Affecting Factors and Variation of Sap Flow of Seed Maize in Different Planting Densities

SHI Rongchao; TONG Ling

doi:10.13522/j.cnki.ggps.2017.0501

Abstract：[Objective]Study the affecting factors and variation of sap flow of seed maize in different planting density.[Method]Field experiments were conducted from March to September in 2015, and the experimental treatments consisted of four planting densities (97500, 112500, 127500 and 142500 plants/hm2). The meteoro-logical factors and sap flow of seed maize plants in different densities condition were observed.[Result]The variation trends of sap flow rate with each planting density were similar and the sap flow rates decreased with the increase of planting density. The correlation analysis and path analysis indicated that the meteorological variables affecting hourly sap flow (Qh)and daily sap flow (Qd) in different planting density were ranked as solar radiation (Rs)> water vapor pressure diference (VPD)>air temperature (Ta)>ralative humidity (RH)>wind speed (Ws) and VPD>Ta>Rs>RH>Ws, respectively. The correlation between Qd and leaf area index (LAI) was higher than stem di-ameter (D), but the Qd was not significantly correlated with the plant height (H). Transpiration (T) increased with the increase of planting density and the transpiration ratio (T/(E+T))was 88％～89％over the whole growth stage. The evapotranspiration measured by micro-lysimeter method (E) plus sap flow method (T) underestimate 9％than water balance method.[Conclusion]Rs is the main driving factor of Qh and the VPD is the main driving fac-tor of the daily Qd. The nightime sap flow of seed maize should not be neglected.