Relationship between canopy coverage at the initiation of stem elongation and lodging in wheat

Abstract

While lodging in wheat appears to correlate with the ratio of canopy coverage at the initiation of stem elongation (CC30), a mechanistic understanding of the relationship between lodging index and CC30 is lacking. The objective of this study was to examine more closely the relationship between lodging and CC30 and to identify the most effective sowing densities and/or planting patterns in reducing lodging. The CC30 was adjusted by varying the sowing density and planting pattern, i.e., wide vs narrow-spaced rows and altering the seed spacing within the row and by spread sowing. We found that CC30 was positively correlated with the lodging degree at maturity and was negatively correlated with internode dry weight per unit length. The CC30 for a sowing density of 3 g m−2 (which is about half the conventional sowing density in Japan) was low at a range of 28–75 %. In these treatments, CC30 was lowest under spread sowing where the spacing between plants was greatest. The yield of the 3 g m−2 spread-seed treatments was more than 500 g m−2. This yield is comparable to that of the other treatments even though the sowing density was much lower. The aboveground N accumulation at maturity of the 3 g m−2 spread-seed treatments was similar to that of the other treatments. As found in the spread-seed treatments, our results suggest that lowering CC30 by reducing the sowing density and/or by changing the planting pattern, increased the spacing between seedlings and thus helped to prevent lodging while still retaining high yields.