冬种绿肥对早稻产量及稻田杂草群落的影响

【目的】综合评价南方稻区不同冬季绿肥种类种植下水稻生长动态及稻田杂草群落效应，进一步优化稻田种植模式，大力发展冬季作物种植与开发。【方法】从2011年冬开始，在南方双季稻区江西农业大学科技园，采用田间试验，分别选取豆科、禾本科、十字花科冬季绿肥种类，比较冬季绿肥紫云英、油菜、黑麦草及混播绿肥（紫云英×油菜×肥田萝卜）对后作早稻产量及产量构成、干物质生产特性、稻田杂草群落的差异变化。【结果】紫云英前茬处理的早稻（紫云英-早稻-晚稻，MV-R-R）分蘖盛期、孕穗期、抽穗期和成熟期的群体干物重均明显高于其他处理，分别高出14.46%、10.99%、11.83%和7.23%，相应地其产量也分别比黑麦草-早稻-晚稻（RG-R-R）、油菜-早稻-晚稻（RP-R-R）、混播绿肥-早稻-晚稻（MS-R-R）处理高6.61%、3.29%及0.78%。其中产量构成中有效穗数、每穗粒数、结实率和千粒重也均以MV-R-R处理最高。水稻主要生育阶段的干物质积累，除抽穗期至成熟期MV-R-R低于RG-R-R处理外，在播种至分蘖盛期、分蘖盛期至孕穗期、孕穗期至抽穗期均是MV-R-R处理最高；与其他处理相比，增加幅度分别为11.38%-17.72%、4.50%-28.00%、1.85%-35.25%。水稻播种期至分蘖盛期和孕穗期至抽穗期两个生育阶段干物质积累量最大，是物质快速积累的阶段，各处理这2个生育阶段干物质积累量分别达到成熟期干物重的70.43%、60.50%、69.87%、69.08%；而抽穗期至成熟期各处理干物质积累所占比例均最低。干物质在茎鞘、叶片和穗分配情况，茎鞘的分配比例在孕穗期最大，并随着生育进程不断降低，在成熟期达到最低，各处理从58.30%-64.20%降低至27.95%-30.47%；叶片的分配比例也以孕穗期最大，并从该期的35.80%-41.70%降低至成熟期的13.07%-14.62%。另外，据调查，稻田杂草有7科11种，其中稗草（Echinochloa crusgalli）、鸭舌草（Monochoia vaginalis）、矮慈姑（Sagittaria pygmaea）和牛毛毡（Eleocharis yokoscensis）密度最大，群体数量为田间杂草的80.84%。MV-R-R处理对稻田杂草密度有显著影响，对杂草的抑制效果明显优于其他处理，RG-R-R处理的效果最差。通过分析杂草在群落中的相对优势度可以看出，MV-R-R和RG-R-R处理中杂草群落组成主要为稗草+鸭舌草+牛毛毡，而RP-R-R和MS-R-R处理为稗草+鸭舌草+矮慈姑。RG-R-R处理杂草物种丰富度最大，显著高于其他处理。从表征多样性的Shannon指数来看，RG-R-R冬种黑麦草处理的杂草物种多样性指数最高，而MV-R-R处理最低。从表征优势度的Simpson指数来看，MV-R-R处理的杂草优势度最高，RG-R-R处理最低。从Pielou均匀度指数来看，MV-R-R处理下的均匀度指数高于其他处理，但差异不显著，而其他冬季绿肥处理的稻田杂草均匀度有所下降，其中RG-R-R处理最低。【结论】紫云英-早稻-晚稻处理能保证较高的干物质积累量，具有较高的增产潜力，对杂草发生种类和密度有显著影响，并且有利于提高杂草均匀度，弱化稻田优势种杂草在田间的危害性。

Effects of Different Winter Planting-Green Manure on the Grain Yield of Rice and Weed Community of Paddy Field

【Objective】 This study aims at comprehensively evaluate different winter green manures on rice growth dynamics and paddy field weed community in southern rice region for further optimization of rice cropping patterns, and development of winter crop planting and development. 【Method】 From winter in 2011 in double cropping area in southern Jiangxi Agricultural University Science Park, winter green manure species including legumes, grasses, and cruciferous were selected to make comparison of milk vetch, rapeseed, ryegrass and mixed of green manure (vetch × rapeseed × fertile turnip) on rice yield and its components, dry matter production characteristics and weed communities. 【Result】 The results showed that the dry matter weight of population of rice in the treatment of MV-R-R(milk vetch-rice-rice) are all higher than others at tillering stage, booting stage, heading stage and maturity. The rate of increase was 14.46%, 10.99%, 11.83% and 7.23%, respectively. Compared with RG-R-R (ryegrass-rice-rice), RP-R-R (rapeseed-rice-rice), MS-R-R (mixed green manure-rice-rice), rice yield of MV-R-R was higher, increased by 6.61%, 3.29%, and 0.78%, respectively. Among the 4 different winter green manures, rice yield and yield components (effective panicles, grain number per panicle, seed-setting rate and 1000-grain weight) in treatment of MV-R-R were higher than other treatments. Dry matter accumulation in treatment of MV-R-R was higher than others in main growth periods of rice except for heading to maturity. Compared with RG-R-R, RP-R-R, MS-R-R (mixed green manure-rice-rice), the increasing rate were 11.38%-17.72%, 4.50%-28.00%, and 1.85%-35.25%, respectively. The dry matter accumulation in the periods of sowing to tillering and booting to heading were the biggest, which is the stage of rapid accumulation of substances. In the four treatments, dry matter accumulation at the two growth stages reached 70.43%, 60.50%, 69.87%, and 69.08% of that at maturity. While the proportion of dry matter accumulation from heading to maturity was the lowest. Analysis of dry weight ratio of stem-sheath, leaf, and panicle to total plant at middle and late stages of rice, the dry matter ratio of stem-sheath was the biggest at booting stage. But they continued to decrease with the growth, reached a minimum at maturity, and in each treatment decreased from 58.30%-64.20% to 27.95%-30.47%. Dry matter ratio of leaf was the biggest at booting stage, reduced from 35.80%-41.70% to 13.07%-14.62%. According to the survey, weeds in paddy field belong to seven families, eleven species. The weed densities of Echinochloa crusgalli, Monochoia vaginalis, Sagittaria pygmaea and Eleocharis yokoscensis were greater than others, accounting for 80.84% of field weeds. The treatment of MV-R-R had a significant effect on paddy weed density and the effect on inhibiting weeds was obvious better than other treatments. The treatment of RG-R-R was the lowest. By analyzing the relative abundance of weed species, the following conclusions could be drawn. The basic weed community compositions of the MV-R-R and RG-R-R were Monochoia vaginalis+ Echinochloa crusgalli+Eleocharis yokoscensis, but that of the RP-R-R and MS-R-R were Monochoia vaginalis+ Echinochloa crusgalli+ Sagittaria pygmaea. The species richness of the RG-R-R were maximum, significantly higher than other treatments. For the Shannon index, the species diversity of the treatment of winter planting-ryegrass was the highest, while the MV-R-R was the lowest. From the point of view of Simpson index, the weed dominance of MV-R-R was the highest, while the RG-R-R was the lowest. From the point of view Pielou evenness index, the weed evenness of the MV-R-R was higher than other treatments, but the difference was not significant. While the weed evenness of the other winter planting-green manure pattern decreased, of which the RG-R-R was the lowest.【Conclusion】In conclusion, the treatment of milk vetch-rice-rice can ensure higher dry matter accumulation and yield potential, which have a significant impact on weed species and density. Also it can help to improve weed uniformity and decrease the harm of dominant species of weeds in paddy field.