Effects of tillage on growth, yield and root lodging of six maize hybrids in upland fields converted from paddy fields in Andosol

We investigated the effects of tillage on growth, grain yield and root lodging of maize hybrids in upland fields converted from paddy fields in Andosol of northern Tohoku. Six hybrids were grown with rotary tilling or plowing (chisel plowing plus power harrow) in 2016 and 2017. Soil penetration resistance was higher in plowing than in rotary tilling under a soil depth of 5 cm. There were no significant interactions between hybrid and tillage method in plant height, SPAD value, grain yield, and yield components, indicating that growth and grain yield of the six hybrids were unaffected by tillage method. Maize hybrids had similar culm length and ear height, while horizontal pulling resistance was higher in plowing than in rotary tilling. In addition, root lodged plants caused by typhoons were fewer in plowing than in rotary tilling in 2017. There was a negative correlation between horizontal pulling resistance and the number of root lodged plants. The highest horizontal pulling resistance and the least number of root lodged plants were found in a maize hybrid KD641 grown by plowing. The results suggest that root lodging can be alleviated by growing root-lodging-resistant maize hybrids such as KD641 with plowing.