Abstract

The relay strip intercropping system of maize-soybean is dominant in southwest China. Compared to monoculture, the productivity of soybean is unstable in this system, since soybean seedling grow under shading by maize, which beget elongated plants and prone to lodging. Therefore, a 3-year study was conducted to determine the influence of K on lodging and lodging-related traits of soybean, and to identify the key traits associated with lodging resistance in relay strip intercropping system in Sichuan Province, China during 2008-2010. The results showed that K application significantly affected basal stem diameter, stem breaking strength, total nonstructural carbohydrate (TNC) concentration, concentration of K and lignin, while differences in plant height and weight of basal internode were not significantly. The K-fertilized treatments had higher seed yield and seed ratio than treatment without K application. The lodging had significantly negative correlation with grain yield, seed ratio, basal stem diameter, weight of basal internode, stem breaking strength, concentration of lignin and K, but no correlation was observed between lodging and TNC in both pot and field trial. The plant height was positively correlated with lodging only in field trial. Thus, these results suggested that K application could alter the lodging-related traits in soybean for greater lodging resistance, and it may be worthwhile to focus on basal stem diameter, stem breaking strength, and lignin concentration.

Key words: Lodging, potassium, relay strip intercropping, soybean, stem characteristic.