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Sapota (Manilkara zapota L.) family sapotaceae is one of the fruit trees which is adapted
to humid tropical climate and diversified soil conditions. Softwood grafting in sapota has become
common among farmers and horticulture nursery sector because it is an easy, as well as cheap
method and helps in rapid multiplication of plants with considerable success rate. Generally,
Khirni (Manilkara hexandra L.) is used as rootstock for grafting in sapota. The investigation
entitled “Refinement of softwood grafting technique in sapota (Manilkara zapota L.)” was
carried out at department of Horticulture, College of Agriculture, Padannakkad, Kasaragod,
during 2020-2021.The study was conducted in completely randomized block design with factorial
concept.
The first experiment was done with the objective to find out the best practice for enhancing
success percent in softwood grafting of sapota varieties under different environmental conditions
with different precuring treatments having 27 treatment combinations replicated twice. The
factors of first experiment were environmental conditions (open-C1, polyhouse-C₂ and
polytunnel followed by shade net-C3) with cultivars (Cricket Ball-V1, Pala-V₂ and Oval-V₃) and
scion precuring treatments (defoliation 10 days prior to grafting-S₁, defoliation followed by
grafting on the same day-S₂ and grafting without defoliation-S₃).
Interaction effect of environmental conditions, cultivars and scion precuring up to final
stage of growth indicated that C3V1S3 (Polytunnel+ Cricket Ball+ Without defoliation) had
maximum value with respect to growth parameters viz. girth of stem except 30 DAG(3.05),leaf
area (35.42), length of leaf except 30 DAG (11.22), breadth of leaf except 60 DAG (4.32),
number of leaves except 30 DAG, length of scion except 30 DAG and height of graft (34.75),
fresh weight (32.06) and dry weight (15.04). C1V3S2 (Open+ Oval+ Same day defoliation)
recorded lowest value with respect to growth parameters viz. length of scion (16.83 cm), girth of
stem (2.32 cm), number of successful grafts (3.00), success percentage (20.00 %), survival
percentage (20.00 % ), leaf area (16.45cm2
), length of leaf (7.25 cm), breadth of leaf (3.11 cm),
number of leaves
(except 120 DAG) and height of graft(31.13 cm).
The second experiment was undertaken to study the effect of cytokinin on success of sapota
grafting. Factors are different concentration of cytokinin (P₁-100 ppm, P₂-150 ppm, P₃-200 ppm
and P₄-control) and different days of application (D₁-0
thday, D₂-5
thday and D₃-10thday prior to
grafting). Among the individual effect of cytokinin concentration, P3- cytokinin at 200ppm was
found to be highest in terms of number of successful grafts, success percentage (82.22%), survival
percentage (77%), length of leaf(12.06cm ), leaf area, breadth of leaf, girth of stem at 30,90 and 120
DAG, length of scion (120,150 and 180 DAG) and number of leaves (except 60 DAG). Considering
individual effect of days of cytokinin application, D1 had the maximum value on observations like
length of leaf (11.80cm), number of leaf (22.62), dry weight (11.26g), fresh weight (27.05g), height
of graft, leaf area and girth of stem (3.06 cm), length of scion and breadth of leaf. Considering the
interaction effect between concentration of cytokinin and days of cytokinin application, P3D1
(cytokinin at 200 ppm+ 0th day prior to grafting) proved to be the best treatment combination in
terms of observations like length of scion, number of leaf (24.30), height of graft, leaf area (41.27
cm2
), breadth of leaf (30 and 150DAG), length of leaf (90 to 150 DAG) and girth of stem
(90,120,180 DAG). P4D3 (control treatment+10th day prior to grafting) was found to be lowest in
terms of observations like number of leaf (18.80), leaf area (21.27 cm2
) and length of scion (13.40
cm).
The results obtained from present study revealed that grafting of sapota cv. Cricket ball
without defoliation of scion and kept under polytunnel condition (T21-C₃V₁S₃) as the best treatment
which recorded highest graft success and survival percentage. Grafts under C3-polytunnel found to
be better in growth parameters compared to open and polyhouse conditions. Among scion precuring
treatments, defoliation 10 days prior to grafting-S₁ provided highest percentage of graft success.
Hence, modified grafting technique can be recommended as an ideal approach for sapota
propagation during off season also. Application of cytokinin at 200ppm concentration on the same
day of grafting (T₇-P₃D₁) enhanced graft growth. Regarding concentration of cytokinin, at 200ppm
showed higher value which was on par with P1 and P2 in terms of success and survival percentage.
So, cytokinin application at 100ppm (lower dose) for graft success can be recommend as
economically beneficial.