Slender leaf (
Leafy vegetables contribute to additional taste and flavour as well as a source of protein, fibre, mineral, and vitamins, to human diet [
Most of the African indigenous leafy vegetables have been proven to have the potential to contribute to the dietary improvement and food security for small households and less privileged families [
Despite the high economic value of slender leaf, it has been for a long time neglected by researchers, farmers, and other stakeholders, who have concentrated on exotic and already improved popular vegetables [
Field experiments were set up at the University of Embu research farm for two seasons in October to December 2018 and March to May 2019. The University of Embu lies at 0° 35′ 25″ S and 37° 25′ 31″ E with an elevation of 1494 m above sea level. It lies within the upper midland 2 agro-ecological zone. The area receives an annual rainfall of up to 1230 mm. The rainfall pattern is bimodal with long rains falling between March and June and short rains between October and December [
The seeds of thirteen accessions of
Map of Kenya showing the sampled counties and the collection points.
Twenty-nine slender leaf accessions collected from nine counties in Kenya.
S/no. | Accession code | County | Species | Altitude (m.a.s.l.) | GPS coordinates |
---|---|---|---|---|---|
1 | BHM198 | Homabay |
|
1080 | −0.4367°S, 34.2060°E |
2 | BHM213 | Homabay |
|
1198 | −0.5108°S, 34.7351°E |
3 | BKK091 | Kakamega |
|
1103 | 0.5999°S, 34.5627°E |
4 | BKK129 | Kakamega |
|
1483 | 0.1561°S, 34.5627°E |
5 | BKS220 | Kisii |
|
1525 | −0.7709°S, 34.6242°E |
6 | BKM197 | Kisumu |
|
1641 | −0.3819°S, 34.9791°E |
7 | BKM203 | Kisumu |
|
1170 | −0.1097°S, 34.9792°E |
8 | BMG234 | Migori |
|
1366 | −1.0693°S, 34.4694°E |
9 | BMG239 | Migori |
|
1481 | −0.7573°S, 34.6027°E |
10 | BSY111 | Siaya |
|
1310 | 0.0650°S, 34.2884°E |
11 | BSY113 | Siaya |
|
1321 | 0.1552°S, 34.3799°E |
12 | BVG001 | Vihiga |
|
1790 | 0.1282°S, 34.8610°E |
13 | BVG004 | Vihiga |
|
1608 | 0.1179°S, 34.7331°E |
14 | MBG086 | Bungoma |
|
1427 | 0.5611°S, 34.5605°E |
15 | MBS064 | Busia |
|
1302 | 0.3157°S, 34.2346°E |
16 | MBS065 | Busia |
|
1290 | 0.3263°S, 34.3063°E |
17 | MHM207 | Homabay |
|
1364 | −0.7296°S, 34.3074°E |
18 | MHM215 | Homabay |
|
1421 | −0.5108°S, 34.7351°E |
19 | MKK011 | Kakamega |
|
1338 | 0.3259°S, 34.5036°E |
20 | MKS221 | Kisii |
|
1526 | −0.7695°S, 34.6239°E |
21 | MKS226 | Kisii |
|
1556 | −0.6137°S, 34.7568°E |
22 | MKM204 | Kisumu |
|
1152 | −0.2414°S, 34.9580°E |
23 | MKM218 | Kisumu |
|
1560 | −0.0045°S, 34.6115°E |
24 | MMG029 | Migori |
|
1561 | 0.2864°S, 34.7547°E |
25 | MMG234 | Migori |
|
1366 | −1.0693°S, 34.4694°E |
26 | MSY110 | Siaya |
|
1251 | 0.1805°S, 34.2952°E |
27 | MSY216 | Siaya |
|
1373 | −0.0210°S, 34.5031°E |
28 | MVG003 | Vihiga |
|
1608 | 0.1179°S, 34.7331°E |
29 | MVG125 | Vihiga |
|
1528 | −0.0245°S, 34.7474°E |
Field experiments were laid out in Randomized Complete Block Design (RCBD) with the 29 accessions as the treatments and replicated three times. Each treatment/accession was allocated a plot measuring 2 m × 2 m with a 0.5 m alley between plots. The seeds were directly sown through drilling in rows spaced 30 cm apart and then covered lightly with soil. Thinning was done four weeks after sowing to attain a spacing of 30 cm × 15 cm [
Twenty quantitative and qualitative morphological traits were used to estimate the level of variation among the accessions based on
Qualitative and quantitative data were organized into a matrix and subjected to cluster analysis using XLSTAT Version 2019. Estimates of similarity among the morphotypes were calculated using Euclidean genetic distance, and dissimilarity indices were used to generate a dendrogram using the unweighted pair-group method with arithmetic average (UPGMA). Principal component analysis (PCA) was conducted to get information on the importance of the characters. A two-way analysis of variance (ANOVA) was used to analyze the quantitative data using XLSTAT Version 2019 to obtain the accessional variations, seasonal variations, and interactions between accessions and seasons. The means were then separated using Student’s Newman Keuls (SNK) test at 95% level of confidence. Pearson’s correlation coefficients were performed to compare the degree of association between quantitative traits.
A summary of the qualitative characters of slender leaf accessions that were studied is shown in Table
Variation in qualitative characters among the 29 slender leaf accessions.
S/no. | Accession code | Stem hairiness | Stem colour | Leaf type | Leaf colour | Flower colour | Dry pod colour | Seed colour |
---|---|---|---|---|---|---|---|---|
1 | BHM198 | Absent | Green | Ovate | Green | Cream-yellow | Black | Mixture 1 |
2 | BHM213 | Absent | Green | Lanceolate | Green | Yellow | Black | Pale yellow |
3 | BKK091 | Absent | Green | Lanceolate | Green | Yellow | Black | Pale yellow |
4 | BKK129 | Absent | Green | Lanceolate | Green | Yellow | Black | Mixture 1 |
5 | BKS220 | Absent | Green | Ovate | Green | Cream-yellow | Black | Pale yellow |
6 | BKM197 | Absent | Green | Lanceolate | Green | Yellow | Black | Mixture 2 |
7 | BKM203 | Absent | Green | Lanceolate | Green | Yellow | Black | Pale yellow |
8 | BMG234 | Absent | Green | Lanceolate | Green | Yellow | Black | Pale yellow |
9 | BMG239 | Absent | Green | Lanceolate | Green | Yellow | Black | Mixture 1 |
10 | BSY111 | Absent | Green | Ovate | Green | Yellow | Black | Pale yellow |
11 | BSY113 | Absent | Green | Linear | Green | Yellow | Black | Mixture 1 |
12 | BVG001 | Absent | Green | Lanceolate | Green | Yellow | Black | Pale yellow |
13 | BVG004 | Absent | Green | Linear | Green | Yellow | Black | Black |
14 | MBG086 | Absent | Green | Linear | Green | Yellow | Black | Pale yellow |
15 | MBS064 | Absent | Green | Lanceolate | Green | Yellow | Black | Pale yellow |
16 | MBS065 | Absent | Green | Lanceolate | Green | Cream-yellow | Black | Mixture 1 |
17 | MHM207 | Absent | Green | Ovate | Green | Yellow | Black | Reddish |
18 | MHM215 | Absent | Green | Linear | Green | Cream-yellow | Black | Mixture 2 |
19 | MKK011 | Absent | Green | Linear | Green | Cream-yellow | Black | Reddish |
20 | MKS221 | Absent | Green | Lanceolate | Green | Cream-yellow | Black | Mixture 1 |
21 | MKS226 | Absent | Green | Lanceolate | Green | Cream-yellow | Black | Reddish |
22 | MKM204 | Absent | Green | Linear | Green | Cream-yellow | Black | Pale yellow |
23 | MKM218 | Absent | Green | Ovate | Green | Yellow | Black | Reddish |
24 | MMG029 | Absent | Green | Ovate | Green | Cream-yellow | Black | Pale yellow |
25 | MMG234 | Absent | Green | Ovate | Green | Cream-yellow | Black | Mixture 2 |
26 | MSY110 | Absent | Green | Ovate | Green | Cream-yellow | Black | Pale yellow |
27 | MSY216 | Absent | Green | Lanceolate | Green | Yellow | Black | Pale yellow |
28 | MVG003 | Absent | Green | Ovate | Green | Yellow | Black | Reddish |
29 | MVG125 | Absent | Green | Ovate | Green | Cream-yellow | Black | Reddish |
Mixture 1 = pale yellow and reddish; Mixture 2 = pale yellow, reddish, and black; the accessions whose code starts with letter B belongs to
Significant variations
Means of quantitative growth and yield variables of selected slender leaf accessions.
S/no. | Accession code | Plant height (cm) | Branch number | Leaf area index | Petiole length (cm) | Pod width (cm) | Pod length (cm) | Pods/plant | Seeds/pod | 1000 seed wgt (g) | Days to 50% flowering | Days to maturity |
---|---|---|---|---|---|---|---|---|---|---|---|---|
1 | BHM198 | 85.73 | 9.08 | 9.58ab | 4.11 | 1.76ab | 5.63 | 13.69 | 88.05 | 6.87bc | 73.66a | 113.66a |
2 | BHM213 | 73.91 | 6.95 | 11.10ab | 4.06 | 1.66ab | 5.42 | 14.97 | 99.55 | 6.60bc | 68.33ab | 113.00a |
3 | BKK091 | 73.07 | 7.56 | 9.24ab | 3.78 | 1.83ab | 5.33 | 14.50 | 88.38 | 5.70bc | 72.33a | 113.33a |
4 | BKK129 | 75.42 | 6.56 | 9.46ab | 3.58 | 1.66ab | 5.48 | 12.70 | 92.77 | 5.61bc | 74.33a | 115.00a |
5 | BKS220 | 69.55 | 7.33 | 9.30ab | 3.81 | 1.25b | 5.06 | 17.70 | 78.44 | 6.00bc | 64.00b | 105.60ab |
6 | BKM197 | 77.41 | 9.92 | 12.02ab | 3.90 | 1.41ab | 5.16 | 14.49 | 66.11 | 6.35bc | 71.00ab | 104.83ab |
7 | BKM203 | 70.88 | 8.08 | 10.49ab | 4.35 | 1.69ab | 5.50 | 15.25 | 93.22 | 7.50b | 74.33a | 115.33a |
8 | BMG234 | 83.09 | 9.63 | 11.93ab | 4.15 | 1.70ab | 5.47 | 11.87 | 88.11 | 7.28b | 71.33ab | 111.66a |
9 | BMG239 | 72.52 | 8.06 | 9.08ab | 3.85 | 1.30ab | 5.19 | 12.79 | 73.38 | 6.18bc | 68.83ab | 111.16a |
10 | BSY111 | 90.87 | 7.01 | 11.16ab | 4.20 | 1.85ab | 5.58 | 14.02 | 96.27 | 7.43b | 73.33a | 117.00a |
11 | BSY113 | 72.02 | 8.65 | 7.17b | 3.40 | 1.48ab | 5.18 | 17.80 | 77.72 | 5.44c | 70.00ab | 111.33a |
12 | BVG001 | 70.23 | 7.25 | 10.35ab | 3.80 | 1.04b | 5.30 | 14.16 | 79.61 | 5.84bc | 68.00ab | 101.00ab |
13 | BVG004 | 76.37 | 8.93 | 9.74ab | 4.05 | 1.43ab | 5.44 | 17.56 | 80.72 | 6.54bc | 70.67ab | 103.66a |
14 | MBG086 | 76.44 | 7.56 | 11.35ab | 3.88 | 1.71ab | 5.62 | 14.53 | 71.05 | 6.23bc | 72.00ab | 107.60ab |
15 | MBS064 | 73.97 | 9.53 | 10.11ab | 3.87 | 1.70ab | 5.55 | 15.31 | 91.05 | 6.19bc | 72.33a | 110.00a |
16 | MBS065 | 73.28 | 7.57 | 9.11ab | 4.07 | 1.60ab | 5.44 | 9.71 | 92.94 | 6.82bc | 71.00ab | 111.00a |
17 | MHM207 | 84.11 | 9.87 | 10.90ab | 3.99 | 1.85ab | 5.87 | 15.39 | 90.44 | 6.37bc | 74.33a | 116.33a |
18 | MHM215 | 80.13 | 7.85 | 11.07ab | 4.06 | 1.78ab | 5.47 | 15.29 | 81.99 | 6.56bc | 70.67ab | 113.50a |
19 | MKK011 | 86.27 | 6.46 | 12.19ab | 4.16 | 1.74ab | 5.73 | 15.96 | 91.44 | 7.36b | 73.66a | 112.60a |
20 | MKS221 | 62.18 | 8.22 | 12.54a | 4.59 | 1.53ab | 5.25 | 17.66 | 87.66 | 7.84a | 71.67ab | 110.33a |
21 | MKS226 | 82.25 | 9.33 | 10.65ab | 4.07 | 1.78ab | 5.62 | 13.10 | 83.66 | 6.61bc | 74.00a | 114.00a |
22 | MKM204 | 76.55 | 8.60 | 10.17ab | 3.84 | 1.71ab | 5.55 | 15.07 | 88.83 | 6.06bc | 67.67ab | 112.00a |
23 | MKM218 | 78.47 | 8.76 | 10.55ab | 3.71 | 1.67ab | 5.63 | 15.31 | 91.77 | 5.68bc | 74.33a | 106.00ab |
24 | MMG029 | 65.41 | 7.65 | 8.82ab | 3.81 | 1.25b | 5.13 | 15.38 | 82.05 | 5.98bc | 67.00ab | 95.00b |
25 | MMG234 | 75.29 | 8.00 | 10.38ab | 4.15 | 2.20a | 5.48 | 10.97 | 93.16 | 7.03bc | 70.67ab | 112.30a |
26 | MSY110 | 70.49 | 8.20 | 9.63ab | 4.10 | 1.69ab | 5.43 | 12.91 | 82.33 | 6.86bc | 68.33ab | 111.33a |
27 | MSY216 | 72.03 | 8.78 | 10.65ab | 3.95 | 1.42ab | 5.16 | 15.76 | 76.61 | 6.37bc | 71.66ab | 106.00ab |
28 | MVG003 | 81.02 | 8.16 | 12.9a | 3.89 | 1.83ab | 5.55 | 12.87 | 85.50 | 6.30bc | 72.00ab | 114.33a |
29 | MVG125 | 75.19 | 8.98 | 10.57ab | 3.84 | 1.83ab | 5.20 | 18.00 | 88.83 | 6.18bc | 68.83ab | 112.33a |
|
0.079NS | 0.092NS |
|
0.151NS |
|
0.168NS | 0.911NS | 0.128NS |
|
|
| |
Standard error | 5.233 | 0.800 | 0.970 | 0.202 | 0.161 | 0.175 | 2.550 | 6.734 | 0.449 | 1.591 | 3.318 |
Means with the same letter within the column are not significantly different.
There were significant
Pearson correlation between selected quantitative variables.
Variables | Plant height | Petiole length | Leaf length | Leaf width | Leaf area | Pod width | Pod length | No. of seeds/pod | Days to flowering |
---|---|---|---|---|---|---|---|---|---|
Petiole length | 0.097 | ||||||||
Leaf length | 0.198 |
|
|||||||
Leaf width |
|
0.306 |
|
||||||
Leaf area | 0.349 |
|
|
|
|||||
Pod width |
|
0.287 | 0.313 | 0.176 | 0.297 | ||||
Pod length |
|
0.257 | 0.322 | 0.242 | 0.344 |
|
|||
No. of seeds per pod | 0.251 | 0.313 | 0.273 | −0.121 | 0.100 |
|
|
||
Days to flowering |
|
0.310 |
|
0.278 |
|
|
|
|
|
Days to maturity |
|
0.268 | 0.295 | 0.002 | 0.199 |
|
|
|
|
Values in bold are different from 0 with a significance level of
Agglomerative hierarchical cluster analysis of both qualitative and quantitative traits grouped the 29 accessions into seven major classes (Figure
Dendrogram showing morphological diversity of 29 accessions of
The first three diversity factors accounted for 92.36% of the total agro-morphological variability among the accessions, out of which 84.30% variation was explained by the first two factors (Table
Contribution of the variables to the first three diversity factors.
Variables |
|
|
|
---|---|---|---|
Plant height |
|
|
|
Branch number | 0.019 | 0.254 | 0.010 |
Petiole length | 0.007 | 0.001 | 0.004 |
Leaf length | 0.038 | 0.001 | 0.014 |
Leaf width | 0.000 | 0.009 | 0.006 |
Leaf area | 0.115 | 0.324 | 0.040 |
Days to 50% flowering |
|
1.580 | 0.333 |
Pod width | 0.037 | 0.005 | 0.028 |
Pod length | 0.025 | 0.012 | 0.004 |
Days to maturity |
|
|
|
Weight of 1000 seeds | 0.002 | 0.070 | 0.008 |
No. of seeds per pod |
|
|
|
No. of pods per plant | 0.411 | 0.178 | 0.088 |
Leaf type | 0.005 | 0.008 | 0.001 |
Seed colour | 0.013 | 0.092 | 0.001 |
Flower colour | 0.000 | 0.000 | 0.000 |
|
|||
Eigenvalue | 79.504 | 35.505 | 10.989 |
Variability (%) | 58.278 | 26.026 | 8.055 |
Cumulative (%) | 58.278 | 84.304 | 92.360 |
Correlations between variables and factors and between accessions and factors are illustrated in Figure
Pictorial illustration of correlations between variables and factors (a) and biplot between accessions and factors (b).
The success of crop breeding programmes depends on the availability and identification of genetic diversity among the breeding materials [
Variation within and among species was observed in only three out of the seven qualitative characters. The three variable traits were leaf type, seed colour, and flower colour. The flower colour was observed to vary from pale yellow to creamish yellow with the former being more dominant in
Similar to qualitative variables, most of the quantitative variables did not differ significantly among and within accessions. This could have been limited by the relatively fewer number of each species that were characterized in this study. Significant variation was demonstrated in only five out of the eleven quantitative variables studied. These included three morphological variables, namely, leaf area index (LAI), pod width, and weight of 1000 seeds and two agronomic variables, namely, days to 50% flowering and days to maturity. According to Roux and Wyk [
Significant and positive correlations were observed between several quantitative variables. This was an indication that some variables can be indirectly targeted in a selection criterion by using other related variables especially if the target trait does not provide better grounds for discriminative selection [
A cluster dendrogram is a good measure of diversity among and within species as it groups similar entries under one cluster [
Principal component analysis highlights and measures how each component contributes to total variation [
This study revealed a moderate level of morphological diversity between and within
Some of the data used to support the findings of this study are included in the article. Additional data are available from the corresponding author upon request.
The authors declare that there are no conflicts of interest regarding the publication of this paper.
This study was funded by the Kenyan Government through the National Research Fund (NRF). The experimental site was provided by the University of Embu.