MSc

The Project on 'Dwarfing potential of indigenous mango varieties' was
undertaken at the Department of Pornology and Floriculture, College of
Horticulture, Kerala Agricultural University, Vellanikkara during the period 1999-
2000.
Observations on the shoot extension growth of the parent rootstock trees
for a period of one year, showed a rhythmic growth with periods of active growth
and quiescence, except in the variety Moovandan. However no definite synchrony
between the climatic parameters and flushing pattern of the varieties could be
.
noticed.
Among the different morphological characters, a fair amount of
variation could be noted with regard to number of shoots per half meter square,
internodal length and number of leaves. But as such, no definite relationship could
be noted between the growth potential of the tree and other characters.
The varieties viz., Moovandan, Olour and Vellaikolumban exhibited
distinct polyembryony, whereas only one sprout per stone could be noted in the
case of other varieties including the variety Chandrakkaran. Mechanical
manipulation through splitting of endocarp of the seed stone was advantageous by
reducing the days taken for germination, enhancing the rate of germination and
increasing the extent of polyembryony.
Anatomy of the roots and leaves, made it possible to approximately
place the varieties into groups of 'low growth potential' (LGP) and 'high growth
potential' (HGP). Accordingly Vellaikolumban, Kalapady and Olour could be
brought under the former and Moovandan, Chandrakkaran and Mundappa under
the latter.

The varieties showed a clear variation with respect to the stomatal
density of leaves. Stomatal density was highest in Moovandan and lowest 111
Vellaikolumban.
Anatomy of the graft union indicated higher accumulation of calcium
containing crystals in the conducting phloem of Bangalora/Vellaikolumban graft
combination.
The electrical resistance of the rootstock seedlings was found to be
higher in Moovandan and Chandrakkaran and lower in Vellaikolumban, Olour and
Kalapady.
The apparent velocity of sap flow/transpiration stream in the grafted
plants showed higher rates in the graft combinations involving Moovandan,
Chandrakkaran and Mundappa and lower rates in Vellaikolumban, Kalapady and
Olour as rootstocks.
The rate of leaf respiration 111 one year old graft combination of
Bangalora/Moovandan and Bangalora/ Vellaikolumban and their seedlings showed
relatively higher rate of respiration in the grafted plants on Moovandan rootstocks
than those on Vellaikolumban.
Total phenol content in the dormant buds as well as in leaves of the
mango rootstocks varieties showed higher values in Vellaikolumban and Kalapady
and lower values in Moovandan and Chandrakkaran.
Observations of the one year old graft plants in the nursery in terms of
the maiden shoot growth did not reflect an immediate expected effect of the
rootstock on the total growth and vigour of the combinations.


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