EFFECT OF SEEDLING DIP AND PRE-HARVEST SPRAY OF CHEMICALS ON STORAGE BEHAVIOR OF ONION VAR. ARKA KALYAN
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Date
2016-06
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University of Horticultural Sciences, Bagalkot
Abstract
The present investigation was conducted in the Department of Post Harvest
Technology, College of Horticulture, Bagalkot, Karnataka during the year 2015-16 to
evaluate the effectiveness of seedling dip (salicylic acid 2mM) and pre-harvest foliar
sprays with different chemicals (salicylic acid 2mM, azoxystrobin at 0.05% and 0.1%,
ethephon at 5000 ppm) at different time intervals (60 and 90 DAT) on storage
behavior, physiological, physio-chemical changes, sprouting, rotting, disease control
and sensory parameters of onion bulbs (Var. Arka Kalyan) packed in gunny bags and
stored at ambient temperature.
All the treatments showed non-significant differences for yield, number of
bulbs per kg and bulb diameter. The physiological loss in weight (PLW) was found to
be minimum (11.62%) in the treatment T5 (seedling dip and 2 mM salicylic acid at 60
and 90 DAT), whereas minimum respiration rate (18.58 ml CO2/kg/h) was observed
in the treatment T2 (salicylic acid- 2mM 90 DAT). Minimum sprouting was present in
T8 (azoxystrobin- 0.1% at 90 DAT) and T6 (azoxystrobin- 0.05%) (0.96%). Minimum
black mould disease incidence was noted in the treatment T8 (azoxystrobin- 0.1% at
90 DAT) (0.74%). Pyruvic acid, indicating pungency was noted to be maximum in T5
(Seedling dip+salicylic acid-2mM at 60+90 DAT) (8.92 μmoles/g). The treatment T9
(azoxystrobin- 0.1% at 60+90 DAT) recorded maximum total phenol (13.92 mg/100
g), minimum rotting (1.86%) and maximum marketable bulbs (94.97%). The
maximum firmness was seen in the treatment T3 (salicylic acid- 2mM at 60+90 DAT)
(9.89 kg/cm2). Onions of treatment T10 (ethephon- 5000 ppm at 90 DAT) with
maximum dry matter (20.96%), minimum per cent moisture (77.91%) and maximum
TSS (16.30°B) obtained the highest overall acceptability scores (7.89) which had no
statistical difference with other treatments.
In conclusion, azoxystrobin 0.1% at 60+90 DAT and SA 2mM seedling
dip+pre-harvest spray at 60+90 DAT were found effective in maintaining quality and
shelf life of onions. Pre-harvest spray of ethephon was found to be ineffective in
extending the shelf life of onions as it increased PLW, respiration, sprouting, rotting
thus decreasing marketable bulbs.
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