Interactions between Pythium nunn and Pythium ultimum on bean leaves

1988 ◽  
Vol 34 (8) ◽  
pp. 947-951 ◽  
Author(s):  
T. C. Paulitz ◽  
R. Baker
Keyword(s):  
Sandy Loam ◽  
Pythium Ultimum ◽  
Soil P ◽  
Pythium Nunn ◽  
Bean Leaves

Colonization of bean leaf fragments by Pythium nunn and Pythium ultimum in naturally and artificially infested soils was studied. In soil naturally infested with both P. ultimum and P. nunn (Ascalon sandy loam), the fungi colonized 20 and 0% of the fragments after 6 h, and 54 and 78% after 12 h, respectively. After 24 h, 73% of the fragments were co-colonized by both fungi, but after 72 h, less than 10% of the fragments were colonized by P. ultimum, and over 90% were colonized by P. nunn. In soil artificially infested with P. nunn (300 cfu/g), colonization by P. ultimum was significantly reduced after 18 h. Similar trends were observed in aerated–steamed and other soils artificially infested with P. nunn. When fragments were precolonized by P. ultimum for 24 h and then challenged with P. nunn, 77% were colonized by P. nunn after 24 h. In the reciprocal treatment, less than 5% of the fragments precolonized by P. nunn were colonized by P. ultimum. In bean leaf fragments placed in aerated–steamed soil, P. nunn reduced the density of sporangia of P. ultimum. This evidence suggests that P. nunn is both a primary and secondary colonizer capable of possession of substrates previously occupied by P. ultimum, and that P. nunn can displace P. ultimum from bean leaf fragments.

Influence of soil texture on fertilizer and soil phosphorus transformations in Gleysolic soils

2003 ◽  
Vol 83 (4) ◽  
pp. 395-403 ◽  
Author(s):  
Z. Zheng ◽  
L. E. Parent ◽  
J. A. MacLeod
Keyword(s):  
Soil Texture ◽  
Agricultural Soils ◽  
Sandy Loam ◽  
Clay Content ◽  
P Uptake ◽  
Hordeum Vulgare L ◽  
P Fractionation ◽  
Soil P ◽  
Plant P Uptake ◽  
Heavy Clay

The P dynamics in soils should be quantified in agricultural soils to improve fertilizer P (FP) efficiency while limiting the risk of P transfer from soils to water bodies. This study assessed P transformations following FP addition to Gleysolic soils. A pot experiment was conducted with five soils varying in texture from sandy loam to heavy clay, and receiving four FP rates under barley (Hordeum vulgare L.)-soybean (Glycine max L.) rotations. A modified Hedley procedure was used for soil P fractionation. Soil resin-P and NaHCO3-Pi contents were interactively affected by texture and FP. The NaHCO3-Po, NaOH-Po, HCl-P and H2SO4-P were only affected by soil texture. Proportions of 78 and 90% of the variation in labile and total P were, respectively, related to soil clay content. The FP addition increased resin-P, NaHCO3-Pi and NaOH-Pi and -Po contents in coarse-textured soils, but the amount added was not sufficient to mask the initial influence of soil texture on the sizes of soil P pools. Plant P uptake was proportional to FP rate but less closely linked to clay content. The average increase in labile P per unit of total FP added in excess of plant exports was 0.85, 0.8 2 , 0.73, 0.55 and 0.24 for the sandy loam, loam, clay loam, clay and heavy clay soil, respectively. The results of this study stress the important of considering soil texture in Gleysolic soils when assessing P accumulation and transformations in soils, due to commercial fertilizers applied in excess of crop removal. Key words: P fractions, clay content, fertilizer P, plant P uptake, soil texture

Turgor Pressure in Mechanically Impeded Lupin Roots

1990 ◽  
Vol 17 (1) ◽  
pp. 49 ◽  
Author(s):  
BJ Atwell ◽  
JC Newsome
Keyword(s):  
Volume Expansion ◽  
Root Elongation ◽  
Sandy Loam ◽  
Turgor Pressure ◽  
Mechanical Impedance ◽  
Pressure Probe ◽  
Soil P ◽  
Primary Roots ◽  
Root Apices ◽  
Probe Measurements

Seedlings of lupin (Lupinus angustifolius cv. 75A-258) were grown in cores of sandy loam which was compacted to bulk densities of 1.6 and 1.8 Mg m-3 . There was a substantial decrease in root elongation rate at the higher bulk density. After 4-7 d, roots were rinsed free of soil and clamped loosely in a Perspex block for measurement of turgor pressure (P) using a pressure probe. Measurements were made at 3-4 positions on each root, each estimation taking 2 min. Turgor pressures in the terminal 15 mm of the axes ranged between 0.213 and 0.530 at 1.6 Mg m-3 and 0.210 and 0.570 MPa at 1.8 Mg m-3; mean P values were 0.365 and 0.351 MPa in roots growing at 1.6 and 1.8 Mg m-3, respectively. These measurements were made on roots removed from the soil; P could have been greater in roots still growing in compact soil. Anatomical studies showed that the distal boundary of the zone of cell expansion was 2-4 mm nearer the apex in roots growing at 1.8 than at 1.6 Mg m-3. Using this information, we showed that the mean P of expanding tissue was the same in roots of the two treatments. The apparent rise in P near the apex of roots at 1.8 Mg m-3 was not statistically significant. Primary roots growing against high mechanical impedance had a 34% lower rate of elongation and a 22% greater diameter, resulting in nearly identical rates of volume expansion (35.1 and 34.9 mm3 d-1 at 1.6 and 1.8 Mg m-3 respectively). Furthermore, the rate of O2 uptake was the same in 10 mm root apices from both treatments so that there was no evidence that the carbohydrate requirement for respiration was enhanced by high soil strength. Moreover, while mechanical impedance decreased root elongation, it did not significantly affect our estimate of P. We believe that P in lupin roots changes in response to mechanical impedance only when volume expansion or utilization of solutes are affected.

Changes in chemical properties of 48 intensively grazed, rain-fed dairy paddocks on sandy soils over 11 years of liming in south-western Australia

Soil Research ◽  
2010 ◽  
Vol 48 (8) ◽  
pp. 682 ◽  
Author(s):  
M. D. A. Bolland ◽  
W. K. Russell
Keyword(s):  
Western Australia ◽  
Root Zone ◽  
Sandy Loam ◽  
Chemical Properties ◽  
Soil Testing ◽  
Soil Test ◽  
Organic Carbon Content ◽  
Pasture Production ◽  
Soil P ◽  
Soil Test P

Soil testing was conducted during 1999–2009 to determine lime and fertiliser phosphorus (P), potassium (K), and sulfur (S) requirements of intensively grazed, rain-fed, ryegrass dairy pastures in 48 paddocks on sand to sandy loam soils in the Mediterranean-type climate of south-western Australia. The study demonstrated that tissue testing was required in conjunction with soil testing to confirm decisions based on soil testing, and to assess management decisions for elements not covered by soil testing. Soil testing for pH was reliable for indicating paddocks requiring lime to ameliorate soil acidity, and to monitor progress of liming. Soil P testing proved reliable for indicating when P fertiliser applications were required, with no P being required when soil-test P was above the critical value for that soil, and when no P was applied, tissue testing indicated that P remained adequate for ryegrass production. Soil testing could not be used to determine paddocks requiring fertiliser K and S, because both elements can leach below the root-zone, with rainfall determining the extent of leaching and magnitude of the decrease in pasture production resulting from deficiency, which cannot be predicted. The solution is to apply fertiliser K and S each year, and use tissue testing to improve fertiliser K and S management. Research has shown that, for dairy and other grazing industries in the region, laboratories need measure and report every year soil pH and soil-test P only, together with measuring every 3–5 years the P-buffering index (estimating P sorption of soil), organic carbon content, and electrical conductivity.

Output and sustainability of organic ley/arable crop rotations at two sites in northern Scotland

2006 ◽  
Vol 144 (5) ◽  
pp. 435-447 ◽  
Author(s):  
B. R. TAYLOR ◽  
D. YOUNIE ◽  
S. MATHESON ◽  
M. COUTTS ◽  
C. MAYER ◽  
...  
Keyword(s):  
Sandy Loam ◽  
Farmyard Manure ◽  
Early Summer ◽  
Crop Rotations ◽  
Weed Invasion ◽  
Progressive Decline ◽  
Arable Crops ◽  
Soil P ◽  
Loam Soil ◽  
Organically Managed

Trials at Tulloch, Aberdeen (sandy loam soil, 820 mm rainfall) and Woodside, Elgin (light sandy loam, 730 mm) compared organically managed crop rotations containing different proportions of spring oats, swedes, potatoes and grass/clover leys (0·50 and 0·67 of the rotation at Tulloch; 0·38 and 0·50 at Woodside). The trials simulated farm conditions through the use of grazing animals and the recycling of farmyard manure. The rotations at each site gave similar financial outputs. Yields of oats were higher where these were grown after the main ley phase of the rotation than where they were grown later in the rotation (more ears/m2 and grains/ear), but were not significantly higher after a 4-year ley than after a 3-year ley at Tulloch. It was concluded that all of the rotations were agronomically and financially sustainable. Cereal yields showed large year-to-year variations but little indication of a progressive decline. There were only small changes in soil organic matter, soil P and soil K. Increased early summer weed cover in the arable crops was not matched by increases in weed invasion in the grass/clover leys and did not appear to be affecting yields.

scholarly journals POTATO RESPONSES TO FERTILIZER AND INDIGENOUS SOIL PHOSPHOROUS

HortScience ◽  
1991 ◽  
Vol 26 (6) ◽  
pp. 759F-759
Author(s):  
W.B. Evans ◽  
D.D. Warncke
Keyword(s):  
Sandy Loam ◽  
P Uptake ◽  
Solution Culture ◽  
Marketable Yield ◽  
Soil P ◽  
Russet Norkotah ◽  
P Concentration ◽  
Triple Super Phosphate ◽  
Tuber Specific Gravity ◽  
Phosphorous Level

Single-plant microplots of `Russet Norkotah' potatoes (Solanum tuberosum L.) were grown outdoors in a 5 × 5 factorial RCBD of indigenous phosphorous level (200, 325, 450, 575, 700 kg·ha-1 Bray-Kurtz Pl extractable; McBride sandy loam) and banded triple super phosphate (0, 50, 100, 150, 200 kg P2O5/ha). Disease in the low P soil that was used to create the four lower P soil blends completely confounds response of the plants across indigenous P levels and might have accentuated responses within levels. Plants responded to fertilizer P with tuber yield increases of 100, 70, 40, and 10 percent within the 200, 325, 450, and 575 indigenous P levels, respectively. Fertilizer P also increased marketable yield and tuber P concentration. Neither indigenous nor fertilizer P altered tuber specific gravity. Companion studies compare the responses of corn (Zea mays L.) and potato to indigenous soil P levels and quantify P uptake among potato cultivars in solution culture.

Soil phosphorus fractionation after co-applying biochar and paper mill biosolids

2020 ◽  
Author(s):  
Noura Ziadi ◽  
Xiangru Zhang ◽  
Bernard Gagnon ◽  
Eric Manirakiza
Keyword(s):  
Sandy Loam ◽  
Paper Mill ◽  
Phosphorus Fractionation ◽  
Stable Form ◽  
P Availability ◽  
P Fractions ◽  
Soil P ◽  
Soil P Fractions ◽  
Soil P Availability ◽  
Incubation Study

In recent decades, there has been a growing interest in the recycling of organic materials such as paper mill biosolids (PB) and biochar for use as soil amendments. However, the benefits of co-application of PB and biochar and its effects on soil P availability remain unknown. An incubation study was conducted on two acidic soils to assess the effect of two PB types (2.5% w/w) co-applied with three rates (0%, 2.5%, and 5% w/w) of pine (Pinus strobus L.) biochar on soil P fractions. An unfertilized control and a mineral NP fertilizer were used as a reference. Soil P fractions were determined by Hedley procedure after 2 and 16 weeks of incubation. Material fractionation indicated that the PB containing the highest total P and the lowest Al content had the highest proportion of labile P, whereas most P in the biochar was in a stable form. The incubation study revealed that the P-rich PB increased P availability in both soils to a level comparable to mineral fertilizer at the end of the incubation. The addition of biochar to PB, however, did not affect soil P availability, but the highest rate induced a conversion of P fixed to Al and Fe oxides towards recalcitrant forms, particularly in the sandy loam soil. We conclude that co-applying biochar and PB could be more beneficial than application biochar alone and soils amended with such a mixture would be expected to release part of their P slowly over a longer period of time.

Concentrations of K, Ca and Mg in maize colonized by arbuscular mycorrhizal fungi under field conditions

2002 ◽  
Vol 82 (3) ◽  
pp. 272-278 ◽  
Author(s):  
A. Liu ◽  
C. Hamel ◽  
A. Elmi ◽  
C. Costa ◽  
B. Ma ◽  
...  
Keyword(s):  
Arbuscular Mycorrhizal Fungi ◽  
Mycorrhizal Fungi ◽  
Sandy Loam ◽  
Arbuscular Mycorrhizal ◽  
Am Fungi ◽  
Dry Weight ◽  
Soil Fumigation ◽  
Soil P ◽  
Shoot Dry Weight ◽  
Loamy Sand Soil

Little attention has been paid to the effect of arbuscular mycorrhizal (AM) fungi on the uptake of nutrients that move mainly by mass flow. The objective of this study was to assess the possible contribution of indigenous AM fungi to the K, Ca and Mg nutrition of maize (Zea mays L.) as influenced by soil P levels and its impact on plant dry mass. The field experiment had a split plot design with four replicates. Treatments included soil fumigation status (fumigation and non-fumigation) and three levels of P fertilization (0, 60 and 120 kg P2O5 ha-1) in a loamy sand soil in 1997 and a fine sandy loam soil in 1998. Soil fumigati on with Basamid® was used to suppress indigenous AM fungi. Plants were sampled at four different growth stages (6-leaf stage, 10-leaf stage, tasseling and silking). Soil fumigation decreased shoot dry weight, but P fertilization increased shoot dry weight at most sampling times. When no P fertilizer was added, fumigation in the loamy sand soil reduced shoot K and Ca concentrations while, in contrast, in the fine sandy loam soil only Mg concentration was reduced by soil fumigation. The concentration of K in maize shoots was positively correlated (P < 0.05) with extraradicular hyphal length in both soils. The correlation between the abundance of extraradicular hyphae and the concentrations of Ca and Mg in maize shoots was significant only for soils where available Ca or Mg was relatively low. Arbuscular mycorrhizal fungi could increase corn biomass production and K, Ca and Mg uptake in soil low in these elements and low in P. These results indicate that the contribution of mycorrhizae to maize K, Ca and Mg nutrition can be significant in a field situation and that the extent of this contribution depends on the availability of these nutrients and of P in soils. Key words: Arbuscular mycorrhizal fungi, soil fumigation, extraradicular hyphae, uptake of K, Ca, and Mg, soil P levels, maize

scholarly journals Effect of Land Application of Phosphorus-Saturated Gypsum on Soil Phosphorus in a Laboratory Incubation

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
Karen L. Grubb ◽  
Joshua M. McGrath ◽  
Chad J. Penn ◽  
Ray B. Bryant
Keyword(s):  
Sandy Loam ◽  
Soil Phosphorus ◽  
Land Application ◽  
Agricultural Drainage ◽  
Soil P ◽  
Fertilizer Value ◽  
Laboratory Incubation ◽  
Agricultural Drainage Ditches ◽  
P Fertilizer ◽  
Filter Structures

Agricultural drainage ditches can deliver high loads of phosphorus (P) to surface water. Installation of filter structures containing P sorbing materials (PSMs), including gypsum, is an emerging practice that has shown promise to reduce these P loads. The objective of this study was to evaluate what effect soil amendment with gypsum would have on soil P concentrations and forms in a laboratory incubation experiment. Gypsum was saturated at two levels with P, and applied to a silt loam and a sandy loam at two rates. The treated soils were incubated in the laboratory at 25°C, and samples were collected on eight dates between 0 and 183 days after amendment. Spent gypsum application did not significantly increase soil water-extractable or Mehlich 3 P when applied at typical agronomic rates. This appears to be a viable strategy to remove P from agricultural drainage waters but does not appear to provide any additional P fertilizer value.

scholarly journals Interactions Between Trichoderma harzianum Strain T22 and Maize Inbred Line Mo17 and Effects of These Interactions on Diseases Caused by Pythium ultimum and Colletotrichum graminicola

2004 ◽  
Vol 94 (2) ◽  
pp. 147-153 ◽  
Author(s):  
Gary E. Harman ◽  
Rixana Petzoldt ◽  
Alfio Comis ◽  
Jie Chen
Keyword(s):  
Inbred Line ◽  
Trichoderma Harzianum ◽  
Root Hair ◽  
Sandy Loam ◽  
Pythium Ultimum ◽  
Maize Inbred Line ◽  
Systemic Resistance ◽  
Field Soil ◽  
Colletotrichum Graminicola ◽  
Untreated Soil

Seed treatment with Trichoderma harzianum strain T22, which results in colonization of plant roots but little or no colonization of shoots or leaves, had substantial effects on growth of and disease expression in maize inbred line Mo17. Shoots and roots of 10-day-old seedlings grown in a sandy loam field soil were larger (roots were nearly twice as long) in the presence of T22 than in its absence. Both main and secondary roots were increased in size and area and the root hair area was greater with T22. However, root hair area per unit of root length was greater in control plants. Increased growth probably was due to direct stimulation of plant growth in addition to effects from biological control of deleterious microflora. Seedlings of Mo17 grown in autoclaved or mefenoxamtreated sandy loam field soil were larger than those produced in untreated soil. However, seedlings grown in the presence of T22, either in treated or untreated soil, were larger than those produced in its absence. Infestation of soil with Pythium ultimum had little effect upon growth of Mo17. The presence of T22 increased protein levels and activities of β-1,3 glucanase, exochitinase, and endochitinase in both roots and shoots, even though T22 colonized roots well but colonized shoots hardly at all. With some enzymes, the combination of T22 plus P. ultimum gave the greatest activity. Plants grown from T22-treated seed had reduced symptoms of anthracnose following inoculation of leaves with Colletotrichum graminicola, which indicates that root colonization by T22 induces systemic resistance in maize.

scholarly journals Yield responses to P fertilisation of onion (Allium cepa L.) and cabbage (Brassica oleracea Capitata Group L.) in Finland

2018 ◽  
Vol 27 (1) ◽  
Author(s):  
Risto Uusitalo ◽  
Terhi Suojala-Ahlfors ◽  
Pirjo Kivijärvi ◽  
Timo Hurme
Keyword(s):  
Sandy Loam ◽  
Field Trials ◽  
Vegetable Crops ◽  
Soil P ◽  
National Regulation ◽  
Safety Margins ◽  
P Rate ◽  
Soil Test P ◽  
Few Data ◽  
Yield Responses

Finnish data on vegetable crops’ yield responses to phosphorus (P) applications are scarce, but P is usually applied in quantities that meet the crop demand with wide safety margins. We determined yield responses to P fertilisation of onion and cabbage at three sites in 3-year field trials. Only on a sandy loam with low P status did annual P applications give statistically significant yield increases, 7% and 20% over the P-unfertilised treatment for onion and cabbage, respectively. The maximum P rate allowed by national regulation for this soil is 80 kg ha-1, but P rates of 10–12 kg ha-1 were sufficient to produce 97% of the yield maxima. The results strongly suggest that the P demand of the studied vegetables is smaller than previously thought also in a boreal climate. Critical soil test P concentrations for vegetables should be established to avoid unnecessary build-up of soil P that may be uneconomical and elevate the risk for P losses to waterways. However, too few data exist for this at present.

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