Stress on the radicle during the change from water to sand

I was hydrating some seeds (dicotyledonous) in water for 5 days and most of them started with the development of the radicle so I thought I was going to do well with germination, the problem occurs when I transfer them from the water to the sand and I end up without any sprouts. I understand that it could have been due to stress, perhaps from being in an environment with excess water to one with less humidity, but I can’t find anything to help me support that.

If anyone knows a reason or has any related reference I would be very grateful.

Hi Francisca, seeds need two things to germinate: water and oxygen. By leaving them in the water 5 days maybe they lacked oxygen and actually suffocated, if they were under water. This is why it is best to germinate on moist paper and then transfer into pots carefully. Sometimes people will soak seed in water for 3-6 hours before planting in the field, but if you soak too long it will kill the seed, especially in warm temperatures.

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David brought up a good point about oxygen. Even a seed that is not killed by lack of oxygen per se may succumb soon after due to infection from bacteria or fungus due to being compromised by lack of oxygen and thus rendered less healthy and able to defend itself through natural defense mechanisms. Or the fungus hyphae had a chance to penetrate the protective coating because the seed coat was wet too long. Some seed is sold coated with fungicide to aid in protection since excessive rain, clay, deep planting, or compaction may provide conditions for too much moisture and too little oxygen and subsequent fungal attack when planted in the ground. Also sand may not have enough moisture or be excessively hot. Some mulch between the rows of seed can keep down the temperature and preserve moisture but too much on top of the seed will not allow the seed to reach light or produce a weak sprout.

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