Effect of Corona Treatment and Dielectric Separation on Seed Vigor of Hybrid Rice

[Objectives] The aim was to investigate the effects of corona field and dielectric separation on the seed vigor of hybrid rice. [Methods] The seeds of6 hybrid rice varieties were processed with corona field,dielectric separation and corona field + dielectric separation. [Results] When the field intensity was200 km/m and the processing time was 4 min,the seed vigor was significantly increased. The seed vigor of Y Liangyou 9918( 2014) increased the most,and the germination potential and the germination rate increased by 17 and 12 percentage points respectively compared to the control. Corona field reduced seed conductivity,and for seedlings,it decreased their MDA content,increased proline content,improved peroxidase activity,and enhanced root activity. When the rotating speed of the drum was 30 r/min,the dielectric separation voltage of 4 500 V could achieve good separation effect,and the vitality of seeds at different grades was significantly different. Under the optimized corona field combined with optimized voltage processing of dielectric separation,the seed vigor at all grades from the separation was significantly higher than that of the dielectric separation processing alone. The combined separation processing separated no seeds with germination rate of higher than 80% from the hybrid rice seeds with germination rate of lower than 60%,yet it could effectively separate the seeds with germination rate of higher than 80%from the hybrid rice seeds with germination rate of 65%-70%. After the combined processing,the germination rates of separated Grade I seeds of Wangliangyou6( 2015),N Liangyouhuazhan( 2015),Wangliangyou 6( 2016) increased by 20,15,20 percentage points from the germination rates of the control,while the germination rates of N Liangyouhuazhan( 2016) and Y Liangyou 9918( 2016),which had the germination rates of higher than 80%,increased by 3 and 9 percentage points from the control,suggesting insignificant separation effect. [Conclusions] This study provided a new technical approach for the processing of hybrid rice seeds.

Effect of wind field below unmanned helicopter on droplet deposition distribution of aerial spraying

Wind field is one of the important factors affecting the distribution characteristics of aerial spraying droplet deposition.In order to reveal the impact mechanism of droplet deposition distribution by the wind field below agricultural unmanned helicopter rotor,in this study,the wind field distribution below uniaxial single-rotor electric unmanned helicopter rotor was measured by using a wireless wind speed sensor network measurement system for unmanned helicopter.The effects of wind field in three directions(X,Y,Z)below the rotor on droplet deposition distribution were analyzed with the condition of aerial spraying droplet deposition in rice canopy,and the regression model was established via variance and regression analyses of experiment results.The results showed that,the wind field in Y direction had a significant effect on droplet deposition in effective spray area,the wind field in Z direction had an extremely significant effect on droplet deposition in effective spray area,and the corresponding significance(sig.)values were 0.011 and 0.000.Furthermore,the wind field in Z direction had a significant effect on the penetrability and uniformity of droplet deposition in effective spray area,the corresponding sig.values were 0.025 and 0.011 respectively.The wind speed in Y direction at the edge of effective spray area had a significant effect on droplet drift,the sig.value was 0.021.In addition,the correlation coefficient R of the regression model was 0.869 between droplet deposition in effective spray area and the wind speed in Y and Z directions,and 0.915 between the uniformity of droplet deposition in effective spray area and the maximum wind speed in Z direction.The result revealed the influencing mechanism of the wind field below the rotor of uniaxial single-rotor electric unmanned helicopter on the distribution of aerial spraying droplet deposition.The results can provide guidance for the actual production application of aerial spraying to reduce liquid drift and improve the utilization rate of pesticide.