Traits of plant morphology, stalk mechanical strength, and biomass accumulation in the selection of lodging-resistant maize cultivars

Abstract

• There is no correlation in current maize cultivar’s resistance to stalk or root lodging. • Stalk breakage is primarily affected by dry weight per unit length during grain filling. • Vertical root pulling resistance is primarily affected by the ratio of root depth to width. • High ratios of shoot fresh weight to vertical root pulling resistance increase maize root lodging risk. Lodging resistance is a major desired trait in modern maize breeding. Identifying parameters to evaluate lodging resistance could help crop breeders develop maize cultivars with improved lodging resistance. Thirty-four summer maize cultivars currently planted in China were grown in 2017 and 2018 in order to identify relationships between stalk and root lodging resistance and to analyze the main reasons for differences in lodging resistance between maize cultivars. Twenty-five lodging resistance indicators, including aspects of morphology, dry matter, moisture content, and the mechanical strength of the stalk and root, were investigated at silking and 35 d after silking. The experiments showed that the ratio of shoot fresh weight to vertical root pulling resistance (VRPR) was a better indicator of root lodging potential than VRPR alone. Stalk breaking force was not associated with VRPR and was significantly positively correlated with shoot fresh weight/VRPR. Classification of the 34 cultivars revealed that resistance to stalk and root lodging were not correlated. Correlation and regression analyses revealed that approximately 63 % of the breaking force was explained by the average dry weight per unit length (DWUL) of the basal three internodes, ear height, and fresh weight of the basal three internodes at silking. At 35 d after silking, approximately 88 % of the difference in breaking force was explained by the plant height, ear ratio, crush strength (CS) of the fourth internode, average DWUL and fresh weight per unit volume (FWUV) of the basal three internodes. The main indicator affecting VRPR was the ratio of root depth to width at 35 d after silking. Therefore, an important strategy for increasing maize lodging resistance is to breed cultivars with high internode DWUL, low ear position, and deep roots.