中文摘要：

借助高速摄影观察发现,水稻气力式精量穴播排种器吸种盘上吸孔所吸附的种子会由于吸力不足,在离心力作用下,在到达投种区前从吸孔附近落下,从而产生＂飞种＂现象,进而对排种器排出的每穴种子数量以及成穴性产生影响,降低排种精度。为此,设计了一种挡种装置,以含水率为21.1%的培杂泰丰种子为对象,采用多因素试验的方法,研究了不同吸室负压和不同排种盘转速下,安装挡种装置前后对＂飞种＂现象的影响;采用单因素试验的方法,研究了安装挡种装置后不同吸室负压下,不同排种盘转速对排种器吸种精度的影响。结果表明,安装挡种装置后,＂飞种＂出现范围减小,＂飞种＂出现的数量减少,排种器排种精度与成穴性能提高;当转速在25～40 r/min,吸室负压1.6 k Pa时,（1-3）粒/穴概率在93%～97%之间变化。试验结果显示安装挡种装置后能控制＂飞种＂的跌落范围,并使部分＂飞种＂落回充种室内,从而提高排种器排种精度。

英文摘要：

The seeds often suck on the sucking hole when the sucking plate rotates. The area between the sucked seeds and sucking hole is smaller than the area between the normal sucked seeds and sucking hole, which leaded to a shortage of suction. As the suction is less than a sum of external forces, sucked seeds will be separated from the seed sucking hole and do a parabolic movement with a particular velocity. This phenomenon is called ＂early dropping seeds＂. To avoid this and increase the stability of seed sowing and the performance of hill formation of rice pneumatic metering device, a shield device was designed. Shield device was fixed on seed chamber shell through bolted connections. It was able to stop the seeds flying to the second half of sucking process after the parabolic movement drove by ＂early dropping seeds＂. Indic hybrid peizataifeng was taken as research subjects, of which the water content was 21.1%. ＂Early dropping seeds＂ phenomenon was observed by means of high-speed photography technology, which enabled moving process of sucked seed to be clearly photographed. The probability of ＂early dropping seeds＂ was studied by using multi-factor experiment under different negative pressures for seeds sucked, rotation rates and shield device. Precision of seed metering was also counted, as shield devices were installed on the metering device. The experimental results showed the ＂early dropping seeds＂ phenomenon and precision of seed metering were improved with a shield device. The optimized condition was that the sucking plate rotation speeds of 25 -40 r/min and the negative pressure for seeds sucked of 1.6 kPa. The probability of 1 -3 seeds was 93% -97%. In the experiment, a shield device on the metering device could control the ＂early dropping seeds＂, and improve the stability of seed sowing and the performance of hill formation.