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