From danamex@mail.internet.com.mx Sat Jun 19 14:28:57 1999 Date: Sat, 19 Jun 1999 09:57:45 -0500 From: Ronald Nigh To: sanet-mg@ces.ncsu.edu Subject: Re: Vanadium: Nature's "Junk Food" For Plants [ The following text is in the "iso-8859-1" character set. ] [ Your display is set for the "US-ASCII" character set. ] [ Some characters may be displayed incorrectly. ] Dear SANET, The argument presented here seems a little strange. Vanadium is an essential element, though not much is really known about its functions. It seems to work in some N fixing systems to replace Mo, as we have commented on this list. It is necessary in such small quantities that defciencies do not seem to have been reported, as I recall. It seems highly unlikely that millions of years of plant evolution would result in plants being so easily "fooled" by an element that is so widespread. Certainly, there are levels of V, particularly with respect to other trace elements, that could be excessive or at least be suboptimal for plant health. I find it hard to believe that "root cells can't tell them apart" (i.e. V and P). I think it would be important to consider this problem in the overall context of the mineral content and availability of the particular soil in question and the other factors affecting P. >MORRIS, Minn., June 16--Gardeners and farmers who are used to >checking the >N-P-K (nitrogen-phosphorus-potassium) levels on their >fertilizer bags may >someday be checking N-P-K-V levels in their soil. That's V for vanadium. > >Vanadium "impersonates" phosphorus and can confuse a plant into >eating it >instead of phosphorus. That can cause the plant to experience a >phenomenon >akin to that of people who eat junk food in place of a nutritious meal, >reports soil scientist Alan F. Olness with the USDA's >Agricultural Research >Service. >(snip) >"Phosphorus is an essential nutrient plants need for growth. >But vanadium, a >trace element abundant in soils throughout the world, is useless to many >plants, including corn, soybean, tomatoes, Impatiens and petunias." >(snip) >During a growing season," he said, "plants may have only two >or three time >windows during which they can take in phosphorus. If they fill up on >vanadium instead, they miss out on phosphorus, because their root cells >can't tell them apart. Their growth and development--and >yields--suffer. The >more vanadium, the more the plant slows down and the lower the >yield. For >ornamentals, the slowdown could result in less beauty and hardiness." > Ronald Nigh Dana, A.C. Mexico, D.F. & San Cristóbal de Las Casas, Chiapas Tel. y FAX 525-666-73-66 (DF) 529-678-72-15 (Chiapas) danamex@mail.internet.com.mx To Unsubscribe: Email majordomo@ces.ncsu.edu with the command "unsubscribe sanet-mg". If you receive the digest format, use the command "unsubscribe sanet-mg-digest". To Subscribe to Digest: Email majordomo@ces.ncsu.edu with the command "subscribe sanet-mg-digest". All messages to sanet-mg are archived at: http://www.sare.org/san/htdocs/hypermail From WILSONDO@phibred.com Sat Jun 19 22:43:33 1999 Date: Sat, 19 Jun 1999 19:00:17 -0500 From: "Wilson, Dale" To: sanet-mg@ces.ncsu.edu Subject: RE: Vanadium: Nature's "Junk Food" For Plants [ The following text is in the "iso-8859-1" character set. ] [ Your display is set for the "US-ASCII" character set. ] [ Some characters may be displayed incorrectly. ] Ronald, > Certainly, there are levels of V, particularly with respect > to other trace elements, that could be excessive or at least > be suboptimal for plant health. I find it hard to believe > that "root cells can't tell them apart" (i.e. V and P). I > think it would be important to consider this problem in the > overall context of the mineral content and availability of > the particular soil in question and the other factors > affecting P. I was curious so I searched for info on vanadium toxicity. I didn't find anything in the literature suggesting that this is an important problem, but I did find out about the mechanism of toxicity. It does mimic phosphate, inhibiting plasmamembrane ATPase, and so inhibits active transport of PO4 and everything else. Vanadium (V) also oxidizes ascorbate producing free radicals and associated membrane damage. If you want the 8 abstracts I found, let me know. Dale To Unsubscribe: Email majordomo@ces.ncsu.edu with the command "unsubscribe sanet-mg". If you receive the digest format, use the command "unsubscribe sanet-mg-digest". To Subscribe to Digest: Email majordomo@ces.ncsu.edu with the command "subscribe sanet-mg-digest". All messages to sanet-mg are archived at: http://www.sare.org/san/htdocs/hypermail From timj@mainmin.co.nz Sun Jun 20 22:36:12 1999 Date: Mon, 21 Jun 1999 12:41:54 +1200 From: Tim Jenkins To: sanet-mg@ces.ncsu.edu Subject: Re: Vanadium: Nature's "Junk Food" For Plants [ The following text is in the "iso-8859-1" character set. ] [ Your display is set for the "US-ASCII" character set. ] [ Some characters may be displayed incorrectly. ] Vanadium can take the form of vanadate (V5+) which has the same bipyramidal structure of ligands (i.e. with oxygen and hydroxyl groups) as phosphate. Therefore vanadium could compete with phosphate for uptake by plants but the significance of this would depend on the relative levels of vanadate and phosphate. Vanadium can be at high levels in some plants e.g. parsley at 30 ppm but just 10% of that in lettuce. This is much lower than the levels of phosphorus e.g. 5000 ppm and so the uptake of phosphorus may not be a significant problem. The inhibition of Na+-K+ ATPase seems to be to be much more of a possibility. At very low levels, vanadate can have a significant effect on this enzyme which mistakes the vanadate for phosphorus and becomes locked in an unusable form. I am going to be looking in to the significance of this and would appreciate any more information that is out there. It could be, of course, that any relationship between vanadium levels and phosphorus availability/uptake could just be due to soil type difference and it just happens that the soil types that have lower P availability also have high vanadium levels. Vanadium is associated with ores and it is likely that high vanadium soils may be higher in aluminium and iron than other soils (iron and aluminium as well as potentially vanadium causing problems with P availability). I imagine that this has already been checked out to some extent. If it is established that vanadium is a significant problem I would be interested in how to test for it (probably a nitric/perchloric digest to get a total level?) and how to reduce its effects (e.g. liming?). Dale mentioned vitamin C being oxidised by vanadate. This is likely to be a vice versa thing in that excess vanadium levels can be controlled by vitamin C. The trick would then be to produce plants with as high levels of vitamin C and other antioxidants as possible - in other words produce high quality plants and vanadium problems could be limited. Tim Tim Jenkins SoilTech P.O. Box 558 CHRISTCHURCH NEW ZEALAND > >I was curious so I searched for info on vanadium toxicity. I didn't find >anything in the literature suggesting that this is an important problem, but >I did find out about the mechanism of toxicity. It does mimic phosphate, >inhibiting plasmamembrane ATPase, and so inhibits active transport of PO4 >and everything else. Vanadium (V) also oxidizes ascorbate producing free >radicals and associated membrane damage. If you want the 8 abstracts I >found, let me know. > >Dale To Unsubscribe: Email majordomo@ces.ncsu.edu with the command "unsubscribe sanet-mg". If you receive the digest format, use the command "unsubscribe sanet-mg-digest". To Subscribe to Digest: Email majordomo@ces.ncsu.edu with the command "subscribe sanet-mg-digest". All messages to sanet-mg are archived at: http://www.sare.org/san/htdocs/hypermail From timj@mainmin.co.nz Mon Jun 21 11:12:08 1999 Date: Mon, 21 Jun 1999 12:41:54 +1200 From: Tim Jenkins To: sanet-mg@ces.ncsu.edu Subject: Re: Vanadium: Nature's "Junk Food" For Plants [ The following text is in the "iso-8859-1" character set. ] [ Your display is set for the "US-ASCII" character set. ] [ Some characters may be displayed incorrectly. ] Vanadium can take the form of vanadate (V5+) which has the same bipyramidal structure of ligands (i.e. with oxygen and hydroxyl groups) as phosphate. Therefore vanadium could compete with phosphate for uptake by plants but the significance of this would depend on the relative levels of vanadate and phosphate. Vanadium can be at high levels in some plants e.g. parsley at 30 ppm but just 10% of that in lettuce. This is much lower than the levels of phosphorus e.g. 5000 ppm and so the uptake of phosphorus may not be a significant problem. The inhibition of Na+-K+ ATPase seems to be to be much more of a possibility. At very low levels, vanadate can have a significant effect on this enzyme which mistakes the vanadate for phosphorus and becomes locked in an unusable form. I am going to be looking in to the significance of this and would appreciate any more information that is out there. It could be, of course, that any relationship between vanadium levels and phosphorus availability/uptake could just be due to soil type difference and it just happens that the soil types that have lower P availability also have high vanadium levels. Vanadium is associated with ores and it is likely that high vanadium soils may be higher in aluminium and iron than other soils (iron and aluminium as well as potentially vanadium causing problems with P availability). I imagine that this has already been checked out to some extent. If it is established that vanadium is a significant problem I would be interested in how to test for it (probably a nitric/perchloric digest to get a total level?) and how to reduce its effects (e.g. liming?). Dale mentioned vitamin C being oxidised by vanadate. This is likely to be a vice versa thing in that excess vanadium levels can be controlled by vitamin C. The trick would then be to produce plants with as high levels of vitamin C and other antioxidants as possible - in other words produce high quality plants and vanadium problems could be limited. Tim Tim Jenkins SoilTech P.O. Box 558 CHRISTCHURCH NEW ZEALAND > >I was curious so I searched for info on vanadium toxicity. I didn't find >anything in the literature suggesting that this is an important problem, but >I did find out about the mechanism of toxicity. It does mimic phosphate, >inhibiting plasmamembrane ATPase, and so inhibits active transport of PO4 >and everything else. Vanadium (V) also oxidizes ascorbate producing free >radicals and associated membrane damage. If you want the 8 abstracts I >found, let me know. > >Dale To Unsubscribe: Email majordomo@ces.ncsu.edu with the command "unsubscribe sanet-mg". If you receive the digest format, use the command "unsubscribe sanet-mg-digest". To Subscribe to Digest: Email majordomo@ces.ncsu.edu with the command "subscribe sanet-mg-digest". All messages to sanet-mg are archived at: http://www.sare.org/san/htdocs/hypermail