Mingliang DING,Qiuhong PU,Chunqiong GAO,Pingrong YUAN,Zhenxi SU*

1.Institute of Food Crops,Yunnan Academy of Agricultural Sciences,Kunming 650205,China;

2.Xuanwei Middle School,Xuanwei 655400,China;3.Xuanwei Municipal Bureau of Agriculture,Xuanwei 655400,China

Principal Component Analysis on Traits Related to Lodging Resistance of Plateau Japonica Rice

Mingliang DING1,Qiuhong PU2,Chunqiong GAO3,Pingrong YUAN1,Zhenxi SU1*

1.Institute of Food Crops,Yunnan Academy of Agricultural Sciences,Kunming 650205,China;

2.Xuanwei Middle School,Xuanwei 655400,China;3.Xuanwei Municipal Bureau of Agriculture,Xuanwei 655400,China

[Objective]This study was conducted to investigate the main factors affecting the lodging resistance of plateau japonica rice.[Method]Twenty agronomic traits related to lodging resistance of plateau japonica rice were analyzed by principal component analysis and correlation analysis among 26 varieties/lines of plateau japonica rice.[Result]The lodging resistance of the 26 varieties/lines had great difference among different agronomic traits.Plant height,and wall thickness of the 4th, 3rdand 2ndinternodes under the panicle had the most important influence on lodging resistance,while the diameter of the 3rd,2nd,4th,1stnodes under the panicle,length of the 4thand 3rdinternodes under the panicle,wall thickness of the 1stinternode under the panicle had less influence.The other nine agronomic traits of rice culm did not affect or indirectly affected lodging resistance through above-mentioned agronomic traits.Lodging resistance had significant correlations with plant height,length of the 4thand 3rdinternodes under the panicle,wall thickness of the 1st,2nd,3rdand 4thinternodes under the panicle and diameter of the 1st,2nd,3rdand 4thnode sunder the panicle,had insignificant correlations with panicle length,panicle weight,length of the 1stand 2ndinternodes under the panicle,diameter of the 1st,2nd,3rdand 4thinternodes under the panicle,diameter of the 5thnode under the panicle.[Conclusion]More attention should be paid to the main factors affecting lodging resistance in breeding to improve lodging resistance of plateau japonica rice.

Plateau japonica rice;Lodging resistance;Agronomic traits;Principal component analysis

R ice is widely planted on 1 million hectares in Yunnan Province,in which plateau japonica rice occupies half of the area. Lodging,one of the most important factors affecting the production of japonica rice,not only decreases rice yield and quality,but also bring difficulties to rice harvest.Rice lodging is a complex quantitative trait,which has certain relation with the internal factors of rice such as plant height,culm trait and biological yield,but also is affected by extrinsic factors like cultivation and management measures and climate[1-4].Lodging resistance of plateau japonica rice has been rarely reported so far.Ding et al.[5]believed that rice lodging resistance had insignificant correlation with panicle length,panicle weight and internode diameter,but significant or extremely significant correlations with plant height,length of internodes under the panicle,wall thickness of internodes under the panicle and diameter of internodes under the panicle.However,the effects or contributions of these factors on lodging resistance of rice remain elusive.Therefore,plant height,panicle weight,panicle length,internode length,internode wall thickness,internode diameter and node diameter all of which were related to lodging resistance of commonly planted plateau japonica rice varieties were measured to conduct correlation analysis and principal component analysis,with an

Materials and Methods

Materials

Fifteen commonly planted rice varieties and 11 newly bred lines by Institute of Food Crops,Yunnan Academy of Agricultural Sciences were selected as the experimental materials,as shown in Table 1.

The field trials were carried out at Yiliang County(103.14°E,24.92°N at an elevation of 1 500 m)and Songming County(102.81°E,25.22°N at an elevation of 1 900 m)of Kunming City,China in 2010.According to their adaptability,Yunjing 32,Yunjing 31, Yinguang,H150,H149,H148,08-3, and 09-1 were grown at Songming and the other varieties/lines at Yiliang. Bean was planted before them in both bases.Rice seeds were sown in March 2010 under plastic films.Then, 45-day-old seedlings were transplanted into filed in May,spacing(27+15) cm×12.9 cm,with 20 rows for each rice variety/line.Fertilizers and water were supplied timely and appropriately.Soils in both bases were sampled on April 30,2010,and sent to the Institute of Agricultural Environment and Resources,Yunnan Academy of Agricultural Sciences for chemical analysis and test.The results revealed that soil sample collected from Yiliang County maintained a pH at 7.45,and contained 3.04%organic matter,86.15 mg/kg available nitrogen(N),9.37 mg/kg available phosphorus(P),and 117.30 mg/kg available potassium(K); the soil sample from Songming County had a pH at 6.94,and contained 4.55%organic matter,132.17 mg/kg available nitrogen(N),10.71 mg/kg available phosphorus(P)and 67.38 mg/kg available potassium(K).According to the soil properties,246.0 kg/hm2pure N was applied in both bases,65%as base and tillering fertilizer,and 35%as panicle fertilizer (base fertilizer∶tillering fertilizer=6∶4, first fertilization∶second fertilization at panicle stage=6∶4).Moreover,the base fertilizer also contained 127.5 kg/hm2pure P,102 kg/hm2pure K and 30 kg/hm2pure Zn.

Methods

Test on rice lodging resistance

The lodging resistance of rice was measured at maturity(95%spikelets at waxen maturity).The lodging of rice is divided into four levels.In detail,level 1 was defined as rice stems were straight or mostly straight;level 2 was defined as rice stems leaned at an angle less than 45°;level 3 was defined as rice stems leaned at an angle more than 45°;level 4 was defined as rice stems completely leaned down to the ground.In this study,rice varieties of level 1 and level 2 were considered as lodging resistant,and those of level 3 and level 4 as lodging.

Determination of agronomic traits

At maturity,nine seedlings at three sites for each variety/line were collected with roots,leaf sheathes, leaves and panicle.Then,plant height,panicle length,panicle weight, the length,wall thickness,diameter of the 1st,2nd,3rd,4thinternodes under the panicle,and the diameter of the 1st,2nd,3rd,4th,5thnodes under the panicle were measured.Among them, plant height,panicle length,internode length were measured with a ruler (accurate to 0.1 cm);panicle weight was measured with an electronic balance(accurate to 0.01g);the wall thickness of internodes and the diameter of internodes and nodes were measured with a vernier caliper (accurate to 0.002 cm).The averages of nine seedlings of each variety/line were finally calculated.

Data analysis

SPSS 17.0 software was employed for correlation analysis and principal component analysis.

Results and Analysis

Lodging resistance of these plateauJaponicarice varieties/lines

As shown in Table 1,among the 26 plateau japonica rice varieties/lines 15 exhibited better resistance to lodging.The traits related to lodging resistance showed abundant variation among these varieties/lines,among which the length of the 4thinternode under the panicle had the largest variation coefficient(29.2%),while plant height and the diameter of the 4thnode under the panicle had the smallest (7.3%).The variation coefficients of other traits were also significantly different.The 20 lodging related traits were listed according to their variation coefficients from large to small as length of the 4thinternode under the panicle＞panicle weight＞wall thickness of the 4thinternode under the panicle＞length of the 3rd internode under the panicle＞wall thickness of the 1stinternode under the panicle＞wall thickness of the 2ndinternode under the panicle＞wall thickness of the 3rdinternode under the panicle＞diameter of the 1stinternode under the panicle＞diameter of the 1stnode under the panicle＞diameter of the 5thnode under the panicle＞length of the 1stinternode under the panicle＞diameter of the 4thinternode under the panicle＞length of the 2ndinternode under the panicle＞diameter of the 3rdnode under the panicle＞diameter of the 2ndnode under the panicle＞panicle length＞diameter of the 2ndnode under the panicle＞diameter of the 3rdinternode under the panicle＞plant height=diameter of the 4thnode under the panicle.

The larger variation coefficients for length of the 4thinternode under the panicle,panicle weight,wall thickness of the 4thinternode under the panicle and length of the 3rdinternode under the panicle suggested that improving these traits through appropriate breeding and cultivation measures could greatly improve the lodging resistance of plateau japonica rice varieties.The large variation coefficients for wall thickness of the 1st,2nd,3rdinternodes under the panicle and diameter of the 1stinternode under the panicle indicated that improving these traits through appropriate breeding and cultivation measures could improve the lodging resistance of plateau japonica rice varieties to some extent. The small variation coefficients and difference for plant height and diameter of the 4thnode under the panicle among the rice varieties/lines indicated that the lodging resistance of plateau japonica rice varieties could not be improved through improving these traits.

Correlation between lodging resistance and agronomic traits of these plateaujaponicarice varieties/lines

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Correlation analysis showed thatamong the 20 traits measured,11 had significant or extremely significant correlations with lodging resistance. Among the 11 traits,plant height, length of the 3rdand 4thinternodes under the panicle was negatively correlated with lodging resistance,while wall thickness of the 1st,2nd,3rdand 4thinternodes under the panicle,diameter of the 1st,2nd,3rdand 4thnodes under the panicle was positively correlated with lodging resistance.Panicle length, panicle weight,length of the 1stand 2ndinternodes under the panicle,diameter of the 1st,2nd,3rdand 4thinternodes under the panicle,diameter of the 5thnode under the panicle showed no significant correlations with lodging resistance in these plateau japonica rice varieties/lines.In addition,there were complicated correlations among these culm traits,as shown in Table 2.In summary,plant height,length of the 3rdand 4thinternodes under the panicle, wall thickness of the 1st,2nd,3rdand 4thinternodes under the panicle,diameter of the 1st,2nd,3rdand 4thnodes under the panicle had greater influence on lodging resistance of plateau japonica rice.So,appropriately reducing plant height,length of the 3rdand 4thinternodes under the panicle,increasing wall thickness of the 1st,2nd,3rdand 4thinternodes under the panicle,diameter of the 1st,2nd,3rdand 4thnodes through breeding and cultivation measures will help to enhance the lodging resistance of plateau japonica rice.

Principal component analysis on lodging resistance and related agronomic traits of plateaujaponicarice

In order to measure the contribution of lodging resistance related factors,principal component analysis on the 20 traits of plateau japonica rice was carried out.As shown in Table 3, five principal components whose eigenvalues were greater than 1 were extracted,and their cumulative contribution rate was 88.943%,which could explain 88.943%of the variance. Therefore,the five principal components epitomized most information of lodging resistance and related culm traits of plateau japonica rice.

It could be concluded from Table 4 that among Principal component 1, the diameter of the 2ndinternode underthe panicle,the diameter of the 3rd,2nd, 4thand 1stnodes under the panicle had larger loading.The diameter of the 2ndinternode under the panicle had no significant correlation with lodging resistance,while the diameter of the 3rd, 2nd,4thand 1stnodes under the panicle had significantly positive correlations with lodging resistance,indicating increasing diameter of the nodes under the panicle especially diameter of the 3rdnode under the panicle helped to improve the lodging resistance of plateau japonica rice.Among Principal component 2,plant height,panicle length,wall thickness of the 4thinternode under the panicle and length of the 1st internode under the panicle had greater loading.Panicle length and length of the 1stinternode under the panicle showed no significant correlation with lodging resistance,while plant height exhibited extremely significant negative correction,and the wall thickness of the 4thinternode under the panicle showed extremely significant positive correlation with lodging resistance,indicating appropriately reducing plant height and increasing wall thickness of the 4thinternode under the panicle could improve the lodging resistance of plateau japonica rice. Among Principal component 3,the length of the 4thinternode under the panicle,wall thickness of the 1stinternode under the panicle,length of the 1st, 2ndand 3rdinternodes under the panicle had greater loading.The length of the 1stand 2ndinternodes under the panicle showed no significant correlation with lodging resistance,while the length of the 4thand 3rdinternodes under the panicle showed significant negative correlation,and the wall thickness of the 1stinternode under the panicle exhibited significant positive correlation with lodging resistance,indicating that appropriately reducing the 4thand 3rdinternodes under the panicle and increasing the wall thickness of the 1stinternode under the panicle helped to improve the lodging resistance of plateau japonica rice.Among Principal component 4,the wall thickness of the 1stinternode under the panicle, length of the 2ndinternode under the panicle,wall thickness of the 2ndinternode under the panicle,panicle weight and wall thickness of the 3rdinternode under the panicle had larger loading.The length of the 2ndinternode under the panicle and panicle weight had no significant correlation with lodging resistance,while the wall thickness of the 1st,2ndand 3rdinternodes under the panicle showed significant positive correlation with lodging resistance,indicating that increasing the wall thickness of the 1st,2ndand 3rdinternodes under the panicle could improve the lodging resistance of plateau japonica rice.Among Principal component 5, panicle length,diameter of the 4thand 5thnodes under the panicle,length of the 2ndinternode under the panicle and panicle weight had larger loading.Panicle length,diameter of the 5thnode under the panicle,length of the 2ndinternode under the panicle and panicle weight had no significant correlation with lodging resistance,while diameter of the 4thnode under the panicle ex-hibited significant positive correlation with lodging resistance,indicating that increasing the diameter of the 4thnode under the panicle could improve the lodging resistance of plateau japonica rice.

Table 3The characteristic value and cumulative contribution rate of five principal components

Table 4Component matrix of lodging resistance and related traits of plateau japonica rice

In summary,the lodging resistance of these plateau japonica rice varieties(lines)had the largest eigenvector on Principal component 2 (-0.632),indicating that Principal component 2 were most closely related to lodging resistance,while plant height,wall thickness of the 4th,3rdand 2ndinternodes under the panicle had larger loading among Principal component 2(0.918,-0.548,-0.503 and -0.481),and extremely significant correlations with lodging resistance (r=-0.661**,r=0.665**,r=0.619**and r=0.606**).In addition,among the traits those showed significant positive correlations with lodging resistance, the diameter of the 3rd,2nd,4thand 1stnodes under the panicle had greater loading on the Principal component 1; the length of the 4thand 3rdinternodes under the panicle and the wall thickness of the 1stinternode under the panicle had greater loading on Principal component 3;the wall thickness of the 1st,2ndand 3rdinternodes under the panicle had greater loading on Principal component 4;the diameter of the 4thnode under the panicle had greater loading on Principal component 5.All the results revealed that plant height, and wall thickness of the 4th,3rdand 2ndinternodes under the panicle had the most important influence on lodging resistance,while the diameter of the 3rd,2nd,4th,1stnodes under the panicle, length of the 4thand 3rdinternodes under the panicle,wall thickness of the 1stinternode under the panicle had less influence.The other nine agronomic traits of rice culm did not affect or indirectly affected lodging resistance through above-mentioned agronomic traits.

Conclusion and Discussion

Lodging has been one of the main factors deceasing rice production.Studies have shown that plant height[5,7-12],internode length[5,7-16],internode diameter[5,9,12,13],internode wall thickness[5,9,12-14],node diameter[5],panicle length[14]and panicle weight[11,14]are closely related to lodging resistance, and their influence are different[18].Our results showed that plant height,wall thickness of the 4th,3rdand 2ndinternodes under the panicle had the most important influence on the lodging resistance of plateau japonica rice,followed by the diameter of the 3rd,2nd,4th, 1stnodes under the panicle,length of the 4thand 3rdinternodes under the panicle,wall thickness of the 1stinternode under the panicle,while other nine agronomic traits of rice culm had no significant influence.To obtain excellent rice varieties highly resistant to lodging,it is important to improve plant height,wall thickness of the 4th,3rdand 2ndinternodes under the panicle in breeding.

[1]SUN XC(孙旭初).Study on rice lodging resistance(水稻茎秆抗倒性的研究)[J]. Scientia Agricultura Sinica(中国农业科学),1987,20(4):32-37.

[2]LI RT(李荣田),JIANG YB(姜延波),QIU TQ(秋太权),et al.Effect of lodging on rice yield and the correlation between lodging and plant height(水稻倒伏对产量影响及倒伏和株高关系的研究)[J]. Heilongjiang Agricultural Sciences(黑龙江农业科学),1996,2(1):13-17.

[3]YANG HJ(杨惠杰),YANG RC(杨仁崔), LI YZ(李义珍),et al.Relationship between culm traits and lodging resistance of rice cultivars(水稻茎秆性状与抗倒性的关系)[J].Fujian Journal of Agricultural Sciences(福建农业学报),2000,15(2): 1-7.

[4]LIN JZ(林俊泽).Rice traits related to lodging(与倒伏有关的性状)[J].Korean Journal of Crop Science(韩国作物学会志),1991,36(4):319-323.

[5]DING ML(丁明亮),SU ZX(苏振喜),ZOU Q(邹茜),et al.Relationship between lodging resistance and either agronomic traits or parents’lodging resistance in plateau japonica rice(高原粳稻抗倒性与农艺性状及亲本抗倒性的关系)[J].Chinese Journal of Rice Science(中国水稻科学),2012,26(3):325-330.

[6]TIAN BM(田保明),YANG GS(杨光圣). The performance of lodging and developing a standard test for lodging resistance in crops(农作物倒伏及其评价方法)[J].Chinese Agricultural Science Bulletin(中国农学通报),2005,21(7): 111-114.

[7]BAO LF(包灵丰),LIN G(林纲),ZHAO DM(赵德明),et al.Relationship of resistant index of the third internode to the top of crossing cultivars during riped stage and their parent rices(杂交籼稻成熟期倒3节间倒伏指数与亲本的关系) [J].Journal of Northeast Agricultural U-niversity(东北农业大学学报),2009,40 (1):4-8.

[8]ZHAO LM(赵黎明),GUI CM(顾春梅), CHEN SJ(陈淑洁),et al.Study on lodging of rice and analysis of affecting factors(水稻倒伏研究及其影响因素分析) [J].North Rice(北方水稻),2009,39(4): 66-70.

[9]YANG YH(杨艳华),ZHU Z(朱镇), ZHANG YD(张亚东),et al.Relationship between lodging resistance and stem morphological traits in different rice varieties(lines)(不同水稻品种(系)抗倒伏能力与茎秆形态性状的关系)[J].Jiangsu Journal of Agricultural Sciences(江苏农业学报),2011,27(2):231-235.

[10]DONG MH(董明辉),ZHANG HC(张洪程),DAI QG(戴其根),et al.Analysis of lodging indices and correlative agronomic characters of different japonica rice varieties(不同粳稻品种倒伏指数及其相关农艺性状的分析)[J].Journal of Jilin Agricultural University(吉林农业大学学报),2003,25(2):120-123.

[11]AI ZY(艾治勇).Correlations of lodging resistance with morphological and physiological characteristics super hybrid rice(超级杂交稻形态及生理特性与抗倒性关系的研究)[D].Hunan:Hunan Agricultural University(湖南:湖南农业大学),2006.

[12]MA R(马瑞).The original research on the anti-lodging characters of the cold area rice(寒地水稻茎秆抗倒伏性状的

初步研究)[J].North rice(北方水稻), 2009,39(5):13-15.

[13]MO YS(莫永生),CAI ZQ(蔡中全), YANG QQ(杨亲琼),et al.The breaking resistance of higher,thicker,and tougher rice(高大韧稻茎秆的抗折力研究)[J].Chinese Agricultural Science Bulletin(中国农学通报),2008,24(4): 193-198.

[14]ZHANG YL(张云雷),LIANG WW(梁卫卫),ZHANG HY(张海燕).Correlations between plant traits and lodging resistance of different rice varieties(水稻不同品种植株性状与倒伏发生关系研究) [J].Modernizing Agriculture(现代化农业),2010,369(4):50-51.

[15]ZHANG XJ(张喜娟),JIANG SK(姜树坤),ZHENG X(郑旭),et al.Correlation between traits of basal elongating internodes and culm mechanical strength and QTL location in rice(水稻基部伸长节间性状与茎秆机械强度的相关分析和QTL定位)[J].Plant Physiology Communications(植物生理学通讯),2009,45(3):223-228.

[16]ZHANG JX(张晋贤),RUAN G(阮冠), LIANG SJ(梁社坚).Lodging resistance of stems in rice(Oryza sativa L.)(水稻茎秆抗倒伏研究)[J].Journal of Anhui Agricultural Sciences(安徽农业科学), 2012,40(23):11664-11667.

Responsible editor:Qingqing YIN

Responsible proofreader:Xiaoyan WU

高原粳稻抗倒性相关性状的主成分分析

丁明亮1，浦秋红2，高春琼3，袁平荣1，苏振喜1*
（1.云南省农业科学院粮食作物研究所，云南昆明650205；2.云南省宣威市民族中学，云南宣威655400；3.云南省宣威市农业局，云南宣威655400）

[目的]探讨影响高原粳稻抗倒性的主要因素。[方法]该试验以26份云南高原粳稻品种（系）为供试材料，对高原粳稻抗倒性及其相关的20个农艺性状进行了相关分析和主成分分析。[结果]供试材料的抗倒性在在不同性状间存在较大差异。株高、穗下第4、3、2节间壁厚4个性状对抗倒性影响最大，而穗下第3、2、4、1节直径、穗下第4、3节间距离和穗下第1节间壁厚7个性状对抗倒性影响较小，其余9个茎秆性状不影响或者通过上述茎秆性状而间接影响抗倒性。株高、穗下第4、3节间距离、穗下第1、2、3、4节间壁厚和穗下第1、2、3、4节直径共11个农艺性状与抗倒性存在显著相关关系，而穗长、穗重、穗下第1、2节间距离、穗下第1、2、3、4节间直径和穗下第5节直径9个性状与抗倒性的相关性不显著。[结论]在高原粳稻的育种中，应注重这些主要影响因素的改良以提高高原粳稻品种（系）抗倒性。

高原粳稻；抗倒性；农艺性状；主成分分析attempt to clarify their effects on lodging resistance and provide theoretical basis for breeding and cultivation of lodging-resistant of plateau japonica rice varieties(lines).

常规水稻新品种选育及产业化开发项目（2010BB013）；云南省技术创新人才培养项目（2010CⅠ075）。

丁明亮(1987-)，男，江西丰城人，研究实习员，从事水稻遗传育种研究，E-mail：414108128@qq.com。*通讯作者，研究员，从事水稻遗传育种研究，E-mail：suzhengx@yahoo. com.cn。

2015-03-05

修回日期 2015-05-28

Supported by Program for the Breeding and Industrial Development of Conventional Rice Varieties(2010BB013);Training Plan of Technological Innovation Talents of Yunnan Province(2010CI075).

*Corresponding author.E-mail:suzhengx@yahoo.com.cn

Received:March 5,2015 Accepted:May 28,2015