No abstract

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 rootlodging-resistant maize hybrids such as KD641 with plowing.

Plowing is a more efficient tillage method than conventional rotary tilling in paddy fields. We thus investigated growth, grain yield, and quality of maize (Zea mays L.) using two tillage systems in crop rotation of paddy fields at Morioka (Andosol) and Hanamaki (Gleysol). Maize was grown with rotary tilling after growing transplanted rice with puddling and leveling, and alternatively, with plowing (chisel plowing plus power harrow) after direct seeding of rice with plowing and compaction. There was no significant difference in seedling establishment between the two tillage treatments. Although silking was slightly earlier and root lodging was less severe in plowing than in rotary tilling, there was no significant difference in plant height, SPAD value, dry weight at maturity, Kernel number, grain weight, grain yield, starch content, crude protein content, or mycotoxin accumulation, irrespective of soil type. These results indicate that growth and yield of maize were similar for the plowing system and the rotary tilling system. Thus, the plowing system could improve work efficiency for maize cultivation in crop rotation of paddy fields for large-scale farm management.