Abstract:To explore the internal relationship between stalk qualitative trait and strength of the basal internodes in maize, this experiment selected different densitytolerant maize cultivars as materials. Random block design was used in the experiment to comparing the basal internode characteristics and analyzing the internal relation between lignin accumulation, enzyme activities and the rind penetration strength (RPS) under field conditions. The results showed that: (1) the dry weight per unit length (DWUL) and diameter of ‘XY335’ was higher. The rapid formation period of stalk strength was different among different cultivars and was closely related to the lignin accumulation. (2) The RPS formation period for densitytolerant cultivars was 5-7 days longer than ‘XY41’(a cultivar with poor density tolerance). The RPS and lignin accumulation amount were significantly higher than that of ‘XY41’ of 24.9%-36.6% and 12.5%-47.0%, respectively. (3) Before the tasseling stage (VT) is the key period for the rapid accumulation of lignin. The activities of enzymes for lignin synthesis in the V12-V15 stage were significant or extremely significant correlated with the lignin accumulation in the tasseling stage (VT). (4) Especially in V12 stages, the lignin synthesisrelated enzymes of ‘XY335’ were significantly higher than ‘XY41’, the PAL, TAL, CAD and POD of ‘XY335’ were 1.85, 0.30, 0.11 and 0.42 U·mg-1 higher than that of ‘XY41’. Which indicating that V12-V15 stage was crucial for the formation of maize basal internode stalk strength. The higher activities of enzymes in V12-V15 stage could effectively promote the rapid accumulation of lignin, then improve the stalk strength, and thus enhance the lodging resistance of maize stalk.