Jing ZHOP，Guiyuan MENG*，Chenzhong JlNGuohui MA，Jirui LONG

1.Science and TechnologY，Hunan UniversitY of Humanities，Loudi 417000，China；

2.Hunan Coordinated lnnovation Center，Loudi 417000，China；

3.China National HYbrid Rice R&D Center，Hunan HYbrid Rice Research Center，Changsha 410125，China

Effects of Nitrogen Rate on Blast Resistance and Grain Yield of SuPer Early Hybrid Rice Luliangyou 996

Jing ZHOP1，2，Guiyuan MENG1，2*，Chenzhong JlN1，2Guohui MA3，Jirui LONG3

1.Science and TechnologY，Hunan UniversitY of Humanities，Loudi 417000，China；

2.Hunan Coordinated lnnovation Center，Loudi 417000，China；

3.China National HYbrid Rice R&D Center，Hunan HYbrid Rice Research Center，Changsha 410125，China

Super earlY hYbrid rice LuliangYou 996 was the materials for this experiment.This paper focused on the influences of different nitrogen rates on blast resistance and grain Yield.Studies suggested that with the increase of nitrogen rate，there were no distinct changes in the sick grain rate and sickness index，but the fifth grade of panicle blast rate rose graduallY.When the nitrogen was too much（270 kg/hm2），the sick grain rate and sickness index were the highest.The Yield rose along with the addition of nitrogen if the amount of applied nitrogen was within the range of 0 to 180 kg/hm2，and the Yield would decrease with the addition of nitrogen if the amount of applied nitrogen was over 180 kg/hm2.Considering the sickness，output and economic benefit of rice，it is better to applied 90 to 135 kg/hm2of nitrogen for LuliangYou 996.

Super earlY hYbrid rice；LuliangYou 996；The amount of applied nitrogen；Blast resistance；Yield

D uring the rice production，farmers have no idea how much fertilizer should be applied，so that there are various kinds of problems，such as high use of fertilizer，irrational applYing period，disproportion of nitrogen，phosphorus and potassium［1］，leading to higher rate of useless tillering，declining group qualitY，serious rice collapsing，declining of particle weight，and decreasing of rice qualitY［2］.The over application of nitrogen decreases the rice blast resistance and restricts the further development of rice Yield［3］.The Site-specific nitrogen management can improve the rice qualitY and enhance the efficiencY of nitrogen［4-7］.While the Yield increas es，the nitrogen fertilizer use rate also rises significantlY，so is the resource use rate［8］.However，the super earlY hYbrid rice resistance under different nitrogen application conditions is not clear.This studY aims to explore the influences of different nitrogen application on the blast resistance and Yield of super hYbrid rice，to improve the nitrogen fertilizer managementtechniques and to provide theoretical references and technological support to the efficient cultivation of super earlY hYbrid rice.

Materials and Methods

Test materials

Super earlY hYbrid rice LuliangYou 996 was the materials for this experiment.The tested fertilizer was the efficient compound fertilizer provided bY StanleY Group （23-7-15）.The tested soil was the fluiroaquic sandY soil with moderate level of fertilizer.

Test design

The experiment was carried out in the demonstration base of the China National HYbrid Rice R&D Center. There were six treatments in this experiment:N1:no nitrogen，onlY phosphorus and potassium；N2:90 kg/hm2pure nitrogen；N3:135 kg/hm2purenitrogen；N4:180 kg/hm2pure nitrogen；N5:225 kg/hm2pure nitrogen；N6:270 kg/hm2pure nitrogen.lf the phosphorus and potassium in each treatment were not enough，we would applY 82.2 kg/hm2of P2O5and 176.3 kg/hm2of K20 （Table 1）together as base fertilizer.18 regions were divided randomlY for designing，and it repeated for three times.The test area was 30 m2，with 20 cm high and 30 cm wide.LuliangYou 996 was sowed on Narch 18 and transplanted on April 22. The strain distance was 20 cm ×20 cm.The cultivation management of each treatment was the same as that in high-Yield field.

Collection and determination of samPles

Survey of rice blast According to the investigation of rice blast in the next ten daYs of June in 2009，this paper studied the seriousness of rice blast.50 holes were surveYed in each region to record the total number of ears，sick ear number，and the number of sick ears.Grade standard includes: grade 1，little branch was stricken bY blast；grade 2，one third branches were sick；grade 3，the main spike neck was sick；grade 4，the spike neck was sick；grade 5，there was white head［9］.Rice blast rate（%）=The number of sick ears/Total number of ears× 100%.The sick ear rate of each grade（%）=The number of sick ears of each grade/Total number of ears×100%. The sickness index（%）=Σ（The number of sick ears of each grade×The representative value of each grade）/（Total number of ears×The representative value of the highest grade）× 100%.

SPecies and yield determination

We investigated the average number of effective ears in 50 holes in each region on the first and second daY before the harvest.Ten holes in each region were studied to measure the total particle number of each ear，the number of filled grains in each ear，the fertilitY rate，and the 1 000-grain weight. When harvesting，the particles in each region were processed separatelY.

Economic benefit We analYzed the grain output，Yield，labor cost，material cost，total cost，net production and profit of different treatments.

Table 1 The application of fertilizer in each treatmentkg/hm2

Table 2 lnfluences of applied nitrogen on the rice blast of LuliangYou 996

Results and Analyses

According to Table 2，with the addition of nitrogen，the sick ear rate of N5 was the lowest，38.22%.The 2nd，3rd，and 4thgrade sick ear rate of N5 also were the lowest.The 5thgrade sick ear rate increased along with the addition of nitrogen，and the 5thgrade of N6 was 14.74%，which was 4.63% higher than N1，and was substantiallY higher than other treatments.The sick rice rate above 4thgrade rose at first and then declined before rising again. The sick rice rate above 4thgrade in N1 and N2 treatment rose，while that of N2，N3，N4 and N5 treatment declined. The ones in N5 and N6 climbed again，and the sick rice rate above 4thgrade in N6 was the highest one，at 23.28%. lnfluences of nitrogen aPPlication on the occurrence of rice blast in Luliangyou 996 and the disease index

Table 2 suggested that with the addition of nitrogen，there was not anY distinct rules regarding sick earring rate.The disease occurrence of N6 treatment was the highest，64.9%，and the sick earring rate of N5 treatment was the lowest，38.22% ，which reached 1%extreme significant level among other treatments.The sickness index and sick earring rate showed similar rules，among which the N6 treatment was the highest，35.64%. The sickness index of N5 treatment was the lowest，25.67%，which was 1%extreme significant level along with other treatment.The N5 treatment and sickness index were low，which was suitable for rice production.

lnfluences of nitrogen on the yield of Luliangyou 996

According to Table 3，with the addition of nitrogen，the Yield tendencY at first increased before declining.From N1 treatment to N4 treatment，the nitrogen amount was proportional to the Yield，and the Yield in the N4 treatment was the highest，6.59 t/hm2.From N4 to N6 treatment，with the addition of nitrogen，the Yield decreased.The Yieldof each nitrogen treatment was obviouslY more than N1 treatment.Results suggest that among the five nitrogen amounts，the critical value of nitrogen was 180 kg/hm2in N4 treatment.Too much or too little nitrogen would lead to Yield reduction.

Judging from the Yield component，the N4 processed-effective earring was 2.595 million/hm2，which was insignificant different from the N3 and N5 treatments，but far lower than N2 and N6 treatments.The total number of particles on each earring and the number of filled particles processed bY N4 treatment were 117.4 and 89.8 respectivelY.The difference between the total number of particles on each ear and that of other nitrogen treatments were insignificant，while the number of filled particles on each Year was significantlY lower than N3 treatment，which was similar to that of other treatments. The percentage of filled particles of N1 treatment was the highest，87.5%，which was significantlY higher than other treatments，while the percentage of filled particles of N1 treatment was 76.7%，which was significantlY higher than N5 treatment.The 1000-particles weight in N4 process was insignificant to other treatments.Therefore，the fact that the N4 treatment was the highest，and was far higher than that of other treatment was the result of each Yield factor.

lnfluences of nitrogen aPPlication on the economic benefits of Luliangyou 996

ln terms of the economic benefits（Table 4），the net income of N2 treatmentwasthehighest，3687.0Yuan/hm2，followed bY N3 and N4 treatment，which accounted for 3 261.3 and 2 912.1 Yuan/hm2.This suggested that based on 90 kg/hm2of net nitrogen，increasing fertilizer input does not necessarilY result in more net income. Therefore，in terms of economic benefit，the 90 to 135 kg/hm2of N2 and N3 treatments were suitable.

Table 3 lnfluences of nitrogen application on the Yield of LuliangYou 996 and its component factors

Table 4 lnfluences of nitrogen use on the economic benefit of LuliangYou 996

Discussions

Qian BangYou et al.believed that the occurrence of sick blast was related to the application of fertilizer in the field，especiallY when there was too much nitrogen［10］.Lin XianYong et al. claimed that reducing the use of nitrogen can lower the soluble sugar content with the rice so that decreasing the nutritional source of pathological bacteria would weaken the spread of bacteria and enhance the paddY resistance to diseases［11］.Liu Lingling et al. also thought that too much use of nitrogen was responsible for rice blast［9］. ln this studY，with the addition of nitrogen，there was not anY distinct changing rules in sick ear rate of LuliangYou 996 and the sickness index.However，with the gradual increase of the fifth grade of sick ear rate，when there was too much nitrogen （270 kg/hm2），the sick ear percentage and sickness index were the highest one.

Zhang Wenxiang et al.believed that the reasonable application of nitrogen can enhance the biomass of rice，and increase the number of ears，the number of particles，the 1 000 particles weight.The Yield increased along with the rise in nitrogen when the applied nitrogen was within a certain range，and if the amount was too much，the Yield would decrease［12］.ln this experiment，the Yield rose along with the addition of nitrogen if the amount of applied nitrogen was within the range of 0 to 180 kg/hm2，and the Yield would decrease with the addition of nitrogen if the amount of applied nitrogen was over 180 kg/hm2.Considering the sickness，output and economic benefit of rice，it is better to applied 90 to 135 kg/hm2of nitrogen for LuliangY-ou 996.

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ResPonsible editor：Nana FAN

ResPonsible Proofreader：Xiaoyan WP

施氮量對超級雜交早稻陸兩優(yōu)996產(chǎn)量和抗瘟性的影響

周靜1，2，孟桂元1，2*，金晨鐘1，2，馬國輝3，龍繼銳3
（1.湖南人文科技學院農(nóng)業(yè)與生物技術(shù)學院，湖南婁底417000；2.湖南省協(xié)同創(chuàng)新中心，湖南婁底417000；3.國家雜交水稻工程技術(shù)研究中心，湖南長沙 410125）

以超級雜交早稻陸兩優(yōu)996為材料，研究不同施氮量對其稻瘟病抗性和產(chǎn)量的影響。結(jié)果表明：隨著施N量的增加，病穗率和病情指數(shù)并無明顯的變化規(guī)律，但5級瘟穗率逐漸升高，當施N量過大時（270 kg/hm2）病穗率和病情指數(shù)都最高；施N量在0～180 kg/hm2范圍內(nèi)產(chǎn)量隨著施氮量的增加而增加，施N量超過180 kg/hm2后產(chǎn)量隨著施氮量的增加反而下降；綜合考慮稻穗病發(fā)病情況、產(chǎn)量和經(jīng)濟效益，陸兩優(yōu)996以施N量90～135 kg/hm2為好。

級雜交早稻；陸兩優(yōu)996；施氮量；稻瘟病抗性；產(chǎn)量

婁底市科技計劃項目（2014-1）；“農(nóng)藥無害化應用”湖南省高校重點實驗室；“農(nóng)藥學”湖南省“十二五”重點建設學科。

周靜（1983－），女，湖北武漢人，講師，在讀博士生，從事水稻栽培方面的研究，E-mail：kiki010206@163．com。*通訊作者，E-mail：meng-guiyuan@126.com。

2015-07-05

Supported bY the Scientific and Technological Program in Loudi（2014-1）；KeY Lab of Hunan Universities；KeY subjects of the Twelfth-five Year Plan in Hunan.

*Corresponding author.E-mail:meng-guiYuan@126.com

Received:JulY 5，2015 Accepted:September 7，2015

修回日期 2015-09-07