Submitted to: Field Crops Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/2/1998
Publication Date: N/A
Citation: Interpretive Summary: Simulation models that predict corn development assume a constant degree-day sum for each leaf to appear. In this study, we looked at leaf appearance rate data from a wide range of locations to quantify how environments can affect corn leaf appearance rate. We collected leaf appearance data in the Netherlands, Texas, and Mexico. We also used similar data from the literature.
Technical Abstract: Modelling crop canopies requires accurate values for the thermal interval for leaf tip appearance (phyllochron). However, phyllochron varies across environments. Currently models use constant values for each environment. A method of adjusting the value of phyllochron according to geneotype adaptation or environmental conditions is required. Recently, phyllochron in maize was related to light intensity. The data suggests that phyllochron depends on the adequacy of current photosynthesis (source). Maize was grown in field experiments in the Netherlands, in Texas, and in Mexico. The experiment in Texas included grain sorghum and shading treatments to alter irradiance. Detailed data on leaf production were collected. These data were combined with published and unpublished data. Maize phyllochron increased as mean temperature increased from 12.5 to 25.5 degrees C before tassel initiation, and was increased by low irradiance. Only small differences in phyllochron occurred among cultivars. Phyllochron increased by 1.9 degree Cd per degree C increase in daily temperature. Phyllochron declined when mean daily temperature before tassel initiation exceeded 25.5 degrees C, but we did not have sufficient data to define the response - further research is needed to define acclimation to these higher temperatures in tropical areas. Phyllochron increased by 2 to 4 oCd per MJ photosynthetically active radiation (PAR) as irradiance decreased from 8 MJ PAR m-2 d-1. However, further research is needed to better define the response of phyllochron to irradiance.