Primary Study on Influencing Factors of Rice Seed Germination Rate

Guodong HUA,Guanxi LI*,Ying CHENG,Dijuan CHEN,Delong MENG,Duoming WANG

1.Lianyungang Academy of Agricultural Sciences,Lianyungang 222006,China;

2.Institute of Agricultural Sciences in Ganyu District,Lianyungang City,Lianyungang 222006,China

Primary Study on Influencing Factors of Rice Seed Germination Rate

Guodong HUA1,Guanxi LI1*,Ying CHENG2,Dijuan CHEN2,Delong MENG1,Duoming WANG1

1.Lianyungang Academy of Agricultural Sciences,Lianyungang 222006,China;

2.Institute of Agricultural Sciences in Ganyu District,Lianyungang City,Lianyungang 222006,China

In order to investigate the change rule of rice seed germination rate during the storage,the effects of moisture content and storage temperature on Lianjing 7 rice seed germination rate were investigated.The 3×3 factorial design was adopted.The test data was analyzed using SPSS.The results showed that after the Lianjing 7 rice seeds with moisture content of 14.5%were stored at 25℃for 180 d,the germination rate still reached 89%;after the rice seeds with moisture content of 11.5%were stored at 5℃for 180 d,the germination rate was up to 96.6%;the rice seed germination rate was decreased gradually with the prolonging of storage time;the moisture content and storage temperature were two key factors affecting the Lianjing 7 rice seed germination rate,and there was significant interaction between moisture content and storage temperature.

Rice;Temperature;Moisture;Factorial design;Germination rate

R ice(Oryza sativa L.)is one of the world’s most important food crops,and it is also a crop with the largest cultivation area in China.Rice has a very prominent position in China’s grain production[1].Rice seeds are a scientific part of rice,and their quality directly affects the security of agricultural production[2].With the adjustment of agricultural structure and transfer of rural land,the seed threshing and seedling transplanting methods have been changed;the seed sunning ground has been reduced,and the drying method has also been changed.All these light cultivation modes have brought new challenges to seed production[3].In particular,for the cultivation of directly-sowed rice,the rice seeds are needed to be stored for a long time after their purchasing,and the long storage time and high storage temperature may all reduce the germination rate of rice seeds.So the cultivation of directlysowed rice shows higher requirements for seed quality[4].In recent years,it often occurs that some Chinese seed enterprises are claimed for low rice seed quality[5-6].Therefore,the rice seed quality has aroused more and more attention.

Seed quality includes aspects of seed germination,moisture content, purity,shape,color,plumpness,etc. Among them,seed germination rate is the most important indicator reflecting seed quality.Moreover,storage temperature and moisture content are the most important factors influencing seed germination rate[7].Roberts[8]calculated theoretically that the storage life of seeds with low moisture content could last for over 50 years at low temperature.Specht et al.[9]found that after the seeds with low moisture content were stored at low temperature for 15 years,the germination rate was reduced by 15%.Lu et al.[10]found that the germination rates of carrot seeds and lettuce seeds that had been stored in the National Germplasm Bank of China over 10 years were reduced by about 10%.So it can be con-

Material and Methods

Material

The test material was Lianjing 7, bred by the Lianyungang Academy of Agricultural Sciences.The Lianjing 7 was approved by the Jiangsu Provincial Crop Variety Approval Committee in 2010.

Test design

The 3×3 factorial design(Table 1) was adopted.The moisture content (A)was designed as three levels,including 11.5%,14.5%and 17.5%.The storage temperature(B)was also designed as three levels,including 5℃, 15℃and 25℃.According to factorial design,the two-way classification test was performed,and a total of 9 treatments were designed.There were three replications for each treatment.

Methods

In October,2013,the newly-harvested same-batch Lianjing 7 rice seeds were divided into three groups, which were placed in low-temperature drying chambers and dried at 43℃. The moisture contents in rice seeds of the three groups were controlled at 11.5%,14.5%and 17.5%,respectively.The rice seeds with the same moisture content were further divided into three groups,which were packed with PE film and then stored in thermostatic incubators at temperatures of 5,15 and 25℃,respectively.The germination rates of rice seeds stored in incubators were determined once every 30 days.Factorial analysis was performed for the determined germination rates on the 180thd.

Determination of germination rate

In the germination rate determination,two layers of filter,moistened with distilled water,were laid in each of the plastic germination boxes.A total of 200 full seeds were placed in each of the boxes.The rice seeds were incubated at 28℃for 10 d.Subsequently, the germination rate in each box was determined[13].The test was repeated three times.

Data processing and statistics

The data statistics and analysis and graphing were performed using SPSS 16.0 and Origin 8.6.

Table 13×3 factorial test design

Results and Analysis

Variation of germination rate with prolonging of storage time

As shown in Fig.1(a-f),the germination rates of rice seeds were all trended to be decreased with the prolonging of storage time.As shown in Fig.1(a-c),during the storage,the higher the moisture content in rice seeds is,the larger the decrement of germination rate is.Fig.1(d-f)showed that during the storage,the higher the storage temperature is,the larger the decrement of germination rate is.After the rice seeds with moisture content of 14.5%were stored at 25℃for 180 d, the germination rate still reached 89%, which was decreased by 9.2%compared with the original germination rate.After the rice seeds with moisture content of 11.5%were stored at 5℃for 180 d,the germination rate was still up to 96.6%,which was decreased by only 0.7%compared with the original germination rate.So it can be preliminarily concluded that the storage temperature and moisture content are all negatively related to rice seed germination rate.Therefore,lowering storage temperature and moisture content in seeds all contribute to the maintaining of rice seed germination rate.

Normality test of germination rate data

The normality test was performed for the germination rate data obtained on the 180thd.Using the Shapiro-Wilk method,the P(sig.value)was deduced as＞0.05,thereby accepting the null hypothesis.It indicated that the germination rate data were all normally distributed,and they could be used for further main effect analysis and interaction effect analysis.

Variance analysis and multiple composition

The variance analysis results were shown in Table 3.The F value of moisture content(A)was 183.627,and the P value was 0.000(＜0.05);the F value of storage temperature(B)was 320.293,and the P value was 0.000(＜0.05);for the joint action between moisture content(A)and storage tem-perature(B),the F value was 31.644, and the P value was 0.000(＜0.05).It was suggested that the rice seed germination rate differed among different moisture contents and different storage temperatures,and there was joint action between moisture content and storage temperature.The main effects of moisture content(A)and storage temperature(B)and the interaction effect between moisture content(A)and storage temperature(B)all reached the significant level.The multiple comparison results of main effects were shown in Table 4.The differences among different levels of moisture content(A)and storage temperature (B)all reached the significant level(P＜0.05).

Table 2Normality test of germination rate data obtained on the 180thd

Joint action between moisture content(A)and storage temperature(B)

The factorial analysis results of joint action showed that high moisture content and storage temperature all could reduce the germination rate of rice seeds(P＜0.05).There was significant joint action between moisture content and storage temperature, which reduced the germination rate of rice seeds(P＜0.05).Fig.2a showed the variation of joint action between moisture content and storage temperature with the increase of moisture content in rice seeds,and Fig.2b showed the variation of joint action between moisture content and storage temperature with the increase of storage temperature.As shown in Fig.2a and Fig.2b,the three variation lines were all not parallel,and the distances among them were increased with the increased variable value at the horizontal axis.It was indicated that therewas joint action between increased moisture content and storage temperature that reduced the rice seed germination rate.

Table 3Interaction test between main bodies(variable:germination rate)

Table 4Multiple comparisons of main effects,moisture content(A)and storage temperature(B)

Conclusions and Discussion

During the storage,the rice seeds are commonly evaluated by germination rate,germination vigor,vigor index,half-life period and germination index[14].Due to the simple and practicable determination method of germination rate,it is usually used as index evaluating rice seed quality.The results of this study showed that during the storage of rice seeds,moisture content and storage temperature all significantly affected the seed germination rate,and there was significant joint action between moisture content and storage temperature on seed germination rate.Currently,the national standards for conventional rice seeds are as follows:moisture content≤14.5%;germination rate≥85%.This study found that after the Lianjing 7 rice seeds with moisture content of 14.5%were stored at 25℃for 180 d, the germination rate still reached 89%, which was decreased by 9.2%compared with the original germination rate.Therefore,for seed enterprises, the rice seeds controlled within national standards can be stored at room temperature.Thus the germination rate of rice seeds can still meet the national standards after 6-month storage (till the seeding).As shown in Fig.1,after the rice seeds with moisture content of 11.5%were stored at 5℃for 180 d,the germination rate was only reduced by 0.7%.Due to the seeds stored in low-temperature germplasm banks are usually preserved for several years,the moisture content in rice seeds should be controlled below 11.5%,and the storage temperature should be controlled below 5℃.

Factorial design,also known as full factorial experimental design,is a multifactorial cross-block design,and it is widely used in scientific experiments.Factorial analysis not only can test the differences among different levels of each factor,but also can test the interactions among various factors. Factorial analysis can obtain large amounts of information,and it can also accurately estimate the size of main effect of each experimental factor and the size of interaction between two of the factors.In recent years,factorial design has been applied by many scholars to conduct scientific researches[15-16].For the germination rate of rice seeds that had been stored for 180 d, the influencing factors were analyzed by factorial design,and the variance analysis of main effects and interaction effect was performed using the General Linear Model of SPSS.The multiple comparisons among different levels of each factor were performed using the Post Hoc.,and the interaction analysis among factors was conducted using the interaction plots.All the study results above will provide certain reference for the processing and storage of rice seeds.

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Responsible editor:Tingting XU

Responsible proofreader:Xiaoyan WU

水稻种子发芽率影响因素初探

华国栋1，李冠喜1*，成英2，陈迪娟2，孟德龙1，王多明1
（1.连云港市农业科学院，江苏连云港222006；2.连云港市赣榆区农业科学研究所，江苏连云港222006）

为探明水稻种子发芽率在贮存期间的变化规律，以"连粳7号"水稻种子的发芽率为指标，以含水量和贮存温度为考察因素，选用3×3析因试验设计、采用SPSS软件辅助数据分析进行了试验研究。结果表明，含水量为14.5%的水稻种子在25℃下贮存180 d后其发芽率仍可达89%，含水量为11.5%的水稻种子在5℃下贮存180 d后其发芽率仍可达96.6%，水稻种子发芽率随贮存时间的延长而逐渐下降，含水量和贮存温度为影响其变化的关键因素且二者存在显著的交互作用。

水稻；温度；水分；析因设计；发芽率cluded that low moisture content and low storage temperature are critical to the maintaining of seed germination rate.In general,rice seeds should experience a storage period of 6 months from their harvesting to sowing.During the storage of rice seeds,there are many factors influencing the germination rate.Among them,the storage temperature and moisture content in seeds are the key factors[11-12].In this study,the high-yielding rice variety Lianjing 7 was used as test material, and the 3×3 factorial design was adopted.The germination rate of Lianjing 7 was determined once a month for 6 consecutive months.Based on the germination rate of Lianjing 7 in the 6thmonth during the storage,the effect of joint action between temperature and moisture content on germination rate of rice seeds was investigated so as to provide some reference and basis for the processing and storage of rice seeds in seed enterprises and the safe production of rice crop in China.

江苏省科技成果转化专项“连粳7号、3优88水稻新品种产业化及配套技术集成应用”（BA2011098）。

华国栋（1961-），男，江苏赣榆人，推广研究员，主要从事农业技术研究与推广工作，E-mail：lgx6060@126.com。*通讯作者，副研究员，博士，主要从事资源微生物与农业技术研究工作，E-mail：guanxili@163.com。

2015-03-09

修回日期 2015-05-20

Supported by Agricultural Science and Technology Achievement Transformation Fund of Jiangsu Province(BA2011098).

*Corresponding author.E-mail:guanxili@163.com

Received:March 9,2015 Accepted:May 20,2015