International Journal of Horticulture, 2017, Vol.7, No.17, 138-145
144
(35) days old microtubers contained 1.775 mg/dl sucrose and 0.9665 mg/dl starch while 60 days old microtubers
contained 0.702 mg/dl sucrose while 1.4577 mg/dl starch (Table 5). These results depicted that sucrose is more in
microtubers of less physiological age while at this stage starch content is low. Contrary to this, increase in
physiological age resulting in low sucrose content but high starch content.
Table 5 Sucrose and starch contents in microtubers of different physiological age
Age of microtubers
Sucrose contents
Starch contents
35 days
1.775 dl
0.9665 dl
60 days
0.702 dl
1.4577 dl
Note: *dl= deciliter
Effect of photomixotrophic conditions on biochemical characteristics of microtubers:
For comparative
biochemical analysis, proximate analysis was performed to estimate the chemical composition of the in vitro
grown microtubers and field grown potato tuber. In proximate analysis, dry matter, crude protein, fiber extracts,
fats and ash contents on dry basis were estimated. Thereby a comparative chart was made (Table 6) which
depicted that dry matter, crude proteins and fiber extracts were more in microtubers as compared to field grown
tuber except fat percentage that was observed as same in both cases. But ash percentage was more in field grown
tubers as compared to microtubers.
Table 6 Proximate analysis of field grown potato tubers and
in vitro
grown microtubers
Field grown potato tuber
In vitro grown Microtuber
Dry matter
29 %
34 %
Crude protein
13.3 %
14.6 %
Fats
0.7 %
0.66 %
Fiber extract
1%
1.4 %
Ash content
7 %
6 %
As discussed already in this paper,
in vitro
micropropagated shoots of potato, cv. PRI-Red were used as explant,
which were cultured on nine tuberization media having different photomixotrophic conditions. These media
supplemented with basal MS salt in common contained sucrose, kinetin and BAP at varying concentrations and in
different combination as well. While maximum number of microtubers per explant was achieved on medium,
TM5 containing 100 g/l sucrose, 4.75 mg/l kinetin and no BAP. The results of this study revealed that sucrose has
significant effect on microtuberization. In this study three levels of sucrose viz., 60 g/l, 80 g/l and 100 g/l were
investigated and at sucrose concentration 60 g/l, no tuberization response was observed while medium (TM5)
containing 100 g/l sucrose and 4.75 mg/l kinetin showed excellent response for microtuberization followed by
medium (TM4) having 80 g/l sucrose and 4.75 mg/l kinetin. The importance of sucrose at increased level in
tissue culture regime for efficient microtuberization was also documented by Yu et al. (2000); Shibli et al. (2001);
Rida et al. (2001); Gopal et al. (2004). Similarly response of media containing kinetin was good rather than media
having BAP. This showed that kinetin is more important for microtuberization as compared to BAP. Similar
findings were reported by Gopal et al. (1998); Amma and Maity (1998) and Rodrigues-otubo et al. (1999).
Acknowledgement
We highly acknowledge Director Potato Research Institute Sahiwal, Pakistan for providing us potato germplasm for research works
and also acknowledge, Dr. Mansoor Hameed, Associate Professor, Department of Botany; University of Agriculture Faisalabad for
providing help in histoanatomy section of this research work.
References
Altindal D., and T. Karadogan, 2010, The effect of carbon sources on
in vitro
microtuberization of potato (Solanum tuberosum L.), Turk. J. Field. Crops., 15(1):
7-11
Amma K., and S. Maity, 1998, Role of nodal position and hormones on microtuber production in potato (Solanum tuberosum L.). J. Hort., 11: 65–7
Arndt G.C., and S.J. Peloquin, 1990, The identification and evaluation of hybrid plants among open pollinated true seed families, Am. Pot J., 67: 293-304
