You can refer to these papers below

10.3923/rjb.2015.73.87

http://www.tropicalgrasslands.asn.au/Tropical%20Grasslands%20Journal%20archive/PDFs/Vol_44%20(1_2_3_4)/Vol%2044%20(2)%20Suleyman%20et%20al%20123.pdf

Based on that papers, IAA and NAA are the best auxin for rooting in plant tissue culture. Moreover, you have to check the optimum concentration for your research.

IAA and NAA are the best rooting hormones for plant tissue culture. but the concentration can be changed according to the crop. Therefore, you have to optimize your protocol for your crop.

IBA (Indole-3-butyric acid) is widely used rooting hormone also.

Addition of activated charcoal (usually 2g/L) also helps during in vitro rooting in addition to IBA or IAA.

K salt of IBA is the most appropriate in general when you need to keep the control of the root number and at the same time you would like to avoid excess of callus. Keep your initial IBA mother solution in the dark (it is the same with IAA!). You can get additionnal auxin activity using different substances (Vit D2, proline, as examples) and treatment (3-5 days in complete darkness at the lab temperature from the begining of the rooting stage as example) and control callus formation by using riboflavine that oxydize exogenous auxin from the moment you move the culture to the light). The results could be variable according to the physiological status of your plant material. try to homogenize your plant material before its transfer to auxin medium)

IAA (indoleacetic acid) is one of the best rooting hormones for plant tissue culture, the concentration is variable, normally 1 mg/L.

You can read to these papers below

There is nothing like best hormone for rooting in plant tissue culture. IAA, NAA, or IBA are generally suitable for in vitro rooting of plants, yet some more phytohormones have been used for this purpose depending on requirement of specific plants.

In fact, nothing like best phytohormone for rooting in in vitro culture. Rather, it defense on the plant species, sub-species or cultivar. For monocot plants mostly IAA and NAA are generally suitable.

I stand to be corrected !

Dear Majid

Several factors affects in vitro rooting. Apart from Auxins (IBA, IAA and NAA); Half strength of Nutrient medium (With or without auxins), and other additives viz. Activated charcoal (1-2g/L), Ascorbic acid (0.5-1g/L), riboflavin improves percent rooting.

Try to use combination of IBA, and NAA (0.1 to 2mg/L, for example: IBA 2mg/L the keep 0.1 or 0.01mg/L NAA) for better rooting.

Try to keep cultures in dark for at least 1 week in medium supplemented with IBA/ IAA/NAA (if medium having no activated charcoal, this dark condition avoid photo oxidation, so auxins will work better). If you’re medium is supplemented with Activated charcoal, then no need to keep in dark.

I am also agreeing with Dr. P. Druart opinion.

Best regards

You can using IBA is generally suitable hormon for in vitro

rooting of plants

Maily we use IBA, IAA for rooting... but in some plants it can occur at half strength MS medium also....

Let us know what is the plant material you want to root and more precised conditions of plant material preparation and shoot induction would be given.

Auxins such as IAA, IBA, NAA promotes rooting. Concentrations ranging from 0.5 - 2.0 mg/L can be employed. In addition, half strength MS without the addition of any hormones also promotes rooting.

First of all the reaults vary according to plant species hence it is not necessary that conditions for one species will work for another. But generally IBA,NAA and IAA is being used for in vitro rooting but along with that there are many other factors as said by Dr. P.Druart and Dr. Rajesh Pati. Strength of medium affects rooting and full,half and quarter can be tried for optimization. Try to keep low sucrose level i.e. 1% will work.

Also if the main aim is hardening of tissue culture plant, then you can try ex vitro rooting using planting substrates like cocopeat, vermiculite, perlite, sand, soil etc. individually and in combination. This will decrease the time of micropropagation and also the survival rate will increase.

All the best.

IBA and NAA are the best auxins for rooting in plant tissue culture. you can vary their concentration ranging from 1.0 to 2.5 mg/L based on your crop chosen with half MS.

Dear Dr. Ibrahim

Based on personal experience, each of the auxins alone or in combination can be best in terms of plant species

Dear Dr. Ibrahim

It depends on plant species. For example Ahmed et al. (2007) reported NAA as a best auxin for root initiation in Aloe vera. However, Zakia et al. (2013) observed that IBA was the best for root proliferation (Venkatachalam et al., 2017).

In Digitalis lanata Ehrh., among the various concentrations of auxins IAA, IBA and NAA tried for rooting, the best response occurred on MS basal medium supplemented with 17.13 μmol/l IAA (Behusare et al., 2018).

Best wishes

you know doctor it is depend on plant response and concentration of auxin but i think IBA best than NAA because with NAA rooting will be easy to broken