SUITABILITY OF PLANT SPACINGS AGAINST MEPIQUAT CHLORIDE TREATED COTTON PLANT FOR IMPROVEMENT OF YIELD AND QUALITY

Abstract

Plant growth regulators (PGRs) are used in cotton production to optimize yield and quality and even suppressing excess growth whenever necessary. Experiments were conducted in three consecutive years (2016-17, 2017-18 and 2018-19) at Cotton Seed Multiplication, Training and Research Farm, Sreepur, Bangladesh to study the response of cotton yield and quality to different plant spacings, concentration and time of application of mepiquat chloride (MC) growth regulator. Plant spacings like 45 cm × 30 cm, 60 cm × 20 cm, 60 cm × 30 cm, 60 cm × 40 cm, 75 cm × 30 cm, 75 cm × 40 cm, 90 cm × 10 cm and 90 cm × 45 cm; MC spray @ 1.0 ml L -1 water at 25, 50, 75, 100 and 125 DAE; MC spray @ 1.0, 2.0, 3.0 and 4.0 ml L water at 25, 50 and 75 DAE for each concentration; MC spray @ 2.0 and 4.0 ml L -1 water

at 25 DAE, 2.0 and 4.0 ml L -1 water

at 50 DAE, 2.0 ml L -1 water

at 25 & 50 DAE along with water spray as control, were the treatment variables. Plant spacing of 60 cm × 30 cm showed the highest values of different parameters of cotton across the years (2016, 2017 and 2018) as maximum seed cotton yield (4.20, 3.48 and 4.04 t ha -1 ) and lint yield (9.08, 7.59 and 7.57 bales ha -1 ); higher LAI (0.75 and 0.80) and boll weight (4.94 and 4.9 g) during 2016 and 2017, internode (4.46 and 4.16 cm) and leaf canopy size (0.29 and 0.33 m 2 ) during 2016 and 2017; maximum squares plant -1 (10.21 and 12.67) and bolls plant -1 (11.56 and 11.37) during 2017 and 2018 were evident. In case of MC application, maximum seed cotton (2.62 t ha -1 ) and lint yield (6.79 bales ha -1 ) were noted from 1.0 ml MC L -1 water

sprayed at 25 DAE during 2016. In 2017 and 2018, treatment 2 ml MC L water at 25 DAE gave higher squares plant -1 (10.94 and 13.83), bolls plant -1 (14.56 and 10.97), boll weight (4.98 and 5.00 g), seed cotton yield (3.96 and 4.03 t ha -1 ) and lint yield (8.78 and 7.71 bales ha -1 ), respectively. Plant spacing of 60 cm × 30 cm along with application of 2 ml MC L -1 water at 25 DAE gave significantly higher values of squares plant -1 (15.24 and 16.6), bolls plant -1 (17.33 and 16.6), seed cotton yield (4.53 and 4.67 t ha ) and lint yield (9.43 and 10.06 bales ha -1 ) as compared to control treatments (without MC and conventional wider spacing of 90 cm × 45 cm) in 2017 and 2018. So, cotton cultivation in Sreepur, Gazipur areas may be accelerated with foliar application of mepiquat chloride @ 2 ml L -1 water at 25 DAE along with plant spacing of 60 cm x 30 cm for higher yield and quality.