GPP and maximum light use efficiency estimates using different approaches over a rotating biodiesel crop

Overall, ɛ0LUE yielded 3.33 ± 0.10 g C MJ−1 although this varied depending on crop architecture, phenology and prevailing meteorological conditions. Crop-to-crop ɛ0LUE ranged from 2.74 ± 0.17 to 3.95 ± 0.19 g C MJ−1 for peas and rye, respectively, yielding intermediate values for rapeseed and wheat, 2.92 ± 0.18 and 2.86 ± 0.23 g C MJ−1, respectively. ɛ0MODIS, derived from the linear fit of GPP versus GPPMODIS estimates, yielded 2.13 ± 0.10 g C MJ−1 and crop-to-crop ranged from 1.28 ± 0.17 to 2.41 ± 0.12 g C MJ−1 for wheat and rapeseed, respectively. The best linear fits corresponded to crops growing under well-watered conditions, rapeseed and peas, and the worst fits were for wheat, affected by drought. GPP annuals were 1680, 710, 730 and 1410 g C m−2 for rapeseed, wheat, peas and rye, respectively.