Mepiquat chloride effects on cotton yield and biomass accumulation under late sowing and high density

Cotton production is challenged by high cost with multiple management and material inputs including mepiquat chloride (MC) application to avoid excess vegetative growth and yield losses. A competitive planting model has been practiced in recent years in Yangtze River Valley, China characterized with late sowing, high density and low fertilization. We hypothesized that MC could also be ignored under this planting model to cut down the cost further. A 2-year field experiment was performed to determine cotton response to MC in allied growth and yield dynamics in 2015 and 2016. MC was applied thrice with 5 leaf intervals initiated from the 6th leaf stage in 5 different dosages i.e. 0 (control), 30, 60, 90, and 120 g ha(-1). The results showed that the lint yield was reduced by 6-29% with increase in MC dosages resulted from the reduced cotton plants biomass (from 1036 gm(-2) of MC0 to 841 gm(-2) of MC120) especially the reproductive organs biomass (492 gm(-2) of MC0 to 376 gm(-2) of MC120) averaged across two years. The biomass accumulation for control (MC0) during the fast accumulation period (FAP) had a higher rate (10.1 and 29.8 gm(-2) d(-1) in 2015 and 2016, respectively) for plant biomass and a longer period (34.5 and 28.0 d in 2015 and 2016, respectively) for reproductive organs biomass. The results suggested that MC application could be omitted in the new cotton planting model, ensuring more economic benefits by waiving off the labor and chemicals cost involved.