Comparative assessment of whole plant water use efficiency (wue) of coconut seedlings (cocos nucifera) to drought tolerance
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Date
2017
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Academy of Climate Change Education and Research Vellanikkara
Abstract
A study was conducted at ICAR-CPCRI, Kasaragod to determine the whole plant WUE
of two dwarf (Malayan Yellow Dwarf (MYD) and Chowghat Green Dwarf (CGD)) and
two tall varieties of coconut seedlings (Kalpatharu (KT) and Kalpa Pratibha (KP)) of
coconuts. The seedlings were grown in large buckets and exposed to three moisture
regimes- 100% ASM (available soil moisture), 50% ASM and 25% ASM. Coconut
seedlings were found to be highly sensitive to moisture and observed that with the first
observation made i.e., within 25 days after stress imposition there was significant decline
in morphological and physiological traits. Plant height, collar girth, leaf number showed
an increasing trend up to 57 days after 50% ASM imposition while at 25% ASM there
was no further increment in growth of above parameters. Both Pn and leaf area which
contribute to the biomass significantly declined under stress condition. However biomass
accumulation over the stress period was high in KT and KP compared to CGD and MYD.
Thus KT and KP had high WUE both under 50% and 25% ASM 5.48 g/L and 5.68 g/L
and 5.42 g/L and 4.55 g/L respectively. CGD on the other hand had lower WUE at 50%
ASM (3.68 g/L) and increased slightly at 25% ASM (3.84 g/L). WUE was the least in
MYD both at 50% (3.54 g/L) and 25% ASM (2.74 g/L). The higher WUE in KT and KP
was found to be imparted by high biomass partitioning to roots and drought tolerance
mechanisms like epicuticular wax deposition and higher activity of antioxidant
scavenging systems. Thus, tall varieties KP and KT are found to be better adapted to
water deficit stress compared to the dwarf varieties CGD and MYD.
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