干湿交替灌溉条件下不同种稗草对水稻光合特性和产量的影响

Effects of Different Species in Echinochloa on Photosynthetic Characteristics and Grain Yield in Rice under Alternate Wetting and Moderate Drying Condition

以两优培九和南粳9108为试验材料,自水稻移栽至成熟分别与无芒稗（T1）、稗（T2）、西来稗（T3）和光头稗（T4）共生,以无稗草水稻处理（CK）为对照,研究干湿交替灌溉条件下不同稗草对水稻光合特性和产量的影响。结果表明,稗草对水稻产量的干扰因稗草种和水稻品种的不同而异。稗草种间干扰强度表现为T3〉T1〉T2〉T4,两优培九减产率小于南粳9108。T1、T2、T3和T4处理后两优培九的减产幅度分别为11.16%~13.78%、10.19%~10.60%、19.00%~23.79%和0.50%~1.57%,除T4外其他处理较对照显著降低；南粳9108的减产幅度分别为38.44%~45.51%、31.29%~36.86%、54.88%~60.65%和8.28%~15.14%,均达显著差异。T1、T2和T3处理后对两优培九叶面积指数和叶绿体色素含量无显著影响,但使南粳9108的叶面积指数降低和叶绿体色素含量增加。4种处理还显著降低了水稻冠层的透光率、剑叶光合速率、蒸腾速率和气孔导度以及干物质积累量。冠层透光率、光合速率、气孔导度、蒸腾速率和成熟期干物质积累量降低以及灌浆期叶绿体色素含量不同程度增加可能是水稻产量降低的重要原因。

In order to investigate the effects of different barnyardgrass species on photosynthetic characteristic and grain yield of rice, two rice cultivars, Liangyoupeijiu （anindicahybrid cultivar） and Nanjing 9108 （ajaponica cultivar）, were co-cultured with four barnyardgrass species from transplanting to maturity under alternate wetting and moderate drying condition. The treatments were designed as follow： weed free （control）, rice withEchinochloa crusgalli var.mitis （T1）, rice withEchinochloacrusgalli （T2）, rice withEchinochloacrusgalivar.zelayensis （T3）, and rice withEchinochloacolonum（T4）. The results showed that the degree of interference of barnyardgrass on rice yield depended on different barnyardgrass species and rice cultivars. The interference intensity of barnyardgrass was in the order of T3〉T1〉T2〉T4, and grain yield loss rate in Liangyoupeijiu was less than that in Nanjing 9108. T1, T2, T3, and T4 treatments respectively reduced 11.16%–13.78%, 10.19%–10.60%, 19.00%–23.79%, and 0.50%–1.57%, for Liangyoupeijiu of the grain yield and 38.44%–45.51%, 31.29%–36.86%, 54.88%–60.65%, and 8.28%–15.14% for Nanjing 9108, T1, T2, and T3 significantly reduced rice grain yield, while the effect of T4 was significant for Nanijng 9108 but not for Liangyoupeijiu when compared with CK. Moreover T1, T2, and T3 had no effects on leaf area index and contents of photosynthetic pigments for Liangyoupeijiu, but Nanjing 9108 significantly reduced leaf area index and increased contents of photosynthetic pigments under the same treatment condition. Furthermore, four treatments significantly reduced rice canopy light transmission, leaf photosynthetic rate, stomata conductance, transpiration rate and dry matter accumulation during grain filling stage. The results indicated that the decrease in canopy light transmission, photosynthetic rate, transpiration rate, stomata conduc-tance and the increase in some degree in contents of photosynthetic pigments during grain filling stage may contribute to grain yield reduction of rice.