Effects of laboratory germination, soil temperature and moisture content on the emergence of spring wheat

1986 ◽  
Vol 107 (2) ◽  
pp. 431-438 ◽  
Author(s):  
E. M. Khah ◽  
R. H. Ellis ◽  
E. H. Roberts

SummaryIn field investigations in a sandy-loam soil, probit percentage seedling emergence of commercial and aged seed lots of spring wheat (Triticum aestivum L., cv. Timmo) was a positive linear function of probit percentage laboratory germination and mean soil temperature and a negative linear function of percentage soil moisture content over the ranges 12·1–15·5% moisture content and 7·0–11·0 °C. In a laboratory investigation using the same soil a similar form of relationship was observed in six lots over a range of constant soil moisture contents between 10 and 18% and at constant soil temperatures of 8 and 20 °C. In all cases there was no interaction between any of these determinants of seedling emergence.Linear relationships between the mean rate of seedling emergence in the field (i.e. reciprocal of mean emergence time) and probit percentage laboratory germination and mean soil temperature were shown, but there was no obvious effect of mean scil moisture content between 12·1 and 15·5% on rate of field emergence. Seed lots of different percentage laboratory germination had the same base tsmperature for emergence (1·9 °C): differences between seed lots in mean emergence rate were due to different thermal time (day-degree) requirements for emergence; the thermal times required were a function of probit percentage germination in a standard laboratory test. The implications of these results in providing better advice on sowing rates are discussed.

1938 ◽  
Vol 16c (5) ◽  
pp. 203-213 ◽  
Author(s):  
G. B. Sanford

The effects of soil temperatures between 16° and 25 °C., and of soil moisture content between 19 and 40% of the moisture-holding capacity, on the virulence and type of attack of Rhizodonia Solani on young potato sprouts, were studied under controlled conditions and the results from 13 separate tests are discussed. The comparative growth rates of the pathogen on nutrient agar and in soil are outlined.At 25 °C. the disease diminished very abruptly. Between 23° and 16 °C., the pathogen appeared equally virulent throughout the range of soil moisture mentioned. The fluctuations which occurred in separate tests were not definite or consistent enough to warrant a conclusion that the virulence is greater at 16° than at 23°, or that a dry soil is more or less favorable to it than a wet one.In a fertile, steam sterilized loam, at medium moisture content, it required about ten days for the pathogen to grow as far as it did on the surface of a nutrient medium in four days. The growth rate at either 23° or 16 °C. was slightly higher in a wet soil than in one of medium moisture content, but in a dry soil the rate was somewhat less at 23° than at 16° in a medium or wet soil. Even in a fairly dry soil (19% moisture-holding capacity) at 16° the growth of the pathogen covered a distance of 5 cm. in ten days, which would appear adequate for infection of young sprouts from a set bearing viable sclerotia.The effort of the host to recover, by means of secondary and tertiary sprouts from the attacked primary sprout, was better in a wet soil than in a dry one at both 16° and 23 °C. The best effort was in a wet soil at 23°. A distinction is made between the effects of soil moisture and temperature in stimulating growth of the host, and their effect on parasitism itself.The remarkable tendency of the secondary sprouts to escape infection, regardless of soil temperature and soil moisture, is indicated. There was evidence that certain factors other than soil temperature and moisture may play an important role in the parasitism of R. Solani.


Weed Science ◽  
1974 ◽  
Vol 22 (6) ◽  
pp. 571-574 ◽  
Author(s):  
Chu-Huang Wu ◽  
P. W. Santelmann ◽  
J. M. Davidson

The phytotoxicity of soil-applied terbutryn [2-(tert-butylamino)-4-(ethylamino)-6-(methylthio)-s-triazine] to wheat (Triticum aestivumVill.) was significantly affected by soil moisture and soil temperature. Distribution coefficients (Kd) provided a better indication of the phytotoxicity of terbutryn to wheat than any single measured parameter contributing to herbicide adsorption by the soil. Soil temperatures and soil moisture levels suitable for good plant growth tended to enhance the phytotoxicity of terbutryn. No phytotoxic levels of terbutryn to wheat were detected in Teller sandy loam after 20 weeks of incubation at above 10C and 14% soil moisture by weight. However, phytotoxicity to wheat was observed in air-dry terbutryntreated soil after an incubation period of 20 weeks, regardless of incubation temperature. Significant quantities of terbutryn may remain in the field under dry soil conditions.


1981 ◽  
Vol 61 (4) ◽  
pp. 851-857 ◽  
Author(s):  
J.-M. DESCHENES ◽  
J.-P. DUBUC

Soil moisture and weeds were evaluated under two seeding dates on a St. André sandy loam to explain the increase in grain yield observed with the early sowing of oats (Avena sativa L.), barley (Hordeum vulgare L.), and wheat (Triticum aestivum L.). For each seeding date (early and late May), two soil moisture levels were obtained using the seasonal precipitation as the first level and by adding 25 mm of water/week as the second level. Weed cover was noted on each plot. A greenhouse experiment was conducted by simulating the soil moisture and soil temperature conditions measured in the field. In the field, early seeding and irrigation increased the yield of cereals but the yield differences observed between seeding dates were greater than the yield differences obtained between soil moisture levels. Soil moisture does not explain by itself the increased yield obtained with early seeding because the plots sown in late May and irrigated produced about 80% of the yield obtained on plots sown early and not irrigated. The regression analysis has shown that the soil thermal units between sowing and emergence and the total amount of water between emergence and heading explain more than 50% of the yield variation of cereals. Weeds did not play an important role. Greenhouse results were comparable to those obtained in the field although the importance of soil moisture was more evident. On light soils at La Pocatière, the yield of cereals is regulated by cool soil temperatures at seeding and by high soil moisture level between emergence and heading. These conditions are generally met when seeding is done in early May.


Weed Science ◽  
1976 ◽  
Vol 24 (1) ◽  
pp. 134-136 ◽  
Author(s):  
Stephen D. Miller ◽  
John D. Nalewaja

Wild oat (Avena fatuaL.) seedlings were exposed to vapors arising from soil treated with triallate [S-(2,3,3-trichloroallyl)diisopropylthiocarbamate]. Vapor from the liquid triallate formulation inhibited seedling growth more than vapor from the granular formulation, and the degree of inhibition was least in Fargo clay, intermediate in Hecla sandy loam and greatest in washed sand. Growth inhibition from vapors of soil-applied liquid or granular triallate increased as soil moisture content and soil temperature increased. The site of effective vapor action on wild oat seedlings was below the soil surface.


Nematology ◽  
2002 ◽  
Vol 4 (3) ◽  
pp. 381-386
Author(s):  
Christopher Steel ◽  
John Kirkegaard ◽  
Rod McLeod

AbstractThe effects of seed treatments with pesticides, soil temperature at sowing, cutting of plants with and without glyphosate herbicide, root disruption and age of crop at inoculation on reproduction of Meloidogyne javanica on Brassica napus were investigated. When inoculated at sowing, plants grown from fodder rape cv. Rangi seed treated with fenamiphos (0.35 g a.i. per 100 g) and from fodder swede cv. Highlander seed with a coating including imidacloprid had fewer galls than plants from seed untreated or treated with omethoate (0.7 g a.i. per 100 g). When nematode inoculation was delayed until 4 weeks after sowing, omethoate and the imadacloprid treatments had no effect while fenamiphos (0.7 g a.i. per 100 g seed) suppressed galling but also impaired seedling emergence and induced chlorosis. Green manure rape plants cvs Rangi and Humus transplanted into infested soil in the field in mid-autumn (soil temperature 17°C) remained nematode and gall-free, but tomato cv. Grosse Lisse plants were heavily galled. All three cultivars were gall-free when transplanted and grown in early winter (soil temperatures 8-14°C). Cutting off the tops of cv. Rangi plants at from 6 to 11 weeks after sowing and inoculation had no effect on egg production compared to that on intact plants. Predominant nematode stages in cut plants ranged from developing juveniles to egg-laying females. Application of glyphosate to freshly cut stems had no effect on egg production at any stage. Infesting soil with roots of cv. Rangi, finely chopped while nematodes in them were still juveniles, resulted in a low incidence of infection of bioassay tomato plants compared with infesting soil with rape roots chopped later, when females and females with eggs predominated. Young females in tomato roots laid eggs despite fine chopping of the roots. When cv. Rangi plants were inoculated at 3, 5 and 7 weeks after sowing, the 7-week-old plants were the least invaded and fewer eggs were produced on the 5 and 7-week-old plants than on the 3-week-old ones.


Agriculture ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 933
Author(s):  
Xiaohe Sun ◽  
Changyuan Zhai ◽  
Shuo Yang ◽  
Haolin Ma ◽  
Chunjiang Zhao

Microwave treatment is a green and pollution-free soil disinfection method. The application of microwaves to disinfect soil before cultivation is highly important to increase crop yields and protect the ecological environment. The electromagnetic field is an important parameter influencing the soil temperature field in the process of microwave soil treatment, and the change in soil temperature directly affects soil disinfection. Therefore, this article carried out research on the heating pattern in North China loess due to microwave treatment. First, COMSOL software was employed to simulate the microwave soil treatment process to analyze microwave penetration into soil. Second, with the application of microwaves at the designed frequency produced with a 2.45-GHz tunable microwave generating microdevice, soil with water contents of 0%, 10%, 20%, and 30% was treated for 10~60 s (at 10-s time intervals), and experiments on the influence of the microwave output power, treatment time, and soil moisture content on the soil temperature were performed via the controlled variable method. The simulation results indicate that with increasing soil moisture content, the microwave frequency inside the soil model increases, and the electric field intensity value decreases in the model at the same depth. After microwaves traverse through the 20-cm soil model, the incident field strength is three orders of magnitude lower than the outgoing field strength. The results of the microwave soil treatment experiment reveal that: (1) Compared to microwave output power levels of 1.8 and 1.6 kW, a level of 2 kW is more suitable for microwave soil disinfection. (2) After treatment, the highest temperature occurs on the soil surface, not within the soil. (3) The location of the highest soil internal temperature after microwave treatment increasingly approaches the soil surface with increasing soil moisture content, and the microwave output power does not affect the location of the highest soil internal temperature. Combining the electromagnetic field simulation and microwave soil treatment experiment results, it was found that the higher the field strength is, the higher the temperature value, and the highest soil internal temperature after microwave treatment often occurs at the first electromagnetic wave peak.


1962 ◽  
Vol 42 (3) ◽  
pp. 481-487 ◽  
Author(s):  
S. Dubetz ◽  
G. C. Russell ◽  
D. T. Anderson

Rate and percentage of emergence of 19 native and cultivated herbaceous species were studied at the following soil temperature: 6°, 13°, 18°, and 24 °C. The soil temperatures were held uniformly constant, and emergence data at the end of 5 weeks from four replications in time were obtained. The rate of emergence of all species was greater at 18 °C. than at 6 °C., and of all but five species was greater at 24 °C. than at 18 °C.The percentage of emergence of barley, bromegrass, crested wheatgrass, mustard, oats, peas, spring wheat, and wild oats was not significantly affected by soil temperature. Beans, corn, sugar beets, and sunflowers showed significantly lower emergence percentages at 6 °C. than at the three higher soil temperatures. Alfalfa, creeping red fescue, winter wheat, orchardgrass, rough fescue, sweet clover, and flax emerged best at moderate soil temperatures.


Weed Science ◽  
1973 ◽  
Vol 21 (5) ◽  
pp. 485-489 ◽  
Author(s):  
L. E. Bode ◽  
C. L. Day ◽  
M. R. Gebhardt ◽  
C. E. Goering

In the range of 4.4 to 49 C, there is an exponential relationship between temperature and trifluralin (α,α,α-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine) diffusion coefficients. Diffusion is low in air-dry soil for all temperatures. It increases to a maximum value when the soil has between 8 and 15% w/w soil moisture content and then decreases steadily as moisture content increases. When the air-filled fraction of soil void space is reduced below approximately 40% v/v by either compression or addition of moisture, diffusion begins to decrease. An equation was developed to predict trifluralin diffusion coefficients from a factorial experiment with seven soil moisture contents, five soil temperatures, and two bulk densities. Diffusion coefficients range from 3.8 X 10-11 cm2/sec to 2.8 X 10-6 cm2/sec. Fifteen terms are required in the prediction model to describe accurately the response surface of trifluralin diffusion coefficients. With the equation it is possible to predict trifluralin diffusion coefficients for any combination of measured soil parameters as long as they are represented by the range of the variables used in the experiment.


2019 ◽  
Vol 11 (20) ◽  
pp. 5609
Author(s):  
Junwei Liu ◽  
Vinay Kumar Gadi ◽  
Ankit Garg ◽  
Suriya Prakash Ganesan ◽  
Anasua GuhaRay

Preservation of green infrastructure (GI) needs continuous monitoring of soil moisture. Moisture content in soil is generally interpreted on the basis electrical conductivity (EC), soil temperature and relative humidity (RH). However, validity of previous approaches to interpret moisture content in urban landscape was rarely investigated. There is a need to relate the moisture content with other parameters (EC, temperature and RH) to economize the sensor installation. This study aims to quantify the dynamics of the above-mentioned parameters in an urban green space, and to further develop correlations between moisture content and other parameters (EC, temperature and RH). An integrated field monitoring and statistical modelling approach were adopted to achieve the objective. Four distinct sites comprising treed (younger and mature tree), grassed and bare soil were selected for investigation. Field monitoring was conducted for two months to measure four parameters. This was followed by statistical modelling by artificial neural networks (ANN). Correlations were developed for estimating soil moisture as a function of other parameters for the selected sites. Irrespective of the type of site, EC was found to be the most significant parameter affecting soil moisture, followed by RH and soil temperature. This correlation with EC is found to be stronger in vegetated soil as compared to that without vegetation. The correlations of soil temperature with water content do not have a conclusive trend. A considerable increase in temperature was not found due to the subsequent drying of soil after rainfall. A normal distribution function was found from the uncertainty analysis of soil moisture in the case of treed soil, whereas soil moisture was observed to follow a skewed distribution in the bare and grassed soils.


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