Maybe not the exact reason, but Hoaglands is a fairly concentrated mix. I felt it was always promoted as a way of "easing" the seedlings into a nutrient rich environment before loading them up with full strength solution.

There may be a physiological reason for it, but 1/2 strength solution also effectively doubles the water gradient between roots and solution, so might increase the diffusion of some nutrients out of the very young roots.

Why don't you test it out and see what happens with your particular plants?

Also, are you conducting an actual field-scale hydroponic experiment? Or do you mean to say that you are using field crop species in a hydroponic lab-scale experiment? Your question's wording is slightly ambiguous.

May by scarcity cause

Are you going to grow in soil and use a half-strength Hoagland solution? If so, it is not hydroponic. Soil has mineral nutrients then it is better to use a half-strength hydroponic feed

Dear Matthew,

I am using field crops (wheat, rice, etc) to test under only hydroponics, not in the field.

Ya, I accept the seedling stage may be one reason, but I didn't find exact reason.

I should go for full strength and find the answer.

Thankyou.

What is the rooting medium? As you wrote, the half-strength liquid feed can be used for seedlings but you can also use low salinity hydroponic feed for seedlings. After planting you have to use full strength main feed.

In hydroponics, there are two types of feed:

Winter feed is more concentrated because plants take less water.

Summer feed is less concentrated because plants take more water.

Hoagland is a winter feed. In summer use liquid feeds which have low EC.

One of the reasons for using 1/2 Hoagland is to reduce the salinity of the feed.

Dear Servet Varis,

Thank you for your valuable information,

Distilled water with Hoagland solution is the rooting medium we use.

Wheat (Triticum aestivum) is a moderately salt-tolerant crop (Maas and Hoffman, 1977).

The literature indicates that rice is sensitive to salinity, particularly during the seedling stage (Maas and Hoffman 1977).

Therefore you have to use a low EC feed for these crops.

When making a low EC feed, P and trace element levels are not reduced, the other element levels are reduced but their ratios to each other are kept the same as in the first feed.

Dear Servet Varis,

Thank you for your valuable information.