The efficient use of radiation, water, and nitrogen uptake by low-nitrogen-tolerant broomcorn millet (Panicum miliaceum L.) increased grain yield in the Loess Plateau, China

ABSTRACT

• Low N input decreased broomcorn millet grain yield by poor resource use efficiency. • Low-N-tolerant cultivars performed better than low-N-sensitive cultivars at low N. • Low-N-tolerant cultivars had increased photosynthesis and dry matter transport. • Low-N-tolerant cultivars had high productivity under field conditions. The development of highly productive, low-N-tolerant cultivars is important to facilitate green and sustainable agriculture. However, it is unclear how low-N-tolerant cultivars achieve high grain yields under field conditions. In this study, the physiology facilitating the strong growth and efficient resource use of four low-N-tolerant Panicum miliaceum L. cultivars was compared with two low-N-sensitive cultivars using low and typical N fertilization applications (0, 75, and 150 kg N ha−1) on the semiarid Loess Plateau, China in 2019 and 2020. Compared to normal N fertilization, low N fertilization treatments significantly decreased plant photosynthetic capacity by regulating leaf stomatal closing, resulting in reduced dry matter accumulation and transportation, growth inhibition, weakened resource utilization, and consequently, a 28.9% decrease in grain yield. Compared to the low-N-sensitive cultivars, the low-N-tolerant cultivars had improved growth, leaf photosynthetic capacity, and dry matter transportation. These improved physiological characteristics resulted in more effective resource capture in the low-N-tolerant cultivars. This included higher and more efficient radiation use (24.4% and 26.9%), water use (63.5% and 48.2%), and N uptake (37.0% and 33.7%) in 2019 and 2020, respectively. Furthermore, the low-N-tolerant cultivars had increased productivity, with higher grain yields (38.6-41.6%) and harvest index values (16.7-28.2%) under low N conditions in the two years of the study. Overall, the results of this study determined the effect of low N input on broomcorn millet productivity and illustrated the strategies by which low-N-tolerant cultivars increased grain yield in semiarid field conditions. [Display omitted] [ABSTRACT FROM AUTHOR] Copyright of Agricultural & Forest Meteorology is the property of Elsevier B.V. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)