Dear Gaurav,

Chloride tolerance of various crops

The element chlorine is ubiquitous in nature, and occurs in aqueous solutions as the anion chloride (CI-). In this form it is also readily taken up by plants and average chlorine contents in plant tissues are in the range of 2-20 mg g-1 dry matter. In most plant species the requirement for optimal plant growth, however, is 10 to 100 times lower which means that chlorine is a typical micronutrient. Because it is usually supplied to plants as chloride from various sources (soil reserves, irrigation water, rain, fertilisers, air pollution), chlorine deficiency is rarely found. On the contrary, there is much more concern about chlorine toxicity world-wide. Plant species vary greatly in their susceptibility to high chloride concentrations in the soil solution and four main groups in this respect can be distinguished: 

1.       Chloride loving crops.

2.       Chloride tolerant crops.

3.       Partly chloride tolerant crops.

4.       Chloride sensitive crops 

Chloride-loving crops include sugar beet, fodder beet, celery, asparagus and Swiss chard.

Chloride-sensitive crops include many fruit and vegetable varieties, and special crops such as hops or tobacco.

 For these crops only fertilisers with potassium in sulphatic form should be used, 

The effects of high CI- concentrations in the soil solution on yields of various crops is shown in the following graphs. The steeper the yield decline with increasing CI- soil concentrations the more sensitive to chloride is a crop and hence the better will be the response to virtually CI- free fertilisers,

Prior to these substantial yield depressions, uptake of large amounts of chloride may lead to negative effects on crop quality such as: 

 Reduced content of organic acids, resulting in a flat taste

Accumulation of low molecular organic substances and thus decreased contents of valuable storage compounds (sugar, starch, protein)

Increase hydration of plant tissue and decreased storage or processing properties. 

 To avoid yield, quality and hence income losses in chloride sensitive and especially high value crops, where quality counts, the use of our low chlorine potassium fertilizers,

Please find attached herewith Graph & Crops Classifications,

Regards,

Prem Baboo

An interesting question. I found the following in the net.

Reduced combustibility and “Wet dog” symptoms in tobacco (tobacco becomes dark and smelly after packing).

Read the following article 

http://naldc.nal.usda.gov/download/IND43967751/PDF

Dear Gaurav,

Chloride tolerance of various crops

The element chlorine is ubiquitous in nature, and occurs in aqueous solutions as the anion chloride (CI-). In this form it is also readily taken up by plants and average chlorine contents in plant tissues are in the range of 2-20 mg g-1 dry matter. In most plant species the requirement for optimal plant growth, however, is 10 to 100 times lower which means that chlorine is a typical micronutrient. Because it is usually supplied to plants as chloride from various sources (soil reserves, irrigation water, rain, fertilisers, air pollution), chlorine deficiency is rarely found. On the contrary, there is much more concern about chlorine toxicity world-wide. Plant species vary greatly in their susceptibility to high chloride concentrations in the soil solution and four main groups in this respect can be distinguished: 

1.       Chloride loving crops.

2.       Chloride tolerant crops.

3.       Partly chloride tolerant crops.

4.       Chloride sensitive crops 

Chloride-loving crops include sugar beet, fodder beet, celery, asparagus and Swiss chard.

Chloride-sensitive crops include many fruit and vegetable varieties, and special crops such as hops or tobacco.

 For these crops only fertilisers with potassium in sulphatic form should be used, 

The effects of high CI- concentrations in the soil solution on yields of various crops is shown in the following graphs. The steeper the yield decline with increasing CI- soil concentrations the more sensitive to chloride is a crop and hence the better will be the response to virtually CI- free fertilisers,

Prior to these substantial yield depressions, uptake of large amounts of chloride may lead to negative effects on crop quality such as: 

 Reduced content of organic acids, resulting in a flat taste

Accumulation of low molecular organic substances and thus decreased contents of valuable storage compounds (sugar, starch, protein)

Increase hydration of plant tissue and decreased storage or processing properties. 

 To avoid yield, quality and hence income losses in chloride sensitive and especially high value crops, where quality counts, the use of our low chlorine potassium fertilizers,

Please find attached herewith Graph & Crops Classifications,

Regards,

Prem Baboo

nice explanation, Prem, the figures shows the sensitivity of Cl to crops, accordingly suggesting in which crops chloride free fertilizer to be used

regards

degree of sensitivity towards chlorine diifers for crops, due to plant processes as osmosis, water uptake mechanism, interaction with other nutrients (in terms of differential uptake as influenced by mass flow and diffusion processes) and quality aspects.Review uploaded by Ramesh nicely covers the aspects, as well Prem has provided the inter-crop differential response

regards

Thank you very much for very nice explanation By Prem ji and Dr Kalra, but what happen inside the tissue when chloride concentration goes beyond the certain limit? why this high concentration of chloride effect on certain plants only why not all?

Dear Prem Baboo, your classification on crop Chlorine reaction very enlightening! Congratulations on your excellent summary!!.

I would like to suggest that your producing a table which gives the negative slope values from your salt versus yield regression graphic.

I think since the 100% yield  starts at about the salt point that slope will very clearly separates the reactions. This can be used to give a quantitative sense of  relative reactions. I believe these can be made very useful for your followers.

Thank you for shedding light on this area. PRH

Dr Hepperly , Gaurav has raised a very pertinent question , why is it chloride only which is so disrupting to plant metabolism compared to rest of the other anion like sulphate .  The right answer is yet to arrive  ?. I personally  feel , it is maximum ionization potential( easily dissociates into atomic sizes) of diatomic chlorine molecule , which effectively forms salts with other cations after dissociation .  Let us listen from other colleagues. I am enclosing one nice PDF explaining , how to live with salinity , hope , you find it interesting .

Dr Srivastava and Gaurav, I liked your differentiation of the chlorine reaction of different plant species.

Dr Wade Elmer University of Connecticut  investigated the validity of using salt application purposely to control Fusarium root rot of Asparagus. It was very efficacy helping produce a plant that otherwise would be severely compromised.

Indeed the use of saline water in irrigation has much utility for some crops  and situations as Dr Anoop Srivastava's attachment demonstrates.

When we look at toxicology the mantra that stands out is the dose makes the poison.

In fact something considered toxic can be highly beneficial at the right dilution. While Chlorine can be considered very toxic it also in an essential nutrient.

Text books would suggest chlorine toxicity is related to a disruption of photosynthesis and chlorosis would be a primary symptom.

If we look at salt as sodium chloride the sodium competes in plant with Potassium and Calcium. The use of Gypsum as a way to displace sodium improved the structure and the utility of soil.

In addition the requirement of plants for Calcium and Potassium is much greater than any metabolic need for sodium. In a similar way I suspect that the need for Sulfur is much greater than the need for Chlorine and the threshold for Sulfur toxicity I suspect is  much higher than that of Chlorine.

I suspect where salt issues where suspected the use of sulfate forms might be judicious. This based on the following reasoning Potassium applied as muriate will give a high generation of chloride which will go to soil and plants. Potassium applied as sulfate will provide potassium but will not necessary have a toxicity because more is needed in the plants and its toxicity threshold is much higher in the plants.

As long as we are talking toxicity the use humic and fulvic acid is very well known to alleviate toxicity reaction while stimulating nutrient uptake and allowing growth regulator type reactions.

In saline situations where irrigation is done in drip lines I suspect that the inclusion of humic and fulvic acids would be very beneficial along with using sulfate and nitrate nutrient forms rather than chlorides in many environments.

I hope this might seed some confirming investigation which will give a better explanation and result in some practical treatment options.

I have enclosed your insights immensely. Kudos to your keen observations.

Congratulations on your excellent discussion forum.

 Dr.Hepperly, your hypothesis of relative requirement of chlorine and sulfur and relative toxcity of chloride and sulphate in plant is interesting. To my understanding the relative role of chlorde and sulphate anions with potassium in potato nutrition is much studied area.Many studies showed improvement  in potatoes quality for processing for chips and fries etc.when potassium sulphate is used as K source.There are reports which showed greater tuber size,dry weight and starch content with potassium sulphate application. However simiar behavior was shown by potassium cholide also.at low concentration-Only at higer concentrations the adverse affect of choride was seen. But such effect was not seen with sulphate  at high concentration also indicating relative tolerance of chloride and sulphate in plant system.

Thank you very much for Dr Subba rao, Dr Hepperly and other scientists, for your very nice explanation regarding the chlorine sensitivity.