Heterogeneous light delayed leaf senescence and ensure yield in maize

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.