Effects of mepiquat chloride on yield and main properties of cottonseed under different plant densities

Background:Cottonseed oil and protein content as well as germination traits are major indicators of seed quality.However,the responses of these indicators to plant density and mepiquat chloride(MC)are still uncertain.To investigate plant density and MC effects on cotto nseed yield and main quality parameters,we con ducted a twoyear field experiment including four plant densities(1.35,2.55,3.75 and 4.95 plants·m^-2)and two closes of MC(0 and 135g·hm^-2)in Dafeng,Jiangsu Province,in 2013 and 2014.Results:The application of MC reduced plant height,fruit branch length and fruiting branch number under different plant densities,resulting in a lower and more compact plant canopy.Cottonseed yield showed a nonlinear increase as plant density increasing and achieved the highest value at 3.75 plants·m^-2,regardless of MC application.No significant interactio ns were found between plant density and MC for cotton seed yield and quality parameters.The 100-seed weight,cottonseed oil content and vigor index significantly decreased as plant density increased,while these parameters significantly increased with MC applying under different plant densities.Seed vigor index was positively correlated with 100-seed weight and seed oil con tent across different plant densities and MC treatments.Conclusions:Thus,application of MC could realize a win-win situation between cottonseed yield and main quality parameters under various densities;and plant density of 3.75 plants·m^-2 combined with 135 g·hm^-2 of MC applying is optimal for high cottonseed yield and quality in this cotton production area.

Background:Cottonseed oil and protein content as well as germination traits are major indicators of seed quality.However,the responses of these indicators to plant density and mepiquat chloride（MC） are still uncertain.To investigate plant density and MC effects on cottonseed yield and main quality parameters,we conducted a twoyear field experiment including four plant densities(1.35,2.55,3.75 and 4.95 plants-m-2) and two doses of MC(0 and135 g·hm-2) in Dafeng,Jiangsu Province,in 2013 and 2014.Results:The application of MC reduced plant height,fruit branch length and fruiting branch number under different plant densities,resulting in a lower and more compact plant canopy.Cottonseed yield showed a nonlinear increase as plant density increasing and achieved the highest value at 3.75 plants·m-2,regardless of MC application.No significant interactions were found between plant density and MC for cottonseed yield and quality parameters.The 100-seed weight cottonseed oil content and vigor index significantly decreased as plant density increased,while these parameters significantly increased with MC applying under different plant densities.Seed vigor index was positively correlated with 100-seed weight and seed oil content across different plant densities and MC treatments.Conclusions:Thus,application of MC could realize a win-win situation between cottonseed yield and main quality parameters under various densities;and plant density of 3.75 plants-m-2 combined with 135 g·hm-2 of MC applying is optimal for high cottonseed yield and quality in this cotton production area.