Diurnal variations of half-hourly crop evapotranspiration (<i>λET</i>) calculated by the dual-source with the big-leaf (<i>λET<sub>1</sub></i>) and dual-leaf models (<i>λET<sub>2</sub></i>), and measured <i>λET</i> (<i>λET<sub>m</sub></i>), respectively for four typical clear-sky days in different growth stages of maize in 2009.

<p>Leaf area index (<i>LAI</i>) was 0.16, 2.62, 5.38 and 2.99, on (a) May 22, (b) June 23, (c) July 27, and (d) September 17, respectively.</p>