Plant Materials and Growth Conditions
Maize (Zea mays ) cultivar Zhongyu 3 widely planted in maize
soybean relay strip intercropping in China was used in this study. Maize
seeds were pre-germinated on a sterilized, wet gauze for three days at
25℃ in a light chamber (I-66VL, Percival Scientific Inc., Watson, USA).
Each germinated seed was transferred in a pot with 20 cm height and 30
cm diameter, filled with a mixed matrix of PINDSTRUP organic soil
(Pindstrup Mosebrug A/S, Ryomgaard, Denmark). After three weeks, the
plants were subjected to simulated heterogeneous light conditions
(Normal light; NL and Partial light; PL) till the flowering stage (i.e.
76 days after sowing (DAS) (Fig.1A). The normal light (NL) intensity
which was measured on a clear and cloudless weather day was about 1200
μmol m-2 s-1 and 80% transmittance
of NL in the simulated shade was considered as partial light (PL). One
side of maize was fully exposed to existing light conditions (Normal
full-NF in NL and Partial full-PF in PL), and the other side was shaded
using a black sunshade (Normal shade-NS and Partial shade-PS in NL and
PL, respectively). Both sides of maize shaded by a black sunshade (80%
transmittance of normal light) were used as a negative control (Full
shade-FS; Supporting Information Figure S1) for phenotypic analyses. The
maize ear leaves were harvested on the 0,
1st,10th, 20th,
30th, and 40th days after light
treatment for analyses. At maturity, dry seed matter accumulation with
an interval of 5 days was determined on maize plants under normal light
and partial shading. The place was exchanged between the pots daily to
avoid any possible boundary effects. HR350 (Hi-point Inc., Gaoxiong,
Taiwan) was used for light intensity and spectral irradiance (λ=380-760
nm) measurement. To further confirm the experimental results. Every
treatment was performed with three replicates.