Deol, J.S.Brar, Ajaypal Singh2017-11-252017-11-252017http://krishikosh.egranth.ac.in/handle/1/5810036362A field study entitled ‘Growth and productivity of soybean (Glycine max L. Merrill) as influenced by growth retardant and defoliants’ was conducted at two locations viz. Research farm, Department of Agronomy, Punjab Agricultural University, Ludhiana and Research farm, Research Station, Faridkot during kharif season of 2016. The experiments were conducted in a randomized complete block design comprising nine treatments with three replications. The treatments comprised of mepiquat chloride @ 200 ppm and 250 ppm (50-55 and 65-70 DAS), ethrel @ 250 ppm (110-115 DAS), thidiazuron @ 200 g ha-1 (110-115 DAS), mepiquat chloride @ 200 and 250 ppm (50-55 and 65-70 DAS) + ethrel @ 250 ppm (110- 115 DAS), mepiquat chloride @ 200 and 250 ppm (50-55 and 65-70 DAS) + thidiazuron @ 200 g ha-1 (110-115 DAS) and control. Results showed that soyabean phenology was not affected at all with the application of various growth retardants and defoliants used in the study. Plant height at harvest was not significantly affected by the growth retardant and defoliants. Dry matter accumulation at harvest was significantly higher with the mepiquat chloride @ 200, 250 ppm and ethrel @ 250 ppm either applied individually or in combination. Specific leaf weight increased significantly with the application of mepiquat chloride at both the locations. Abscission of flowers and pods was significantly less with application of growth retardant and defoliant. Highest seed yield (18.6 q ha-1 at Ludhiana and 16.7 q ha-1 at Faridkot) was recorded with the mepiquat chloride @ 250 ppm + ethrel @ 250 ppm which was statistically at par with mepiquat chloride @ 200 ppm (16.7 q ha-1 at Ludhiana and 14.8 q ha-1 at Faridkot), mepiquat chloride @ 250 ppm (18.3 q ha-1 at Ludhiana and 15.0 q ha-1 at Faridkot), ethrel @ 250 ppm (18.1 q ha-1 at Ludhiana and 14.6 q ha-1 at Faridkot) and mepiquat chloride @ 200 ppm + ethrel @ 250 ppm (18.3 q ha-1 at Ludhiana and 15.3 q ha-1 at Faridkot). However, the B:C was highest with ethrel @ 250 ppm.ennullThesis