Pre-harvest desiccation may increase the efficiency of seed production. Field studies were conducted to determine the effects of diquat, paraquat, and ethephon applications on grain moisture, grain weight, and seed ge...Pre-harvest desiccation may increase the efficiency of seed production. Field studies were conducted to determine the effects of diquat, paraquat, and ethephon applications on grain moisture, grain weight, and seed ger- mination of hybrid rice Yanliangyou 88 （Oryza sativa ssp. indica） and conventional rice Wuyunjing 7 （Oryza sativa ssp. japonica）. In 2013, we tested 12 treatments applied at four weeks （Yanliangyou 88） and six weeks （Wuyunjing 7） after heading. Results showed that reductions in moisture content were significant two and four days after chemical ap- plication. Chemical applications had no adverse effects on lO00-grain weight, germination percentage, or germination index, but there were negative effects on the percentage of normal seedlings. Desiccation effects increased with increase in the period after application, while the effect of ethephon combined with diquat or paraquat on desiccation was limited compared with that of diquat or paraquat alone in a short period after application. In 2013, chemical ap- plications reduced the moisture content by from 0.5% to 6.4%, the germination percentage by from 0% to 3.3%, and the percentage of normal seedlings by from 13.3% to 100.0%. Among the treatments, diquat applied at 120 g/ha resulted in effective desiccation with fewer negative effects on grain weight and seed germination in 2013 and 2014. Therefore, diquat may have potential as a pre-harvest chemical desiccation treatment for rice. These results may provide a basis for developing and implementing protocols for large scale field trials.展开更多
Water relation parameters of bare-root seedlings of Chinese fir (Cunninghamia lanceolata Hook.) and Masson pine (Pinus massoniana Lamb.) were measured and changes of root growth potential as well as field survival rat...Water relation parameters of bare-root seedlings of Chinese fir (Cunninghamia lanceolata Hook.) and Masson pine (Pinus massoniana Lamb.) were measured and changes of root growth potential as well as field survival rate of both species were studied after the bare-root seedlings were exposed in a sunny field condition. The results showed that Masson pine had a lower osmotic potential (-2.07Mpa) at turgor loss point and at full turgor (-1.29Mpa), compared with Chinese fir (-1.80Mpa and -1.08Mpa respectively). The parameter Vp/V0 (63.27%) of Masson pine was higher than that of Chinese fir (58.03%). This means that Masson pine has a stronger ability to tolerate desiccation, compared to Chinese fir according to analysis of above water relation parameters. Root growth potential and field survival rate decreased with prolonging duration of exposure. The field survival rate of both species was reduced to less than 40% after the seedling being exposed only two hours. Water poten-tials of 1.60 Mpa and -1.70 Mpa were suggested to be critical values for Chinese fir and Masson pine respectively in successful reforestation.展开更多
基金supported by the Special Fund for Agro-scientific Research in the Public Interest(No.201203052)the Fundamental Research Funds for the Central Universities(Nos.KYZ201402 and KYZ201202-9)the National Natural Science Foundation of China(No.31271806)
文摘Pre-harvest desiccation may increase the efficiency of seed production. Field studies were conducted to determine the effects of diquat, paraquat, and ethephon applications on grain moisture, grain weight, and seed ger- mination of hybrid rice Yanliangyou 88 （Oryza sativa ssp. indica） and conventional rice Wuyunjing 7 （Oryza sativa ssp. japonica）. In 2013, we tested 12 treatments applied at four weeks （Yanliangyou 88） and six weeks （Wuyunjing 7） after heading. Results showed that reductions in moisture content were significant two and four days after chemical ap- plication. Chemical applications had no adverse effects on lO00-grain weight, germination percentage, or germination index, but there were negative effects on the percentage of normal seedlings. Desiccation effects increased with increase in the period after application, while the effect of ethephon combined with diquat or paraquat on desiccation was limited compared with that of diquat or paraquat alone in a short period after application. In 2013, chemical ap- plications reduced the moisture content by from 0.5% to 6.4%, the germination percentage by from 0% to 3.3%, and the percentage of normal seedlings by from 13.3% to 100.0%. Among the treatments, diquat applied at 120 g/ha resulted in effective desiccation with fewer negative effects on grain weight and seed germination in 2013 and 2014. Therefore, diquat may have potential as a pre-harvest chemical desiccation treatment for rice. These results may provide a basis for developing and implementing protocols for large scale field trials.
基金This research was supported by the Sciences Research Foundation of Nanjing Forestry University.
文摘Water relation parameters of bare-root seedlings of Chinese fir (Cunninghamia lanceolata Hook.) and Masson pine (Pinus massoniana Lamb.) were measured and changes of root growth potential as well as field survival rate of both species were studied after the bare-root seedlings were exposed in a sunny field condition. The results showed that Masson pine had a lower osmotic potential (-2.07Mpa) at turgor loss point and at full turgor (-1.29Mpa), compared with Chinese fir (-1.80Mpa and -1.08Mpa respectively). The parameter Vp/V0 (63.27%) of Masson pine was higher than that of Chinese fir (58.03%). This means that Masson pine has a stronger ability to tolerate desiccation, compared to Chinese fir according to analysis of above water relation parameters. Root growth potential and field survival rate decreased with prolonging duration of exposure. The field survival rate of both species was reduced to less than 40% after the seedling being exposed only two hours. Water poten-tials of 1.60 Mpa and -1.70 Mpa were suggested to be critical values for Chinese fir and Masson pine respectively in successful reforestation.
