Effects of winter cover crops on physiological and biochemical properties and growth of double cropping rice in South China

The effects of four different winter cover crops, rygrass (Lolium multiflorum L.), Chinese mild vetch (Astragalus sinicus L.), rape (Brassica napus L.) and potato (Solanum tuberosum L.), on physiological and biochemical properties and growth of double cropping rice in South China were studied in a located experiment from 2004 to 2009. The results show that chlorophyll content, activities of SOD, POD and CAT in leaves of double cropping rice increase under four winter cover crops compared with CK (fallow of paddy field in winter) during growing season. MDA content decreases except at seedling and tillering stages of early rice. Four winter cover crops increase early rice effective tillers number by 18.08×104·hm^-2, 21.25×104·hm^-2, 12.75×104·hm^-2, 17.26×104·hm^-2; seed setting rate by 4.98%, 8.50%, 13.62%, 6.99%; 1000-grain weight by 0.24 g, 0.10 g, 0.14 g, 0.43 g; yield by 324.44 kg·hm^-2, 381.17 kg·hm^-2, 91.04 kg·hm^-2, 303.46 kg·hm^-2, respectively. They increase late rice effective tillers number by 9.81×104·hm^-2, 11.48×104·hm^-2, 5.06×104·hm^-2, 14.91×104·hm^-2; seed setting rate by 6.29%, 8.81%, 15.11%, 8.50%; 1000-grain weight by 0.93 g, 0.88 g, 0.10 g, 0.90 g; yield by 302.28 kg·hm^-2, 316.03 kg·hm^-2, 110.13 kg·hm^-2, 468.17 kg·hm^-2, respectively. The results indicate that the winter cover crops in double cropping rice paddy field may increase antioxidases activities, promote growth and development, and ultimately improve yield and yield components of rice.