Abstract:
The study entitled "Standardisation of grafting in
bitter gourd{Momordica charantia L.)" was conducted in the Department of Vegetable Science,
College of Agriculture, Vellayani during 2017-2019 in order to identify suitable
rootstocks, standardise grafting techniques and evaluate growth and performance of
grafts in bitter gourd. The study was conducted in two parts. Standardisation of
grafting in bitter gourd using four rootstocks was done in part I and evaluation ofthe
grafted bitter gourd for growth, yield and quality was attempted in part II.
Bitter gourd scion (Preetlii) and four rootstocks (sponge gourd, pumpkin,
bottle gourd and bittCT gourd) were raised in protrays. Separate experiments for each
roolstock, were laid out in CRD, replicated thrice for standardization of grafting.
Growth regulators (alar and cycocel) at two different concentrations /.e.,10 mgL"' and
50 mgL*' were sprayed at second leaf stage forreducing seedling height of rootstocks
and then grafted using three methods (hole insertion grafting, one cotyledon grafting
and cleft grafting).
Alar @10 mg L*' reduced plant height(7.50 cm) and enhanced diameter (2.97
mm) in sponge gourd rootstock. Faster graft union(4.11 days) was recorded forfiole
insertion grafting withhighest success percentage (77.07 %). Spraying of cycocel @
50 mg L ' resulted in the highest success percentage of 56.44 per cent. Combination
of cycocel @ 50 mg L"'+ hole insertion grafting recorded highest success percentage
of 86.67 when bitter gourd grafted onto sponge gourd.
Though cycocel @ 10 mgL"'and 50 mgL"'improved the diameter of pumpkin
rootstock, alar@ 10 mgL"' and 50 mgL'reduced the height ofthe rootstock. New leaf
emerged faster (3.51 days) in hole insertion grafting but one cotyledon grafting
recorded the highest success percentage (68.60 %). Cleft grafting not only took more
days for graft union but also recorded least success percentage (11.20 %). Though
alar @ 10 mgL*^ alar@50 mg L'* and cycocel @10 mg L'' were equally effective to
improve success percentage but the combination of alar @ 10 mg L'^ + one cotyledon
grafting recorded the highest success percentage of 81 per centwhen bitter gourd was
grafted onto pumpkin.
Application of alar @ 10 mg L'onto bottle gourd rootstock improved
diameter (4.65 mm) and @ 50 mg L"'reduced height (12.61 cm). Among the grafting
methods, graft united faster (3.69 days) in hole insertion method, while success
percentage was tlie highest (86.40 %)for one cotyledon grafting. Growth regulator
had no role in days taken for graft union and could not improve success percentage
over distilled water.
Application of alar @ lOmg L*' cycocel @ 10 mg L*' and 50 mg L*' were
equally effective in reducing the height of bitter gourd rootstock. Alar @ 50 mg L"\
cycocel @ 10 mg L'and @ 50 mg L ' improved the diameter of the rootstock.
Among grafting methods, hole insertion grafting exhibited faster union (3.57 days)
with highest percentage of success (68.13 %). Cycocel @ 50 mg L"' recorded the
highest percentage success among growth regulators.
Based on the results of part I, grafts produced by cycocel @ 50 mgL*^ + hole
insertion grafting in sponge gourd, alar @ 10 mgL'^ + one cotyledon grafting in
pumpkin, distilled water (control) + one cotyledon grafting in bottle gourd and
cycocel @ 50 mg L*^ + hole insertion grafting in bittergourd were selected and
planted in main field along witli non grafted control in randomised block design
replicated four times for evaluating growth, yield and quality of grafted bitter gourd.
All grafts exhibited lower establishment over non grafted control.Bitter gourd
grafted onsponge gourd andbottle gourd rootstocks as well asnon grafted control had
similar vine length. Inlemodal length was more in non grafted control (6.00 cm).
More branches were produced when bitter gourd and sponge gourd were used as
rootstocks.Pumpkin rootstock produced longer primary root, higher root volume and
root weight. Early appearance of first male and female flowers at lower nodes was
also recorded in bitter gourd grafted on pumpkin rootstock.
Though grafting did not significantly influence number of male flowers, the
number of female flowers was higher in non grafted control and bitter gourd grafted
on sponge gourd. Non grafted control, bitter gourd grafted on sponge gourd, bottle
gourd and bitter gourd rootstock exhibited on par sex ratio.Non grafted control, bitter
gourd grafted on pumpkin and bitter gourd recorded early harvest but bitter gourd
grafted on sponge gourd and bottle gourd rootstock extended duration of the crop.
Non grafted control and bitter gourd grafted on sponge gourd rootstock recorded
more fruits per plant and yield per plant.
Non grafted control, bitter gourd grafted onto bitter gourd and bitter gourd
grafted on to sponge gourdexhibited on par fmit length. Bitter gourd grafted onto
pumpkin, bitter gourd grafted onto sponge gourd, non grafted control and bitter gourd
grafted onto bitter gourd had similar flesh thickness. Bottle gourd and bitter gourd
rootstock enhanced fruit weight (181.50 g). Grafts did not differ for fruit girth,
vitamin C content and organoleptic properties. Nongrafted control recorded highest
B:C ratio (1.67)followed by sponge gourd (1.50).
In conclusion, grafts of bitter gourd variety Treethi' can be produced with
highest success percentage by cycocel @ 50 mgL'' + hole insertion graftingusing
sponge gourd as rootstock, alar @ 10 mgL"' + one cotyledon grafting using pumpkin
as rootstock, one cotyledon grafting without growth regulator using bottle gourd as
rootstock. Among these grafts, sponge gourd as rootstock produced longest vine,
more branches, longer crop duration, on par female flowers, sex ratio, fruits per plant
and yield per plant compared to control. However, cultivation of non grafted plants
recorded higher B:C ratio which necessitate further evaluation of biotic and abiotic
tolerance of grafts for benefitting farming community.