Effects Of Different Sowing Rate And Transplanting Depth On Root Characteristics And Its Relationship With Above Ground Growth And Yield In Rice

In order to reveal the relationship between root growth and yield of super hybrid indica rice with different sowing and transplanting depth,field experiments were conducted using Zhunliangyou 527 as material in 2015 and 2016 in Suiyang County,Guizhou Province.Treatments were arranged in split-plot design with sowing quantity(B)as main plots and planting depth(S)as subplots.B1(40 g dry grain/tray),B2(60 g dry grain/tray),B3(80 g dry grain/tray),formed the main plot and S1(shallow planting),S2(middle planted),S3(deep planting)formed the three subplots.A bowl shaped blanket shaped seedling tray was used for seeding in the middle of April.In this study,yield and yield formation of mechanical transplanting rice,leaf area index,dry matter accumulation,photosynthesis potential,net assimilation rate and leaf area ratio,crop growth rate and root related traits including the ratio of crown to root,root activity,total absorption area and active absorption area,surface area,total root length,root length density,root diameter,root length,root number,root and branch number were analyzed.The main results are listed below:1.The effects of different sowing rate and transplanting depth on the yield and yield formation of machine transplanted rice The actual yield of different sowing rate was 8536.8 kg/ha.With the increasing of sowing rate,the yield decreased firstly and then increased.The number of effective panicles decreased with the increasing of sowing rate in the mature stage,which showed that the B3(80 g dry grain/tray)>B1(40 g dry grain/tray)>B2(60 g dry grain/tray)and it were significantly different among them.The number of grains decreased with the increasing of seeding rate,that is,B1>B2>B3.The seed setting rate decreased firstly and then increased with the increasing of seeding rate,that is,B1>B3>B2.The 1000 grain weight was decreased with the increasing of sowing and planting depth,that is B1>B2>B3.The highest yield of different planting depth was 8563.4 kg/ha,but the yield decreased with the increasing of depth.The number of effective panicles decreased gradually with the increasing of random insertion depth.Performance as S1(shallow planting),S2(middle planted),S3(deep planting),and there were significant differences.The total number of grains per panicle increased gradually with the increasing of random insertion depth,that is,S1<S2<S3.The seed setting rate decreased with the increasing of depth,which was S1>S2>S3.The 1000 grain weight decreased with the increasing of planting depth,S1>S2>S3.2.The effect of different sowing and transplanting depth on leaf area index The leaf area index of jointing stage and heading stage increased gradually with the increasing of sowing rate,which was B1>B2>B3 and there were significantlydifferent at the heading stage.At booting stage,with the increasing of sowing rate,it increased firstly and then decreased,and the performance was B2>B1>B3,and the leaf area index of B2 was significantly higher than that of B3 treatment,and there was no significant difference between B1 and B2 treatment.The depth of processing machine under different interpolation,leaf area index were decreased with increasing depth,first increased after S2>S1>S3,in addition to the 2016 jointing stage were significantly different.3.The effect of different sowing amount and transplanting depth on dry matter accumulation of mechanical transplanting riceFrom jointing to heading stage,dry matter accumulation decreased gradually with the sowing quantity increased,the performance was B1>B2>B3,the treatment of B1 were significantly higher than that of B3;during the mature period,dry matter accumulation firstly decreased and then increased with the increasing of sowing quantity: B1>B3>B2,which was reaching the level of significant difference.With the increasing of depth,the biological accumulation of jointing stage to maturity stage decreased with the increasing of depth,and the performance of S1>S2>S3 was not significant.4.The effects of different sowing and transplanting depth on the photosynthetic potential,leaf area ratio,net assimilation rate and crop growth rate The photosynthetic potential gradually increased with the increasing of sowing rate,and first increased and then decreased with the increasing of depth,respectively.The ranking were as follows: B3>B2>B1,S2>S1>S3,which have reached the level of significant difference.Leaf area ratio decreased with the increasing of sowing quantity.The net assimilation rate increased first and then decreased with increasing sowing rate,in the middle of sowing amount reached the maximum value,namely B2>B1>B3;crop growth rate increased with the sowing quantity decreased,the performance were B1>B2>B3,seeding rates did not reach the significant level of 5%.With the increasing of depth,the photosynthetic potential increased first and then decreased,and reached the maximum value at the middle depth,which was S2>S1>S3.The net assimilation rate decreased gradually with the increase of depth,that is,S1>S2>S3,and the average net assimilation rate of S1 treatment was significantly higher than that of S2 and S3 24.75% and 33.57%,and there was no significant difference between S2 and S3 treatments.The increasing depth of crop growth rate showed a decreasing trend,which was S1>S2>S3,and there was significant difference in depth treatment.5.The correlation and simulation model of rice root characteristics and yield(1)correlation between root characteristics and yield of rice There was a significant positive correlation between yield and root activity at jointing stage,and the correlation coefficient was 0.4832.At booting stage,single plant root dry weight and root number and panicle number showed significant or significant negative correlation,while the ratio of crown to root and the specific surface area showed significant or significant negative correlation;It was showed significant or significant negative correlation at booting stage,root vigor and grain weight;booting crown root ratio and dry matteraccumulation the amount of significant or significant negative correlation at booting stage;active absorption area and leaf area index had a significant positive correlation.Heading total root length and root number were positively correlated with panicle number,active absorption area and single plant root volume and leaf area,which showed a significant positive correlation.(2)simulation model of rice root characteristics and yield The root activity,total absorption area,active absorption area and yield of jointing stage were constructed by multiple nonlinear regression equation,and the fitting degree of regression equation was 0.5469.The regression equation fitting of total root length,root diameter,root tip number and yield at jointing stage reached0.6873,and the model reached a significant level.From jointing to heading,crown root ratio,single plant root dry weight,root volume and yield regression equation model were not significant different,the fitting degree was 0.2841,0.3473,0.2046.Heading root branch number,surface area,root length and yield regression model reached significant level,fitting is 0.4309.