Dear Parth Desai .....

you can decrease the Light intensity for a week in first sub culture, or also use low concentration of GA3, that will effective in elongation of your new shoots

Best regards

Hi

Try to separate the shoot clump into smaller clumps and culture them on basal media for 7-10 days to reduce the endogenous harmone concentration. Then try on different media combinations like BAP, BAP+NAA etc.

Hope this info will helps you..

Dear Parth,

GA3 is quite efective in elongation of internodal spaces. How are you using it? Dosage, sterilization....

Dear Parth, I do agree with Ricardo. In spite of GA3, you may also use IAA in low concerntration. Subculture without any growth regalator will also help in regenerating shoots with long internodes. Regards....

Dear Parth Desai .....

you can decrease the Light intensity for a week in first sub culture, or also use low concentration of GA3, that will effective in elongation of your new shoots

Best regards

Many ways-

1- Reduce concentration of cytokinin

2- Add GA3 at low concentration (if your media is devoid of GA3)

3- Use of basal media with charcoal only

4- reduce light so plants will be with increased inter nodal length

Use hormone free media or use Paclobutrazol less than 4 mg/l

Add Gibbrelic acid 2-3mg in plant nutrient medium try better if you get success.

Try to optimize medium salts such as Fe Source, NH4NO3 or Micros

Thank you everyone for your suggestions

Dear Ricardo,

I have used 1-2 mg per litre GA3 using filter steriliztion.

Dear Parth,

With these dosages should be enough for elongation. Many factors might be affecting the results. With the details that you have provided I only can hypothetize two causes: (1) low concentration and/or (2) GA3 break down.

We used to multiply many papaya cultivars on a modified De Fossard basal medium that contained 0.5 µM of both BAP and NAA plus 2% sucrose and 8 g/L agar (4 weeks). Shoots would elongate nicely on this media in preparation for rooting.

Shoots that were developed from multiplication step were dissected and cultured for 3 days on rooting medium low De Fossard with 10 µM IBA. After 3 days shoots were transferred to hormone-free (Drew-Smith J. Hort. Sci. 61:535-543 1986) (DS) medium + Riboflavin. These shoots rooted within 7 days and elongated and grew nicely until next multiplication cycle.

Growth conditions for papaya plants were as follows:

Cultures were incubated at 25 ± 1C with cool-white fluorescent tubes that provided a 16-h photoperiod and a photosynthetic photon flux of 60 µmol·m-2 ·s -l

as published by Drew HORTSCIENCE 27(10):1122-1124. 1992.

I used 3% Sucrose and 2% Glucose 1/2-1MS + 0.1-10ppm IAA, 0.1-10ppm BA for hop cultivation. After that I used + 0.2-0.8ppm + 0.1-10ppm TDZ for transformation of hop. So I tried many condition for this culture for example, potato, apple, pear, rice, and so on. You try many media and many condition for culture. I think this is better and more fast to establish your work.

You can evaluated different concentrations of GA3 to find the best results

GA3 concentration is important with some auxin, I think. In my case hop tissue culture is effective to use GA3 0.1-10ppm. But depending on crops you could use different concentrations of hormone.

Subculturing on cytokinin-rich media can induces the juvenile branching characteristics that provide micropropagated plants with the desirable morphological and growth habits of seedlings with the benefits associated with asexual propagation. For more information :

https://www.researchgate.net/publication/228842835

Reduce the growth regulator level and addition of charcoal will also support to increase the length of internode of the existing shoot. Addition of GA3 and charcoal will also be useful to achieve the goal.

GA3 is useful I agree, but IAA in low concentrations is also useful to increase the length of inter nodes. You may also decrease the light intensity of the culture room for a week or so, might work.

Low light will increase the inter nodal length but the shoot quality will be thin and week. The out come should be shoots with increasing inter nodal length with standard shoot quality. For the purpose, charcoal and low BA will be useful.