Abstract
Lodging is a critical constraint to yield increase. There appear to be tradeoffs between yield formation and lodging resistance in maize. Hypothetically, it is feasible to reduce lodging risk as well as increase grain yield by optimizing dry-matter allocation to different organs under different environments. A three-year field experiment was conducted using four maize cultivars with differing lodging resistances and five growing environments in 2018–2020. Lodging-susceptible (LS) cultivars on average yielded more than lodging-resistant (LR) cultivars when lodging was not present. The yield components kernel number per ear (KN) and thousand-kernel weight (TKW) were both negatively correlated with lodging resistance traits (stalk bending strength, rind penetration strength, and dry matter weight per internode length). Before silking, the LR cultivar Lishou 1 (LS1) transported more assimilates to the basal stem, resulting in a thicker basal stem, which reduced dry matter allocation to the ear and in turn KN. The lower KN of LS1 was also due partly to the lower plant height (PH), which increased lodging resistance but limited plant dry matter production. In contrast, the LS cultivars Xianyu 335 (XY335) and Xundan 20 (XD20) produced and allocated more photoassimilates to ears, but limited dry matter allocation to stems. After silking, LS cultivars showed higher TKW than LR cultivars as a function of high photoassimilate productivity and high assimilate allocation to the ear. The higher lodging resistance of LS1 was due mainly to the greater assimilate allocation to stem after silking and lower PH and ear height (EH). High-yielding and high-LR traits of Fumin (FM985) were related to optimized EH and stem anatomical structure, higher leaf productivity, low assimilate demand for kernel formation, and assimilate partitioning to ear. A high pre-silking temperature accelerated stem extension but reduced stem dry matter accumulation and basal stem strength. Post-silking temperature influences lodging resistance and yield more than other environmental factors. These results will be useful in understanding the tradeoffs between KN, KW, and LR in maize and environmental influences on these tradeoffs.
