Evaluation of elicitor treatment on biochemical changes in cotton seedlings subjected to high temperature stress
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Date
2019
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Punjab Agricultural University, Ludhiana
Abstract
In the present study effect of elicitors; salicylic acid (SA, 50 ppm), calcium chloride
(CaCl2, 50ppm), gibberellic acid (GA3, 5ppm) and succinic acid (100ppm recommended
by PAU) on heat stress amelioration in seven day old cotton seedlings (Gossypium
hirsutum - LH 2298 and LH 2076; Gossypium arboreum - LD 949 and LD 1019) was
evaluated in terms of changes in morphophysiological, carbohydrate and protein status
and oxidative and antioxidant parameters. High temperature (HT) stresswas given for 1 hr
at 40, 45, 50 and 55°C to seven day old cotton seedlings. Seedlings of LH2298, LD949
depicted 50% survival at 55°C followed by LH 2076 (43%) and LD 1019 (41%). HT
stress decreased the root and shoot length in seedling which got revived after recovery.
Loss of moisture increased with increase in stress temperature. The chlorophyll content
decreased from 26-37% with maximum decrease in LD 949. LH 2298 control had highest
total carbohydrates, which were negatively affected by HT. The soluble sugars and
soluble proteins registered increase. HT stress inceased electrolyte leakage, H2O2 as well
as MDA content to minimum in LH 2298 and LD 949. Maximum increase in SOD, POD,
APX and GR activity was seen in LH 2298 and LD949 whereas CAT activity declined
after HT exposure. Proline, phenolics, ascorbic acid, tocopherols and carotenoids also
depicted increase. Seed priming treatment with SA@50ppm was most effective in
decreasing the negative effect of HT in terms of improving various estimated parameters
in seven day old cotton seedlings, followed by treatment with CaCl2, succinic acid and
GA. SA effect was demonstrated maximum in LH 2298 and LD 949. Priming treatment
was more effective than seedling spray. In conclusion the given cotton genotypes showed
heat tolerance with the order of tolerance as LH 2298>LD 949>LH 2076>LD 1019 and
among the elicitors used, SA priming ameliorated the heat stress to maximum. The
various parameters in cotton genotypes showed differential response towards heat stress.
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