Journal

Journal of Applied Horticulture, 21(1): 81-84, 2019 Appl

Seed development and maturation in African marigold (Tagetes

erecta L.)

C.N. Murali*1, S.K. Jain1, M.A. Joshi1 and Anjula Pandey2

ICAR-Indian Agricultural Research Institute, New Delhi-110012. 2ICAR-National Bureau of Plant Genetic Resources,
1

New Delhi-110012. *E-mail: muralicnagri@gmail.com

Abstract
Marigold is an annual flower crop and it is mainly cultivated and propagated through seeds. Seed quality is the key issue in flower
seed industry. Indeterminate flowering in marigold leads to differential maturity of seeds resulting in wide differences in the seed
quality, major constraints in marigold seed production are optimum stage of physiological maturity and stage of seed harvest. Hence,
a study was undertaken to identify the optimum stages of seed maturity in African marigold varieties. The experimental results showed
that, on-set of germination starts at 8-10 DFA; and quality seeds in marigold can be harvested between 46-48 DFA. Besides, total oil
content in seeds recorded of about 35 % during physiological maturity and of about 33% at harvest maturity; its content also varied
with genotype as well as stage of seed maturity.
Key words: Seed development, Tagetes seeds, on-set of germination, physiological maturity, harvest maturity and total oil in seeds.

Introduction pattern of seed development and maturation in selected varieties

of African marigold.
Marigold (Tagetes spp L.), a member of Asteraceae family, is an
important annual flower crop native to Central America (Nehr, Materials and methods
1968). African marigold (Tagetes erecta) and French marigold
(Tagetes patula), the two commonly found species in marigold, To study the seed development and maturation, the African
African type is noted for large flower heads and French types marigold cultivars Pusa Basanti Gainda (PBG) and Pusa Narangi
are well known for their smaller flowers. Marigold is mainly Gainda (PNG) were raised during rabi 2015-16 and 2016-17
cultivated and propagated through seeds hence the seed quality in 60 cm (row) x 45 cm (plant) spacing, following RBD with
standard agronomic practices. The flower buds were tagged in
is the issue in the seed industry to meet the desired standards and
each genotype everyday throughout the flowering period. The
to compete with the global seed trade. It becomes imperative
developing seeds were harvested at seven days interval i.e. 0 to 49
to evolve a strategy to produce quality seeds and make them
days from anthesis (DFA) and tested for seed quality parameters
available in time at a reasonable price to the farming community.
like, fresh weight, dry weight, seed moisture content and seed
The improvement of flower seed industries in developed germination in the first year of crop growth. Subsequently, during
countries like India requires high quality seeds. In India, the second year of crop growth, the flower buds were harvested at
mass production of the flowers is limited due to poor seed quality periodic intervals of one day to confirm the on-set of germination
(Gornik and Grzesik, 2005), which is majorly due to improper (0-14 days), and physiological and harvest maturity (35-49 days).
seed development and maturation under unfavourable weather
conditions, as well as by short period of day light (Gornik and For determining seed moisture content, the fresh and dry weight
Grzesik, 2002; Janakiram, 2004). of flower buds were estimated following ISTA rules (ISTA, 2015)
in each genotype using three replicates, ten flower buds in each
Indeterminate flowering of marigold leads to differential maturity replicate were weighed a fresh and dried at 80 °C for 24 hrs in
of seeds resulting in wide difference in seed quality (Pramila, an electric hot air oven.
2010). Major constraints in marigold quality seed production
a. Seed germination (%): The seed germination was tested using
are optimum stage of physiological maturity and stage of harvest
four replicates of 50 seeds each, which were placed on pre-soaked
(Mathad et al, 2005). Physiological maturity is the stage at which filter paper in a Petri-plates and were kept at 200~30 0C. The final
the quality of the seed is at its maximum; early harvested seeds count was taken on 14 day from seed incubation (ISTA, 2015).
results in immature seeds with low vigour, whereas late harvest
ends in seed deterioration and seed loss (Still and Bradford, b. Seedling growth (cm): To determine the seedling growth,
1998). It is needless to emphasize that good quality seed is a ten normal seedlings on 14th day from standard germination test
pre-requisite for optimum returns from the seed crop. Hence, a in each replicate were taken randomly; and the seedling growth
detailed study is the needed to determine the optimum stage of was measured from the tip of the primary root to the tip of the
physiological maturity and stage of harvesting so as to obtain primary leaf.
the quality seeds with maximum germination and vigour. Hence, c. Seedling dry weight (mg): Estimation of seedling dry weight
the present study was undertaken with an objective to study the was done using ten normal seedlings, randomly drawn from
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82 Seed development and maturation in African marigold

standard germination test, on 14 day in each replicate, which seed development, seed moisture content among the genotypes
were dried using hot air oven at 80o ± 2 °C for 24 hrs, cooled over was very high (83.51 to 86.61 %) which declined to about 18 %
silica gel and weighed to assess the biomass. at seed maturity. During in the first year of seed development,
seed germination was witnessed during 14 DFP and gradually
d. Seedling vigour index: Seedling vigour indices (SVI-I and
SVI-II) were calculated following Abdul-Baki and Anderson germination quality in in seeds increased and it reached up to
(1973). 88 % during 35 DFA at which seed quality attains its maximum
since seeds accumulated with all the available reserves required
e. Estimation of total oil in seeds (%): The total oil in seeds for germination.
was estimated during seed maturity (at physiological and harvest
maturity) using Soxhelt method as described by AOAC (2016), A During the subsequent year of seed crop growth (2016-17),
known quantity (5g) of seed sample was grinded into fine powder developing seeds were harvested at a periodic interval of one
using sodium sulphate (Na2SO4) and subjected it into the Soxhelt day (0-14 & 35-49 days, respectively) and similar observations
apparatus; in which sample was boiled with a petroleum ether (80 were made (table 2 and 3) to confirm on-set of germination,
0
C) up to 14 hrs. At the end, distilled the solvent completely and and physiological and harvest maturity, respectively. On-set of
repeatedly heated the sample until constant weight was recorded. germination started during 8-9 DFA and seed moisture content
The obtained oil content (g/g) was expressed in percentage (%). during on-set of germination was recorded about 82 % in both
varieties. Physiological maturity was noticed with higher seed
Results and discussion germination 86 to 88 % during 42-44 DFA and it associated
with higher fresh weight of 3.21 to 3.47 and dry weights of 1.98
The results on fresh weight, dry weight, seed moisture content, to 2.18 g. Harvest maturity started noticing after 46 DFA and it
and seed quality parameters during 2015-16 are presented in table was confirmed with negligible decline in dry weight; and when
1. The flower buds harvested at periodic intervals of seven days dry weight was about to coincide with dry weight in a few days.
and tested for fresh weight, dry weight and seed quality. During
2015-16 fresh weight among the genotypes is increased from Physiological maturity in seeds is to recapture a high reproducing
0.69 g to a maximum of 3.48 g at 42 DFA; followed a decrease capacity and it usually coincides with attainment of maximum dry
in it up to 2.26 g at final interval (49 DFA), and dry weight weight (Natarajan and Srimathi, 2008), during which the flow of
increased from 0.11 g and reached up to 2.18 g and reaches its nutrients from mother plant to the seed freezes. Seed maturation
minimum and constant at harvest maturity. At the initial stage of is a period from fertilization to harvest during which the seed
Table 1. Fresh weight (g), dry weight (g), moisture content (%) of flower buds and seed quality during seed development (2015-16)
Parameter* Days from anthesis LSD
Genotype
0 7 14 21 28 35 42 49 P=0.05
Fresh weight* (g) PBG 0.69 1.77 2.18 2.47 2.86 3.12 3.21 2.26 0.088
PNG 0.78 1.82 2.86 3.21 3.37 3.43 3.48 2.68 0.085
Dry weight* (g) PBG 0.11 0.35 0.53 0.79 1.24 1.67 1.98 1.86 0.059
PNG 0.10 0.24 0.81 1.01 1.43 1.87 2.18 2.18 0.068
Moisture content (%) PBG 83.51 80.04 75.53 68.18 56.60 46.42 38.21 17.54 3.603
PNG 86.61 86.67 71.68 68.49 57.42 45.33 37.31 18.86 3.180
Seed germination1 PBG 0.00 0.00 21.00 36.00 74.00 80.00 86.00 78.00 3.337
(%) PNG 0.00 0.00 17.00 34.00 57.00 78.00 88.00 79.00 3.443
Seedling growth2 PBG 0.00 0.00 4.18 6.21 9.81 10.84 11.96 11.76 0.625
(cm) PNG 0.00 0.00 4.26 6.58 10.54 12.19 13.48 12.69 0.722
Seedling dry weight2 PBG 0.00 0.00 14.21 17.53 21.77 23.06 23.95 22.16 0.549
(mg) PNG 0.00 0.00 14.48 17.61 22.11 23.19 24.78 23.25 0.600
SVI-I PBG 0.00 0.00 89.11 223.48 732.72 852.87 1019.53 909.08 49.175
PNG 0.00 0.00 73.61 219.05 588.79 958.75 1186.07 999.24 74.159
SVI-II PBG 0.00 0.00 302.72 631.24 1626.27 1814.21 2044.31 1713.41 100.168
PNG 0.00 0.00 251.01 587.29 1237.43 1824.19 2179.17 1829.51 91.607
Where, PBG: Pusa Basanti Gainda; PNG: Pusa Narangi Gainda; *Average of three replicate of 10 flower buds in each replicate; 1Average of four
replicates from 50 seeds in each replicate; 2Average of four replicates from 10 seedlings in each replicate.
Table 2. Fresh weight (g), dry weight (g), moisture content (%) and seed germination during seed development (2016-17)
Parameter Genotype Days from anthesis (DFA) LSD
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 P=0.05
PBG 84.13 84.09 83.00 82.78 82.36 81.55 79.73 80.20 79.12 78.07 77.01 76.77 76.86 76.16 75.58 4.189
Moisture (%)
1
PNG 87.54 87.18 87.44 87.12 87.77 87.72 87.46 86.84 83.82 82.19 80.09 76.62 73.03 72.77 71.56 2.532
Seed germination2 PBG 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 2.00 6.00 9.00 14.0 17.0 20.0 21.0 1.952
(%) PNG 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 2.00 5.00 7.00 10.0 12.0 17.0 2.130
Where, PBG: Pusa Basanti Gainda; PNG: Pusa Narangi Gainda; 1Average of three replicates from 10 flower buds in each replicate; 2Average of four
replicates from 50 seeds in each replicate

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 Seed development and maturation in African marigold 83

Table 3. Fresh weight (g), dry weight (g), moisture content (%) and seed germination during seed maturation (2016-17)
Parameter Genotype Days from anthesis LSD
35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 P=0.05
Fresh weight1 PBG 3.12 3.12 3.13 3.13 3.14 3.17 3.19 3.21 3.17 2.84 2.68 2.57 2.48 2.35 2.26 0.052
(g) PNG 3.42 3.42 3.43 3.45 3.45 3.47 3.48 3.48 3.49 3.47 3.41 3.24 2.85 2.76 2.68 0.047
Dry weight1 PBG 1.67 1.72 1.76 1.81 1.87 1.91 1.94 1.98 1.96 1.94 1.92 1.88 1.88 1.86 1.86 0.039
(g) PNG 1.87 1.91 1.96 1.99 2.03 2.09 2.14 2.18 2.21 2.21 2.20 2.19 2.19 2.18 2.18 0.032
Moisture PBG 46.35 44.87 43.77 42.06 40.45 39.58 39.25 38.21 38.16 31.69 28.34 26.71 24.09 20.82 17.54 1.762
content (%) PNG 45.32 44.05 42.85 42.27 41.16 39.83 38.50 37.31 36.77 36.21 35.55 32.40 23.06 20.89 18.86 1.399
Seed PBG 80.00 82.00 82.00 84.00 84.00 86.00 86.00 86.00 86.00 86.00 82.00 82.00 78.00 78.00 78.00 3.615
germination2 PNG 78.00 81.00 82.00 84.00 84.00 86.00 88.00 88.00 88.00 88.00 84.00 84.00 80.00 79.00 79.00 4.108
(%)
Where, PBG: Pusa Basanti Gainda; PNG: Pusa Narangi Gainda; 1Average of three replicates from 10 flower buds in each replicate; 2Average of four
replicates from 50 seeds in each replicate

Table 4. Total oil content (%) during seed maturation among the genotypes at two different stages of seed maturity.
Genotypes Physiological Harvest maturity Mean Thus, it provides a biochemical basis for seed maturation in
maturity marigold. However, total oil content in marigold seeds is reporting
PBG 35.47 31.26 33.37 here for the first time it may be further studied elaborately
PNG 36.83 33.10 34.97 particularly on seed oil content.
Mean 36.15 32.18 From the present study (over two years), it can be concluded that
Factors SE(m) ± CD @ 0.05 on-set of germination starts between 8 to 10 DFA and matured
seeds of marigold can be safely harvested between 46-48 DFA
Genotype 0.407 1.231 in African types. Further, total oil content in developing seeds
Stage 0.288 0.870 provided a biochemical basis for the seed maturation in marigold
and the oil quantity obtained was significantly high alike in
Genotype x Stage 0.576 NS
Asteraceae crops like sunflower and calendula.
Where, PBG: Pusa Basanti Gainda; PNG: Pusa Narangi Gainda
crop undergoes a physiological, biochemical and morphological Acknowledgement
changes in seeds (Delouche, 1973). To reap the maximum quality The authors thank Dr. K. Ali, Division of Plant Bio-Chemistry,
in seeds, understanding the optimum stage of seed harvest is ICAR-Indian Agricultural Research Institute, New Delhi for his
crucial. In our results, maximum germination was achieved
assistance during Soxhlet method of seed oil estimation.
during 42-44 DFA in African marigold; but at this stage, seeds
possess a higher moisture content, which it is not advisable to
safe harvest. As the seed maturity advances, moisture content
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