Contaminated seeds (inner infection) became a main factor of new pathogens entrance to agricultural areas, and yield losses caused by bacteria and viruses. Is there any reliable seed treatment methods without reduction of seeds viability? Hot water treatment is not considered.
In the seed industry we use two methods, 1) Sodium hypochlorite bleach diluted to 0,5% strength rinse for one minute then rinse in water for 5 minutes. However for seeds with thin seed coats can cause damage sometimes. 2.) 3% Hydrogen peroxide solution rinse for three minutes then water rinse. Cannot cause any seed damages, only kills the surface pathogens.
It greatly depends on the location of the pathogen (internal vs. external). If the pathogen is present only on the testa, then it can generally be washed off with a high degree of success (no guarantees, always scout seedlings from suspect lots!).
Trisodium phosphate (~10%) is an effective treatment for removing external contaminants. 3N HCl is also effective.
If a pathogen is internal, then thermotherapy is probably your best option. Fortunately, many (if not most) seed-transmitted pathogens are external.
We found with wheat that 11 days of dry heat (70C) was a surprisingly good way to get rid of Xanthomonas and Pseudomonas (for foundation seed).. Seed must be put in envelopes and care must be made to avoit their contact with metal. Also we found that tobacco seeds could survive microwave ovens for 10 minutes. This too cleaned the seed of Erwinia aroidae. If you want refs email me [email protected]
Nature uses acids and acid fermentation of seeds are interesting. Tartaric acid at 50 mM pH 3 is a good spray for bacteria. Most pathogens give up the ghost at pH 3.5
A combination of Organic acids and oxygen releasing compounds with Biopesticides may be useful and effective.
pure oxygen in a seed storage jar seems to do a good job against microbes in general
Don't have any open flames agound
Thank everybody for shared ideas.
@David, my Japanese colleagues had good results at 1990-s with 2-step dry heating for vegetables seeds. They used pre-treatment at 40-50oC, and the seeds could stand much higher temperature after, with significantly reduced time of the treatment. They used too indolyl-propionic acid compounds to kill specifically some plant pathogenic bacteria.
I believe, that combination of chemical antibacterial agents (silver, copper, organic acids, systemic pesticides, antibiotics) with physical methods will be more efficient comparing to chemical or physical treatments alone. It would be interesting to use microwave treatment instead of physical heat, because EMF can increase temperature of particular nano-scale centers of EMF absorption.
Interesting discussion! Definitely, there are a couple of methods for surface sterilization, majority of them have been mention. However, these methods may not be very effective against internal viruses/pathogens. In this case strong infiltration require. Also, one can look on this mixture, which may be effective against contamination: http://www.plantcelltechnology.com/ppm-protocols/
One of the way to clean plants (not seeds, but seedlings) is a rapid micro-clonal propagation through culture in vitro. In many case this way is very effective, but time consuming.
To enable penetration of the products conceived one can incorpotate usage of 5 Nitro Phenolate.
Best Regards
Dear friends; Though it is difficult to remove inner virus but in my country India, intermittent heat treatment before storing the seeds through drying the seeds in sunlight during summer when temperature rises up to 50o C works effectively. Thanks
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