Abstract:

To explore the feasibility and optimum sowing date of intercropping Italian ryegrass (Lolium multiflorum L.) into rice field in the lower reaches of Yangtze River, we studied the growth and physiological characteristics of Italian ryegrass under different shade intensity and duration. We also evaluated the performance of Italian ryegrass after being released from shade stress, and under different sowing date conditions. Our results showed that the dry matter yield (DMY), tiller number and plant height decreased significantly with the increase of shade intensity and delayed sowing time in pot experiments. In the field experiment, the DMY, tiller number, plant height, stem diameter before winter and overwintering survival rate were significantly greater in plots of sowing 25 days before rice harvest than those in plots seeded 15 days or 0 day before rice harvest. The plants could grow normally after shade stress was removed. The peroxidase activity (POD) and malonaldehyde content (MDA) of seedlings could restore to control levels 7~14 days after removing stress. In field experiment, The DMY and nutrient yield were significantly greater in plots of sowing 25 days than those in plot seeded 15 days or 0 day before rice harvest. The DMY and nutrient yield was closely related to individual growth before winter. In conclusion, Italian ryegrass could be sowed into paddy field 25 days before rice harvest.

Key words: Italian ryegrass, Paddy rice, Shade stress, Overwintering survival rate, Dry matter yield

摘要：

本实验主要研究长江下游农区水稻套播多花黑麦草（Lolium multiflorum L.）的可行性及适宜播种时间。本实验通过盆栽模拟试验及稻田实地试验，研究了不同遮荫强度、遮荫时间及遮荫解除后小苗生长和生理特性的变化，以及不同套播时间对多花黑麦草生产性能的影响。结果表明：盆栽小苗的单株生物量、分蘖数及株高随遮荫强度的增强及播种时间的延迟而显著降低（P<0.05）；水稻收获前25 d套播的小苗越冬前的生物量、分蘖数、株高、茎粗及越冬率均显著高于收获前15 d套播和收割后播种的小苗（P<0.05）。遮荫胁迫解除后，各遮荫处理的小苗均可正常生长。其中在全光照30.6%以上的弱光条件下，小苗的POD活性及MDA含量能够在胁迫解除后7~14 d恢复至对照水平。水稻收获前25 d套播的小苗次年干物质及营养物质产量均显著高于收获前15 d套播和收割后播种处理（P<0.05），其干物质及营养物质产量与冬前植株的强弱有密切关联。综上可知，多花黑麦草能在水稻收获前套播，并以水稻收割前25 d播种为宜。

关键词: 多花黑麦草, 水稻, 遮荫胁迫, 越冬率, 干物质产量