PhD

Studies on 'Regulation of growth and flowering m dendrobium var.
,.
'Sonia 1 T were conducted in the Department ofPomology and Floriculture, College of
Horticulture, Vellanikkara from June 1998 to November 1999 and at Padikkala
Orchids, Thrissur from February to September 1999. The main objectives of the studies
were to reduce the pre-blooming period, to improve the yield and quality and to
, .....
enhance the post harvest life of spikes using various treatments.
Plant height was significantly superior (19.50 cm at 10 MAP) with the
combination of NPK 30: 10: 10 at 0.2 per cent, applied weekly twice + GAJ 20 ppm.
With respect to number of shoots, NPK 30: 10: 1 0 at 0.2 per cent, applied weekly twice
+ BA 200 ppm was most effective (with 7.67 shoots). Shoot girth recorded maximum
value (5.80 cm) at 10 MAP in the treatment combination ofNPK 30:10:10 at 0.2 per
cent, applied weekly twice + IAA 500 ppm.
Plants which received NPK 30: 10: 10 at 0.2 per cent weekly twice along
with BA 200 ppm recorded maximum leaf production (19.83 leaves at 10 MAP). In
the case of total leaf area, BA 200 ppm produced maximum value (210.12 ~2) in
combination with NPK 30: 10: 10 at 0.2 per cent, applied weekly twice. Number of
roots was markedly higher for NPK 30: 10: 10 at 0.2 per cent weekly twice with BA
200 ppm, which produced 42.0 roots.
Biomass production (dry weight) was the highest (6.94 g/plant) for NPK
30: 10: 10 at 0.2 per cent, applied weekly twice + BA 200 ppm. The combination of
NPK 30: 1 0: 1 0 at 0.2 per cent, applied weekly twice + lAA 250 ppm recorded the
highest nitrogen content of 2.4 7 per cent. This was on par with BA 200 ppm, IAA 50
ppm and BA 100 ppm in combination with the same level of nutrients. Maximum
value for P content (0.6~1o) was observed in the combination ofNPK 30:10:10 at 0.2
per cent, sprayed weekly twice + IAA 500 ppm. The growth regulator component was
on par with lAA 250 ppm. The combination which yielded highest value for K content





(4.00%) was NPK 30: 10: 10 at 0.2 per cent, applied weekly twice + IAA 250 ppm. The
same level of nutrients with IAA 500 ppm was on par with this.
The contents of Ca and Mg were higher with higher nitrogen levels and
frequencies, coupled with BA 200 ppmIfor Ca) or IAA 250 ppm (for Mg) .. In the case
of micro-nutrients (Cu, Fe, Zn and Mn), lower levels of nitrogen at higher frequencies,
in combination with IAA 500 ppm, recorded higher values.
Uptake of N,. P, and K was the highest with the combination of. NPK
30:10:10 at 0.2 per cent, applied weekly twice + BA 200 ppm (1l.73 g, 2.7~ g and
19.50 g, respectively). Uptake ofP was on par for lAA 500 ppm, with the above level
of nutrients.
Earliest flowering (300 DAP) was recorded in plants which received a
treatment combination of NPK 30: 1 0: 1 0 at 0.2 per cent, applied weekly twice + BA
200 ppm .. Plants receiving the nutrient level of NPK 20: 10: lOin the above
combination flowered next (308 DAP).
Nutrients, their frequency C?! application and .. growth regulators markedly
influenced flower yield and quality. A combination of NPK 10:20: 1 0 at 0.2 per cent,
applied weekly twice + BA 100 PP!ll recorded. the maximum number of spikes :Q~r year
(12.98) and number of florets per spike (10.50). Spike length was significantly superior
(55.40 cm) for NPK 10:20:20 at 0.2 percent, applied weekly twice + GA3 20. ppm.
Longest stalks (30.10 cm) were produced at the same level of nutrients, coupled with
BA 100 ppm. A treatment combination of NPK 10:20: 10 at 0.2 per cent applied
weekly twice + (BA 50 ppm + GAJ 10 ppm) produced the longest rachis (30.25 cm),
which was on par (30.16 cm) with the above nutrients applied weekly once + GAJ 20
ppm. Intemodallength was the highest (5.14 cm) in the combination ofNPK 10:20:10
at 0.2 p~r cent, applied weekly once + GAJ 20 ppm. Girth of spike was. maximum
(2.95 cm) with NPK 10:20: 1 0 at 0.2 per cent, applied weekly twice + BA 100 ppm.

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The interval of spike production was the least (28.12 days) for NPK
10:20: 1 0 at 0.2 per cent, applied weekly twice + BA 100 ppm. Floret size was reduced
to 6.0 cm x 6.0 cm by- the treatment combinations NPK 10: 10: 10 at O. 1 per cent
(weekly once or twice) or 0.2 per cent (weekly once) + BA 100 ppm. Largest floret
. . . ,
size of8.0 cm x 8.5 cm was observed in plants receiving NPK 10:20:10 at 0.1 or 0.2
per cent, applied weekly twice + GA3 20 ppm.
Various pulsing and holding treatments and their combinations significantly
influenced the post. harvest behaviour of spikes. Among. the pulsing . treatments,
minimum loss of weight (0.93 g) of spikes was recorded when kept in HQ 500 ppm +
sucrose 5 per cent for 6 hours. Spikes took the 101:1ges~ time (19.92 days) for the ~ilting
of one floret (vase life) when pulsed with HQ 500 ppm + suctose 5 per cent for 12
hours. Final BC (2.13 mS il) and water uptake (19.99 ml) were the highest in hot
water dip treatment at 50°-60°C for 10 seconds. Days to wilt of the last floret was the
highest (25.00 days) when treated with HQ 500 ppm + sucrose 5 per cent for 12 hours.
Minimum loss of weight of spike (0.13 g), maximum days to wilt of the last
floret (30.50 days) and maximum vase life of spike (24.73 days) were recorded by the
holding treatment containing AgN03 50 ppm + HQ 400 ppm + sucrose 5 per cent.
Maximum BC (3.75 mS g-l) was recorded for Triadimefon 20 ppm. Difference
between initial and final BC was maximum (0.11 mS g-l) for AgN03 50 ppm + HQ
400 ppm + sucrose 5 per cent. Water uptake was highest (19.50 ml) in AgN03 25 ppm
+ sucrose 5 per cent.
Pulsing and holding treatments, in combination, gave significant differences
ill post harvest characters. Minimum weight loss (0.07 g) was observed when
pulsed with HQ 500 ppm + sucrose 5 per cent for 12 hours and kept in the holding
solution containing AgN03 5Q ppm + HQ 400 ppm + sucrose 5 per cent. Final EC
(0.28 IllS g-l) of holding solution was the highest for the combination of pulsing
treatment of• HQ 500 ppm + sucrose 5 per cent for 12 hours and holding treatment of

quality more treatments with combinations of GA3 and BA can be studied. The results
of the experiment can also be extended to find effects on other important varieties of
dendrobium as well as other genera. The results of experiment I and experiment II
have to be tried to the same lot of plants to find the combined effect.