Exogenous abscisic acid promotes the nitrogen use efficiency of Brassica napus by increasing nitrogen remobilization in the leaves

ABSTRACT

The effect of exogenous abscisic acid (ABA) on the nitrogen use efficiency (NUE) of Brassica napus was studied by pot experiments using ABA (1 mg L⁻¹) daubed on the leaves at the early siliquing stage. The results showed that activities of proteases and glutamine synthetase (GS) were significantly promoted by the ABA treatment, which increased the capacity of degradation of foliar proteins and biosynthesis of glutamine (N-transport compounds), both of which promote decreased N in leaves of the ABA treatment. L-glutamine, other free amino acids, and soluble sugar content in the phloem sap of the ABA treatment were significantly higher than those of the control. A ¹⁵N label trial showed that more ¹⁵N was distributed from leaves to the grain by the ABA treatment, which resulted in a significantly higher NUE in the ABA treatment relative to the control.

KEYWORDS:

• Brassica napus
• nitrogen
• nitrogen remobilization
• nitrogen use efficiency (NUE)

Funding

This study was supported by the National Natural Science Foundation of China (Grant nos. 31372130, 31101596); Hunan Provincial Recruitment Program of Foreign Experts; National Oilseed Rape Production Technology System of China; “2011 Plan” supported by The Ministry of Education in China; the Science Foundation of Hunan Province (2016JJ3069).