Abstract
As an essential regulator of photosynthesis and hormone signaling, light
plays a critical role in leaf senescence and yield gain in crops.
Previously, numerous studies have shown that the narrow-wide-row
planting pattern, especially under intercropping systems, is more
beneficial for crops to enhance light interception, energy conversion,
and yield improvement. However, the narrow-wide-row planting pattern
inevitably leads to a heterogeneous light environment for crops (i. e.,
maize in maize-based intercropping systems) on both sides of the plant.
The mechanism by which it affects leaf senescence and yield of maize
under a narrow-wide-row planting pattern is still unclear. Therefore, in
this study, we compared the leaf senescence and yield formation process
of maize under homogeneous (normal light, NL and full shade, FS) and
heterogeneous (partial light, PL) light conditions. Results revealed
that partial light treatment influenced the homeostasis of growth and
senescence hormones by regulating the expression of ZmPHYA and ZmPIF5.
Compared to normal light and full shade treatments, partial light
delayed leaf senescence by 3.6 and 5.9 days with 2.2 and 3.3 more green
leaves and 1.1 and 1.4 fold nitrogen uptake, respectively. Partial light
reduced oxidative stress by enhancing antioxidant enzyme activities of
PS (shade side of partial light) leaves, which improved photosynthetic
assimilation, balanced sucrose, and starch ultimately maintaining the
similar maize yield to NL. Overall, these results are important for
understanding the mechanism of leaf senescence in maize, especially
under heterogeneous light environments, which maize experienced in
maize-based intercropping systems. Furthermore, these findings are
providing proof of getting a high yield of maize with less land in
intercropping systems. Thus, we can conclude that maize-based
intercropping systems can be used for obtaining high maize yields
maintained under the current climate change scenario.