Funding for this research was provided by:
Hainan Provincial Natural Science Foundation of China (618QN220)
Hainan University (hdjy1730)
Agriculture Department of Shaanxi Province (2016NY-176)
Shaanxi Normal University (GK201703054, GK201603083, GK201703058)
Education Department of Shaanxi Province (2014KTC-18)
National Natural Science Foundation of China (61373120)
Article History
Received: 10 September 2017
Revised: 3 April 2018
Accepted: 8 May 2018
First Online: 11 June 2018