I need to give salt stress treatment to Carica papaya plant. The salt treatment will be given using sodium chloride, NaCl solution with the concentration of 200mM. I've read some papers but I am still unsure about the steps on how to subject the plants to salt stress. The seeds will be sown in soil and allowed to germinate. How many weeks old seedlings are suitable to be subjected to salt stress treatment? What is the appropriate volume of NaCl (200mM) can be used? How many days intervals should be given for the treatment, is it has to be treated daily or two days once? My control will be normal tap water. I am going to isolate RNA to study the role of WRKY gene in stress tolerant mechanism.
Please guide me by giving some suggestions.
Thank you in advance.
Regards,
Sarannia.
Hello Sarannia,
Firstly, you may need to choose appropriate concentration of salt for your treatments (May be based on LD 50 ). This can be achieved by treating range of NaCl concentrations to the seedlings.
1. About subjecting salt treatments, you can find various methods which are crop specific. For example salt treatment can be done to the seeds in perti dish or can also be treated to the seedlings by soil treatment in pots. So you might have to choose based on the critical stages of plant growth which affected most or depending on your objective.
2. Choosing appropriate concentration is dependent on the plant phenotype, please refer the introductory point.
3. The treatment duration and intervals treatment can be decided based on the type of treatment you for. For example in pots one can apply salt solution to its field capacity (can be derived by weighing dry and FC pots).
4. It is okay to use tap water. However you need to pay attention to the tissue damage. Given that, it is very hard to isolate RNA from dried tissues you might again standardize the salt treatment protocol based on previous literature.
Hope this is helpful, please refer the links below for the ideas of experimentation.
Thanks,
Vijaya
1. https://www.frontiersin.org/articles/10.3389/fpls.2017.00864/full
2. http://www.ipublishing.co.in/ijesarticles/fourteen/articles/volsix/EIJES6026.pdf
3. Article Salt stress-induced responses in cucumber plants
Watering is constant salinity concentration, but the exposure of seeds and small plants to salt stress should be considered to be highly sensitive
Vijaya R. Chitnis Thank you for the suggestions.
Yes, salt stress treatment will be done using seedlings by soil treatment in pots. As i read few papers, it was stated to give the treatment gradually (add 25mM or 50mM daily until reach 200mM). The volume of NaCl stated was 10mL to 25mL.
I am still unsure because I've already tried to treat 3 weeks old seedlings using 200mM NaCl (25mL), but the seedlings were unable to survive. This may be due to the osmotic potential and salt shock.
Regards,
Sarannia.
Saddam H. Cheyed Yes, salt stress treatment to young seedlings is highly sensitive. As I've tried with 3 weeks old seedling and it failed.
One week seedlings are good to start treating with salt in pots/poly bags. Choose concentration you want( e.x 200 mM). Give at the interval of week (for successive 3-4 weeks) or interval of 10 days. In some cases people start treating after days days of growth from emergence of cotyledons. Depending upon crop people treat till the time of flowering and not during fruit/pod setting.
S it all depends upon plan/crop you select and concentration (LD value of the plant).
Hello Sarannia,
It seems Papaya cultivar you use is very sensitive to salt stress. However, if you provide only 25 ml of salt how are you maintaining adequate soil moisture ?
Can you please describe your methodology in detail?
Vijaya
Hukam Gehlot Thank you. But I think for papaya one week seedling is not suitable because I treated with 3 weeks old seedling at its failed. This might be due to osmotic potential and salt shock.
For papaya you can use one month two month and three month of age. Interval of one month.
Hi sarannia,
First you have to standardize experiment (100, 150, 200, 300 mM) which concentration suitable to your plant, see the survival rate and if you take one month plants, stress duration 15 days will be better, because of you can observe phenotypic variations . or if you take one week plant you reduce stress duration also. My idea is if you do seedling stage and vegetative stage (one month Plants) that will be better
Ragula Seenaiah Thank you for the suggestions. :)
Regards,
Sarannia.
I agree with Mr Seenaiah. In general, in seed studies, if there is no reliable source, there should be a test in different periods and with different concentrations of materials in order to obtain the desired result. Although, the cost and time of study goes up.
You can use the magnetic treated irrigation water on salt removal from a sandy Soil.
I think using NaCl only as a source of salinity is not good choice because there will be specific toxic effect of these elements. It is better to combine NaCl with other salt like CaCl2 or another salt.
I agree with Ragula Seenaiah and Youssef Sassine. and I would like to draw your attention to the fact that salt will accumulate with time if you can not grantee enough drainage to remove accumulated salts specially if you used long irrigation intervals and did not give enough amount of irrigation water. as plants absorb water more than nutrients or salts, salts will accumulate in the root zone resulting in higher EC than your target point. So, you must irrigate with enough water in each treatment until the drainage has an EC similar to your set point. this ensure that your EC in the root zone is at the set point.
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