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The study entitled “Management of button shedding in coconut by root feeding
of nutrients and growth regulators” was conducted to determine the physiological
management of button shedding in coconut by using nutrients and growth regulators
through root feeding and to determine the role of beneficial microbes on auxin
production in coconut. Two experiments were conducted at Coconut Research Station,
Balaramapuram during 2020-2021. Survey was conducted for the first experiment to
select the palms with uniform age having significant button shedding. The respective
solutions were prepared and administered to the palms through root feeding. The yield
parameters, biochemical and physiological parameters were estimated and recorded
for the first six months. The results shown that the yield parameters such as the number
of female flowers and the number of buttons retained showed non siginificant variation
in all the treatments. The percentage of button shedding also showed non siginificant
variation during 5th and 6th month. Among the 7 treatments, T2 [Hoagland solution -
2X] reported the lowest button shedding percentage (22.9, 24.2, 28.4 and 31.1%) for
the first four months respectively followed by T6 [Salicylic acid-200ppm] and T5
[Borax (0.5 g palm-1
) + 2, 4- D (50 ppm)] .T1 [Control] reported the highest level of
button shedding percentage (32.88, 37.21, 44.25 and 50%) for the first four months
respectively.
The physiological parameters such as transpiration rate shown the highest level
(3.8, 4.0, 4.3, 4.2, 4.3, 4.4 mmol H2O m-2
sec-1
) in the T2 treatment followed by T6
respectively for the first six months. T2 reported the maximum photosynthetic rate (4.4,
4.6, 4.9, 4.8, 4.9 and 5.2 µmol CO2 m-2
sec-1
) for a period of first six months respectively
which was on par with T6. T1 reported the minimum photosynthetic rate and
transpiration rate for the first six months. The biochemical parameters such as
carbohydrate content was maximum (21.84,79.65, 77.42, 84.33,96.66 mg g-1
) in the T2
treated palms respectively except 2nd month. There was no significant variation in
between the treatments during 2nd month. The macronutrients such as N (2.07, 2.26,
2.5, 2.37, 2.41, and 2.54 %), K (1.27, 1.46, 1.7, 1.65, 1.87, 2.14%), Mg (1.56, 1.74,
1.95, 1.6, 1.78, and 1.89 %), Ca (0.57, 0.88, 1.05, 0.88, 1.08 and 1.16%) and S (0.57,
0.75, 1.06, 0.86, 1.01 and 1.19%) were higher in T2 treated palms respectively for six
months. T7 [SA (200 ppm) + 2, 4- D (50ppm)] recorded the maximum phosphorus
content (0.13, 0.14, 0.18, 0.08, 0.15, and 0.22 %) during the observation of first six
months respectively. Micronutrients such as Fe (158.5, 175.45, 240, 234, 258.33 and
275.66 ppm), B (15.06, 19.16, 26.93, 20.33, 25.33 and 31.33ppm) and Mn (169.55,
179.66, 188.66, 181.92, 186.66 and 195.33 ppm) was also higher in the T2 treated
palms for the first six months respectively. Except 1st month, T2 reported higher copper
content (54, 67.66, 61.66, 71, 81.33ppm) from 2nd to 6th month. T5 [Borax (0.5 gm
palm-1
) + 2, 4- D (50 ppm)] reported the highest Zinc content (42.33, 43.9, 55.34, 46.43,
53.32 and 62.06 ppm) for the first six months respectively. T1 reported the lowest level
of carbohydrate content and nutritional (macro and micro) content in the leaf during the
six months period.
The second experiment was performed to evaluate the role of beneficial
microbes on auxin production in coconut. Piriformospora indica vermiculite mixture
and Rhizobium radiobacter suspension were prepared and inoculated in the 3 months
old coconut seedlings and the colonization was evaluated after 15 days of inoculation
and recurred until the result was obtained. The results revealed that the chlamydospores
similar to the P. indica were colonized in the cortex region of the root hairs of the
coconut seedlings. Colonization of Rhizobium radiobacter were not observed in the
roots of coconut seedlings. In coconut, considerable loss in yield had been observed
due to the phenomenon of shedding of buttons. It varies from 55 to 95 per cent
depending on the conditions prevailing, and on the variety of the coconut. In my study,
root feeding of Hoagland solution (2X) recorded 43.03, 53.6, 55.7, 60.7% lower button
shedding percentage over the control during the first four months respectively. Salicylic
acid-200 ppm and [Borax (0.5 g palm-1
) + 2, 4- D (50 ppm)] was also able to control
the button shedding effectively.