TEMPERATURE AFFECTS RADIATION USE EFFICIENCY IN MAIZE

The objective of this work was to study, under field conditions, the effect of temperature on radiation use efficiency (RUE) of maize. Field evidence of the negative effect of low temperature on this variable is lacking. Experiments with different sowing dates and five years of experimentation with October plantings provided a range of average temperatures during the vegetative period from 15.8 to 20.9-degrees-C. Delaying the sowing time from September to November produced a highly significant increase in RUE. There was a positive association between RUE and mean temperature from emergence to flowering. Efficiencies varied from 2.27 to 3.17 g of dry matter per MJ of intercepted photosynthetically active radiation for October plantings of five different years. With these data, a positive and significant association between RUE and mean temperature during the November-December vegetative period was found. Across years and planting dates, RUE and mean temperature during the vegetative period were closely correlated (r = 0.87). The regression equation was RUE = -1.8 + 0.27 T. Based on this evidence, it was concluded that low temperatures reduce RUE in maize.