Interference of Rice with Different Morphological Types and Allelopathy on Barnyardgrass under Three Planting Patterns

Abstract

The interference effects of 17 rice materials with different morphological and allelopathic characteristics on Echinochloa crus-galli were studied using split-split plot experiment design. Three common rice planting patterns including water direct seeding, small rice seedling transplanting and big rice seedling transplanting were designed as main treatment, and two weeding inoculations, barnyardgrass mixture transplanting and without barnyardgrass as split treatment, and 17 rice materials as split-split treatment. The results showed that direct seeding and small seedling transplanting treatments had better inhibitory effects on plant height, tiller ability and dry weight of barnyardgrass compared with big seedling transplanting treatment. The rice with advantageous morphological and allelopathic characteristics could suppress barnyardgrass effectively. With 30 plants per square meter of barnyardgrass interference competition, the rice yield under three different planting patterns was not significantly different, with 21.73% of reduction due to weed interference. On the other hand, the allelopathic rice materials Xiayitiao, IR644-1-63-1-1 and Gumei 2 controlled barnyardgrass effectively, remaining relatively better rice yield in spite of weed infestation. Barnyardgrass competition restrained rice growth, especially in direct seeding treatment. Under such circumstances, the rice plant height, tillering ability and dry weight in most growth stages of direct seeding treatment were worse than those of transplanting treatments. The effects of weed competition on rice agronomic traits were quite different. Allelopathic rice material Xiayitiao had better tillering ability in tiller stage, and higher plant height and dry weight at most growth stages. Weed infestation could not affect the rice ultimat plant height, but influence rice tillering ability, stem and panicle dry weight remarkably. Weed competition did not change grain weight significantly under three rice planting patterns. The grain weight per rice plant in transplanting treatments was significantly greater than that in direct seeding. The panicle length, total panicle number, setting number and seed setting percentage were also notably larger than those in direct seeding. Both panicle number and setting number of allelopathic rice materials Gumei 2, IR644-1-63-1-1, TN1, and PI312777 were smaller. Although panicle number of allelopathic rice Xiayitiao was smaller, the seed setting percentage was quite higher. Rice materials Zhongzao 27, Zhe 207, Zhe 101, and Zhongzao 22 had higher 1000-grain weight. The 1000-grain weight of allelopathic rice Gumei 2 was significantly larger than those of IR644-1-63-1-1, TN1, and PI312777. The grain weight of Zhe 101, Zhe 207, and Zhongzao 22 was higher; meanwhile, the grain weight of allelopathic rice 156 was significantly larger than that of Gumei 2, Xiayitiao, IR644-1-63-1-1, TN1, and PI312777.