Growth and yield response of Swiss chard (Beta vulgaris (L.) to media mixture ratios of sand, acacia soil, and goat manure

Abstract

Northern Namibian soils are predominantly sandy. A mixture of Acacia soils, sandy and goat manure is frequently used for growing various plants. However, the extent to which variations in proportions of these substrates affect growth and yield is not known. The study was conducted at the University of Namibia, Ogongo campus during the period April to August 2020 to determine optimum mixing ratios for sandy, Acacia erioloba soil and goat manure on the growth and yield of Swiss chard. Treatments were Sandy, Acacia soil and goat manure mixed in 5 different ratios of respectively; 1:2:1; 2:3:2; 1:1:1, 2:1:2, 1:1:2 and Acacia soil (control). Samples from each mixture used for pot filling were taken to the soil laboratory for textural analysis. A complete randomized experiment with 8 replications was laid under the University’s shade house. Measured parameters were plant height, leaf area, fresh and dry matter weight and chlorophyll content. Results showed that media was significantly different across all the measured parameters at 1 % probability level. The medium mixture 2:3:2 outperformed the rest of the mixtures in almost all the parameters. The results of the study indicated that acacia soil alone is not optimum for pot filling but must be supplemented with substrate that is rich in mineral content like goat manure. However, the mixing ratio is a key consideration for optimal vegetable production. We recommend the use of media mixture 2:3:2 to improve yield of Swiss chard.

Full text

Magna Scientia Advanced Biology and Pharmacy, 2020, 01(01), 018–024
Magna Scientia Advanced Biology and Pharmacy
Cross Ref DOI: 10.30574/msabp
Journal homepage: https://magnascientiapub.com/journals/msabp/
 Corresponding author: Kudakwashe Hove
University of Namibia, Faculty of Agriculture and Natural Resources, Department of Crop Science, Private Bag 5520, Oshakati,
Namibia.
Copyright © 2020 Author(s) retain the copyright of this article. This article is published under the terms of the Creative Commons Attribution Liscense 4.0.
(RESEARCH ARTICLE)
Growth and yield response of Swiss chard (Beta vulgaris (L.) to media mixture ratios
of sand, acacia soil, and goat manure
Kudakwashe Hove *, Justina Johannes, Gervasius Hatutale, Simon Kamwele Awala and Petrus Ausiku
University of Namibia, Faculty of Agriculture and Natural Resources, Department of Crop Science, Private Bag 5520,
Oshakati, Namibia.
Publication history: Received on 22 September 2020; revised on 10 October 2020; accepted on 20 October 2020
Article DOI: https://doi.org/10.30574/msabp.2020.1.1.0015
Abstract
Northern Namibian soils are predominantly sandy. A mixture of Acacia soils, sandy and goat manure is frequently used
for growing various plants. However, the extent to which variations in proportions of these substrates affect growth
and yield is not known. The study was conducted at the University of Namibia, Ogongo campus during the period April
to August 2020 to determine optimum mixing ratios for sandy, Acacia erioloba soil and goat manure on the growth and
yield of Swiss chard. Treatments were Sandy, Acacia soil and goat manure mixed in 5 different ratios of respectively;
1:2:1; 2:3:2; 1:1:1, 2:1:2, 1:1:2 and Acacia soil (control). Samples from each mixture used for pot filling were taken to
the soil laboratory for textural analysis. A complete randomized experiment with 8 replications was laid under the
University’s shade house. Measured parameters were plant height, leaf area, fresh and dry matter weight and
chlorophyll content. Results showed that media was significantly different across all the measured parameters at 1 %
probability level. The medium mixture 2:3:2 outperformed the rest of the mixtures in almost all the parameters. The
results of the study indicated that acacia soil alone is not optimum for pot filling but must be supplemented with
substrate that is rich in mineral content like goat manure. However, the mixing ratio is a key consideration for optimal
vegetable production. We recommend the use of media mixture 2:3:2 to improve yield of Swiss chard.
Keywords: Nursery; chlorophyll content; leaf area; fresh weight; basin; leaf elongation
1. Introduction
Swiss chard (Beta vulgaris L.) incorrectly referred to as Spinach [1] is a biennial leafy vegetable belonging to
Chenopodiaceous family [2, 3, 4] which has been cultivated in Europe for thousands of years, with its extensive
cultivation in Switzerland earning it the name “Swiss chard” [5]. The leaves are often used in salads because of its
attractive flavor and delicate texture [6]. The stalks are eaten because they are tender and rich in fiber [4,7]. Swiss chard
can grow in any soil if it’s well-drained, contains organic manure [8], with temperature ranging from 7-24 °C, its half
hardy, and can stand light frost conditions. Typically, in hot climate conditions, leaves remain small and are of inferior
quantity [2,6].
Swiss chard has been cultivated since 300 B.C. and the wild type is found in the Canary Islands, Mediterranean region,
and east to southern Asia [10]. The first records of Swiss chard cultivation suggest the Mediterranean area, perhaps
Italy as the center of origin [8,10]. In Africa it is mainly produced in South Africa [12], with small scale cultivation in
other countries such as Zimbabwe, Botswana, Zambia, Namibia and so on.
Northern Namibia is the most densely populated area in the country [13], as well as the poorest with high rate of
extreme poverty [12,13], majority of the population are resource-poor subsistence farmers, mainly living on natural

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resources, livestock farming, and rain fed agriculture [15]. In fact, it is estimated that 700 000 people or over,
representing one third of the total population lives in the northern part of the country [16].
Though Swiss chard has been successfully grown in Namibia, production remains low. The reason for low production
not only of Swiss Chard, but vegetables in generally, is partly due to poor soil fertility in the northern part which is
predominantly sandy [17], concurrent with high evapotranspiration and lack of resources for poor farmers to buy
commercial fertilizers to improve soil fertility.
Despite the low level of vegetables cultivation in Namibia, demand for vegetables has been on the rise, resulting in a
variety of major imported horticultural products becoming visible in the shelves of major shops in the country.
Consequently, there is need to improve the local production of many vegetables in the country by generating scientific
agronomic information which is currently limited for a number of vegetables.
Low soil fertility and high evapotranspiration have caused Swiss chard growers to prefer producing the crop in
polyethylene plastic pots which create a number of advantages such a reduction in soil borne diseases, nematodes and
weeds. Detrimental effects of poor soil conditions can be drastically reduced by switching to a container garden [18].
In fact, container garden is cheap to start, and guarantees better control over growing conditions, water, nutrients, and
sunlight. Furthermore, it is easier to defend plants from unsuitable weather conditions, and insect pests [18, 19].
However growing plants in pots require the use of suitable growing medium. A suitable medium has sufficient plant
nutrient, optimum pH and has the ability to maintain optimum moisture. Such media are however costly, not locally
available and require expertise for proper utilization. Examples of these media include, palm peat, coconut peat, posting
soil and compost. Local producers growing Swiss chard in pots have been using garden soil, acacia soil (soil collected
from under the canopy of Acacia erioloba trees), animal manure and sometimes mixing them in varying proportions.
The crop yield from these growers varies significantly.
The variation in yield and growth rate of Swiss chard in these media calls for more research to be done to determine
the optimum media mix ratio of garden soil, animal manure and acacia soil to obtain maximum yield. Critical to note is
the fact that these media are readily available in the country at no cost at all. What is required is to establish the optimum
mixing ratios for higher yield. Research have shown that there are two major factors that determine the successful
production of container-grown plants in commercial nurseries namely: the choice of the media, particularly their
physical properties, and the supply of plant nutrients [21].
The current study was therefore conducted to compare the growth and yield response of Swiss chard under different
media mixture ratios of sand, acacia soil and goat manure. Swiss chard was chosen as the test crop due to its nutritional
and economic importance in most part of the World and equally so, to Namibia. It is the most popular vegetable crop
grown in home gardens [22]. Specifically the study seeks to (1) characterise the experimental growing media by texture
(2) compare growth rate of Swiss chard, (3) compare number and size of leaves, (4) assess chlorophyll content of leaves,
and (5) compare fresh and dry weight of Swiss chard under different media mixture ratios.
2. Methodology
2.1. Study area
The study was conducted in the nursery at the University of Namibia, Ogongo Campus (latitude 17°43'S, longitude
15°15'E), Northern part of Namibia, Omusati region between 10 April and July 2020. The area is characterized by sandy
loam soil, approximately 20°C temperature and an average rainfall of about 300mm to 400mm annually.
2.2. Soil/ media collection
The representative soil samples were collected before planting. Acacia soil was collected under acacia tree (Acacia
erioloba), goat manure from the goat kraal as well as sand soil (garden soil) was collected from the garden. Both samples
were collected from the University of Namibia, Ogongo Campus farm and was used in pot filling.
2.3. Media preparation and pot filling
Black cylindrical polyethylene plant bags with a volume of 6401.53cm² were used, filled with different media mixture
ratios of sand, Acacia erioloba soil, and goat manure. A small container was used to measure soil from collected samples
for mixing. Different soil samples were poured in a basin and thoroughly mixed using hands to ensure homogeneity. A
total of 48 plastic pots were used, 8 filled with 1:3:0 (1 container of sand, 3 containers of acacia soil and 0 of goat
manure), 1:2:1 x 8 (1container of sand, 2 containers of acacia soil, 1 container of goat manure), 1:1:1 x 8 (1 container of

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sand,1 container acacia soil,1 container of goat manure ), 1:1:2 x 8 (1container of sand,1 container of acacia soil ,2
containers of goat manure), 2:1:2 x 8 (2 containers of sand, 1 container of acacia soil, 2 containers of goat manure), 2:3:2
x 8 (2 containers of sand, 3 containers of acacia soil, 2 containers of goat manure). After mixing of ratios, pots were
filled, transported to the nursery and watered.
2.4. Planting
Seed of Swiss chard variety Fordhook giant was bought from Oshakati Pharmacy and sown directly into the pots on the
10th April 2020 a day after pot filling at a depth of 1 inch deep (2.54cm) and no starter nutrients or artificial fertilizer
was added. Pots were watered immediately after planting using watering pipe, this is usually done every after 1-2 days.
All the seed germinated on the 13th of April 2020 and seedling thinning was carried out so that each pot only
accommodated one seedling to prevent competition for nutrients and sunlight. The first harvest was carried out on 10th
June and plant leaves were allowed to grow back in the same media for another 14 days without additional nutrients.
2.5. Soil sampling and analyses
The descriptive soil samples were collected before planting, using a shovels. The representative composite samples
were taken and analyzed for the soil texture properties. The samples were taken to the Department of Crop Science in
the Soil Science Laboratory of the University of Namibia, Ogongo Campus for analysis of soil texture. Hydrometer
method was used to determine the soil texture.
2.6. Experimental design
The experiment was arranged in a randomized complete block design with six treatments, comprising different sand:
acacia soil: goat manure ratios respectively mixed as follows:
0:1:0 (control)
1:2:1,
1:1:1,
1:1:2,
2:1:2,
2:3:2.
Each treatment was replicated eight times with pots dispersed over approximately 2 m of the nursery ground area with
20 cm spacing between pots.
2.7. Data collection and statistical analyses
Data were collected 2 weeks after planting. Data were collected from all 8 plant pots of all the treatments before harvest
for 6 weeks. Leaf elongation from the leaf apex to the end of the leaf petiole was measured once every week. Number of
green leaves per plant was recorded before first harvest. Plant height was measured from the leaf apex of the longest
green leaf to the bottom of the plant at the soil level .The length and width of the leaf lamina of all the biggest leaves
were recorded for each medium treatment. The product of the length and width of the leaf lamina was used to estimate
average leaf surface area per plant. Chlorophyll content was measured using a SPAD-502 meter. Fresh and dry weight
was measured every after harvesting and fresh leaves were taken to the oven for drying at 80° for 72 hours to determine
the dry mass.
3. Results and discussion
3.1. Physical characterization of the substrates
Prior to planting of the trial, composite soil core samples were collected to a depth of 0.15 m for determination of basic
soil physical properties (Table 1). Soils have varied nutrients retentive properties depending on their texture, organic
matter content, and cation exchange capacity (CEC). The substrate with high proportion of Acacia soil had the greatest
yield compared with other substrate treatments.

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Table 1 Particle size analyses of the soils using hydrometer method.
Substrate type
Texture %
Texture
Sand
Silt
Clay
Sand
98.000 (0.010)
2.005 (0.009)
0.005 (0.001)
Sand
Acacia organic matter plus sand
98.004 (0.003)
2.000 (0.001)
0.005 (0.002)
Sand
Goat manure plus sand
98.002 (0.001)
2.000 (0.001)
0.003 (0.001)
Sand
Values in brackets are standard deviations.
3.2. Effect of media mixture on growth parameters
3.2.1. Plant height
Media mixtures gave statistically significant results on plant height (
0.01p
). Mixture 2:3:2 gave the highest plant
height 23.18 ± 0.53 belonging to a unique homogeneous group (Table 3), relative to other media mixtures at the terminal
point of the experiment (Fig 1). Mixture 2:1:2 was second with terminal average plant height of 22.25 ± 0.53 (Table 3).
Media mixture 1:1:1 gave the least plant height. The growth dynamics as depicted by plant height are reflected by the
trend graph (Fig 1). Control medium (Acacia soil) gave the highest plant height up to the middle of week 4 and week 5.
Medium mixture 1:1:2 almost maintaining the least plant height on average during the entire experimental period.
3.3. Effect of media mixture on yield parameters of Swiss chard
3.3.1. Leaf area
Medium mixture 2:3:2 significantly influenced leaf area of Swiss chard plants. Its influence is significantly higher 186.65
± 82.71 than that of the rest of media mixtures (Table 3). The least leaf area was observed in the medium mixture 1:1:1
which gave on average 98.79 ± 82.71, leaf area of which was not significantly different from that recorded from the
control treatment.
3.3.2. Number of leaves
Medium mixture 2:3:2 gave the highest number of leaves 8.34 ± 0.70 followed by the 2:1:2 that gave 6.63 ± 0.70 on
average. The least number of leaves were recorded for the 1:1:1 medium that yielded 5.92 ± 0.70.
3.3.3. Chlorophyll content
The chlorophyll content as influenced by media mixture 2:3:2 is significantly higher (32.22 ± 0.77) than that of other
treatments, apart from that of 2:1:2 (31.45 ± 0.77) (Table 3)
3.3.4. Fresh and dry weight
Significant different results were recorded on dry and fresh weight at 1 % probability level. 2:3:2 gave highest results
on fresh weight 55.97 ± 3.30, followed by the control 44.87 ± 3.30, although belonging to the same homogeneous group.
The least yield was recorded for the mixture 1:2:1 with a fresh weight of 21.81 ± 3.30 and the least dry weight of 2.29 ±
0.28.
Table 2 Effect of media mixing ratios on growth and yield components of Swiss chard.
Treatment
structure
DF
Leaf area
(cm2)
Number of
leaves
Plant
Height
(cm)
Chlorophyll
content
(µmol/cm-2)
Fresh
weight (g)
Dry weight
(g)
Model
11
10605.22***
154.49***
1736.42***
3029.73***
3435.44***
18.24***
Media
5
5463.14***
4.54***
19.11***
17.33***
3545.02***
18.18***
Week
5
85873.29***
18.05***
615.06***
137.44***
2997.14***
18.46***
Error
25
712.76
2.51
0.63
1.14
115.88
0.86
*** Significant based on probability of 0.001

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Generally, media mixture 2:3:2 outperformed the rest in almost all the parameters across all the weeks. Its parameters
are statistically significantly different from the other mixtures for almost all of the parameters.
Table 3 Comparison of growth and yield components of Swiss chard across different growth media mixing ratios.
Media
(S:A:G)
Leaf area (cm2)
Number of
leaves
Chlorophyll
content
(µmol/cm-2)
Plant Height
(cm)
Fresh weight
(g)
Dry weight
(g)
1:2:1
147.32 ± 82.71b
6.48 ± 0.70ab
30.56 ± 0.77bc
21.83 ± 0.53bc
21.81 ± 3.30b
2.29 ± 0.28b
2:3:2
186.65 ± 82.71a
8.34 ± 0.70a
32.22 ± 0.77a
23.18 ± 0.53a
55.97 ± 3.30a
4.49 ± 0.28a
1:1:1
98.79 ± 82.71c
5.92 ± 0.70b
27.80 ± 0.77d
18.30 ± 0.53e
44.87 ± 3.30a
4.82 ± 0.28a
2:1:2
154.47 ± 82.71b
6.63 ± 0.70ab
31.45 ± 0.77ab
22.25 ± 0.53ab
27.62 ± 1.90b
2.92 ± 0.16b
Control
120.18 ± 82.71bc
6.12 ± 0.70b
28.48 ± 0.77d
19.73 ± 0.53d
46.45 ± 3.30a
4.36 ± 0.28a
1:1:2
135.13 ± 87.28b
6.36 ± 0.78ab
29.92 ± 0.86c
20.93 ± 0.59c
27.62 ± 1.90b
2.92 ± 0.16b
Means with the same letter in a column are not statistical significantly different at 5% probability level.
Post hoc analysis is based on Duncan’s method [23]. Data are 6 week averages ± SE.
Figure 1 Swiss chard growth under the influence of different media mixing ratios across the experimental period
4. Discussion
The study found that the substrate with high proportion of Acacia soil had the greatest yield compared with other
substrate treatments. This finding is supported by some researchers who revealed that acacia soil has a strong effect on
soil nutrient concentration [24]. Higher soil fertility under tree canopies has been reported for a broad range of
savannas [25–27]. Acacia leave are known to have high nitrogen content which promotes chlorophyll formation and
vegetative growth, especially in leafy vegetables like Swiss chard. Besides its nutritional property, Acacia soil is also rich
in organic materials, which improve soil conditions by increasing water infiltration, aeration and water holding capacity
of the soil. Therefore, a combination of nutritional properties and structural improvement capability of the Acacia soil
should have contributed to improved performance of Swiss chard compared with the other substrates.
Several lines of evidence suggest that growth and yield parameters of Swiss chard increase with increase in nitrogen
application [28]. Other researchers also reported an increase in chlorophyll content in maize associated with the
increase in nitrogen levels [29].

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5. Conclusion
We conclude that under the conditions of the current experiment, media mixtures with high proportion of nitrogen
source substrates, has positive effects on chlorophyll content, leaf area, leaf fresh and dry weight and plant height of
Swiss chard.
The results showed that substrates mixed in different proportions affect growth and yield of Swiss chard. This indicates
that growth and development of Swiss chard were affected by nutrient levels in the media which obviously vary
depending on the mixing proportion. Higher nitrogen in media induced positive results. Thus in order to increase yield
of Swiss chard, media mixture of 2:3:2 should be used.
Compliance with ethical standards
Acknowledgments
We are grateful to P. Stefanus, M. Samuel (University of Namibia) for their contribution to the success of the experiment.
We also thank the University of Namibia, Ogongo Campus management for the support rendered during the execution
of the experiment.
Disclosure of conflict of interest
The authors declare no conflict of interest.
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