Abstract: 【Objective】 A field experiment was conducted to study the effects of dislodging subtending leaf on grain yield, grain volume, dry weight, dehydrating rate and grain filling rate of summer maize.【Method】Three maize cultivars XY335, ZD958 and DH661 were used to analyze the effects of subtending leaf on grain yield and yield components, grain filling (grain volume, dry matter and dehydrating rate), and the time of milk lines disappearance and black layer appearance of summer maize by setting different dislodging subtending leaf treatments such as dislodging 1/4 subtending leaf (S1), dislodging 1/2 subtending leaf (S2), dislodging all subtending leaves (S3), and CK. 【Result】 The results showed that grain yield of summer maize decreased significantly after dislodging subtending leaf. Grain yields of S1, S2 and S3 of XY335 decreased by 9.45%, 13.78% and 27.89% respectively, compared to CK. Yields of ZD958 decreased by 10.72%, 15.07% and 24.75%, respectively, compared to CK. Yields of DH661 decreased by 9.31%, 16.01% and 22.35%, respectively. The damage increased with increasing number of dislodging subtending leaf. Grain weight and grain number per panicle of summer maize decreased significantly after subtending leaves were dislodged. The greatest effect was observed under the S3 treatment. Grain weight and grain number per panicle of S3 decreased by 15.30% and 14.87% in XY335 compared to CK, that of ZD958 decreased by 11.22% and 15.24% compared to CK, and that of DH661 decreased by 15.10% and 8.55% compared to CK. In addition, dislodging subtending leaf significantly affected grain filling characteristics. The damage increased with increasing number of dislodging subtending leaf. Days of reaching maximum grain filling rate (D_max) decreased significantly, and was the most susceptible to damage from dislodging all subtending leaves (S3). That of XY335, ZD958 and DH661 decreased by 3 d, 4 d, and 3.5 d compared to CK. Weight of reaching maximum grain filling rate (W_max) and active grain filling period (P) decreased significantly after the subtending leaves were dislodged, of which the most susceptible to damage was from the S3 treatment. W_max of XY335, DH661, and ZD958 is S3 decreased by 12.75%, 17.78%, and 17.12%, respectively, compared to CK. P of S1, S2, and S3 in DH661 decreased by 6.22%, 9.82%, and 11.78%, respectively, compared to CK. XY335 decreased by 5.39%, 8.39%, and 13.09%. ZD958 decreased by 0.17%, 2.39%, and 5.97%, respectively, compared to CK. Furthermore, dislodging subtending leaf decreased grain volume, grain fresh weight and days of reaching milk lines disappearance and black layer appearance, and increased dehydrating rate. Days of reaching milk lines disappearance of S3 decreased by 10 d, 6 d, and 4 d, respectively, compared to CK in XY335, ZD958, and DH661. Days of black layer appearance decreased by 10 d, 5 d, and 4 d, respectively, compared to CK in XY335, ZD958, and DH661.【Conclusion】Dislodging subtending leaf decreased days of maximum grain filling (D_max), weight of maximum grain filling rate (W_max), maximum grain filling (G_max), resulted in the decline of grain dry matter, affected grain filling characteristics, decreased the time of milk lines disappearance and black layer appearance, leading to the decrease of grain yield of summer maize. The effects decreased with the increase of the number of removed subtending leaves.

Key words: summer maize, subtending leaf, grain yield, grain filling