Ecological factors regulate stalk lodging within dense planting maize

Context

Ecological factors affect maize growth and development, and induce stalk lodging. Studying the effects of ecological factors on the stalk lodging within dense planting maize is essential to develop field management strategies.

Objective

To investigate the response of stalk lodging resistance to density and ecological site. To identify the key ecological factors affecting lodging.

Methods

This study conducted field experiments in 2019–2020 at 6 sites in Southwest China, with 6 densities (3.0, 4.5, 6.0, 7.5, 9.0 and 10.5 × 10⁴ plants hm⁻²) to determine the variation in lodging rate and stalk lodging resistance traits.

Results

The dense planting reduced stalk lodging resistance and varied among ecological sites. Plant morphology exhibited relatively high stability, with coefficients of variation (CV) of 0.01143–0.1097. Bending strength and dry matter constituents of basal internodes were more sensitive (CV: 0.1425–0.4446) compared to other traits, while the density effect was more significant. The extreme weather and stalk lodging resistance index jointly determined lodging, with lodging lowest at high stalk lodging resistance index (≥1.367) and low frequency of extreme weather events (＜14.40 %). Among the internode traits, the dry matter constituents contributed more than 55.0 % to mechanical strength. In addition, internode diameter was important for bending strength, while skin group was for rind penetration strength. Altitude or net solar radiation explained 28.70 % or 21.10 % of the mechanical strength, being the most important ecological factor.

Conclusions

Maize stalk lodging resistance decreased with dense planting and also influenced by ecological factors, but the response of different stalk lodging resistance traits to density and ecological site. The higher altitude and net solar radiation favored higher internode mechanical strength, resulting in greater stalk lodging resistance. The lower frequency of extreme weather events and higher stalk lodging resistance index resulted in a lower lodging rate.

Implications

The selection of maize hybrids with high internode plumpness, cellulose and lignin content in the basal internodes and less affected by density and ecological sites, can enhance stalk lodging resistance and its stability. The appropriate planting density should match the ecological conditions of the site.