MSc

Investigations on "Exploitation of induced variability for crop improvement in
ginger (Zingiber officinale Rosc.)" were carried out at Department of Plantation Crops
and Spices and Centre for Plant Biotechnology and Molecular Biology, College of
Horticulture, V ellanikkara during 2001- 2003.
Evaluation of seven induced variants along with three check varieties indicated
the superiority of the autotetraploids V 2 (Z - 0 - 86) and V I (Z - 0 - 78) in quality
attributes. V 2, an autotetraploid from Rio-de-Janeiro was notable for lowest fibre content,
highest oil and oleoresin content and increased driage and high cuticle thickness than its
diploid counterpart. V!, an autotetraploid from Himachal Pradesh exhibited highest
driage, high oleoresin content and highest cuticle thickness. V 2 was more vigorous in
growth exhibiting maximum yield contributing characters such as number of tillers per
plant, number of leaves per plant, leaf area and also leaf area index and root length. V I
showed maximum plant height and pseudo stem height which are correlated with yield.
The fresh and dry yield of rhizomes of V I and V 2 were found to be on par with V 8 the
highest fresh rhizome yielder and V 10 the highest dry rhizome yielder. V 3, a variant from
Himachal Pradesh also produced yield on par with the highest yielder.
The yielding capacity of the autotetraploids especially V 2 was found to be
superseded by the incidence of diseases like soft rot and bacterial wilt. V I was least
susceptible to leaf spot. V 10 (Himachal Pradesh) showing stable performance over the
years had low incidence of soft rot and bacterial wilt.
The high pollen fertility arid viability of the autotetraploids V I and V 2 and the
highest pollen size and tube length observed in V 2 make them ideal as pollen parents in
hybridization programmes.
None of the various in vivo pollination techniques such as stylar, stigmatic, intra
ovarian was effective for inducing fruit set or seed set in ginger.

In vitro placental pollination with pollen grains suspended in ME3 medium was
found to the best with maximum ovule swelling and maximum percentage of cultures
with developed ovules (90 %).
Pollen pistil interaction studies substantiated the lack of seed set under natural
conditions due to failure of pollen germination owing to incompatibility barrieres
operating in stigma, style and ovary. Elimination of these barriers in in vitro placental
pollination enabled pollen germination and enough tube length to bring fertilization.
The experiments on culture establishment showed that MS semi solid medium at
half strength supplemented with NAA (0.5 mg rl) + BAP (2.5 mg rl) along with 3 %
sucrose + CH (200 mg rl) or CW (15 %) v/v supported maximum development of
ovules. Addition of double the quantity of the vitamin stock of the MS medium to the
culture establishment medium and incubation under dark conditions also favoured more
ovule development. Semi solid medium was advantageous in obtaining maximum seed
set and size at maturity.
Controlled selfing and crossing among the autotetraploids and diploid cultivars
using in vitro placental pollination were successful and influenced ovule development.
Mid season of flowering favoured maximum culture establishment and ovule
development compared to early and late season in both selfing and crossing. Crossing
enabled production of maximum number of developed ovules compared to selfing.
Ovules/seeds developed in vitro were creamy white during the initial stage of
development which changed to purple red colour with in a period of 30 - 35 DAP and to
black with in a period of 55 - 80 DAP. The small arillate seeds had two seed coats, outer
one being thick and inner one being thin. The seed coat encloses a cavity, which is typical
of monocots. In the cavity, endosperm with embedded embryo is seen.
Tetrazolium staining of well developed seeds revealed that the embryos were viable
staining red which was more intense at 40 DAP than at 80 DAP seeds.
Seed germination studies indicated that subjecting the seeds to embryo rescue
(embryo culture) and in vivo seed treatments failed to induce germination. Under in vitro

conditions, the seed of 80 DAP obtained from the cross diploid (Rio-de-Janeiro) X
tetraploid (Z - 0 - 78) germinated after seed priming treatment (50 ppm KN03 for 8 h)
and also the cross of tetraploid (Z - 0 - 86) X diploid (Maran) after seed imbibition in
water for one day when cultured in half MS + 2, 4 - D (0.5) mg r', BAP (6.0) mg r' and
GA3 (5.0) mg r' along with 3 per cent sucrose, showing good root development. Seed of
the cross between diploid (Rio-de-Janeiro) X diploid (Maran) and diploid (Rio-de-
Janeiro) X tetraploid (Z - 0 - 86) germinated showing radicle emergence after culturing
in solid medium of half MS + 2, 4 - D (0.25) mg r' and BAP (9.0) mg r' along with 3
per cent sucrose.
Somatic embryoids were developed from seeds cultured in media combinations of
half MS + 2, 4 - D (0.5) mg r', BAP (6.0) mg r' and GA3 (5.0) mg r' along with 3 per
cent sucrose and also in half MS + 2, 4 - D (0.1) mg r', BAP (8.0) mg r' along with
3 per cent sucrose in crosses between diploid and tetraploid. Plant regeneration from the
somatic embryoids was not observed even after subjecting to media with different
concentrations of various growth regulators.
Callus growth was also observed after 25 days of seed germination in the seed culture
medium containing half MS + 2, 4 - D (0.5 mg r'), BAP (6.0 mg r') and GA3
(5.0 mg r') along with 3 per cent sUcrose.