Field Control Of Barnyard Grass (Echinochloa Crusgalli) Through Rice Genetic Diversity

Barnyard grass (Echinochloa crusgalli (L.) Beauv. ) is one of the most vicious weeds in rice-producing area, in which weed control is one of the most important parts of farm practices. Chemical control now is still the main way of barnyard grass control in rice production in China. However, the potential harmful sequence, such as phytotoxicity of herbicides to non-target crops, the explosion of herbicide-resistant mutant, environmental pollution, etc. urges people to find substitute controlling methods for barnyard grass. Based on the successful practice on controlling the pest and diseases by means of rice genetic diversity, the paper tend to test the new hypothesis that if can we success to control barnyard grass (Echinochloa crusgalli, Ec in abbreviation) by constructing a genetically diversified rice population which were consisted of a wide series of weed-resistant cultivars. Three weed-susceptible rice varieties i.e. Xiushui 63, Chunjiang 016 and Zhongjian 2, strong allelopathic variety PI312777 and strong growth competitive variety Guodao 1 for interplanting, were used to compare the response to the barnyard grass both in the field and pot experiments. The main results obtained were as follows.1 Influences of interplanting of various weed-resistant rice varieties on the germination of barnyard grassXiushui63, a weakly weed-resistant variety, showed no inhibiting effect but facilitating effects to the germination of barnyard grass in a Xiushui63-barnyard grass community. The germination rate of Ec in Xiushui 63 monoculture plot increased by 5.56%. But when Xiushui 63 interplanted with PI312777 and Guodao 1, the germination of Ec decreased significantly. The germination rate of Ec decreased by 50% in (Xiushui63 + PI312777) plot, and by 42.11% in (Xiushui 63+ Guodao 1), and by 52.63% in (Xiushui 63+PI312777+Guodao 1) plot.2 Influences of interplanting of various weed-resistant rice varieties on the plant height and tiller number of barnyard grassIn the greenhouse pot experiment, the plant height of Ec decreased significantly when Xiushui63 interplanting with PI312777 and / or Guodao1. he height of Ec decreased by 11.38% in Xiushui 63+PI312777 plot and by 0.98% in Xiushui 63+ Guodao 1 plot and by 12.54% in Xiushui63 +PI312777+Guodaol community.In field experiment, the plant height of Ec decreased significantly in Guodao 1-involved rice interplanting plots. Compared with Xiushui 63 monoculture plot, the plant height of Ec decreased by 13.63% in (Xiushui 63+Guodao1) plot. Compared with Zhongjian 2 (a weed-susceptible variety) monoculture plot, the plant height of Ec decreased by 12.82% in (Zhongjian 2+Guodaol) plot. Compared with Chunjiang 016 (an another weed susceptible variety) monoculture plot, the plant height of Ec decrease by 5.30% in (Chunjiang 016+Guodaol) plot. Compared with that in plot of the monoculture of three weed-susceptible varieties ( Xiushui 63, Chunjiang 016 and Zhongjian 2), the plan height of Ec decrease by 6.66%, 6.66% and 14.49% in the (Xiushui64 + PI312777 + Guodao1), (Chunjiang 016+PI312777+Guodao 1) and (Zhongjian 2 + PI312777 + Guodao 1) communities, respectively.Similarly, genetically-diversified population by various weed-susceptible rice varieties interplanting with allelopathic cultivar PI312777 and competitive cultivar Guodao 1 could significantly inhabit the tiller emergence of Ec. Compared with that in monoculture community of Xiushui 63, the tiller number of Ec decreased by 25.69%, 36.11% and 47.22% in the (Xiushui 63+PI312777), (Xiushui 63+Guodao 1) and (Xiushui 63+ Guodao 1+ PI312777) communities, respectively. Compared with that in Chunjiang 016 monoculture community, the tiller number of Ec decreased by 29.41%,43.03% and 67.80% in (Chunjiang 016+PI312777), (Chunjiang 016 + Guodao 1) and (Chunjiang 016 +Guodao 1+PI312777) communities. Another weed susceptible variety Zhongjian 2, showed a different interaction with allelopathic PI312777 and competitive Guodao1 and had a different influence on the plant height and tiller emergence of Ec in Zhongjian 2 involved communities. There was no difference of plant height of Ec in Zhongjian 2 monoculture community and (Zhongjian 2 +PI312777) community. Compared with that in Zhongjian 2 community, the plant height of Ec decreased by 21.91% in (Zhongjian 2+ Guodao 1) community. The tiller number of Ec in (Zhongjian 2+ PI312777) and (Zhongjhian 2+ PI312777+Guodao 1) communities was 24.16% and 7.12% higher that in Zhongjian 2 monoculture community.3 Influences of interplanting of various weed-resistant rice varieties on the biomass of barnyard grassCompared with that in their monoculture communities, the biomass of Ec significantly decreased in Xiushui 63-involved interplanting community under greenhouse pot experimental conditions. The biomass of Ec decreased by 35.46% in (Xiushui 63+PI312777) community, and by 8.35% in (Xiushui 63+ Guodao 1) community, and by 28.75% in (Xiushui63 + PI312777 + Guodao 1) community. The inhibition of rice genetic diversity established by interplanting of Xiushui 63 with Guodao 1 on the biomass production of Ec in various communities became more obvious in field experiment. Compared with that in Xiushui 63 monoculture community, the biomass of Ec decreased 28.03% in (Xiushui 63+Guodao 1) community, and by 25.22% in (Xiushui 63 +Guodao 1+ PI312777) community. Compared with that in Zhongjian 2 monoculture community, the biomass of Ec decreased by 39.50% in (Zhongajian 2+ Guodao 1) community.4 Influences of interplanting of various weed-resistant rice varieties on the yield of different varietiesCompared with that in monoculture community, grain yield of three weed-susceptible paddy rice varieties increased significantly when they were interplanted with weed-resistant variety Guodao1 and strong allelopathic variety PI312777. The yield of Xiushui 63 increased by 96.61% when it was interplanted with Guodao 1 and PI312777 together, compared with that in monoculture. The grain yield of Chunjiang 016 increased by 102.27% when it was interplanted together with Guodao 1 and PI312777 than that in its monoculture community. The grain yield of Zhongjian 2 increased by 102.03% when it was interplanted together with Guodao1 and PI312777, compared with that in Zhongjian 2 monoculture community.