SEED STRUCTURE AND SEEDLING MORPHOLOGY

JOHN REY S. DE LOS SANTOS

A LABORATORY REPORT SUBMITTED TO DR. ARSENIO D. RAMOS OF

THE HORTICULTURE DEPARTMENT, VISAYAS STATE UNIVERSITY,
VISCA, BAYBAY CITY, LEYTE IN PARTIAL FULFILLMENT OF THE
REQUIREMENTS FOR THE SUBJECT OF

HORT209- CROP SEED PHYSIOLOGY

 ABSTRACT

An essential characteristic for classifying and identifying plants is their seed

structure. It also has horticultural significance because it influences yield, quality,

and market price and reflects genetic, physiological, and ecological factors. The

seed's morphology and anatomy serve as a foundation for the behavior of the seed

throughout germination, particularly that which is connected to dormancy. In order

to properly understand the findings of some fast tests for determining seed viability,

knowledge of seed architecture is crucial. In this study, different species of seeds

were used in the study such as Baguio Beans (10 pcs), String Beans (10 pcs),

Pechay Seeds (10 pcs), Squash Seeds (10 pcs), Kangkong Seeds (10pcs), and

Okra Seeds (10 pcs) to determine the germination pattern and its morphology.

Keywords: Seed, seed germination, seed structure and seedling morphology

SEED STRUCTURE AND SEEDLING MORPHOLOGY
 INTRODUCTION

A seed consists of three essential parts: the embryo, the storage tissue

called the endosperm which nourishes the embryo during its development prior to

or for some time after germination, and a protective coat or coats known as the

testa.

Seeds exhibit a wide array of differences which are seen in internal and

external features as well as in their biochemical attributes. These variations enable

distinction of seeds of different plant species. Oftentimes, variations in external

character alone may be enough to allow positive identification of seeds of different

species. Martin (1975) came up with different seed categories based on internal

variation. These include: 1.) size of the embryo in relation to the endosperm; and

2.) differences in size, shape and position of the embryo in the seed. Based on the

first criterion, there are 5 designations represented volumetrically in quarter units:

small, quarter, half, dominant and total. Based on the position of the embryo in the

seed, a seed may be described as peripheral or axial.

Viable seeds are living entities. They must contain living, healthy embryonic

tissue in order to germinate. All fully developed seeds contain an embryo and, in

most plant species, a store of food reserves, wrapped in a seed coat. Seeds

generally "wake up" and germinate when soil moisture and temperature conditions

are correct for them to grow (Miles and Brown 2007). Each seed type has individual

needs--take a minute and read about their specific germination requirements. The

morphology and anatomy of the seed provide a basis for the behavior of the seed
in germination especially that associated with dormancy. Familiarity with seed

structures is important in the interpretation of results of some quick tests for

evaluating seed viability. For instance, one must know the part of the seed which

contributes to the seedling structure.

For practical reasons, accurate identification of seeds enables one to

recognize the weed seed contaminants from the crops seed. Also, it helps in

tracing the origin and distribution of cultivated plants.

This exercise aims to familiarize the seeds the different observable

characteristics of seeds of different plant species.

OBJECTIVES

1. To be familiar with the external and internal characteristics of seeds of

different plant species.

2. To classify seeds based on the observed characteristics.

3. To relate the morphology and anatomy of the seeds to germination

pattern and seedling development.

 MATERIALS AND METHODS

The experiment was conducted at Visayas State University-Baybay City Campus

at the Department of Horticulture. Different species of seeds were used in the study

such as Baguio Beans (10 pcs), String Beans (10 pcs), Pechay Seeds (10 pcs),

Squash Seeds (10 pcs), Kangkong Seeds (10pcs), and Okra Seeds (10 pcs). Then

each species of seeds was sown in a petri dish. For simpler characterization, the

gathered seeds were analyzed and categorized based on their differences in

internal and external properties using a binocular microscope connected to a

computer. The changes ranged from seed form and architecture to germination

patterns and seedling development. Ten sample seeds from each vegetable crop

were prepared and replicated three times for seed germination. In Microsoft Excel

and SPSS, the acquired data were analyzed using basic mean and percentages

to compute the germination percentage and germination rate of the sample seeds.
DATA GATHERED

Seed Germination Percentage

The seeds were placed in a petri dish with damped water and observed for 7
days. The seed germination percentage were calculated by the help of the
following formula:

% Germination: Number of seed germinated X 100

Number of seed sown

Seed Germination Speed

The seed germination speed was obtained using the following formula

(Throneberry and Smith, 1955; Maguire 1962; Allan et al., 1962).

GRS= Number of Germinated Seeds + ……... + Number of Germinated Seeds

Day of first count Day of final count

 RESULTS AND DISCUSSIONS

Various vegetable crop seeds have been examined and studied based on their

morphology and seed structure. All of the seeds that were analyzed are dicot seeds, which

means that the embryo of the seed has two cotyledons. Both the string bean seed in Figure

2 and the baguio bean seed in Figure 1 are bean seeds with the same seed structure. The

figures make it easy to see the seed coat, epicotyl, hypocotyl, radicle, and cotyledons. The

endosperm, hilum, testa, and hypocotyl are the only sections of the squash seed that can be

clearly seen in figure 3 (the squash seed). Other parts are not visible based on the figure.

Typically, squash seed contains hypocotyl, cotyledons, endosperm, hilum, plumule, and testa

(Bergen ,1896).

In addition, Figure 4 (Pechay seeds), Figure 5 (Okra seeds), and Figure 6 (Kangkong

seeds) have different structures. The numbers showed that in pechay seeds, the seed coat

is thin and protects the embryo, which consists of radicle, cotyledons and plumule. The

cotyledons are relatively large compared to the size of the seed and the stored nutrients that

the germinating seedling can utilize during its initial growth phase. In okra seeds, it is

relatively large and has a distinct shape. Usually cylindrical, within the seed coat is the

embryo, which consists of radicle, cotyledons, and plumule. The cotyledons are thick and

fleshy and serve as a food reserve for the seedling during germination. Kangkong seeds, on

the other hand, are small, round and flattened. Inside the seed coat is an embryo that

includes the radicle, cotyledons, and plumule. The cotyledons of kangkong are thin and

membranous and serve as storage tissue for the nutrients needed during germination. It is

important to note that seed structures can vary slightly within the same plant species due to
factors such as cultivar and environmental conditions. However, the general characteristics

described in the figures are common for baguio bean, string bean, squash, pechay, okra,

and kangkong seeds.

Figure 1. Seed structure of Baguio bean Figure 2. Seed structure of string bean

Figure 3. Seed structure of squash Figure 4. Seed structure of pechay

Figure 5. Seed structure of okra Figure 6. Seed structure of kangkong
Germination Percentage

Based on the data shown in Table 1, it revealed that the All treatments

assumed favorable conditions such as temperature, light, etc. for germination. It

was observed that in treatment 6, the Kangkong seeds had the highest and

complete germination rate within 1 week or 7 days. Treatment 6 was found to be

significantly different but comparable to Treatment 5 (Squash) and Treatment 4

(Pechay) with mean scores of 100, 96.67 and 93.33, respectively. Despite their

seed size. It was evident that their seed size was not an indicator of germination

speed. Anything over 70% indicates that the seed is still good enough to be used.

(Germination Test: How to Test Seeds for Viability - Garden Fundamentals, 2018).

Hou et al. (2021) also added that seeds with different kinds of dormancy shows

different patterns in the relationship between seed size and seed survival.

Therefore, it is important to conduct a seed viability test, especially if the grower

has already planted and is not satisfied with the stocks. A germination test of some

leftover seeds can help to locate and indicate the cause of the problem. Seeds are

tested for germination to determine how they will perform when planted in the field, the

garden, or in a seedling nursery. (Elias, et.al., 2012). It assesses whether a seed is

alive, metabolically active, and possesses enzymes that are capable of catalyzing

metabolic reactions needed for germination and seedling growth (Copeland and

McDonald, 2001). Thus, seed viability testing can measure tissue viability as well as

viability of the entire seed.

Table 1. Characteristics of treatments

First and Last Day of Germination

Germination squirmed with each treatment until reaching final maximum

germination with different time intervals. The water spinach with the highest

number of seeds germinated on the first day after sowing. Pechay had a mean of

7 on the first day and 0 on the last day, meaning that all of the observed seeds

germinated. It was observed that Pechay seeds were able to germinate

significantly faster compared to other treatments. The result was supported by the

report by Kamran et al. completed. (2021) reported that Brassica rapa seeds

reached final germination after 5 days under stress-free conditions. Pechay seeds

tolerate stress with continuous germination. Ozay (2018) stated in his experiment

that the detection of the highest germination percentage of Brassica rapa was due

to the treatment. Ozay (2018) also stated that cabbage is known to be Pb tolerant.
 The results from the first day showed that the highest germination rate was

observed in treatments 3 and 4 with mean scores of 2 and 7, respectively. ANOVA

showed the significant difference between treatments.

Seed Germination Speed

For the seed germination speed of six different vegetable seeds, it was shown in Figure

7 that seeds of pechay, pumpkin/squash and okra germinated on the 1st and 2nd days of

germination. Germinated seeds on days 1 and 2 were 7 and 1.3 for pechay, 2 and 2.3 for

okra, and 0.3 and 3.3 for squash, respectively. On the 3rd day of germination, Kangkong

started to germinate and 4.3 seeds germinated. Pumpkin germinated 5.7 seeds, followed

by okra which germinated 3 seeds and pechay which germinated 1 seed each. Pechay and

okra seeds germinated from 1st to 3rd day. In Pechay, 9.3 seeds germinated, while 7.3

okra seeds germinated for 3 days. On the 4th day of seed germination, baguio beans and

beans started to germinate and germinated to 2.3 seeds in baguio beans and 2 seeds in

beans, followed by kangkong in which germination accumulated to 4.3 seeds and pumpkin

seeds in which 7.

On the 5th day, the Kangkong seeds accumulated to a germination of 1.3 seeds, and

from the 3rd to the 5th day of germination, they accumulated to a total germination of 10

seeds, and all the seeds used in the experiment were all viable. These data showed that

okra seeds have a 100 percent germination rate while seed germination started on the 3rd

to 5th days. On the 6th and 7th days of germination, baguio beans and green beans

accumulated to 3 seeds and 1 seed for baguio beans and for green beans the amount
accumulated to 2 seeds and 2 seeds for the last germination period. The sample seeds

used in the experiment were observed for 7 days, and the highest germination rate, a total

of 10 germinated seeds, are pumpkin and okra seeds, followed by baguio beans, which

have accumulated to 9.7 seeds, and at pechay, which have seeds have accumulated to

9.3 seeds, for beans accumulated to 8.3 seeds and for the okra accumulated to 7.3 seeds

each. The seeds that germinated on the first day were pechay, pumpkin, and okra seeds.

The sample seeds used in the experiment were observed for 7 days and the highest

germination rate accumulated to a total of 10 germinated seeds are squash and okra seeds,

followed by baguio beans which have accumulated to 9.7 seeds, for pechay which have

accumulated to 9.3 seeds, for string beans which have accumulated to 8.3 seeds, and for

the okra which have accumulated to 7.3 seeds respectively. The seeds that germinated on

the 1st day were pechay, squash, and okra seeds. This means that these seeds have a

faster germination rate compared to other vegetable seeds used in this experiment. The

seeds that have germinated last, which started at day 4 were baguio beans and string

beans, followed by the kangkong seeds which started to germinate on the 3rd day. The

non-germinated seeds among the seed samples used in this experiment are caused by the

fungus (molds) due to excessive moisture and less oxygen during storage period and likely

due to thickness of the seed coat which are common in bean seeds and okra seeds.

This means that these seeds have a faster germination rate compared to other

vegetable seeds used in this experiment. The last seeds to germinate, starting on day 4,

were baguio beans and broad beans, followed by the kangkong seeds, which started to

germinate on day 3. The non-germinated seeds among the seed samples used in this
 experiment are caused by the fungus (mold) resulting from excessive moisture and less

oxygen during storage and probably due to the thickness of the seed coat, which is

common in bean seeds and okra seeds occur.

Figure 7. Seed germination speed of different vegetable crops

Seed germination speed of different vegetable crops

Germination Rate

Day 7

Day 6

Day 5

Day 4

Day 3

Day 2

Day 1

0 2 4 6 8 10 12

Squash Seeds Pechay Seeds String Beans Kangkong Seeds Baguio Beans
 CONCLUSION

The morphological description of plant structures is a requisite for

understanding the relationships between structure and function and may contribute

to defining developmental situations composed with genomic composition and

activity. Seed germination in most important factors affect plant growth and

development. Seeds will germinate if it has associated with an optimum

temperature and environmental conditions. Germination and seedling

establishment are critical stages which affected both quality and quantity of crop

yields.

The seeds used in this experiment are dicot seeds only. The seeds have a

distinct seed structure and usually two cotyledons, which are typical of all

dicotyledonous seeds. Seed germination, the process by which a seed develops

into a seedling, is affected by various factors such as water, temperature, light,

oxygen, seed age and seed coat thickness. These factors inhibited the germination

of a seed. The seeds used in this experiment have a high germination rate and are

extremely viable. The germination speed of the seed samples varies due to several

factors such as the type of cultivar, the thickness of the seed coat, the moisture

level during the germination period and the lack of oxygen (sealed petri dish).
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COPELAND, L.O and MCDONALD, M.B. 2001. Principles of seed science

and technology. 4. Dordrecht: Kluwer Academic Publishers;p. 481.
https://www.growveg.com/guides/a-simple-germination-test-for-
seeds/writtenbyAnneMari eHendry/

Elias, S. G., Copeland, L. O., McDonald, M. B., & Baalbaki, R. Z. (2012). Seed
Testing: Principles and Practices. Michigan State University Press.
http://www.jstor.org/stable/10.14321/j.ctt7zt51m

Elias, S. G., Copeland, L. O., McDonald, M. B., & Baalbaki, R. Z. (2012). Why
Seeds are Tested, and When. In Seed Testing: Principles and Practices (pp. 1–10).
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KOZLOWSKI, T.T. (Ed.). Biology of Seeds (Vol. 1)

MARTIN, A.C. Seed Identification Manual (SB115 M37 – Reference Section)

Sliwinska, E. and D.J. Bewley. 2014. Overview of Seed Development, Anatomy

and Morphology. In: Seeds: The Ecology of Regeneration in Plant Communities.
3rd Ed. CAB International
 APPENDICES

Figure 8. Baguio Beans during germination period Figure 9. Kangkong Seeds during germination period

Figure 10. Squash seeds during germination period Figure 11. string beans during germination period