Effects of Mixture of Ethephon and Mepiquat Chloride on Growth and Yield of Summer Corn

Ethephon and mepiquat chloride were mixed and then used for investigation of effects on the growth and yield of summer corn cv. 3315 in 1996. The mixed compound was sprayed at floret differentiation stage, and the related characteristics were determined. The treatment of the mixed compound raised the nodal root number and root dry weight, especially the brace-root number and dry weight, shortened the internode length, increased the stem thickness, decreased the plant height and ear position height, raised index of stem diameter to height, accelerated assimilates partitioning to roots during early grain-filling period, accumulating in shoot organs during middle grain-filling period, and transporting to yield organs during late grain-filling period which is beneficial to earlier maturation, and increased percentage of double ears, decreased percentage of ineffective plants and bare part of ears, which resulted in more ears and grain numbers per ear and good productivity. Thus, application of the mixture of ethephon and mepiquat chloride could reduce plant lodging, accelerate earlier maturation and avoid low temperature damaging in early autumn. It is valuable to popularize and apply in northern and western China.