Barnyardgrass (Echinochloa spp.) is the most common noxious weed in rice paddies as it inhibits rice growth and reduces grain yield.To date,little information is available on above-and belowgroundgrowth changes in ric...Barnyardgrass (Echinochloa spp.) is the most common noxious weed in rice paddies as it inhibits rice growth and reduces grain yield.To date,little information is available on above-and belowgroundgrowth changes in rice due to neighboring barnyardgrass.This study aimed to investigate the changes in root traits and shoot growth of rice when it is grown with different kinds of barnyardgrass.Japonica rice plants (var.Nanjing 9108) were co-cultured with two varieties of Echinochloa crusgalli (L.) Beauv.(EP,var.mitis (pursh) Petern;EH,var.zelayensis (H.B.K.) Hitchc),and E.colonum (L.) Link (EL) in the field in 2017 and 2018.Four treatments included control (i.e.,weed free rice plants) and co-cultures with each of three barnyardgrasses (EP,EH,and EL).The results revealed that EP,EH,and EL treatments significantly reduced rice grain yields by 30.6%–36.2%,42.5%–46.5%,and 10.6%–14.3%,respectively.Shoot growth including shoot dry weight,leaf photosynthetic rate,zeatin (Z) and zeatin riboside (ZR) in grains,and activities of key enzymes involved in sucrose-to-starch conversion in grains and root traits,such as length density,root dry weight,total absorbing surface area,active absorption surface area,oxidation activity,and Z+ZR contents in roots were dramatically reduced during post-heading stages of rice when grown with the three kinds of barnyardgrass.Moreover,above-mentioned rice shoot growth indices were strongly and positively correlated with root traits.These results suggested the decrease in rice shoot growth and root traits during post-heading stages contributes to the reduction in the rice yield when it grows with barnyardgrass neighbors.展开更多
Species of actinomycetes were collected andisolated from soil samples which were pickedfrom vegetable field,park land,and forest inHangzhou,Zhejiang Province.They were in-oculated in 250 ml flasks each containing 50 m...Species of actinomycetes were collected andisolated from soil samples which were pickedfrom vegetable field,park land,and forest inHangzhou,Zhejiang Province.They were in-oculated in 250 ml flasks each containing 50 mlliquid medium and fermented on a rotary shak-er at 28℃.The agents for actinomycetes wereobtained seven days later.Four species of acti-nomycetes were selected through biological as-say.Experiments were conducted in the展开更多
稗草是中国南方双季稻稻田的恶性杂草，对水稻生产造成严重威胁。为明确稗草对双季稻生长的影响及其经济危害允许水平，采用添加系列试验和模型拟合的方法研究了不同稗草密度下水稻生长与产量性状的变化规律。结果表明，在稗草的竞争干...稗草是中国南方双季稻稻田的恶性杂草，对水稻生产造成严重威胁。为明确稗草对双季稻生长的影响及其经济危害允许水平，采用添加系列试验和模型拟合的方法研究了不同稗草密度下水稻生长与产量性状的变化规律。结果表明，在稗草的竞争干扰下，双季早、晚稻的株高、分蘖数、有效穗数、每穗实粒数、千粒重及产量均随稗草密度的增加而逐渐降低。指数模型 y ＝beax 可以较好地拟合稗草对早稻分蘖数、有效穗数和产量的影响，而二次曲线模型 y ＝ax 2＋bx＋c 拟合稗草与株高、每穗实粒数、千粒重和产量损失间的关系最佳；二次曲线模型 y ＝ax 2＋bx＋c 均可较好地拟合稗草与晚稻株高、分蘖数、有效穗数、每穗实粒数、千粒重、产量和产量损失间的关系。稻田使用化学除草剂（丁草胺、二氯喹啉酸、五氟磺草胺）防除时，双季早、晚稻稻田稗草的经济危害水平分别为1．64％～2．91％和1．28％～2．28％，经济阈值分别为0．63～1．23株／m^2和1．30～1．85株／m^2。稗草对水稻生长有抑制作用，并导致水稻产量损失；通过对经济阈值分析，化学除草剂防治稗草具有明显的经济优势。展开更多
基金supported by the National Natural Science Foundation of China (31871982, 31672042)the National Key Research and Development Program of China (2016YFD0200805)the Jiangsu Agricultural Science and Technology Innovation Fund (CX (18)3056)。
文摘Barnyardgrass (Echinochloa spp.) is the most common noxious weed in rice paddies as it inhibits rice growth and reduces grain yield.To date,little information is available on above-and belowgroundgrowth changes in rice due to neighboring barnyardgrass.This study aimed to investigate the changes in root traits and shoot growth of rice when it is grown with different kinds of barnyardgrass.Japonica rice plants (var.Nanjing 9108) were co-cultured with two varieties of Echinochloa crusgalli (L.) Beauv.(EP,var.mitis (pursh) Petern;EH,var.zelayensis (H.B.K.) Hitchc),and E.colonum (L.) Link (EL) in the field in 2017 and 2018.Four treatments included control (i.e.,weed free rice plants) and co-cultures with each of three barnyardgrasses (EP,EH,and EL).The results revealed that EP,EH,and EL treatments significantly reduced rice grain yields by 30.6%–36.2%,42.5%–46.5%,and 10.6%–14.3%,respectively.Shoot growth including shoot dry weight,leaf photosynthetic rate,zeatin (Z) and zeatin riboside (ZR) in grains,and activities of key enzymes involved in sucrose-to-starch conversion in grains and root traits,such as length density,root dry weight,total absorbing surface area,active absorption surface area,oxidation activity,and Z+ZR contents in roots were dramatically reduced during post-heading stages of rice when grown with the three kinds of barnyardgrass.Moreover,above-mentioned rice shoot growth indices were strongly and positively correlated with root traits.These results suggested the decrease in rice shoot growth and root traits during post-heading stages contributes to the reduction in the rice yield when it grows with barnyardgrass neighbors.
文摘Species of actinomycetes were collected andisolated from soil samples which were pickedfrom vegetable field,park land,and forest inHangzhou,Zhejiang Province.They were in-oculated in 250 ml flasks each containing 50 mlliquid medium and fermented on a rotary shak-er at 28℃.The agents for actinomycetes wereobtained seven days later.Four species of acti-nomycetes were selected through biological as-say.Experiments were conducted in the
文摘稗草是中国南方双季稻稻田的恶性杂草，对水稻生产造成严重威胁。为明确稗草对双季稻生长的影响及其经济危害允许水平，采用添加系列试验和模型拟合的方法研究了不同稗草密度下水稻生长与产量性状的变化规律。结果表明，在稗草的竞争干扰下，双季早、晚稻的株高、分蘖数、有效穗数、每穗实粒数、千粒重及产量均随稗草密度的增加而逐渐降低。指数模型 y ＝beax 可以较好地拟合稗草对早稻分蘖数、有效穗数和产量的影响，而二次曲线模型 y ＝ax 2＋bx＋c 拟合稗草与株高、每穗实粒数、千粒重和产量损失间的关系最佳；二次曲线模型 y ＝ax 2＋bx＋c 均可较好地拟合稗草与晚稻株高、分蘖数、有效穗数、每穗实粒数、千粒重、产量和产量损失间的关系。稻田使用化学除草剂（丁草胺、二氯喹啉酸、五氟磺草胺）防除时，双季早、晚稻稻田稗草的经济危害水平分别为1．64％～2．91％和1．28％～2．28％，经济阈值分别为0．63～1．23株／m^2和1．30～1．85株／m^2。稗草对水稻生长有抑制作用，并导致水稻产量损失；通过对经济阈值分析，化学除草剂防治稗草具有明显的经济优势。
