ORIGINAL SCIENTIFIC PAPER | 275

Phenotypic Diversity of Jute Mallow

(Corchorus olitorius L.) Germplasm

Gloria AFOLAYAN1 ( ) ✉
Adesike Oladoyin KOLAWOLE2
Damilare Adewumi ADETUNJI3
Bisola Khadijat OLADIMEJI1
Adam Akinloye OLOSUNDE1
Clement MICHAEL1
Dickson Junior NWOSU1
Salimat SULYMAN1
Anthony Ugochukwu OKERE1
Sunday Ezekiel ALADELE1

Summary

Corchorus olitorious L. is a leafy vegetable with antibacterial properties useful in the

treatment of numerous diseases and having the potential to alleviate malnutrition. Despite
the efficient role that varietal evaluation plays in breeding programmes to improve traits,
C. olitorious is still under-researched. The objective of this study was to (i) characterize
phenotypic variation in agronomic traits of germplasm collection of C. olitorious and (ii)
identify superior accessions exhibiting desirable traits useful in a breeding programme for
further improvement. The study examined 40 core collections of C. olitorious held at the
National Centre for Genetic Resources and Biotechnology (NACGRAB), Ibadan, Nigeria.
The experiment was laid out under field conditions in an 8×5 α-lattice design with three
replicates over two years. Qualitative and quantitative data were collected and analysed.
Combined analysis of variance revealed highly significant (P < 0.001) mean squares between
accessions for all measured traits. This variability can be exploited when selecting for these
traits and can also speed up the identification of outstanding Corchorus accessions. The shift
in mean performance of some accessions from the mean of the 40 accessions suggests that
these accessions are potential sources of favourable alleles that may be useful for C. olitorious
improvement. The results of the principal component analysis revealed discriminating
features. The cluster patterns indicate intra-specific variability useful in selecting
complementary parental lines. Accessions NGB00215, NGB00229, NGB00200, NGB00205,
NGB00221, NGB00224, NGB00230 and NGB01261 were identified as outstanding in their
performance with desirable traits. These accessions will be useful in future Corchorus breeding
programmes.

Key words

breeding, Corchorus olitorious L., characterization, selection, variability

1
National Centre for Genetic Resources and Biotechnology (NACGRAB), PMB 5382, Ibadan, Nigeria
2
Crop Production and Soil Science Department, Ladoke Akintola University of Technology, PMB 4000,
Ogbomoso, Nigeria
3
National Biotechnology Development Agency, Bioresources Development Center, Ilorin, Nigeria

✉ Corresponding author: ogo246@yahoo.com

Received: November 27, 2022 | Accepted: March 12, 2023 | Online first version published: July 20, 2023

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Introduction Materials and Methods

Corchorus olitorious L. belongs to Malvaceae family and is Genetic Material
widely known as jute mallow (Ghosh et al., 2013; Ngomuo et al.,
2017b). Africa is considered the centre of diversity and origin Forty accessions of C. olitorius were provided by the seed
(Dube et al., 2019). The genus Corchorus comprises about 215 genebank of the National Center for Genetic Resources and
species, subspecies, varieties and landraces, with about 60 species Biotechnology (NACGRAB) Ibadan, Nigeria for this study.
distributed across tropical, subtropical and warm temperate
regions of the world (Adjatin et al., 2019). Of these, only wild Experimental Site and Climatic Condition
white jute (C. capsularis L.) and cultivated tossa jute (C. olitorious The trials were conducted during the rainy season in 2019 and
L.), each with 2n = 14, which have evolved through conventional 2020 at the experimental field of NACGRAB (7°23'N latitude and
breeding, are distributed in Africa (Mukul and Akter, 2021). C. 3°53'E longitude), Ibadan, Nigeria.
olitorious has the potential to contribute to improved nutrition
as the leaves and tender shoots are a source of vitamins (A, C,
Experimental Setup and Cultural Practices
D), nutrients (carbohydrates, fat, ash, protein) and minerals
(potassium, calcium, iron, zinc). C. olitorious is also useful The experiment was set up in two phases. The accessions
for treating various diseases as it contains essential nutrients were first sown in the greenhouse, and then the seedlings were
(β-carotene, amino acids), phytochemicals and antioxidants transplanted to the field. In the greenhouse, the seeds were sown
(Mensah et al., 2008; Mavengahama et al., 2013; Nyadanu et al., with sterilised soil in plastic and the germinated seedlings were
2017; Adjatin et al., 2019). watered as needed. The seedlings were transplanted to the field
after 28 days. The field trial was laid out in an 8 x 5 α- lattice
A major constraint to the production of this important but
design with three replicates. Each experimental plot was a single
underutilised vegetable is the unavailability of improved cultivars.
row of 5 m × 0.5 m. The experimental field was ploughed and
Producers and consumers grow local landraces that are quite poor
harrowed with a tractor before the start of the trial. One week after
in terms of adaptability, productivity and nutrient composition,
transplanting and thereafter, the fertilizer was applied as needed.
leading to a drastic decline in returns on investment (Dinssa et al.,
To keep the plots weed-free, hand weeding was done when needed.
2016; Sogbohossou et al., 2018). Improvement of C. olitorious and
other wild relatives of jute mallow consumed as vegetables is very
Data Collection
limited (Nyadanu et al., 2017).
Both quantitative and qualitative morphological traits were
Studies on the morphological variability of the leaves of C.
used to assess the extent of variation between accessions from
olitorius have been reported (Nath and Denton, 1980; Akroda,
seedling stage to maturity. For the quantitative traits, five plants
1985). Due to the great interest in the leafy vegetable, several
per plot were sampled. Data were collected as described by
accessions have been divided into segregating populations of
Loumerem and Alercia (2016) and Ngomuo et al., (2017a).
different leaf types (National Horticultural Research Institute,
1986; Opabode and Adebooye, 2005). In addition, heritability, Days to flowering were measured as the number of days from
genetic advantage and association of quantitative vegetative traits seed germination to flowering of 50% of the plants. Plant height
with leaf yield of C. olitorius were reported by Nwangburuka and (PH) was measured at the time of average flowering (cm). Petiole
Denton (2012). In C. olitorius, only a few studies on leaf yield traits length (PTL) was measured from the petiole (cm). Leaf length
have been conducted with few accessions. (LL) was measured on a mature leaf lamina from the proximal
end of the mid vein to the distal end (cm). Leaf width (LW) was
Germplasm collection and conservation is important for
measured on a mature leaf at the widest point (cm). Leaf length to
creating variation, but genetic variation within C. olitorius is
width ratio (LWR) was measured as the ratio between the length of
low due to self-pollination (Hossain et al., 2002). This narrow
the leaf blade and the leaf width. Stem width (SW) was measured
genetic base makes it vulnerable to biotic and abiotic challenges
as the diameter of the plant base at ground level. The number of
(Kamannavar et al., 2016). Corchorus species have a high degree of
primary (PB) and secondary branches (SB) was counted as the
interspecific variability but a low degree of intra-specific variability
number of branches of the main stem and the number of branches
(Kar et al., 2009). Characterisation of genetic variation in newly
of the secondary stem, respectively, and the number of days to
collected C. olitorious through in-depth study of leaf yield and other
maturity (DM) was measured as the number of days from sowing
agronomic traits is of utmost importance for their improvement
to maturity of the pods of the whole plot.
and utilisation (Ngomuo et al., 2017b). Although molecular
genotyping is a tool for plant characterization, information on Seed characteristics that were measured included the total
phenotype obtained from morphological characterization is only number of mature pods per plant (NPP), the length of the pod
a starting step towards improvement. Phenotypic characterization (PDL) excluding the stem (cm), the total number of mature seeds
would give a clear overview of the traits of interest to breeders and in a pod (S) and the weight of 1,000 dry seeds (WTHS) in grams.
divergent genotypes could be identified (Adebola and Morakinyo,
The qualitative traits measured were: plant growth habit (3 =
2006).
upright 5 = intermediate and 7 = prostrate), leaf colour (1 = light
This study was conducted to: (i) characterise phenotypic green, 2 = dark green, 3 = glossy light green, 4 = glossy dark green
variation in C. olitorious germplasm traits; and (ii) identify and 5 = red), leaf shape (1 = ovate, 2 = elliptical, 3 = lanceolate, 4 =
superior accessions that have desirable traits useful in breeding orbicular and 5 = palmate), leaf margin (1 = entire, 2 = serrulate, 3
for further improvement. = dentate, 4 = serrate 5 = double serrate, 6 = cleft and 7 = crenate),

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stem colour (1= light green, 2 = dark green, 3 = light red and 4 = base, while 25% had a round leaf base. The leaf shapes identified
dark red) stem hair (0 = absent and 1 = present), leaf base (1 = were elliptic (37.5%), lanceolate (30.0%), ovate (17.5%) and
acute, 2 = round). palmate (15%). The variation observed in leaf margins showed
that serrated margins predominated (85%), while 15% of the
Data Analyses accessions had split margins. There was no variation in stem
colour and pubescence, as all C. olitorius accessions evaluated had
Data on qualitative characteristics were recorded and
green stem colour without pubescence (Table 1).
expressed in frequencies. The analysis of variance (ANOVA)
was first conducted on a year-by-year basis before a combined
ANOVA was conducted across the year to determine significant Table 1. Qualitative variation at vegetative and maturity stages among the 40
mean squares for all quantitative traits measured. The collected evaluated Corchorus olitorius L. accessions
data were subjected to ANOVA using the general linear model
Qualitative traits Observation Frequency Percentage
procedure (PROC GLM) of the Statistical Analysis System
software (SAS Institute, 2011) using a random statement with test Plant growth habit Intermediate 27 67.5
option to assess the main effects of year, replication, accession
and their interaction. Replications and years were treated as Upright 13 32.5
random factors and accessions as fixed factors. Input means
were adjusted for block effects according to the lattice design Leaf color Dark green 24 60.0
(Cochran and Cox, 1992). Mean, range, standard error (S.E.)
Glossy dark green 7 17.5
and coefficient of variation (CV) for each trait were estimated,
and the least significant difference (LSD) test was applied for Light green 9 22.5
pairwise comparisons of trait means (P < 0.05). The phenotypic
and genotypic coefficients of variation (PCV, GCV) as well as Leaf base Acute 30 75.0
heritability in a broad sense (H2) were estimated using standard
formulae (Johnson et al., 1955; Mather, 1982; Falconer, 1989). Round 10 25.0
Percentage heritability was categorised as low (< 50%), moderate
Leaf shape Elliptical 15 37.5
(50%) and high (> 50%) as reported by Robinson et al. (1949) and
Afolayan et al. (2020). Lanceolate 12 30.0
Pearson's correlation coefficients (r) were used to determine
Ovate 7 17.5
the relationships between the traits. Multivariate analysis was
performed to identify traits that captured morphological variation Palmate 6 15.0
among accessions. Prior to multivariate analysis, the means of the
data were standardised to eliminate effects resulting from the use Leaf margin Cleft 6 15.0
of different scales. Principal component analysis (PCA) was used
to identify traits contributing to variation between accessions, Serrate 34 85.0
using SAS version 9.4 (SAS Institute, 2011). Hierarchical cluster Stem color Green 40 100
analysis was performed for the accessions, using the Euclidean
distance matrix as input to the clustering algorithm and Ward's Stem hair Absent 40 100
minimum variance criterion (Ward, 1963) to minimise the total
variance within the cluster. The result of the clustering was
presented as a dendrogram that grouped the accessions based on Variation in Quantitative Traits
their phenotypic similarity patterns (R statistical software, version Combined analysis of variance (ANOVA) revealed significant
4.2.0, 2022). Base index selection (Williams, 1962; Kolawole and (P < 0.001) mean squares for years of assessment for all traits
Olayinka, 2022) and rank summation index (RSI) (Mulamba except pod length (Table 2). A significant effect of replication
and Mock, 1978; Kolawole et al., 2021) were used to identify was observed for all traits measured except leaf width, days to
outstanding accessions over two years. maturity, number of pods per plant and pod length. Plant height,
stem width and number of pods per plant were influenced by the
Results block. There were highly significant (P < 0.001) mean squares
between accessions for all traits measured. Similarly, the mean
Variation in Qualitative Traits squares of the interaction between the accessions and the year
were significant (P < 0.001) for all measured traits.
Qualitative traits were recorded on the same day to avoid
variation, and the two years of assessment had no effect on these Mean squares for all measured traits were larger than variances
traits. Clear variations were found in the growth habit of the plants due to accession × year interaction and residual variance. The
and some morphological traits (colour, base, shape and margin). coefficient of variation (CV) ranged from 0.96 to 14.3% for most
Two growth forms were identified, with 67.5% of the accessions measured traits, indicating high experimental precision, except
having a medium growth form and 32.5% having an erect growth for leaf width, number of pods per plant and number of primary
form. The leaf colour of most (60%) accessions was dark green, and secondary branches. There were considerable differences
22.5% had a light green colour and 17.5% had a glossy dark green between the minimum and maximum values for all evaluated
colour. The majority of the accessions (75%) had a pointed leaf traits (Table 3).

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Table 2. Combined analysis of variance for quantitative traits of Corchorus olitorius L. accessions evaluated

Plant height Stem width Leaf length Leaf width Leaf length-width Petiole length Days to flowering
Source of variation df
(cm) (cm) (cm) (cm) ratio (cm) (days)

Year (Y) 1 58337.46*** 22.96*** 511.79*** 187.62*** 0.73*** 930.20*** 2076.82***

Replication (Rep) (Y) 4 1026.23*** 0.26*** 9.08*** 1.93 0.78*** 0.48*** 48.80

Block (Y x Rep) 42 218.51*** 0.03*** 0.40 1.60 0.07 0.05 40.52

Accession 39 423.01*** 0.05*** 6.25** 8.56*** 1.06*** 2.98*** 146.63***

Agric. conspec. sci. Vol. 88 (2023) No. 4

Accession x Y 39 268.87*** 0.04*** 4.20*** 5.94*** 0.27*** 2.50*** 64.67**

Error 144 69.03 0.01 0.4 1.64 0.09 0.05 31.68

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CV 9.0 10.81 0.96 38.64 12.8 7.75 6.66

Days Number of primary Number of secondary Number of Weight of 1000 seeds Seeds Pod length
df
to maturity branches branches pods/plant (g) per pod (cm)

Year (Y) 1 624.04*** 531.78*** 460.73*** 125694.49*** 0.91*** 119207.52*** 0.02

Replication (Rep) (Y) 4 36.93 141.19*** 42.04** 357.76 0.38*** 857.63** 0.24

Block (Y x Rep) 42 20.38 7.71 14.44 448.37*** 0.05 234.82 0.20

Accession 39 76.48*** 10.14** 20.53** 2330.12*** 0.17*** 1594.08*** 0.81***

Accession x Y 39 58.27*** 18.11*** 34.02*** 2244.85*** 0.10** 1455.89*** 0.30*

Error 144 16.53 5.52 11.69 204.92 0.05 217.50 0.19

CV 3.05 23.72 35.04 22.85 14.13 12.26 9.19

Note: *, **, *** significant at 0.05, 0.01 and 0.001 probability levels, respectively
 Phenotypic Diversity of Jute Mallow (Corchorus olitorius L.) Germplasm | 279

Table 3. Descriptive statistics for quantitative traits of Corchorus olitorius L. accessions evaluated over two years

Range
Traits LSD (0.05) % Difference Mean±SE
Minimum Maximum

Plant height (cm) 76.07 117.41 9.5 35 92.34±1.48

Stem width (cm) 0.79 1.27 0.12 38 0.99±0.02

Leaf length (cm) 5.17 10.35 0.72 50 6.94±0.18

Leaf width (cm) 1.94 9.82 1.47 80 3.32±0.21

Leaf length-width ratio 1.24 2.89 0.34 57 2.32±0.07

Petiole length (cm) 1.08 4.59 0.26 77 2.90±0.14

Days to flowering (days) 65.1 97.4 6.44 33 84.48±0.86

Days to maturity 126.13 143.94 4.65 12 133.41±0.60

Number of primary branches 7.26 13.91 2.69 48 9.91±0.24

Number of secondary branches 5.79 12.89 3.91 55 9.75±0.31

Number of pods/plant 34.38 140.54 16.37 76 62.66±3.32

Weight of 1000 seeds (g) 1.19 2.19 0.27 46 1.54±0.03

Seeds per pod 82.2 162.22 14.4 49 121.03±2.76

Pod length (cm) 3.96 5.88 0.54 33 4.73±0.06

The largest range (> 50%) was found for leaf length, leaf length The leaf, the most important edible part of the vegetable,
to leaf width ratio, number of pods per plant, petiole length, also showed significant differences. Leaf length was 5.2 cm in
leaf width and number of primary and secondary branches. The NGB00210 and 10.3 cm in NGB00224 with a mean of 6.9 cm. Leaf
smallest range (< 35 %) was for the number of days to maturity, width ranged from 1.9 cm in NGB00217 to 9.8 cm in NGB00207
pod length and the number of days to flowering. Variations in with a mean of 3.3 cm, while the ratio between leaf length and
vegetative traits were the result of a wide range of values in traits width ranged from 1.2 to 2.9 in NGB00207 and NGB01261 with
such as plant height, stem width, leaf length and leaf width, with a mean of 2.3 cm. The longest petiole (4.6 cm) was recorded for
values ranging from 76.1 to 117.4 cm, 0.8 and 1.3 cm, 5.2 and 10.4 accession NGB00226 and the shortest for NGB00200 (1.1 cm).
cm and 1.9 and 9.8 cm, respectively. A wide range of values was The number of primary branches ranged from 7.3 (NGB00212)
also observed for traits such as number of primary and secondary to 13.9 (NGB00236) with a mean of 9.9, while the number
branches, the weight of 1000 seeds and number of pods per plant. of secondary branches ranged from 5.8 (NGB00195) to 12.9
The number of days to 50% flowering and the number of days to (NGB00207) with a mean of 9.8. The number of days to maturity
maturity also varied considerably, with values ranging from 65 to ranged from 126.1 (NGB01261) to 143.9 days (NGB00207) with
97 days and 126 to 144 days, respectively. Looking at the overall a mean of 133.4 days. The longest pod (5.9 cm) was found in the
average performance of the Corchorus accessions assessed, 23 to variety NGB00277, the shortest was NGB00217 with 4.0 cm. The
50 % of the accessions had a higher mean value for each measured variety NGB00229 had more pods than the other varieties with
trait compared to the overall mean value of the 40 accessions 140.5 pods per plant, while NGB00232 had the lowest number of
assessed (Table 4). pods (34.4). The variety NGB00192 had the highest number of
seeds per pod (162.2), while NGB00199 had the lowest number
The average performance of the accessions showed that the
of seeds per pod (82.2) with a mean of 121.0. The weight of 1000
shortest number of days to flowering was observed in accession
seeds ranged from 1.2 g (NGB00222) to 2.2 g (NGB00210) with a
NGB00195, which flowered in 65 days, and the accession that
mean of 1.5 g.
flowered late (97 days) was NGB00652. The accession NGB00232
was the tallest (117.4 cm), while the accession NGB00193 was the
shortest with a height of 76.1 cm. The stem width of all cultivars
was comparable, with cultivar NGB00237 having the thickest stem
at 1.3 cm, while cultivar NGB00200 had a slender stem with a
diameter of 0.8 cm.

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Table 4. Mean performance of agronomic traits in Corchorus olitorius L. accessions over two years

Accession PH SW LL LW LWR PTL DTF DM PB SB NPP WTHS SP PDL

NGB00189 89.1±3.94 0.9±0.05 6.3±0.30 3.4±0.61 2.5±0.14 1.7±0.11 78.6±2.67 132.9±1.93 11.3±1.11 11.0±1.62 57.7±6.78 1.4±0.10 114.5±6.99 5.0±0.21

NGB00192 87.2±3.98 1.0±0.05 7.3±0.30 3.4±0.61 2.6±0.14 3.2±0.11 79.8±2.69 131.2±1.95 11.0±1.13 9.5±1.64 70.8±6.85 1.5±0.10 162.2±7.06 4.8±0.21

NGB00193 76.1±3.89 1.2±0.05 8.0±0.30 4.4±0.60 2.2±0.14 4.1±0.11 92.0±2.63 138.4±1.90 9.1±1.10 6.9±1.60 38.2±6.70 1.5±0.10 91.5±6.94 4.7±0.21

NGB00195 95.8±3.93 0.9±0.05 7.0±0.30 4.0±0.61 1.9±0.14 3.5±0.11 65.1±2.66 132.1±1.92 8.8±1.11 5.8±1.62 49.9±6.78 1.6±0.10 134.9±6.98 4.9±0.21

NGB00196 82.1±3.92 0.8±0.05 6.7±0.30 2.6±0.61 2.4±0.14 2.9±0.11 87.0±2.66 133.7±1.92 9.8±1.11 9.0±1.61 60.3±6.76 1.4±0.10 120.6±6.97 4.8±0.21

NGB00197 94.6±3.98 1.0±0.05 7.2±0.30 2.7±0.61 2.9±0.14 3.1±0.11 82.8±2.70 133.2±1.95 8.5±1.13 11.3±1.64 60.8±6.86 1.7±0.10 129.8±7.07 5.0±0.21

NGB00198 84.4±3.88 1.0±0.05 6.1±0.30 3.4±0.60 1.9±0.14 2.0±0.10 79.8±2.63 134.7±1.90 9.2±1.10 8.8±1.60 61.6±6.68 1.5±0.10 107.6±6.89 5.1±0.20

NGB00199 87.8±3.87 0.9±0.05 5.4±0.29 2.4±0.60 2.1±0.14 2.1±0.10 83.4±2.62 136.7±1.89 9.4±1.09 7.9±1.59 47.2±6.67 1.5±0.10 82.2±6.92 4.0±0.20
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NGB00200 85.0±3.97 0.8±0.05 5.6±0.30 2.0±0.61 2.8±0.14 1.1±0.11 81.8±2.69 129.4±1.94 7.8±1.12 11.4±1.63 119.5±6.83 1.4±0.10 127.2±7.04 5.0±0.21

NGB00202 83.2±3.92 1.0±0.05 8.0±0.30 3.0±0.60 2.6±0.14 3.3±0.11 87.6±2.65 130.4±1.92 8.9±1.11 7.9±1.61 59.6±6.75 1.6±0.10 143.5±6.95 4.7±0.21

NGB00204 82.1±3.88 1.0±0.05 7.0±0.30 3.1±0.60 2.1±0.14 2.8±0.10 87.0±2.63 132.5±1.90 9.4±1.10 9.5±1.59 62.4±6.68 1.6±0.10 98.4±6.88 4.7±0.20
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NGB00205 103.8±3.95 1.1±0.05 7.4±0.30 3.3±0.61 2.5±0.14 3.4±0.11 86.0±2.67 131.4±1.93 8.5±1.12 10.2±1.62 62.0±6.80 1.6±0.10 152.7±7.01 5.6±0.21

NGB00207 87.6±3.92 1.0±0.05 6.1±0.30 9.8±0.60 1.2±0.14 1.9±0.11 83.2±2.66 143.9±1.92 9.4±1.11 12.9±1.61 76.6±6.75 1.7±0.10 143.3±7.01 4.4±0.21

NGB00208 78.2±3.96 0.9±0.05 5.5±0.30 4.2±0.61 1.6±0.14 1.8±0.11 82.0±2.69 134.2±1.94 8.8±1.12 7.5±1.63 45.3±6.83 1.4±0.10 101.6±7.04 4.5±0.21

NGB00209 80.1±3.94 1.1±0.05 7.4±0.30 2.4±0.61 2.7±0.14 3.8±0.11 86.0±2.67 134.5±1.93 11.3±1.11 12.1±1.62 67.2±6.78 1.2±0.10 124.8±6.99 5.1±0.21

NGB00210 100.0±3.94 1.0±0.05 5.2±0.30 3.4±0.61 1.5±0.14 1.7±0.11 75.2±2.67 126.7±1.93 10.5±1.11 9.6±1.62 101.8±6.79 2.2±0.10 104.3±7.00 4.4±0.21

NGB00212 89.1±3.88 0.9±0.05 6.1±0.30 2.8±0.60 2.4±0.14 1.7±0.10 81.3±2.63 128.5±1.90 7.3±1.10 8.9±1.59 58.5±6.68 1.6±0.10 128.8±6.92 4.5±0.20

NGB00213 88.6±3.93 0.9±0.05 5.7±0.30 2.7±0.61 2.3±0.14 2.6±0.11 86.8±2.66 136.6±1.92 11.8±1.11 11.6±1.62 56.7±6.78 1.4±0.10 119.3±6.98 4.5±0.21

NGB00215 107.9±3.88 1.1±0.05 9.2±0.30 3.9±0.60 2.9±0.14 4.4±0.10 80.8±2.63 132.3±1.90 11.9±1.10 9.0±1.59 73.6±6.68 1.7±0.10 136.4±6.88 4.4±0.20

NGB00217 86.0±3.91 0.9±0.05 5.4±0.30 1.9±0.60 2.2±0.14 2.1±0.11 85.9±2.65 129.6±1.91 8.2±1.11 8.1±1.61 70.9±6.74 1.3±0.10 82.2±6.92 4.0±0.20

NGB00218 92.3±3.93 1.0±0.05 5.5±0.30 3.0±0.61 1.9±0.14 2.9±0.11 83.3±2.66 135.5±1.92 8.6±1.11 8.6±1.62 58.1±6.78 1.3±0.10 101.4±7.04 4.1±0.21

NGB00221 101.8±3.99 1.1±0.05 8.3±0.30 3.4±0.62 2.5±0.14 2.9±0.11 90.6±2.70 131.4±1.95 8.7±1.13 8.3±1.64 46.5±6.87 1.6±0.11 159.2±7.14 5.0±0.21

NGB00222 87.7±3.93 1.1±0.05 6.6±0.30 2.4±0.61 2.7±0.14 3.8±0.11 86.4±2.66 136.4±1.93 11.0±1.11 12.1±1.62 69.2±6.78 1.2±0.10 118.8±6.98 4.3±0.21

NGB00224 106.2±3.91 1.0±0.05 10.3±0.30 4.1±0.60 2.4±0.14 3.8±0.11 86.4±2.65 128.1±1.92 9.9±1.11 10.8±1.61 67.6±6.74 1.7±0.10 114.9±7.00 4.7±0.21
 Table 4. Continued

Accession PH SW LL LW LWR PTL DTF DM PB SB NPP WTHS SP PDL

NGB00225 99.4±3.99 1.1±0.05 6.7±0.30 2.7±0.62 2.4±0.14 3.1±0.11 89.9±2.70 136.9±1.95 8.9±1.13 12.6±1.64 69.9±6.87 1.5±0.11 135.2±7.16 4.3±0.21

NGB00226 99.2±3.90 0.9±0.05 6.7±0.30 4.3±0.60 1.7±0.14 4.6±0.11 79.1±2.64 136.2±1.91 8.9±1.10 9.3±1.61 55.9±6.73 1.6±0.10 110.7±6.93 4.3±0.20

NGB00228 85.0±4.14 0.8±0.05 6.0±0.32 2.5±0.64 2.2±0.15 2.4±0.11 87.2±2.80 130.5±2.02 11.4±1.17 12.3±1.70 40.0±7.12 1.5±0.11 115.6±7.34 4.5±0.22

NGB00229 110.8±4.00 1.1±0.05 7.5±0.30 2.7±0.62 2.6±0.14 3.1±0.11 84.6±2.71 129.2±1.96 9.4±1.13 12.6±1.64 140.5±6.89 1.5±0.10 121.7±7.09 5.1±0.21

NGB00230 93.3±4.08 1.0±0.05 9.0±0.31 3.4±0.63 2.6±0.15 4.1±0.11 81.8±2.76 132.1±1.99 10.7±1.15 8.8±1.68 44.4±7.02 1.6±0.11 125.3±7.23 4.8±0.21

NGB00231 99.1±4.14 1.0±0.05 6.9±0.32 2.5±0.64 2.6±0.15 3.7±0.11 84.5±2.80 137.6±2.02 11.9±1.17 6.0±1.70 82.0±7.12 1.6±0.11 119.6±7.34 4.3±0.22

NGB00232 117.4±3.93 1.2±0.05 6.6±0.30 5.1±0.61 1.4±0.14 4.2±0.11 86.6±2.66 132.9±1.92 8.5±1.11 9.5±1.62 34.4±6.76 1.8±0.10 134.6±6.97 5.1±0.21

NGB00233 88.7±3.93 1.0±0.05 6.6±0.30 2.0±0.61 2.7±0.14 2.3±0.11 82.0±2.66 132.7±1.92 10.1±1.11 10.4±1.62 48.8±6.77 1.6±0.10 118.1±7.02 4.9±0.21
Agric. conspec. sci. Vol. 88 (2023) No. 4

NGB00235 94.5±3.91 1.0±0.05 6.6±0.30 2.4±0.60 2.7±0.14 2.3±0.11 90.6±2.65 139.6±1.91 13.1±1.11 10.9±1.61 69.9±6.74 1.7±0.10 109.6±6.98 4.6±0.21

NGB00236 96.1±3.93 1.0±0.05 7.1±0.30 3.5±0.61 2.6±0.14 2.9±0.11 84.3±2.66 130.9±1.92 13.9±1.11 11.3±1.62 55.9±6.76 1.5±0.10 119.9±6.97 4.9±0.21

NGB00237 92.4±3.89 1.3±0.05 7.0±0.30 4.0±0.60 2.0±0.14 3.4±0.11 94.4±2.63 139.8±1.90 11.6±1.10 8.4±1.60 38.9±6.70 1.6±0.10 112.1±6.90 4.9±0.20

Phenotypic Diversity of Jute Mallow (Corchorus olitorius L.) Germplasm | 281

aCS

NGB00277 102.8±3.87 1.0±0.05 8.2±0.30 2.7±0.60 2.7±0.14 2.3±0.10 85.0±2.62 132.0±1.90 8.0±1.10 7.9±1.59 52.4±6.67 1.9±0.10 126.9±6.93 5.9±0.20

NGB00651 90.8±3.87 0.9±0.05 6.3±0.29 2.3±0.60 2.7±0.14 2.7±0.10 87.2±2.62 134.7±1.89 11.7±1.09 11.3±1.59 68.0±6.66 1.4±0.10 123.1±6.87 5.2±0.20

NGB00652 79.6±3.94 1.2±0.05 7.9±0.30 5.1±0.61 1.7±0.14 3.6±0.11 97.4±2.67 139.0±1.93 9.9±1.11 6.4±1.62 34.5±6.78 1.3±0.10 102.3±6.99 4.2±0.21

NGB00653 92.7±3.88 0.9±0.05 7.7±0.30 2.7±0.60 2.7±0.14 2.6±0.11 87.1±2.63 131.9±1.90 9.0±1.10 11.9±1.60 54.6±6.69 1.3±0.10 101.8±6.89 4.6±0.20

NGB01261 95.2±3.93 1.0±0.05 7.6±0.30 3.0±0.61 2.9±0.14 2.2±0.11 79.2±2.66 126.1±1.92 10.3±1.11 11.9±1.62 74.2±6.77 1.4±0.10 110.4±6.97 5.1±0.21

Mean 92.34 0.99 6.94 3.32 2.32 2.90 84.48 133.41 9.91 9.75 62.66 1.53 119.68 4.72
Standard
9.34 0.10 1.12 1.32 0.44 0.86 5.43 3.83 1.51 1.94 20.97 0.19 18.29 0.41
Deviation
Minimum 76.07 0.79 5.17 1.94 1.24 1.08 65.10 126.13 7.26 5.79 34.38 1.19 82.20 3.96

Maximum 117.41 1.27 10.35 9.82 2.89 4.59 97.40 143.94 13.91 12.89 140.54 2.19 162.22 5.88

Range 41.34 0.48 5.18 7.89 1.65 3.51 32.30 17.81 6.65 7.10 106.16 1.00 80.02 1.92

Note: PH = plant height; SW = stem width; LL = leaf length; LW = leaf width; LWR = leaf length-width ratio; PTL = petiole length; DTF = days to flowering; DM = days to maturity; PB = number of primary branches; SB = number
of secondary branches; NPP = number of pods per plant; WTHS = weight of 1000 seeds; SP = seeds per pod; PDL = pod length
282 | Gloria AFOLAYAN et al.

Selection of Superior Accessions and Estimation of Vari- The number of primary and secondary branches was similarly
ability Components related to other agronomic traits. The number of pods per plant
was positively correlated with all growth-related traits, but had
The results obtained using the selection indices showed that
a negative correlation with the number of days to flowering
the Mulamba and Mock Index (RSI) and the Williams Base
(r = -0.31). All measured traits showed a moderate negative
Index jointly identified 12 accessions as either best or worst
correlation with 1000 seed weight. The number of seeds per pod
performers (Table 5). The weight-based (base index) and weight-
showed a strong positive relationship with other traits, except for
free (RSI) selection indices identified similar accessions as the
the number of days to flowering and the weight of 1000 seeds (r
best (NGB00215 and NGB00229) and the worst (NGB00217,
= -0.28 and r = -0.18). Pod length was positively correlated with
NGB00208, NGB00199 and NGB00652) performers in selecting
plant height, leaf length to width ratio and number of seeds per
the top five accessions. For each of the selection indices used,
pod, while it was negatively correlated with number of days to
about 2 to 4 of the identified outstanding accessions showed high
maturity.
performance on all measured traits compared to the overall mean
of the selected accessions. The highest selection differences for
Principal Component Analysis and Cluster Analysis
most of the measured agronomic traits were predicted by RSI,
except for the number of pods per pod, seeds per pod and pod In order to get a clearer overview of the traits that contribute
length. Of the 40 accessions evaluated, the other outstanding persistently to the variation observed between accessions and the
Corchorus accessions in the top five of the two selection indices similarities between accessions in the traits measured, principal
were NGB00200, NGB00205, NGB00221, NGB00224, NGB00230 component analysis (PCA) and cluster analysis were effective.
and NGB01261. The PCA results showed the contribution of each agronomic trait
to the variation observed within the accessions. The eigenvalue
To identify traits that can be improved later, the estimates
indicating the relative distinctiveness of the principal axes was
of genetic parameters are essential. The values of phenotypic
5.09 for axis 1 to 1.11 for axis 4 (Table 8). The first four major axes
variance were higher than genotypic variance in all years for
had eigenvalues > 1 and accounted for 67% of the total cumulative
all traits measured (Table 6). High phenotypic and genotypic
variation among the agronomic traits of Corchorus accessions.
variance values were found for plant height, number of days to
About 50% (7) of the measured traits, namely plant height, stem
flowering, number of secondary branches, number of pods per
width, leaf length, petiole length, number of primary branches,
plant and seeds per pod. Other traits measured, however, had low
number of pods per plant and seeds per pod, were associated with
phenotypic and genotypic variance values. The highest PCV was
PC1 and accounted for 36% of the total variation. The other PC
recorded for the number of secondary branches and the lowest for
axes had only one trait each, as the highest coefficient for a given
the number of days to maturity. Broad-sense heritability estimates
trait represents relatedness to a PC axis. PC2 was characterized by
were high (58-75%) for leaf length to leaf width ratio, number
the relationship between leaf length and width and contributed
of days to flowering, pod length and number of primary and
16% to the total variation. The only trait related to PC3 was the
secondary branches. Other traits had low broad-sense heritability
number of days to flowering and PC 4 was associated with pod
estimates (7-29%).
length; both traits contributed 9% and 8% to the total variation
between accessions, respectively. It was also observed that leaf
Correlation among Agronomic Traits width, days to maturity, number of secondary branches and 1000
Pearson's correlation coefficient (r) measures the degree of seed weight had negative loadings on PCs 2 to 4 with -0.46, -0.45,
association between two traits and provides information about -0.63 and -0.66, respectively.
the direction and magnitude of the relationships. In this study,
Cluster analysis from this study revealed two distinct groups.
the correlation coefficient (r) showed either positive or negative
The clusters highlight the genetic diversity between accessions and
significant (P < 0.001) relationships between the traits (Table 7).
group together those with similar traits (Fig. 1). Cluster I had only
Of the 14 quantitative characteristics, 10 were observed to have
one unique accession (NGB00207), which had the widest leaf, the
high positive significant correlations. The strongest positive
longest number of days to maturity and the highest number of
significant (P < 0.001) correlation was observed between leaf
secondary branches, but had the smallest leaf length-width ratio,
petiole length and stem width (r = 0.83). On the other hand, the
while cluster II was further divided into subgroups according to
strongest negative significant (P < 0.001) correlation was found
Gower distance (Gower 1971). In this cluster, accession NGB00210
between leaf length-width ratio and leaf width (r = -0.48). A
was isolated, having the shortest leaf length and the highest 1000-
strong positive correlation was found between stem width and
seed weight; the subgroup further isolated accession NGB00200,
plant height (r = 0.82). Leaf length was positively associated with
which had the smallest stem width and the shortest leaf petiole
plant height (r = 0.65) and stem width (r = 0.71). Similarly, leaf
length.
width was positively correlated with the following traits: plant
height (r = 0.29), stem width (r = 0.41) and leaf length (r = 0.40). This large cluster (II) was further subdivided into five (a, b,
A strong positive correlation was found between leaf stem length c, d, e) smaller units with at least two accessions. Five accessions
and the following traits: plant height (r = 0.72), leaf length (r = grouped in the cluster II 'a' are characterized by short leaves and
0.80) and leaf width (r = 0.39). On the other hand, the number of 80% of the accessions have an acute leaf base. The two accessions
days to flowering was negatively associated with plant height, stem in the cluster II 'b' flowered early and both had medium plant
width, leaf length and leaf petiole length, while the number of days growth, a dark green leaf colour, a round leaf base, a palmate leaf
to maturity showed a positive correlation with these traits. shape and a split leaf margin.

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Table 5. Ranking and mean of fourteen traits of Corchorus accessions, identified by selection index and rank summation index

Accessions PH SW LL LW LWR PTL DTF DM PB SB NPP WTHS SP PDL

Top 5 BASE INDEX

NGB00229 110.8 1.1 7.5 2.7 2.6 3.1 84.6 129.2 9.4 12.6 140.5 1.5 121.7 5.1

NGB00215 107.9 1.1 9.2 3.9 2.9 4.4 80.8 132.3 11.9 9.0 73.6 1.7 136.4 4.4

NGB00205 103.8 1.1 7.4 3.3 2.5 3.4 86.0 131.4 8.5 10.2 62.0 1.6 152.7 5.6

NGB00200 85.0 0.8 5.6 2.0 2.8 1.1 81.8 129.4 7.8 11.4 119.5 1.4 127.2 5.0

NGB00221 101.8 1.1 8.3 3.4 2.5 2.9 90.6 131.4 8.7 8.3 46.5 1.6 159.2 5.0

Mean of top 5 101.9 1.0 7.6 3.0 2.6 3.0 84.8 130.7 9.3 10.3 88.4 1.6 139.4 5.0

Grand mean 92.3 1.0 6.9 3.3 2.3 2.9 84.5 133.4 9.9 9.8 62.7 1.5 121.0 4.7

Selection differential (%) 10.3 2.5 9.6 -8.1 13.7 2.4 0.3 -2.0 -6.5 5.7 41.2 1.4 15.2 6.1

Bottom 5

NGB00217 86.0 0.9 5.4 1.9 2.2 2.1 85.9 129.6 8.2 8.1 70.9 1.3 82.2 4.0

NGB00208 78.2 0.9 5.5 4.2 1.6 1.8 82.0 134.2 8.8 7.5 45.3 1.4 101.6 4.5

NGB00199 87.8 0.9 5.4 2.4 2.1 2.1 83.4 136.7 9.4 7.9 47.2 1.5 82.2 4.0

NGB00652 79.6 1.2 7.9 5.1 1.7 3.6 97.4 139.0 9.9 6.4 34.5 1.3 102.3 4.2

NGB00193 76.1 1.2 8.0 4.4 2.2 4.1 92.0 138.4 9.1 6.9 38.2 1.5 91.5 4.7

Mean of bottom 5 81.5 1.0 6.5 3.6 1.9 2.8 88.1 135.6 9.1 7.4 47.2 1.4 92.0 4.3

Top 5 RANK SUMMATION INDEX

NGB00215 107.9 1.1 9.2 3.9 2.9 4.4 80.8 132.3 11.9 9.0 73.6 1.7 136.4 4.4

NGB00224 106.2 1.0 10.3 4.1 2.4 3.8 86.4 128.1 9.9 10.8 67.6 1.7 114.9 4.7

NGB00229 110.8 1.1 7.5 2.7 2.6 3.1 84.6 129.2 9.4 12.6 140.5 1.5 121.7 5.1

NGB01261 95.2 1.0 7.6 3.0 2.9 2.2 79.2 126.1 10.3 11.9 74.2 1.4 110.4 5.1

NGB00230 93.3 1.0 9.0 3.4 2.6 4.1 81.8 132.1 10.7 8.8 44.4 1.6 125.3 4.8

Mean of top 5 102.7 1.0 8.7 3.4 2.7 3.5 82.6 129.6 10.4 10.6 80.1 1.6 121.7 4.8

Grand mean 92.3 1.0 6.9 3.3 2.3 2.9 84.5 133.4 9.9 9.8 62.7 1.5 121.0 4.7

Selection differential (%) 11.2 3.1 25.5 3.1 14.8 20.6 -2.3 -2.9 5.4 8.7 27.8 1.5 0.6 1.8

Bottom 5

NGB00652 79.6 1.2 7.9 5.1 1.7 3.6 97.4 139.0 9.9 6.4 34.5 1.3 102.3 4.2

NGB00218 92.3 1.0 5.5 3.0 1.9 2.9 83.3 135.5 8.6 8.6 58.1 1.3 101.4 4.1

NGB00208 78.2 0.9 5.5 4.2 1.6 1.8 82.0 134.2 8.8 7.5 45.3 1.4 101.6 4.5

NGB00217 86.0 0.9 5.4 1.9 2.2 2.1 85.9 129.6 8.2 8.1 70.9 1.3 82.2 4.0

NGB00199 87.8 0.9 5.4 2.4 2.1 2.1 83.4 136.7 9.4 7.9 47.2 1.5 82.2 4.0

Mean of bottom 5 84.8 1.0 6.0 3.3 1.9 2.5 86.4 135.0 9.0 7.7 51.2 1.4 93.9 4.2

Note: PH = plant height; SW = stem width; LL = leaf length; LW = leaf width; LWR = leaf length-width ratio; PTL = petiole length; DTF = days to flowering; DM = days to
maturity; PB = number of primary branches; SB = number of secondary branches; NPP = number of pods per plant; WTHS = weight of 1000 seeds; SP = seeds per pod; PDL
= pod length. Selection differential is estimated as a proportion (%) of the grand mean.

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Table 6. Estimates of variability parameters and broad-sense heritability for agronomic traits among 40 accessions of Corchorus olitorius L.

Trait δ2p δ2g PCV (%) GCV (%) H2 (%)

Plant height (cm) 88.04 21.34 10.19 5.01 26.36

Stem width (cm) 0.01 0.00 11.11 2.91 9.14

Leaf length (cm) 0.65 0.26 11.69 7.37 21.56

Leaf width (cm) 2.10 0.46 43.79 20.51 28.89

Leaf length-width ratio 0.24 0.15 20.99 16.92 73.24

Petiole length (cm) 0.20 0.15 15.29 13.22 19.56

Days to flowering (days) 47.48 16.67 8.15 4.83 57.60

Days to maturity 19.54 3.60 3.31 1.42 25.04

Number of primary branches 8.23 3.02 28.92 17.53 70.49

Number of secondary branches 23.44 11.62 53.79 37.88 74.69

Number of pods/plant 233.33 30.15 24.51 8.81 6.84

Weight of 1000 seeds (g) 0.06 0.02 16.37 8.48 47.23

Seeds per pod 240.50 29.29 12.89 4.50 9.43

Pod length (cm) 0.29 0.11 11.45 6.92 66.90

Note: δ2p = Phenotypic variance, δ2g = Genotypic variance, PCV = Phenotypic coefficient of variation; GCV = Genotypic coefficient of variation; H2 = Heritability in broad
sense (%)

Table 7. Pearson correlation coefficients (r) for quantitative traits of Corchorus olitorius L. accessions

PH SW LL LW LWR PTL DTF DM PB SB NPP WTHS SP

SW 0.82***

LL 0.65*** 0.71***

LW 0.29*** 0.41*** 0.40***

LWR 0.00 -0.09 0.16*** -0.48***

PTL 0.72*** 0.83*** 0.80*** 0.39*** -0.08

DTF -0.31*** -0.19** -0.14* -0.11 0.03 -0.25***

DM 0.06 0.23*** 0.13* 0.32*** -0.18** 0.25*** 0.04

PB 0.53*** 0.53*** 0.41*** 0.18** 0.10 0.39*** -0.09 0.04

SB 0.39*** 0.34*** 0.27*** 0.22*** 0.06 0.22*** -0.21** -0.04 0.38***

NPP 0.65*** 0.58*** 0.42*** 0.21*** 0.13* 0.42*** -0.31*** -0.03 0.34*** 0.46***

WTHS -0.09 -0.21*** -0.14* -0.07 -0.13* -0.19** -0.09 -0.11 -0.20** -0.22*** -0.09

SP 0.61*** 0.61*** 0.51*** 0.30*** 0.12 0.60*** -0.28*** -0.01 0.31*** 0.26*** 0.51*** -0.18**

PDL 0.14* 0.01 0.09 -0.12 0.23*** 0.02 -0.02 -0.19** 0.08 0.00 0.09 0.08 0.23***

Note: *, **, *** significant at 0.05, 0.01 and 0.001 probability levels, respectively
PH = plant height; SW = stem width; LL = leaf length; LW = leaf width; LWR = leaf length-width ratio; PTL = petiole length; DTF = days to flowering; DM = days to maturity;
PB = number of primary branches; SB = number of secondary branches; NPP = number of pods per plant; WTHS = weight of 1000 seeds; SP = seeds per pod; PDL = pod length

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 Phenotypic Diversity of Jute Mallow (Corchorus olitorius L.) Germplasm | 285

Table 8. Eigenvalues, percentage of total variance and agronomic traits that contributed to the first four principal components of Corchorus olitorius L. accessions

Traits PC1 PC2 PC3 PC4

Plant height (cm) 0.39 0.07 -0.11 0.03

Stem width (cm) 0.40 -0.09 0.06 0.10

Leaf length (cm) 0.36 0.00 0.09 0.27

Leaf width (cm) 0.22 -0.46 -0.13 -0.05

Leaf length-width ratio 0.00 0.56 0.31 0.12

Petiole length (cm) 0.38 -0.12 0.02 0.26

Days to flowering (days) -0.15 -0.08 0.52 0.29

Days to maturity 0.08 -0.45 0.24 0.18

Number of primary branches 0.27 0.11 0.22 -0.15

Number of secondary branches 0.22 0.12 0.07 -0.63

Number of pods/plant 0.31 0.19 -0.14 -0.24

Weight of 1000 seeds (g) -0.11 0.00 -0.66 0.21

Seeds per pod 0.33 0.14 -0.09 0.15

Pod length (cm) 0.04 0.40 -0.17 0.42

Eigenvalue 5.09 1.86 1.26 1.11

% of total variance 36 13 9 8

Cumulative variance (%) 36 50 59 67

Note: only eigenvectors with values ≥0.30 which largely controlled each PC axes are boldfaced

Figure 1. Dendrogram for the 40 Corchorus olitorius L. accessions following Ward’s cluster analysis based on the Euclidean distance

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286 | Gloria AFOLAYAN et al.

The cluster II 'c' was the largest with 20 accessions and had into human diets and livestock feed. Accession NGB00195
the highest number of seeds per pod, primary and secondary flowered early and had the least number of secondary branches.
branches. The growth habit of the plants in this large group was This accession may not be desirable for Corchorus improvement
mostly medium, 95% had a pointed leaf base, but all had serrated as early flowering is a limiting factor for leaf production (Stoilova
leaf margins. The cluster II 'd' included 6 accessions that were et al., 2015). Plant height of Corchorus plant plays an important
superior in terms of plant height, leaf length, pod length and 1000- role in fibre production (Mukul and Akter, 2021), and accession
seed weight. Another characteristic of this cluster is the serrated NGB00232 was the tallest but with the lowest number of pods per
leaf margin and 83% of the accessions had a pointed leaf base as plant. Variety NGB00200 had the smallest stem width and the
well as a lanceolate leaf shape. The 4 accessions in the cluster II 'e' shortest petiole length. The variety NGB00217 had the smallest
had broad stems and leaves. All accessions had a round leaf base, leaf width and the shortest pod length. Variety NGB01261 had the
75% had an erect growth habit, a dark green leaf colour, an ovate highest leaf length to width ratio and early maturity. This accession
leaf shape and a serrated leaf margin. could be a useful gene source for earliness, a trait desirable in
areas with a short rainy season or in areas where crops are grown
Discussion repeatedly in the year to benefit from residual moisture.
In order to identify and select outstanding Corchorus Based on the two selection indices used to identify the top
accessions useful for breeding programmes, characterisation five accessions, NGB00215 and NGB00229 were selected using
of the germplasm is a prerequisite. In this study, considerable both the base index and the RSI method. These two accessions
variation in qualitative traits was found among the 40 Corchorus can be considered well adapted to the test environment as they
accessions. A significant proportion of the accessions had leaves were selected independently by the two indices. The other six
with dark green colour, acute base, elliptical shape and serrated accessions selected as outstanding by the two indices were
margin with a medium growth habit. Leaf shape was the most NGB00205, NGB00200, NGB0022, NGB00224, NGB01261 and
diverse trait among the quality traits. The stems of the accessions NGB00230. These accessions are promising as they performed
were all green and hairless, comparable to the report of Adebo et relatively better in the trait combinations and can be considered
al. (2015) who looked at the variability of cultivars of C. olitorius for further improvement. Moreover, farmers will get more money
in Benin. Stem and leaf morphology of C. olitorious have been if these accessions are developed into varieties with farmers'
described as informative phenotypic traits useful for classification preferred traits. The baseline selection index showed a good
(Ghosh et al., 2013; Ngomuo et al., 2017a). selection differential only for number of pods per plant, seeds per
pod and pod length. The RSI had the highest selection differential
For all quantitative traits measured, analysis of variance
for all other traits, indicating the efficiency of the RSI selection
revealed significant variation among accessions for all agronomic
method in crop improvement (Ajala, 2010; Oloyede-Kamiyo,
traits measured. Our results are consistent with the report of Ghosh
2019). This could be due to the simplicity of the method as no
et al. (2013), who reported significant variability in a different
genetic parameters need to be estimated (Crosbie et al., 1980). In
gene pool of C. olitorius accessions from East Africa and Asian
contrast, Adebayo et al. (2017) and Kolawole and Olayinka (2022)
countries. Similarly, variability in quantitative traits of different
reported the efficiency of the basic index in selecting superior
Corchorus germplasm collections has been reported (Adebo et
genotypes.
al., 2015; Ngomuo et al., 2017a; Biswas et al., 2018). The presence
of variation among accessions suggests that they will respond to The information obtained from PCV and GCV provides
improvement through selection in future breeding programmes. insight into the response of the accessions to their environment.
The highly significant interaction between accession and year The large discrepancy between PCV and GCV indicates a strong
for all measured traits can be attributed to the different edaphic environmental influence for these traits. High PCV and GCV
and climatic factors of the experimental environment in the years estimates for leaf width and number of secondary branches are
of evaluation. These results suggest that further evaluation of further evidence that there is variation between accessions for
accessions across locations and years is needed if the objective is these two traits. On the other hand, the number of days to flowering
to identify those adapted for the measured agronomic trait. and maturity had low PCV and GCV values, indicating a narrow
genetic base. Estimates of heritability are crucial in breeding as
In addition, the variations in agronomic traits showed that
they deal with the reliability of phenotypic performance of a
some accessions had the highest average performance for two or
genotype (Alake and Porbeni, 2019). The high heritability of
more traits. NGB00207 had the widest leaf, the longest number
Corchorus accessions for some agronomic traits suggests that they
of days to maturity, the highest number of secondary branches,
are highly heritable, less influenced by the environment and that
but the smallest leaf length-to-width ratio. In leafy vegetables, the
selection for improvement of these traits is effective. Conversely,
selection of a promising genotype for leaf production depends
plant height, stem width, leaf length, leaf width, leaf petiole length,
primarily on leaf size. Accessions NGB00207 and NGB00224
days to maturity, number of pods per plant, weight of 1000 seeds
showed significantly high performance in both leaf length
and seeds per pod reflect a strong influence of the environment on
and leaf width and can be considered as potential candidates
their expressions.
for broad leaves that are edible and useful for the treatment of
various diseases (Mensah et al., 2008; Mavengahama et al., 2013). In a breeding programme, the correlation coefficient
Accession NGB00210 had the shortest leaf length and the highest determines the strength of the relationship between the traits. A
weight of 1000 seeds and can be considered as source material for strong positive correlation between plant height and stem width
Corchorus seed production. In addition, Isuosuo et al. (2019) report means that the taller the plant grows, the thicker the stem, which
that the seeds of C. olitorius have the potential to be incorporated is an indication of the plant's vigour (Adeyinka and Akintade,

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 Phenotypic Diversity of Jute Mallow (Corchorus olitorius L.) Germplasm | 287

2015). The varieties that were taller produced more pods and Consequently, crosses between accessions from different clusters
had longer leaves, which means more foliage; a trait that is highly are likely to produce useful recombinants in the segregating
desirable in Corchorus. Accessions with thick stems had longer populations. Moreover, hybridization between accessions with
petioles and were taller. The correlation of plant height with most large distance between clusters may benefit from heterosis as a
of the measured traits indicates its importance for agronomic result of genetic divergence between parental lines (Bhadari et al.,
improvement in Corchorus. Comparable positive relationships 2017). The diversity observed among Corchorus accessions in this
between plant growth traits were reported by Dube et al. (2019). study can support the development of new varieties, which is an
In contrast to the reports by Ghosh et al. (2013) and Nyadanu et al. important objective in crop improvement programmes. Therefore,
(2017), our results showed that Corchorus accessions that flowered this study is crucial for the efficient conservation of Corchorus
early produced more secondary branches, pods and seeds per pod. accessions and their future use in breeding programmes.
We also found that accessions with longer pods contained more
seeds. A strong and positive relationship between these measured Acknowledgement
traits means that an improvement in the primary trait is likely to
have an effect on the secondary trait with which it is associated The authors are highly grateful to the Plant Genetic Resources
through indirect selection. It can also be concluded that they are Department (Seed genebank unit) of the National Center for
most likely controlled by a similar gene. This may be a result of Genetic Resources and Biotechnology (NACGRAB) Ibadan,
linkage or pleiotropy, suggesting that these pairs of traits may be Nigeria for providing the germplasm for this study.
simultaneously improved.
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