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.

The size and distribution of leaf area determine light interception in a crop canopy and influence overall photosynthesis and yield. Optimized plant architecture renders modern maize hybrids (Zea mays L.) more productive, owing to their tolerance of high plant densities. To determine physiological and yield response to maize plant architecture, a field experiment was conducted in 2010 and 2011. With the modern maize hybrid ZD958, three plant architectures, namely triangle, diamond and original plants, were included at two plant densities, 60,000 and 90,000plantsha. Triangle and diamond plants were derived from the original plant by spraying the chemical regulator Jindele (active ingredients, ethephon, and cycocel) at different vegetative stages. To assess the effects of plant architecture, a light interception model was developed. Plant height, ear height, leaf size, and leaf orientation of the two regulated plant architectures were significantly reduced or altered compared with those of the original plants. On average across both plant densities and years, the original plants showed higher yield than the triangle and diamond plants, probably because of larger leaf area. The two-year mean grain yield of the original and diamond plants were almost the same at 90,000plantsha (8714 vs. 8798kgha). The yield increase (up to 5%) of the diamonds plant at high plant densities was a result of increased kernel number per ear, which was likely a consequence of improved plant architecture in the top and middle canopy layers. The optimized light distribution within the canopy can delay leaf senescence, especially for triangle plants. The fraction of incident radiation simulated by the interception model successfully reflected plant architecture traits. Integration of canopy openness is expected to increase the simulation accuracy of the present model. Maize plant architecture with increased tolerance of high densities is probably dependent on the smaller but flatter leaves around the ear.