Growth and productivity of American cotton (Gossypium hirsutum L.) as affected by application of plant growth regulators
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Date
2019
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Punjab Agricultural University, Ludhiana
Abstract
The investigation entitled “Growth and productivity of American cotton (Gossypium hirsutum
L.) as affected by application of plant growth regulators” has been carried out at Punjab
Agricultural University, Regional Research Stations of Faridkot and Bathinda during kharif
season of year 2018. The experiment has been laid out in split plot design with three
replications. The main plots consisted of four levels of defoliation treatments i.e. control (no
spray), Dropp ultra @ 175 ml/ha, Dropp ultra @ 200 ml/ha and Ethrel @ 1250 ml/ha to be
applied at 70% boll opening. The sub plot treatments comprised of five levels of plant growth
retardants i.e. control (no spray), mepiquat chloride @ 1250 ml/ha (2 sprays @ 625 ml/ha
starting from 60 DAS [days after sowing] at 30 days interval), mepiquat chloride @ 1500
ml/ha (3 Sprays @ 500 ml/ha each starting from 60 DAS at 20 days interval), Stance @ 400
ml/ha (2 sprays of 200 ml/ha each starting from 60 DAS at 30 days interval) and Stance @
600 ml/ha (3 sprays of 200 ml/ha each starting from 60 DAS at 20 days interval). Results of
the experiment revealed that defoliants had a significant influence on seed cotton yield and
duration of crop. Among defoliation treatments, Dropp ultra @ 175 ml/ha resulted in highest
seed cotton yield (i.e. 2658 and 2394 kg/ha at Faridkot and Bathinda, respectively) than
control (i.e. 2110 and 1903 kg/ha at Faridkot and Bathinda, respectively). However, higher
dose of Dropp ultra i.e. @ 200 ml/ha resulted in maximum defoliation (95.9-98.8%) and
contributed more towards first picking yield (95.1-96.5%). Application of Dropp ultra @ 200
ml/ha could induce crop earliness by 17 days, while lower dose of 175 ml/ha reduced crop
duration by 15-16 days over the control, respectively. Plant growth retardants also exerted
significant impact on growth as well as yield attributes of cotton. Though, Stance @ 600
ml/ha application resulted maximum reduction in plant height, biomass accumulation,
monopods per plant, monopodial length and leaf area index but also exerted negative
influence on yield attributes as indicated by reduced seed cotton yield than other chemical
treatments. Among plant growth retardants, mepiquat chloride @ 1250 ml/ha (i.e. 2621 and
2361 kg/ha) as well as Stance @ 400 ml/ha (i.e. 2590 and 2315 kg/ha) resulted in
significantly improved seed cotton yield over the respective control (i.e. 2225 and 1996
kg/ha) at Faridkot and Bathinda, respectively.