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EFFECT OF SEED SIZE, PLANT GROWTH REGULATORS AND 

SOME CHEMICAL MATERIALS ON GERMINATION 

CHARACTRISTICS AND SEEDLING VIGOUR OF RICE (Oryza sativa 

L.) SEEDS 

Ahmed H. Saudi 

ahmedsaudi86@yahoo.com 

Horti. & Landscape Dept., College of Agric. & Marshes. Univ. of Thi-Qar, Iraq 

ABSTRACT 

In order to evaluate the effect of seed size, plant growth regulators and some 

chemical materials on seed vigour and seedling growth of rice (Oryza sativa L.) 

an experiment was conducted in 2015 at Laboratories of Agriculture and 

Marshes College, University of Thi-Qar. Factorial experiment in CRD was used 

with four replications in two factors. The first factor included three seed sizes 

(4.6-5.1, 5.2-5.7 and 5.8-6.3 mm). The second factor was seeds soaking 

treatments (KNO3 6 g.l
-1, CaCl2 20 g l

-1 , salicylic acid 20 mg l-1, cytokinin 40 

mg l-1, gibberllic acid 400 mg l-1 , ascorbic acid 40 mg l-1 and seeds soaked in 

distilled water). The results showed that the largest seed size influenced 

significantly and gave the higher averages of germination percentage in ageing 

acceleration test , germination speed index, germination percentage, radical 

length, plumule length and seedling vigour. The seeds rice that were soaked with 

gibberellic acid gave the higher averages of germination percentage  in ageing 

acceleration test, germination speed index, germination percentage, radical 

length, plumule  length  and seedling vigour. The largest seed size which was 

soaked with gibberellic acid gave the higher averages of germination percentage 

in ageing acceleration test, germination speed index, germination percentage, 

radical length, plumule length and seedling vigour.     

Key words: Rice, seeds size, seeds enhancement, germination percentage, seedling vigour. 

INTRODUCTION 

Rice considers as one of the important cereal crops in the world and the staple 

food for half of the world  population .More  than 2 billion people obtain more 

than %70 of  their energy need depending on rice and its products. Sowing rice 

in many countries, especially Asian countries regard as a source of their income 

for the national economy (Febri et al., 2014). In addition, some of the countries 

attribute the development of their civilization to the sown and production of rice 

(Al-Lamy, 2014). In spite of that, the increasing of rice productivity is facing as 

many challenges in the world during in the third millennium. Thus, FAO 

estimated the rice productivity in 2025 about 140 million tons (FAO, 2008) 

Received: 23/8/2016 

Accepted: 4/4/2017 

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Therefore, understanding the rice performance through its growth stages is very 

important to reduce and face all rice cultivation difficulties especially the seed 

germination and seedling emergence stages. The rice seeds are distinguished by 

a number of biological qualitative and physical features that influencing rice 

performance since the early growth stages of germination passing to the 

embryonic axes emergence to a full mature plant. The seed germination success 

requires to understand all the features influencing its quality and the seedling 

vigour, especially the seed of crop that facing many challenges causing 

reduction in its germination rates and the field behavior weakness rice crop 

seeds. Thus, rice seeds suffer from the poor activity of seeds enzymes and the 

solidness of the seed coat as well as its entry to secondary dormancy right after 

the harvesting (Al-Selawy, 2011). Some of these challenges can be overcome 

relatively, especially at the study of the biological phenomena, biological 

processes associated with the seed germination and the physical characteristics 

affecting the seeds. Moreover, seed size deemed as one of the physical criterions 

giving a clear idea about the quality and vigour of the seed. Many of the 

scientific sources illustrated that there is a positive correlation between the seed 

size and the ability of emergence (Zareian et al., 2013 ;  Hossein et al., 2011; 

Mut & Akay , 2010) , because of the seed size influence on the physiological 

reactions and morphological changes associated with germination starting from 

seed imbibing to the radicle emergence stages. Regarded seed size is an 

indicator for the stored food forming the necessary potential energy for the 

embryo. This energy requires for the embryo activation and stimulation of 

germination process (Moshatati & Gharineh, 2012; Roy et al., 1996). The seeds 

rice treatment before sowing regarded as low-cost technique enhancing the 

cellular metabolism during germination stage increased seedling vigour and it 

emergence evenness (Hafeez et al., 2010 ; Basra et al., 2005). The seeds 

treatment chemically before sowing aims to stimulating most of the 

physiological and morphological activities during the germination stage which 

contributes to skip the secondary dormancy, improving the germination speed 

and increase the seedling vigour to grow in fast and regulate emergence within a 

wide range of the suitable environmental condition and environmental stress 

(Habib et al., 2010 ; Ruan & Tylkowska, 2002). Abd-albaki & Copeland (1997) 

indicated that the seed size considered one of the important factors effecting the 

wheat seed germination, seedling emergence and field establishment. Moreover, 

seed size and its protein content directly influenced the seed ability to 

germination and seedling growth that reflected the final yield. The big size seed 

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(25-30 mm) achieved high rate of standard germination percentage , seed vigour 

index and the field seedling emergence rate (Roy et al., 1996). Therefore, this 

reasons would increase the problems of rice cultivation especially if planting in 

the direct dry method. It is possible to overcome the problem through treating 

the rice seeds before sowing with chemical materials and plant growth 

regulators which enhance the seeds and increase their stimulation. The use of 

seed stimulation technique helps to improve the seed ability for germination and 

increases the speed of seedling emergence. The reason to treat the seed before 

sowing is due to enhance the biological reaction inside the seed like raising 

enzymes the activity to analyze the stored food and stimulate the process of 

dissolution food move to the seed embryo at the starting of the germination 

stage (Rehman et al., 2011; Habib et al., 2010; Basra et al., 2006; Farooq et al., 

2006).  

Therefore, the aim of this experiment was to study the effect of seed size and 

seed soaking treatments with plant growth regulators and some chemical 

materials on the germination and seedling growth of rice. 

MATERIALS AND METHODS 

A Laboratory experiment was carried out in 2015 at the College of Agriculture 

and Marshes laboratory to study the influence of seeds size and seeds soaking 

with the plant growth regulators and some chemical materials on the 

germination features and seedling vigour of rice (Oryza sativa L.). This study 

was conducted by using rice seeds amber-33 cultivar which was subjected their 

plants to similar environmental conditions and process of soil surface and its  

harvested in the late 2014 agricultural season. Testing of seed vigour and 

features of seedling vigour were conducted at the laboratories of College of 

Agriculture and Marshes, Thi-Qar University after taking a working sample 

from composite sample. Then, the seeds were sterilized in (%5) (V/V) sodium 

hypochloride for 5 minutes and thoroughly washed with a distilled water and 

was left for air dryness for 48 hours in the laboratories (Sozharajian & 

Natarajan, 2014 ; Bahrani & Pourreza, 2012 ; IRRI, 2011). A factorial 

experiment in CRD was used with four replications in two factors, the first 

factor is the seed size in three sizes (4.6-5.1, 5.2-5.7 and 5.8-6.3 mm), the 

second factor represented the seed soaking by a number of plant growth 

regulators and chemical materials for 24 hours for the purpose of stimulating the 

seeds on germination and improving the seedling features. The plant growth 

regulators and chemical material i.e. (KNO3 6 g l
-1, CaCl2 of 20 g l

-1, Salicylic 

acid 20 mg l-1, Cytokinin 40 mg l-1, Gibberellic acid 400 mg l-1 and Ascorbic 

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acid 40 mg l-1 in addition to control treatment seeds soaked in distilled water 

only) were used. After the end of soaking period, the seeds were taken and air-

dried for 24 hours. Then the following tests were conducted: 

1- Accelerated Aging Test (AAT) (%) 

Two hundred seeds were taken randomly out of each experiment. Then, they 

were put in a silk basket containing 40 ml of distilled water so that they do not 

touch it. The basket was sealed with a non- tight seal and was placed in the 

growth cabinet .The seeds were exposed to stress for 72 hours under the degree 

43o C + 2 and a humidity percentage 100% (I.S.T.A , 2010).Then the seeds were 

taken and undergone to laboratory germination standard test by using growth 

cabinet at 25o C and 95% humidity percentage .Then, only one was counted after 

7 days from the day of germination to determine the number of natural seedlings 

and the results were transformed to percentage and recorded on the base that 

they were germination percentage by test of age acceleration according to the 

following equation (I.S.T.A , 2010): 

AAT =  
𝑡ℎ𝑒 𝑛𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝑛𝑎𝑡𝑢𝑟𝑎𝑙 𝑠𝑒𝑒𝑑𝑙𝑖𝑛𝑔𝑠

𝑡𝑜𝑡𝑎𝑙 𝑛𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝑠𝑒𝑒𝑑𝑠
 100 

2- Germination Speed Index (GSI) 

Two hundered pure seeds were taken from each treatment and they were 

cultivated in four replications on towels paper by folding methods. They were 

put at the growth cabinet in 25 oC and 95% humidity percentage. Natural 

seedlings were counted each day beginning from the fifth day from putting the 

seeds in growth cabinet until the end of test period 14 days then the indication of 

germination speed is measured according to the following equation (A.O.S.A, 

1983): 

GSI = 
𝑛𝑜.𝑜𝑓 𝑔𝑒𝑟𝑚𝑖𝑛𝑎𝑡𝑖𝑜𝑛 𝑠𝑒𝑒𝑑 

𝑑𝑎𝑦𝑠 𝑜𝑓 𝑓𝑖𝑟𝑠𝑡 𝑐𝑜𝑢𝑛𝑡
 +⋯+⋯+

𝑛𝑜.𝑜𝑓 𝑔𝑒𝑟𝑚𝑖𝑛𝑎𝑡𝑖𝑜𝑛 𝑠𝑒𝑒𝑑 

𝑑𝑎𝑦𝑠 𝑜𝑓 𝑓𝑖𝑛𝑎𝑙 𝑐𝑜𝑢𝑛𝑡
 

3- Standard Germination Percentage Test (%)  

The standard laboratory germination was measured by accounting the number of 

natural seedlings just after end of test period of 14 days by dividing the gross 

number of the natural seedlings at the end of test period on the gross number of 

the seeds (IRRI, 2011; ISTA 2010). 

4- Radicle and Plumule Length (cm)  

After the end of test time, 10 natural seedlings were taken. The radicle and 

plumule were separated from its connecting point with seed coat. Then, the 

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radicle and plumule were measured (cm) and average was concluded for these 

two features (Febri et al., 2014 ; I.S.T.A, 2010). 

5- Seedling Vigour (SV) 

The seedlings vigour was measured by the following equation (Febri et al., 

2014; Majid et al., 2013) 

SV= Germination Percentage (%)  [radicle length (cm) + plumule length (cm)] 

All data were analyzed statistically by analysis of variance (ANOVA) using 

Genstat software and averages of the main effect and their interactions were 

compared using the least significant difference test (LSD) at 5 % level of 

probability (Steel et al., 1997). 

RESULTS AND DISCUSSION 

Germination Percentage in Age Acceleration Test (%)  

Seeds exposure to stress conditions such as raised temperature and relative 

humidity for certain period of time in age acceleration test aide in determine 

vigour and performance of these seeds. The strong seeds are the seeds that resist 

stress condition and produce high rate of natural seedlings .Results of variance 

analysis indicated significant effect of seed size, seed soaking treatments and 

their interaction on the germination percentage in ageing acceleration (Table 1) 

.The largest seeds size achieved the highest germination percentage in ageing 

acceleration (11.52%) while, smallest seed size recorded lower mean of this 

feature amounted to 8.90%. These results may be attributed to the fact that the 

largest seeds contain large store of nutrient which is considered necessary for 

providing the embryo by the energy to activate and stimulate it for germination 

and that makes the big size seeds perform a perfect act and homogenous 

emergence (Roy et al. 1996). This result agreed with Chaffai & Louhich (2013); 

Zareian et al. (2013) and Hossein et al. (2011) who indicated the concept that 

explain that largest seeds size have highest vigour then other seeds size. Seed 

soaking treatments significantly affected on germination percentage in ageing 

acceleration. The seeds that were soaked by gibberellic acid recorded higher 

mean for this feature which amounted to 13.56 % and it was not significantly 

different with seeds soaked by cytokinin. This may be attributed to the fact that 

the seed germination and the emergence of seedling under stress conditions 

requires active enzyme system with building and demolishing processes during 

germination process. It was found that the synthesis of the system is under the 

control of plant hormones especially the gibberellin that controls the organizing 

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and synthesis α-amylase enzyme by the accumulation of mRNA and gibberellic 

acid may direct certain genes that work on synthesis other enzymes that includes 

protease and nuclease by digesting the nucleic acid. These enzymes transport it 

to the endosperm and saccharides, amino acid and the nucleotides were formed. 

These nutrition products were transported to the embryo that was reflected 

positive on the activation of metabolism during seed germination stage (Al-

Selawy, 2011 ; Attiya & Jaddoa, 1999 ; Phinney, 1983). This result agreed with 

the findings of other researchers (Zare & Zadeh, 2007 ; Farooq et al., 2006) who 

indicated that seeds soaking pre-sowing by gibberellic acid increase the 

viabiliity and vigour of rice seeds which would be reflected positively on the 

ability of germination. The largest seed size which were soaked by gibberellic 

acid exceeded significantly on the germination percentage in ageing acceleration 

and It achieved the highest mean amounting to 15.88% without being significant 

difference with the largest seeds which were soaked by cytokinin which is an 

indication on the ability of proving the viability and vigour of largest size seeds 

as well as increase the ability of performance during germination stage though 

soaking it with plant growth regulators especially gibberellic acid and cytokinin 

which were considered the important germination vigourous stimulators. This 

result agreed with other workers (Zare & Zadeh, 2007 ; Iqbal & Ashraf, 2005) 

who indicated that seeds soaking before sowing with gibberellic acid and 

cytokinin which enhancement the seeds and improving their performance and 

the ability of germination treating them. The smallest seeds size which soaked 

by CaCl2 recoded less mean of this feature amounting to (7.51%).  

Table 1. Effect of seed size, seeds soaking treatments and their interaction on 

germination percentage in age acceleration test (%) of rice seeds 

Soaking treatments Seed size(mm) Mean 

4.6-5.1 5.2-5.7 5.8-6.3 

Distilled water 7.79 8.24 9.62 8.55 

Cytokinin  40 mg.l-1 10.81 12.13 13.45 12.13 

Salicylic Acid  20 mg.l-1 8.50 10.33 11.63 10.15 

Ascorbic Acid  40 mg.l-1 8.12 9.55 11.25 9.64 

Gibberellic acid 400 mg.l-1 11.54 13.26 15.88 13.56 

KNO3  6 g.l
-1 7.98 9.45 10.12 9.18 

CaCl2  20 g.l
-1 7.51 8.48 8.70 8.23 

L.S.D 5% 1.83 1.29 

Mean 8.90 10.21 11.52  

L.S.D 5% 1.11  

 

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Germination Speed Index Test  

The results showed that the effect of seed size was significant on germination 

speed index (Table 2). The largest seeds size had highest germination speed 

index in compared to other seed size and its achieved 24.27. While, the smallest 

seeds size showed lower mean for this feature which amounted to 17.74. This 

may be attributed to that the size of large seeds means nutrition store and the 

largest surface porous which gave the ability for seed to faster and efficient 

water imbibition which gave the large seeds better performance which positively 

reflected on the germination speed. Seed soaking treatments influenced 

significantly on germination speed index. The soaked seeds by gibberellic acid 

recorded higher mean for this feature which amounted to 29.02 and it was not 

significantly different with seeds soaked by cytokinin. This was attributed to the 

fact that the gibberellic acid specially gibberellic GA3 are considered most 

germination stimulators within wide range from plant species (Attiya & Jaddoa, 

1999 ; Phinney, 1983). Also, cytokinin has an important role in organizing seed 

germination through its mediation in cloning RNA as well as cytokinin role in 

increasing permeable of seeds membrane and  their stimulate germination (Zare 

& Zadeh, 2007; Iqbal & Ashraf, 2005) . 

Table 2. Effect of seed size, seeds soaking treatments and their interaction on 

germination speed index of rice seeds 

Soaking treatments Seed size(mm) Mean 

4.6-5.1 5.2-5.7 5.8-6.3 

Distilled water 16.92 17.13 20.51 18.19 

Cytokinin  40 mg.l-1 19.67 28.11 32.20 26.66 

Salicylic Acid  20 mg.l-1 17.40 19.06 24.35 20.27 

Ascorbic Acid  40 mg.l-1 17.13 18.06 21.90 19.09 

Gibberellic acid 400 mg.l-1 22.62 30.01 34.43 29.02 

KNO3  6 g.l
-1 17.56 17.77 20.85 18.73 

CaCl2  20 g.l
-1 12.71 13.13 15.62 13.82 

L.S.D 5% 3.21 1.87 

Mean 17.74 20.47 24.27  

L.S.D 5% 1.60  

The largest seed sizes which were soaked by gibberellic acid exceeded 

significantly in the germination speed index and achieved higher mean of this 

feature amounted to 34.43 while, the smallest seeds size which soaked by CaCl2 

recoded less mean of this feature amounting to 12.71. 

 

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Standard Germination Percentage (%)     

Seed size had significant influence on standard germination percentage (Table 

3). The highest and lowest standard germination percentage was occurred in 

largest seeds size and smallest seeds size (86.89% and 71.80%), respectively. 

This may be attributed to the fact that largest seeds size is characterized by their 

large surface area that allows them to be water imbibition in an efficient and 

quicker manner in their first stage of germination as well as its high content 

carbohydrate and proteins. Its high capability for speedy supply to the embryo 

by the necessary stored nutrition to stimulate germination. This result agreed 

with other workers (Zareian et al., 2013 ; Hossein et al., 2011 ; Kaydan & 

Yagmur, 2008 ; Lafond & Baker, 1986) who indicated  that there is a 

significance increase in viability and vigour of rice seeds with the increase of 

seeds size that contributes in giving higher germination percentage. Seeds 

soaked by gibberellic acid exceeded significantly compared to the others 

soaking treatment in standard germination percentage and it achieved higher 

mean of this feature amounting to 89.57% without being significantly difference 

with seeds soaked by cytokinin which recorded germination percentage 

amounted to 86.04%, that might be attributed to the fact that soaking rice seeds 

with plant growth regulator, especially cytokinin and gibberellin pre  sowing  

help in stimulation of most physiological activity and morphological changes in 

the seed, especially in the earlier germination stages that contribute in surpassing 

seed secondary dormancy and improve germination percentage and germination 

speed. The percentage is within the wide range of suitable conditions and the 

conditions of environmental stress, this result agreed with the findings of other 

researchers (Ken & Jun, 2013; Zare & Zadeh, 2007).  

Table 3. Effect of seed size, seeds soaking treatments and their interaction on standard 

germination percentage (%) of rice seeds 

Soaking treatments Seed size(mm) Mean 

4.6-5.1 5.2-5.7 5.8-6.3 

Distilled water 70.31 75.60 83.45 76.45 

Cytokinin  40 mg.l-1 76.46 89.73 91.92 86.04 

Salicylic Acid  20 mg.l-1 72.11 80.03 86.81 79.65 

Ascorbic Acid  40 mg.l-1 67.80 76.81 81.64 75.42 

Gibberellic acid 400 mg.l-1 79.97 92.45 96.30 89.57 

KNO3  6 g.l
-1 70.57 78.76 84.97 78.10 

CaCl2  20 g.l
-1 65.41 76.66 83.17 75.08 

L.S.D 5% 7.98 4.50 

Mean 71.80 81.43 86.89  

L.S.D 5% 5.27  

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Also, the superiority of the soaking seeds by gibberellic and cytokinin on 

standard germination percentage were attributed to their superiority on 

germination speed index. The lower means of this feature was 75.08% for the 

seeds soaked by CaCl2. Results of variance analysis indicated significant effect 

of interaction between seed size and seed soaking treatments on standard 

germination percentage (Table 3). 

Largest seeds size that soaked with gibberellic acid achieved higher mean of 

standard germination percentage which amounted to 96.30 %, while, the 

smallest seeds size soaked by CaCl2 achieved lower mean which amounted to 

(65.41 %). This result is considered logical because the larger seeds size which 

soaked with gibberellic acid and larger seeds size which soaked with cytokinin 

attained higher means of germination speed index feature (Table 2). That was 

positively reflected on standard germination percentage.  

Radicle Length (cm)  

The results showed that the effect of seed size was significant on radicle length 

(Table 4). The higher mean of radicle length was occurred in largest seeds size 

(10.81 cm). That may be attributed to largest seeds size achieved higher means 

for germination speed index and standard germination percentage features 

(Table 2 and 3). This contributes in giving them vigour seedlings grew and 

developed in a manner better in comparisons with seeds of other sizes. This is 

another index that approve the largest seeds size figure as the vigour seeds have 

maximum radicle length, this result agreed with the finding of other researchers 

(Chaffai & Louhich, 2013 ; Zareian et al., 2013 ; Mut & Akay, 2010). The lower 

mean of radicle length was recorded by smallest seeds size (7.96 cm). 

Table 4. Effect of seed size, seeds soaking treatments and their interaction on radicle 

length (cm) of rice seeds 

Soaking treatments Seed size(mm) Mean 

4.6-5.1 5.2-5.7 5.8-6.3 

Distilled water 7.26 8.55 10.10 8.64 

Cytokinin  40 mg.l-1 8.94 9.81 12.07 10.27 

Salicylic Acid  20 mg.l-1 8.13 9.70 11.10 9.64 

Ascorbic Acid  40 mg.l-1 6.20 8.24 9.76 8.07 

Gibberellic acid 400 mg.l-1 8.78 10.03 12.64 10.48 

KNO3  6 g.l
-1 8.37 9.16 10.57 9.37 

CaCl2  20 g.l
-1 8.05 8.62 9.40 8.69 

L.S.D 5% 1.42 0.87 

Mean 7.96 9.16 10.81  

L.S.D 5% 1.13  

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Seed soaking treatments influenced significantly on radicle length. The seeds 

that were soaked by gibberellic acid recorded higher mean for this feature which 

amounted to 10.84 cm and it was not significantly different with seeds soaked 

by cytokinin and salicylic acid. That may be attributed to the influence of 

gibberellic acid and cytokinin in seed germination acceleration and emergence 

of radicle and plumule that gave them a greater opportunity to grow during the 

test. This agreed with Habib et al. (2010), Zare & Zadeh (2007), Iqbal & Ashraf, 

(2005) and Ruan & Tylkowska (2002) who indicated that the seed that were 

stimulated pre sowing by gibberellic acid and cytokinin where germination was 

speedier and it produced the longest radicle. The largest seeds size that soaked 

with gibberellic acid exceeded significantly and achieved higher mean of the 

radicle length that amounted to 12.64 cm, while, the smallest seeds size soaked 

by ascorbic acid achieved lower mean which amounted to 6.20 cm. 

Plumule Length (cm)  

Seed size, seeds soaking treatments and their interaction significantly affected 

on plumule length (Table 5).The highest plumule length was occurred in largest 

seeds size (10.04 cm). That was attributed to the fact that high nutrition store of 

larger seeds and their main role in raising the seed vigour and increase the 

averages embryonic axes growth to shoot and root contribute in achieving 

higher means of radicle and plumule length. This result consistent with 

Willenborag (2005) and Roy et al. (1996). While, smallest seeds size showed 

lower mean for this feature which amounted to 6.94 cm.  

Table 5. Effect of seed size, seeds soaking treatments and their interaction on plumule 

length (cm) of rice seeds 

Soaking treatments Seed size(mm) Mean 

4.6-5.1 5.2-5.7 5.8-6.3 

Distilled water 6.25 7.73 9.17 7.72 

Cytokinin  40 mg.l-1 7.53 9.91 11.54 9.66 

Salicylic Acid  20 mg.l-1 7.32 9.20 9.78 8.77 

Ascorbic Acid  40 mg.l-1 6.20 7.35 8.50 7.35 

Gibberellic acid 400 mg.l-1 7.66 9.89 11.90 9.82 

KNO3  6 g.l
-1 7.50 10.10 10.81 9.47 

CaCl2  20 g.l
-1 6.15 7.45 8.59 7.10 

L.S.D 5% 1.55 1.10 

Mean 6.94 8.80 10.04  

L.S.D 5% 1.26  

Seed soaking treatments had significant enfluence on the plumule length feature. 

The seeds soaking in gibberellic acid achieve higher mean amounted to 9.82 cm 

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without being significantly difference with seeds soaked by cytokinin and 

salicylic acid. This result is considered reasonable for the increasing average of 

standard germination percentage for the seeds which soaked in gibberellic acid 

and the seeds which soaked with cytokinin (Table 3). Which contributed to give 

a strong seedlings that grew and developed in a better way in comparison with 

other soaking treatments. This result agreed with Bahran & Pourreza (2012), 

Iqbal & Ashraf (2005) and Mathew & Mohanasarida (2005) who indicated that 

seeds soaked with gibberellic acid and cytokinin was speeder in germination and 

plumule emergence. Seeds soaked with CaCl2 gave lowest plumule length 

which amounted to 7.10 cm. The largest seeds size that soaked with gibberellic 

acid achieved higher mean of this feature which amounted to 11.90 cm, while, 

the smallest seeds size soaked by CaCl2 achieved lower mean which amounted 

to 6.15 cm. 

Seedling Vigour  

Results of variance analysis indicated significant effect of both studied factors 

and their interaction (Table 6). The largest seeds size had highest seedling 

vigour in compared to other seed size and its achieved 1822.54. While, smallest 

seeds size showed lower mean for this feature which amounted to 1075.36. That 

may be attributed to the increasing average of physiological and morphological 

activity of large seeds size because of the increasing average of its water 

imbibition and the increasing in supplement of the embryo with the digested 

nutrition essential to stimulate the seeds of germination and encourage the 

emergence of the embryonic axes and that was reflected positively on seedling 

vigour. This result agreed with Zareian et al. (2013) Kaydan & Yagmur (2008) 

and Royo et al. (2006) who indicated that the largest seeds size were better in 

seedling vigour. Seed soaking treatments were different significantly in seedling 

vigour. 

Seeds soaked by gibberellic acid achieved higher mean of this feature amounted 

to 1839.84. It was not different significantly with seed soaked by cytokinin, that 

might be attributed to the fact that soaking rice seeds with plant growth 

regulator, especially gibberellin and cytokinin stimulation led to an increase in 

germination percentage and germination speed index (Table 2 and 3) as well as 

it contributed in stimulating the growing of embryonic axes which gave the best 

means of seedling features. This result agreed with the findings of other 

researchers (Zare & Zadeh, 2007 ; Farooq et al., 2006 ; Phinney, 1983). While, 

seeds soaked with ascorbic acid gave a lower mean of this feature which 

amounted to 1176.31. The largest seeds size that soaked with gibberellic acid 

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exceeded significantly and achieved higher mean of the seedling vigour that 

amounted to 2363.20, while, the smallest seeds size soaked by ascorbic acid 

recorded lower mean which amounted to 840.72. In general, it is observed in 

(Table 6) that the general direction of gibberellic acid and cytokinin is in the 

seedling vigour increase even in the small size seeds.    

Table 6. Effect of seed size, seeds soaking treatments and their interaction on seedling 

vigour of rice seeds 

Soaking treatments Seed size(mm) Mean 

4.6-5.1 5.2-5.7 5.8-6.3 

Distilled water 949.89 1230.77 1608.08 1262.91 

Cytokinin  40 mg.l-1 1259.30 1769.48 2170.23 1733.00 

Salicylic Acid  20 mg.l-1 1114.10 1512.60 1812.60 1479.77 

Ascorbic Acid  40 mg.l-1 840.72 1197.47 1490.75 1176.31 

Gibberellic acid 400 mg.l-1 1314.71 1841.60 2363.20 1839.84 

KNO3  6 g.l
-1 1119.95 1516.92 1816.66 1484.51 

CaCl2  20 g.l
-1 928.82 1231.93 1496.23 1218.99 

L.S.D 5% 212.71 115.45 

Mean 1075.36 1471.54 1822.54  

L.S.D 5% 143.26  

CONCLUSION 

Assessment of treatment in this study showed that seed size had significant  

influence on standard germination percentage and most seedling characteristics 

.The germination percentage in ageing acceleration test , germination speed 

index , germination percentage , radical length, plumule length, seedling vigour 

and increased by increasing seed size .The rice seeds vigour can be improved  

and enhanced to some extent when soaked with gibberellic acid and 

cytokinin.Based on the results, it can be concluded that largest seeds size soaked 

with gibberellic acid and cytokinin have more positive effects on rice seeds 

vigour. 

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منظمات النمو النباتية وبعض المواد الكيميائية في خصائص االنبات ونمو بادرات وتأثير حجم البذرة 

 (.Oryza sativa L)الرز 

 احمد حميد سعودي

 ahmedsaudi86@yahoo.com) ) العراق –جامعة ذي قار  –كلية الزراعة واالهوار 

 المستخلص

بمنظمات النمو النباتية و بعض  النقعو معامالت  راسة الى معرفة تأثير حجم البذرة تهدف هذه الد 

طبقت التجربة في مختبرات كلية الزراعة و االهوار  و نمو بادرات الرز. ةرالبذالمواد الكيميائية في قوة 

 ،باستعمال تصميم تام التعشية للتجارب العاملية بأربعة مكررات بعاملين 5102جامعة ذي قار عام  –

ما العامل ا ،ملم( 4.6- 2.5,  2.5- 2.5,  2.0-6.4العامل االول تضمن حجم البذرة بثالثة احجام و هي ) 

غم.لتر 3KNO 4هي )فشمل معامالت النقع و يالثان
لتر غم 2CaCl 51و  0-

 salicylic acid 51و  0-

 ascorbic acid  61و 0-لتر غممل gibberllic acid  611و 0-لتر غممل cytokinin  61و 0-لتر غممل

بذور الرز كبيرة الحجم معنوياً  . اظهرت نتائج التجربة تفوقوبذور منقوعة بالماء المقطر فقط( 0-لتر غممل

سرعة االنبات ونسبة  دليلبتسجيلها اعلى المتوسطات لصفات نسبة االنبات في فحص تعجيل العمر و

. حققت بذور بادرة والوزن الجاف للبادرةالقياسي وطول الجذير وطول الرويشة وقوة ال االنبات المختبري

 دليللصفات نسبة االنبات في فحص تعجيل العمر والرز المنقعة بحامض الجبرليك اعلى المتوسطات 

سرعة االنبات ونسبة االنبات المختبري القياسي وطول الجذير وطول الرويشة وقوة البادرة والوزن 

تفوقت بذور الرز كبيرة الحجم المنقعة بحامض الجبرليك على بقية التداخالت االخرى الجاف للبادرة. 

دليل سرعة االنبات بة االنبات في فحص تعجيل العمر ولصفات نس معنوياً بتسجيلها اعلى المتوسطات

 .                  ونسبة االنبات المختبري القياسي  وطول الجذير وطول الرويشة و قوة البادرة

    .قوة البادرة ،نسبة االنبات ،تحفيز البذور ،حجم البذور ،محصول الرز الكلمات المفتاحية:

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