Effects of water managements and planting densities on allelopathic rice yields, qualities and the contents of Pb and Cd in rice grains

Objective  To investigate the relationships of the yields, qualities and heavy metals contents of allelopathic rice with water managements and planting densities, and make better use of environmentally friendly characteristics of allelopathic rice.

Method  The rice materials, including ‘Allelopathy rice No.3’, ‘Hualiangyou 78’, ‘Yuxiangyouzhan’ in early season and ‘Baixiangzhan’ in late season, were cultivated under two different water managements (WN: paddy field drainage during booting stage, WS: paddy field continuous irrigation during booting stage) and two different planting densities (DH: high planting density, DN: local planting density). And then their yields, qualities, and Pb and Cd contents in grains were investigated.

Result  The rice yields and qualities had no significant differences in different water and density treatments, but differed among rice cultivars. ‘Hualiangyou 78’ yield was the highest in all materials. WSDN treatment significantly reduced the milled rice percentage of ‘Baixiangzhan’, but had no significant effect on allelopathic rice cultivars. WS treatment reduced the contents of Pb and Cd in rice grains, especially the contents of Cd in allelopathic rice cultivars. The planting densities and rice cultivars had no significant effect on Pb and Cd contents in rice grains.

Conclusion  Both water and density treatments have no significant effect on yields and qualities of allelopathic rice materials, but WS can significantly reduce the Cd contents of allelopathic rice grains.