Can you elaborate on your question please:

• You might need to tell us how much salt is already in the soil,
• which salts (we can only assume you are considering Na+ and Cl-, but there are other salts to consider),
• which crop species are you growing (again, I might assume rice, but we can't tell from the question),
• will the pots be free-draining or sealed?

Also don't limit yourself to a single measurement at maturity: In 60 days you should be able to get growth performance as measured by leaf length, leaf emergence rates, plant height, days to flowering, and days to maturity.

To answer your question slightly more directly: how closely do you need to simulate real-world irrigation conditions? Are you trying to (i) replicate the water supply and inflict salt upon the plants, or are you trying to (ii) determine the salt load that will limit plant growth? If (i) you just water as normal for your location, if (ii) then watering to a strict schedule regardless of water demand is perhaps required.

I might just mention work from a colleague, Yusuf Genc , that you consider both positive and negative ions in your study:

Article Uncoupling of sodium and chloride to assist breeding for sal...

Article Bread Wheat With High Salinity and Sodicity Tolerance

You add it just before the substrate completely dries

I would agree with Andrew to water the pots when they start to feel dry. However if you only apply NaCl for getting the correct EC it will be difficult to tell is growth reduction is caused by the high EC or toxicity of sodium/chloride.

Make sure that when you give water that you give enough water to create drainage (at least 30%). If drainage is low, EC will upbuild inside the pot.

Ur layout and design is imptt to know it

I think u need to take data at 20-40-60 DAS Respectively so please add salt at basal then based on 20 ,40 DAS Data.

Dear Tanjimul Islam,

Some answers to your query have been given by several resource persons. In addition, I would suggest you to give some attention to the texture of your soil.You have written that the water will be free flowing. In that case, light textured soils ,viz.sandy ones ,will allow much of the saline water to leach down while in heavy or clayey soils , good amount of the salts will be retained in the soil. Thus, a common formula for water application will not be tenable for soils with different textural composition.Hope I have been able to make my point clear.

I would agree with Andrew to water the pots when they start to feel dry. However if you only apply NaCl for getting the correct EC it will be difficult to tell is growth reduction is caused by the high EC or toxicity of sodium/chloride.

Make sure that when you give water that you give enough water to create drainage (at least 30%). If drainage is low, EC will upbuild inside the pot.

In the past I used seawater aqarium salt for testing the salt tolerance of turfgrass plants. There are more sources because the salt content of seawater is not constant over the whole world. Work with perlite or rockwool to decrease the "strange influences" of the soil.

it depends on your treatment structure that how much salts you want to add per pot? either at a time of sowing or through different intervals with irrigation.

It depends also one the texture of the soil becuase every soil type have different leaching properties. Also, i suggest you to keep the pot soil tempertaure according field soil temperture then you will when to need add water and when not and how much you needed. Also, be consisten with your watering valume in days interval. I hope it will help

You must do a zero test (a simulation of the experiment). It allows you to set the basics (watering volume, frequency, etc.) of the experiment.