The role of amino acids in hydroponic culture
It is very common for hydroponic nutrient manufacturers to add amino acids to their products. They often cite significant benefits ranging from plant enhancement to a tremendous increase in yield or product quality, but rarely cite evidence examined by peers to study these effects. Today we are going to look at the use of amino acids in hydroponic cultivation and the effects that amino acids have been shown to have when used in different types of crops. We will also look at some of the benefits and problems they have shown and discuss whether they are really worth using in hydroponic nutrient solution.
Amino acids – which I use here to refer to L-alpha amino acids – are essentially organic molecules that are used as the building blocks of protein in all forms of life. Plants can synthesize all the amino acids they need internally, while in animals, many of these amino acids must be obtained from other animal or plant sources. However, since amino acids can be added to nutrient solutions and plants can absorb them (see here), it is interesting to know what effects they may have.
There are two ways amino acids can affect a hydroponic product. They may be absorbed and used directly by the plant, or they may form chelates with a metal ion and affect the absorption of that metal. It is very difficult to separate the two effects – except when certain metal adsorption studies are performed – so the effect on the yield is generally a combination of the two. The specific amino acids used and their proportions are also very important for these effects because both plant uptake and the stability of metal chelates depend on the exact structure of the amino acids in solution.
Because amino acids compete with nitrates in the nitrogen cycle and can be easily absorbed by plants, they can be easily absorbed. This seems to be especially true in cases where nitrate is low and plants are deprived of nitrogen. This effect is very important for glutamine, not surprisingly because the synthesis of glutamate is essentially a mechanism for the synthesis of ammonium by the plants used.
There is also evidence that amino acids can help plants with stress. For example, strawberries under autotoxic conditions – meaning that they poisoned a nutrient solution after excessive recirculation – benefited greatly from the use of amino acid cocktails (here), and canola plants have been shown to be useful in saline conditions. Proline have increased their function (here)). Plants under heavy metal stress can also benefit from the presence of amino acids, for example rice seedlings have been shown to benefit from the amino acid applications under cadmium stress (here).
There are also limited studies on the use of amino acids as metal chelates in hydroponics. A 2012 study (here) compared different iron chelates with Fe EDTA and found that some of these chelates were better at absorbing iron than traditional EDTA chelates. Glycine iron showed the best absorption between roots and shoots plus best performance in tomatoes (second image in this post). This suggests that iron glycine may be a good candidate for Fe EDTA replacement in hydroponic solutions. Another study (here) also compared different copper amino acid chelates containing copper and found that cysteine may be used effectively for copper fertilization and phytoremediation.
Is it worth using amino acids in hydroponics? This may depend on the exact conditions the plants are facing. While amino acids are useful for absorbing certain nutrients – such as iron and copper – or reducing some stress conditions (salinity, auto-toxicity), there is no strong evidence to suggest a wide range of beneficial effects on normal plant growth conditions. Especially if they are close to ideal. In conventional hydroponic solutions, the introduction of large amounts of amino acids may have significant adverse effects due to their effect on ion uptake and nitrogen metabolism. Further evidence is needed before providing general recommendations for exogenous amino acid applications.
This does not mean that amino acids may not be useful under normal circumstances, we just do not yet have any evidence to show which amino acid profiles may work best for which plants and under what concentrations, and we know that if possible harmful effects Have. These parameters have not been carefully studied.