Home - Back to Authors work in Biotechnology
Embryo Culture of Coconut
Physico-Chemical Factors affecting the Germination
By John Paily
[Before I share my experience let me tell an important fact plainly. I view biological system not as a machine but as a dynamic system, which is living and evolving constantly without any preferred direction in the environment in which it is surviving. Thus the information content of the system is specific and varying. This depends on the past and present template. Therefore an observed results are just tendencies of the system growing in particular environment and amenable to particular manipulation within certain range. I have experienced so much uncertainty in dealing with biological information, that I am over looking the presentation of charts, histograms, curves and so on. I believe in random experimentation and fine tuning the tendencies of the system ]
Related Page- Coconut Cloning an Introduction
Aim:- Germinating mature and immature Coconut embryos and studying various factors affecting its germination. The basic objective with which it was pursued was basically get familiarized with the germination and growth of embryo such that the knowledge obtained could be used for growing embryoids obtained from the leaf. The work has several other importance of its own, such as, transportation and preservation of germplasm etc.
Material and Method
About 1cm portion of coconut endosperm containing the embryo is isolated and it is disinfected using mercuric chloride, before isolating it in aseptic conditions.
Results and observation
1] The basal medium best supporting the growth of the mature embryo in our experience was Eeuwen's Y3 liquid medium without any hormones. [C. J. Eeuwen, Physiol Plant 42, 173-178, 1978]
2] The Embryos isolated from mature and partially dried coconut gave good results than the one taken from freshly plucked nuts. It was based on the observation that the traditional agriculturist smoke dries seed nuts [Gradual] then soak in water for few hours before sowing. I found sense in it and picked up the clue.
3] In the standard practice [ Eeuwen's liquid medium ] the germination rate was nearly 90%. for partially died fruits. Full grown plants with 3-4 to leaves, ready for transfer to soil could be obtained in to 80-100 days. see fig below
Fig -1 &nbssp; Fig-2
Fig-3 Fig-4
Fig-5 Fig-6
Fig-7 Fig-8 Fig-9
5] The growth in solid medium is slow when compared to the liquid medium. However embryos transferred from liquid medium to solid medium after germination showed good growth. But in general liquid medium was superior.
6] The initial germination is observed best without any addition of hormone in Eeuwen's Y3 liquid medium with 40to 60gms/l of sucrose.
· However in secondary cultures done after 3 to 4 weeks, addition 0.1 to 1mg/l of NAA helps the growth of the root system. Without significantly affecting the shoot growth. Higher concentration has negative effect on the shoot growth
7] Sucrose concentration has an effect on the growth and the germination percentage. Higher sugar concentration favors the root formation and inhibits shoot formation. 40-60gms/l gives normal growth of root and shoot.
· Higher concentration is inhibitory to growth and the germination in the primary cultures. However, when embryos initially transferred to higher concentration 70 to 90 gm/l of sugar for for a weak and subsequently transferred to normal medium recovered to show good growth, specially in the root
·
Increasing
the sugar concentrations in the secondary cultures lead to stunted growth of the
root but the number of roots formed increases. Secondary roots are suppressed.
8] Embryos grown in high concentration of sugar [90mg/liter] and [NAA 2.5 to 5 mg/liter] when subsiquently transfered to normal media showed a tendency to produce large number of thick roots, in some cases the whole haustoria turned into root, see fig-8
8] Increasing the nitrogen content of the basal medium suppresses the germination rate in the primary medium. However in the secondary culture the effect is less marked, very high concentration limits the growth
Plants were successfully established to soil. But the percentage of successfull transfer was limited. No serious attempts were done in this direction. The main reason was the lack of facilities. The problem stemmed from infection to the haustorial portion.
Conclusion - The work was elaborate but taking into consideration that we are handling a dynamic system constantly evolving in changing environment, I prefer to speak of tendency of the system. The fundamental instinct of the system is to survive and this reflects very much in culture. The observation that embryos obtained form partially dried nuts gave better germination than embryos taken from fresh coconut speaks of the role of stress playing in germination and survival. Few experiment done out of curiosity by partially dehydrating the embryo before the transfer to liquid medium also showed promising result. The observed improvement in rooting when embryos were transferred from higher sucrose content or NAA content to lower sugar and NAA free medium also could be explained from the same premises.
Click here to go to next page – Leaf Tissue Culture of Coconut Plants – Step towards Cloning Coconut