Mycorrhizal Association and Wheat Varieties

[Simon C]

@Clive mentioned this in another thread and there has been a bit of a discussion on Twitter which is a pretty useless place to put any complicated information, so I thought I would just show a few results here from tests I had done a few years ago.

These are percentages of root lengths colonised by arbuscular mycorrhizal fungi.
2010 Viscount 19.3% and 30.2%
2011 Viscount 21.5% without seed dressing, and 7.7% with dressing
2011 Welford Compost in Autumn. 31.5% without dressing, 12.4% with dressing
2012 Conquerer 35.5%
2012 Welford With mycorrhizal inoculant 14.2%, without inoculant 28.8%

These are ten year old varieties so not really representative of the latest offerings, but they do show that they were capable of mycorrhizal association. The link between fungicidal seed dressings and mycorrhizal suppression is clear, but it is strange how an inoculant in 2012 actually lowered the association. I spoke to someone at Plant Works about this and they said that if the inoculation was from a wrong or non native species, it could suppress the natural ones and yet fail to form any association itself. It was given too me to do a small trial, but I believe it came from America.

Another interesting thing is that Conquerer, which produced the highest yield in my own no-till variety trials two years running, has returned the highest percentage of all the test I had done.

 

[damaged]

I was moving back from Claire towards Hereward and further pre high yield. However perhaps I don't need to for AMF association. Good info Simon. We have been leaving off most seed treatment now for a decade.

 

[Simon C]

What we don't know is what these percentages actually mean, they are alright for comparisons, bit would old heritage varieties actually reach 100%, or perhaps 50% is as good as it gets.

 

[Clive]

Very interested to learn today that varieties are being developed with this trait in mind and that the mycorrhizal association trait is not only about plants ability to access nutrition but also immunity from and ability to deal with pathogens. There is a lot more research and knowledge about this being and been done that we are made aware of as farmers it's origins and funding not always being ag based (pharmaceuticals and antibiotic research) UK research is leading the way yet we as farmers are not getting this infomation

As usual commercial interest is creating agenda and traditional farmer groups are failing us badly and in some situations even getting in the way of helping this kind of information inform the policy changes global agriculture needs

If you ever get a chance to visit or hear anyone from here
http://p3.sheffield.ac.uk speak I highly recommend you make the effort !

 

[mikep]

Recently I found a HGCA research trial looking at mychorriza levels in organic and conventional wheat. The organic had higher levels of association but the finding was that the only reason for this was that the organic had insoluble rock phosphate as opposed to soluble. The suggestion was the soluble was affecting the manner in which the association was made. Perhaps when there is a surplus of readily available P the wheat says thanks but no thanks to the little helpers.

 

[The_Swede]

Joel Williams unequivocally said the same at his event a few months back.

 

[Simon C]

Recently I found a HGCA research trial looking at mychorriza levels in organic and conventional wheat. The organic had higher levels of association but the finding was that the only reason for this was that the organic had insoluble rock phosphate as opposed to soluble. The suggestion was the soluble was affecting the manner in which the association was made. Perhaps when there is a surplus of readily available P the wheat says thanks but no thanks to the little helpers.

No P of any sort used on the wheat in these tests.

 

[mikep]

No P of any sort used on the wheat in these tests.

Seems to tie in with the findings.
What time of year did you examine the plants? I will have a look at some heritages and see how they fair. They certainly get up and running a lot faster and produce a comparatively huge amount of root.

 

[Clive]

Recently I found a HGCA research trial looking at mychorriza levels in organic and conventional wheat. The organic had higher levels of association but the finding was that the only reason for this was that the organic had insoluble rock phosphate as opposed to soluble. The suggestion was the soluble was affecting the manner in which the association was made. Perhaps when there is a surplus of readily available P the wheat says thanks but no thanks to the little helpers.

Maybe why when I used placed MAP for a couple of season I saw no yield increase despite initially much more impressive rooting ?

 

[mikep]

Maybe why when I used placed MAP for a couple of season I saw no yield increase despite initially much more impressive rooting ?

Yes but the logical follow on from this idea is a less hopeful one. If a crop of wheat requires X units of P to produce 4 tonne of wheat then can X units be provided by the mychorriza alone? If not and extra is needed can the mychorriza work overtime on a dressing of rock P and produce this or must you introduce soluble?
Now if you have to use soluble then you are into a declining circle of extra SP causing less MP calling for more SP consequently reducing further the MP until you arrive at today's situation with all SP and no MP.
It may be a blind alley this wish to achieve a useful increase in mychorriza if you are not going the whole hog and reverting to an almost century old farming style with century old yields.
The association was a response to a situation where the only P was insoluble so a symbiotic relationship occurred over a LONG period of time. We have short circuited evolution by giving the wheat (and other crops) a cushy deal whereby the need to fend for itself has been removed. This was fine until disease and weeds made the change as the crops did and started to live well off our generosity.
I desperately hope those at Sheffield can come up with something but really think it may be a bit of a blind alley if used in isolation from changing many other ways we farm.
You can never get owt from nowt so the question is where from?

 

[The_Swede]

Cereals excepted what happens when the brassica break crop comes round in the rotation... stick with the Gafsa, compost etc and hope for the best or introduce MAP/DAP/TSP and have the potentially double negative of absolutely no association with MF and lots of soluble P floating around the soil profile again? Think I'd be inclined to scrap the OSR all together and grow linseed in this slot the way the economics of rape are at present.

 

[mikep]

Cereals excepted what happens when the brassica break crop comes round in the rotation... stick with the Gafsa, compost etc and hope for the best or introduce MAP/DAP/TSP and have the potentially double negative of absolutely no association with MF and lots of soluble P floating around the soil profile again? Think I'd be inclined to scrap the OSR all together and grow linseed in this slot the way the economics of rape are at present.

This is all uncharted territory and one solution will only throw up another problem.
Remember the history of farming is very long and our times probably equate to a second in an hour.

 

[willy]

Surley the first obvious thing to do is test seed and dont dress it if results are good.

 

[Joe Boy]

Cereals excepted what happens when the brassica break crop comes round in the rotation... stick with the Gafsa, compost etc and hope for the best or introduce MAP/DAP/TSP and have the potentially double negative of absolutely no association with MF and lots of soluble P floating around the soil profile again? Think I'd be inclined to scrap the OSR all together and grow linseed in this slot the way the economics of rape are at present.

What are the negative effects of having large amounts of soluble P in the soil.? How much is too much soluble P?

 

[The_Swede]

As far as I know its simply that if there is soluble P readily available then MF associations are not made and so you remain on the treadmill of needing to apply more P and so it continues. As for levels - it was suggested to me that none should be applied in order to get the MF system started however is this realistic whilst trying to make a living from that same land here and now...

I must add my understanding of these theories comes entirely from reading papers, attending seminars etc etc, I am not a soil scientist / biologist!

 

[mikep]

As far as I know its simply that if there is soluble P readily available then MF associations are not made and so you remain on the treadmill of needing to apply more P and so it continues. As for levels - it was suggested to me that none should be applied in order to get the MF system started however is this realistic whilst trying to make a living from that same land here and now...

I must add my understanding of these theories comes entirely from reading papers, attending seminars etc etc, I am not a soil scientist / biologist!

The plants use of MF seems to be dependant on need. If there is plenty of available P why bother with the middle man? It would be far more efficient to go direct. This begs the question that in the presence of adequate soluble P why do we even want to get the association? Are their benefits other than P acquisition that the plant gets? if so why does it not still make the effort to associate?
Personally I don't think there will be a huge amount of benefit from bug hunting from the plants point of view, it will make the soil more workable and living but the ability to produce 1 tonne of wheat will still take 40 (or so) units of N no matter where it comes from.
On the subject of undressed seed for goodness sake make sure it is tested as the organic boys are hitting problems with bunt, I am being asked to 'rinse' some seed next year to help out until the approval comes for organic treatments.

 

[The_Swede]

I'll have a dig through my Joel Williams lecture notes, sure he talked through several potential plant benefits from the interaction. I agree re the N and that it would be a brave man to skip the P on a deficient soil and go looking for it through MF though!

 

[Simon Chiles]

I'll have a dig through my Joel Williams lecture notes, sure he talked through several potential plant benefits from the interaction. I agree re the N and that it would be a brave man to skip the P on a deficient soil and go looking for it through MF though!

Because AMF increases the rooting area of a plant enormously then the plant can get better availability of water in a stressed situation. Plants can also signal to each other through AMF to warn each other about imminent disease pressure so that their natural resistance can start to kick in.
I've seen some dramatic yield increases in certain ( not all ) situations in the trial work I have done. Maybe we need to think about using AMF as an insurance policy.

 

[The_Swede]

Agree with all of the above re Joel's notes, he also discussed how it has been used to allow sown species to successfully compete with AMG in amenity situations, imagine if that could be harnessed re the major arable grass weed... On access to moisture, I don't think any of the crops here will be struggling for a drop of that this year!!

As i've said previously I intend to take some total nutrient soil samples once things dry up, from there will make a call on whats there to tap into 'biologically'. Wouldn't mind trying some Gafsa type material on the P hungry naturally acidic land too.

 

[britt]

Because AMF increases the rooting area of a plant enormously then the plant can get better availability of water in a stressed situation. Plants can also signal to each other through AMF to warn each other about imminent disease pressure so that their natural resistance can start to kick in.
I've seen some dramatic yield increases in certain ( not all ) situations in the trial work I have done. Maybe we need to think about using AMF as an insurance policy.

Simon, were they trials where AMF was added, or just measured as part of the monitoring ?