enhancement ◽

Growing Seasons

The interactive influences of ambient (374 μL•L−1) or elevated (713 μL•L−1) CO2, low or high soil fertility, well-watered or water-stressed treatment, and rooting volume on gas exchange and growth were examined in red spruce (Picearubens Sarg.) grown from seed through two growing seasons. Leaf gas exchange throughout two growing seasons and growth after two growing seasons in response to elevated CO2 were independent of soil fertility and water-stress treatments, and rooting volume. During the first growing season, no reduction in leaf photosynthesis of seedlings grown in elevated CO2 compared with seedlings grown in ambient CO2 was observed when measured at the same CO2 concentration. During the second growing season, net photosynthesis was up to 21% lower for elevated CO2-grown seedlings than for ambient CO2-grown seedlings when measured at 358 μL•L−1. Thus, photosynthetic acclimation to growth in elevated CO2 occurred gradually and was not a function of root-sink strength or soil-fertility treatment. However, net photosynthesis of seedlings grown and measured at an elevated CO2 concentration was still over 2 times greater than the photosynthesis of seedlings grown and measured at an ambient CO2 concentration. Growth enhancement by CO2 was maintained, since seedlings grown in elevated CO2 were 40% larger in both size and weight after two growing seasons.

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Red Rice (Oryza sativa) Control in Drill-Seeded Rice (O. sativa)

Weed Science ◽

10.1017/s0043174500083120 ◽

1985 ◽

Vol 33 (5) ◽

pp. 703-707 ◽

Cited By ~ 8

Author(s):

Amadou Diarra ◽

Roy J. Smith ◽

Ronald E. Talbert

Keyword(s):

Oryza Sativa ◽

Grain Yield ◽

Field Experiments ◽

Growing Season ◽

Rice Cultivar ◽

Rice Grain ◽

Rice Seed ◽

Red Rice ◽

Culm Density ◽

High Yields

Field experiments were conducted to investigate methods of controlling red rice (Oryza sativaL. ♯ ORYSA) in drill-seeded rice (O. sativa). Treatments included the rice cultivar ‘Mars', coated with calcium peroxide (CaO2) at 40% (w/w) and a crop protectant, R-33865 (O,O-diethyl-O-phenyl phosphorothioate) at 0.5 and 1% (v/w). Molinate (S-ethyl hexahydro-1H-azepine-1-carbothioate) at 6.7 kg ai/ha was applied preplant incorporated (ppi). The land was flooded (2.5 to 5 cm deep) after seeding with rice (100 kg/ha, 2.5 cm deep), and the water was maintained throughout the growing season. CaO2, with or without molinate, increased rice grain yield 50% and increased rice culm density fivefold above untreated rice. Molinate applied ppi controlled 96% of the red rice. Rice seed coated with only CaO2or with CaO2plus R-33865 at 0.5%, each combined with ppi molinate, produced 5690 and 6030 kg/ha of grain, respectively. These high yields were associated with red rice control by molinate and good stands of rice provided by O2supplied by CaO2. R-33865 applied to rice seed at 1% (v/w) injured rice by reducing rice culm densities 41%, compared with rice without protectant.

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