Tamarind monograph.pdf - Crops for the Future

The girdling of etiolated shoots reportedly stimulates air-layered roots to be
produced within 10 weeks, and the process can be further accelerated by
several weeks through the application of the growth regulator indolebutyric
acid (IBA) (Troup, 1921). Girdling and etiolation increases the percentage of
total sugars, reducing and non-reducing sugars, lowers the starch content and
raises the percentages of soluble and total nitrogen. This results in a lower
C:N ratio, a higher level of the rooting cofactor and lower levels of
indigenous inhibitors compared with nongirdled etiolated shoots. The
application of IBA or IBA + NAA (naphthalene acetic acid) increases the
number and the length of air-layered roots, and reduces the time for rooting
from about 10-6 weeks (Gowda, 1983). Navaneetha et al. (1991) reported
that shoots etiolated for one month before treatment in May with IBA at
1000 ppm gave 75% rooting and resulted in the highest subsequent survival.
No rooting was observed when the treatment was done between January and
March. This demonstrates the importance of marcotting only when the
parent trees are in an optimal physiological condition. In another experiment
IBA/NAA each at 1000 ppm, resulted in only 63% rooting.
5.2.2.4 Micro-propagation
Tamarind may be propagated by tissue culture techniques; however, reports
on in vitro morphogenesis in this species are limited, due to its recalcitrant
and callogenic nature (Hazara et al., 2004). To overcome these limitations,
an attempt was made to induce meristematic activity in seedling explants.
Seedlings were germinated in media with or without thidiazuron (TDZ).
Presence of this growth regulator restricted the differentiation of the apical
meristem to form shoots. It triggered proliferation of the meristematic tissue
at the cotyledonary node and a large number of meristematic buds appeared
in a radial pattern around the node. The meristematic activity extended to the
junction of the epicotyl and hypocotyl, giving rise to buds in the form of
protuberances from all sides of the junction. These buds differentiated to
form shoot primordia and subsequently to shoots in a growth medium devoid
of growth regulators. Plants developed by micrografting of these shoots on
seedling-derived rootstocks survived in soil.
Shoot tips, cotyledons and cotyledonary nodes have been used successfully
as explants for tamarind tissue culture (Splittstoesser and Mohamed, 1991).
The explants were cultured in an MS (Murashige and Skoog, 1962) medium
supplemented with TDZ (thidiazuron) / IBA (indole butyric acid) or BA
(butyric acid) / NAA (naphthalene-acetic acid) and incubated at 28 o C for 5
weeks under an 18 hour photoperiod. The shoot tips of tamarind regenerated
only one shoot while the cotyledonary nodes produced multiple shoots.
Multiple shoots were however induced on shoot tips and nodal explants on
an MS basal medium supplemented with BAP (Benzylaminopurine) (5 x 10 -
6 -6
M). All shoots were rooted on MS with IAA (indole acetic acid) (5 x 10
M) and the micro-propagated plants were successfully transferred to the soil
(Jaiwal and Gulati, 1992). Shoot tips from in vitro grown seedlings have
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