Optimizing quinoa height to counter stem lodging risks in the three main production regions of China.

• A criterion for grading lodging risk levels based on probability was established. • The wind speed risks in three main quinoa production areas of China were analyzed. • Optimizing plant height to counter lodging risks under high-yielding conditions. • The spatial distribution of recommended plant height in study areas was drawn. Stem lodging is a major restriction for further quinoa yield improvement under high-yielding conditions. Plant height is one of the most important factors to affect stem lodging resistance, but how to determine the optimal plant height to meet specific lodging resistance requirements in different areas is rarely discussed. This study analyzed the long-term wind speed data in three main quinoa production regions of China (Inner Mongolia, Qinghai, and Gansu), and calculated the wind speed under different risk conditions (probability = 0.1, 0.3 and 0.5). Then, three high yielding conditions were selected based on a field experiment, and their optimal quinoa plant heights were calculated to ensure adequate lodging resistance in every specific area by using the generalized crop lodging model. Results showed that during the susceptible lodging period, 70–97% of the study regions experienced a maximum daily wind speed of 4–6 m s–1 with a probability of 0.3–0.5. As the probability decreased to 0.1, a higher maximum daily wind speed of 6–8 m s–1 would prevail in 69–75% of the study regions. Besides, central Inner Mongolia, western Qinghai, and northern Gansu experienced higher maximum daily wind speeds than other regions during the susceptible lodging period. To achieve adequate lodging resistance under a probability of 0.3–0.5, quinoa height should be decreased to be lower than 1.2–1.6 m in 72–99% of the study regions. Furthermore, under a probability of 0.1, quinoa height needed to be lower by at least another 0.2 m more in 86–98% of the study regions. [ABSTRACT FROM AUTHOR]