节能环保、无破碎的热泵水稻种子干燥工艺

热源和种子的破碎率是影响水稻种子加工企业加工成本的两大重要指标。近年来,因环保要求燃煤设备大部分被禁用,寻找新的供热方式和降低破碎率已成为种子加工行业的两大难题。酒泉奥凯种子机械股份有限公司研究的节能环保、无破碎的热泵水稻种子干燥工艺,很好地解决了这两大难题,并提出了一些改进意见。

Effects of pre-harvest chemical application on rice desiccation and seed quality

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.

Drying temperature affects rice seed vigor via gibberellin,abscisic acid,and antioxidant enzyme metabolism

Seed vigor is a key factor affecti ng seed quality.The mechanical drying process exerts a sign ificant in fluence on rice seed vigor.The initial moisture con tent(IMC)and drying temperature are considered the main factors affecting rice seed vigor through mechanical drying.This study aimed to determine the optimum drying temperature for rice seeds according to the IMC,and elucidate the mechanisms mediating the effects of drying temperature and IMC on seed vigor.Rice seeds with three different IMCs(20%,25%,and 30%)were dried to the target moisture content(14%)at four different drying temperatures.The results showed that the drying temperature and IMC had significant effects on the drying performance and vigor of the rice seeds.The upper limits of drying temperature for rice seeds with 20%,25%,and 30%IMCs were 45,42,and 38°C,respectively.The drying rate and seed temperature increased sign ificantly with in creasing drying temperature.The drying temperature,drying rate,and seed temperature showed extremely significant negative correlations with germination energy(GE),germination rate,germination index(Gl),and vigor index(VI).A high IMC and drying temperature probably induced a massive accumulation of hydrogen peroxide(H2O2)and superoxide anions in the seeds,enhanced superoxide dismutase(SOD)and catalase(CAT)activity,and increased the abscisic acid(ABA)content.In the early stage of seed germination,the IMC and drying temperature regulated seed germination through the metabolism of H2O2,gibberellin acid(GA),ABA,and a-amylase.These results indicate that the metabolism of reactive oxygen species(ROS),antioxidant enzymes,GA,ABA,and a-amylase might be involved in the mediation of the effects of drying temperature on seed vigor.The results of this study provide a theoretical basis and technical guidance for the mechanical drying of rice seeds.