Researches On The Root Quality And Nitrogen Regulation Of Continuous Yield Increase Of Super Hybrid Rice

Since China started to implement China super rice breeding program since 1996,after more than 20 years of efforts,the super hybrid rice yield has made a breakthrough,leading the development direction of China's "four" super rice,that is,from the first period of 10.5 t/hm~2 to the four period of 15 t/hm~2.In order to clarify the quality characteristics of the roots of the super-hybrid rice,this experiment was conducted in 2015-2016 at the rice test base of Henan agricultural University,Erlang Village,Ganan Office,Pingqiao district,xinyang city.This study selected varieties of the target yields of the super hybrid rice: Liangyoupeijiu,Y Liangyou 1,Y Liangyou 2 and Y Liangyou 900 as materials,study the source of quality difference,the response of Super Hybrid Rice with different nitrogen gradient of different yield potential of nitrogen fertilizer the relationship,and the root quality and quantity of nitrogen between,provide a theoretical basis for large area balanced high yield cultivation and super rice breeding practice.The results are as follows: 1.With the potential yield increase,four super hybrid rice yield increased,the overall Y Liangyou 2,Y Liangyou 900 reached the maximum value(heading in 2015 due to high temperature leads to low seed setting rate leading to Y Liangyou 900 yield did not reach the expected level),The 1000-grain weight showed a decreasing trend,and the number of grains per spike showed a gradually increasing trend.With the increase of nitrogen application rate,the maximum yield was concentrated in N210 and N300,the number of effective panicles increased gradually,the number of panicles increased first and then decreased,while the seed setting rate gradually decreased.2.The total root dry weight of 0-15 cm in the jointing stage,middle grain filling stage and maturity stage of the four-stage hybrid rice decreased firstly and then increased with the increase of yield potential.The dry weight of roots was the highest in Liangyoupeijiu,followed by Y Liangyou 900;The 15-30 cm root dry weight at the heading stage,the mid-filling stage and the mature stage showed a gradually increasing trend with the yield potential;the root-shoot ratio at the tillering stage,the heading stage increased gradually as the yield potential increased.In the high trend,the root-shoot ratio during the middle and mature stages of grain filling is gradually decreasing.With the increase of yield potential,the 15-30 cm,30-45 cm root length,root surface area and root volume in the heading period were gradually increased.With the increase of nitrogen application rate,root dry weight,number of roots,root length,root surface area and root volume showed a trend of increasing first and then decreasing at the middle and late fertility,and reached maximum at N210 and N300.With the development of the growth period,the root dry weight and root number showed a trend of increasing first and then decreasing.The heading reached the maximum,and the root-shoot ratio gradually decreased.The root length was 0-15 cm in the middle to mature filling period.The surface area of the roots gradually decreased,and the root length,root surface area and root volume of 15-30 cm and 30-45 cm were gradually increased.3.The intensity of single plant and single-stem injury in jointing stage,heading stage,mid-filling stage and ripening stage of the four-stage super hybrid rice increased with the yield potential,and it gradually increased with Y Liangyou 2 and Y Liangyou 900 is the largest.With the increase of yield potential,the SOD content gradually increased during the middle period of grain filling;the POD content showed the trend of increasing first and then decreasing at the middle stage of grain filling.The Y Liangyou 2 reached its maximum value and gradually increased during the mature period.The trend of change was that the MDA content in the middle of filling stage gradually decreased.With the increase of nitrogen application rate,the single plant and single-stem intensity showed that no nitrogen or low nitrogen was higher than medium-high nitrogen treatment.SOD and POD showed an overall trend of first increase and then decrease after the middle and late fertility,and the overall trend was N210,N300 maximum.4.There was a significant positive correlation between 0-15 cm root dry weight,15-30 cm root dry weight,number of roots,intensity of single inflorescence and yield in heading period,and the root-shoot ratio was significantly negative in the middle period,mature period and grain yield during grain filling.Correlation;Heading stage 15-30 cm,30-45 cm root length,root surface area,root volume and grains per spike,yield showed significant or extremely significant positive correlation,root length,root surface area,root volume and yield of each layer in the middle of grain filling Significantly or extremely significantly positively correlated,the quality of roots at 30-45 cm in mature stage was significantly or extremely significantly positively correlated with seed setting rate and yield.Injury intensity and seed setting rate were significantly positively correlated.There was a significant positive correlation between POD content and yield at late growth stage.The MDA content at heading stage was significantly negatively correlated with yield.In summary,the improvement of the yield potential of super hybrid rice is the basis for the physiological quality of roots at the heading and flowering stages,and the increase of root mass at 15-30 cm and 30-45 cm in the later growth stage.The increase in the intensity of the wounds from heading to maturing stage and the 30-45 cm root mass in heading,play an important role in the improvement of the seed setting rate in the later period.Under the experimental conditions,the yield and root quality could be improved by applying nitrogen amount between 210 kg/hm~2 and 300 kg/hm~2.