Loading...
The effect of different growth media and salinity on the vegetative growth of Trachyandra ciliata (Wild cabbage) in hydroponics
Author(s)
Ngxabi, Sihle
Date Issued
2020
Type
Thesis
Publisher
Cape Peninsula University of Technology
Abstract
Water scarcity and increasing salinization of agricultural lands will pose a huge threat
to food production in the future. Increasing agricultural production, therefore,
becomes a challenge to keep up with the increasing population and sustain nutrition
and food security. The Western Cape Province of South Africa has been the most
affected by water scarcity and it has been predicted that in a few years, this province
will be unable to supply water for its agricultural needs. This phenomenon
necessitates the development of more innovative techniques and the cultivation of
halophytes to enhance sustainable crop production. Trachyandra ciliata is a
halophytic plant with limited literature and it belongs to the Asphodelaceae family that
is popular for the medicinal properties of its members. The existing literature suggests
that it is edible but there is no scientific evidence of its biochemical properties and
nutrient content. Hydroponically grown plants use 10 times less water than
conventionally grown plants because in soil-grown plants water quickly leaches to the
soil, while water is collected and circulated again in hydroponic cultivation.
The aim of this study was to determine the influence of salinity and soilless media on
the vegetative growth, phytochemical and antioxidant capacity of hydroponically
grown T. ciliata under a greenhouse environment, in order to determine the growth
protocol for this plant. Four identically constructed Nutrient Film Technique (NFT)
systems were used, with each system on a separate metal mesh steel table (2.5 m
long). NutrifeedTM served as a general hydroponics feed while different salt
concentrations of Sodium chloride (NaCl) (100mM, 200mM, 400mM of NaCl) were used
as treatments added into each sump, while nutrient solution without addition of NaCl
was considered as control. Twenty treatments were evaluated with 10 replicates per
treatment. All nutrient solutions containing NaCl were replaced and the system
flushed every week to avoid the buildup of salts in the medium, pots, gutters, and
reservoirs. The treatments were comprised of 3 different soilless media; Leca clay
(LC), silica sand (SS), and a combination of peat: perlite: vermiculite (PPV) at a 1:1:1
ratio. A standard laboratory scale was used to measure the weight and the shoot
length was manually using a standard measuring tape. The chlorophyll content of the
plants was determined using a SPAD-502 Konica-Minolta meter. Antioxidant content
and capacity of metabolites within the mixture of dried and ground roots and shoots
were assessed by means of assays for total Flavonols, total polyphenols, 2,2'-azinobis(
3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), ferric reducing antioxidant power
(FRAP), and 2,2-diphenyl-1-picrylhydrazyl (DPPH). Salinity significantly (P≤0.05) affected shoots wet weight, root wet weight, shoot dry
weight, and both total wet and dry weight. The highest mean values for shoots wet
weight, root wet weight, and total wet weight were observed at 100 mM salinity level,
while high salinity levels recorded the lowest mean values. Growth media had no
significant effect on biomass accumulation. Both salinity and soilless media showed a
significant effect on shoot length and number of leaves with a combination of
100mM+PPV recording the highest mean values. Both salinity and soilless media
significantly affected the inflorescence weight and the number of flowers with
100mM+PPV interaction recording the highest significant mean values. The
chlorophyll content was significantly affected by salinity while soilless media did not
affect chlorophyll accumulation. 0mM and 100mM recorded the highest SPAD values
although there was no significant effect between the treatments. Salinity-induced
oxidative stress and soilless media are significantly (P≤ 0.05) effective for the
accumulation of polyphenols. The interaction of moderate (20mM) and PPV recorded
the highest significant mean values for polyphenols, FRAP, ABTS and DPPH. The
combination of 100mM+PPV recorded the highest significant mean value for the
accumulation of flavonols. It was concluded that low salt levels (100mM) promote
biomass accumulation while high salt levels (400mM) are toxic and decrease growth
significantly. Soilless media has no significant effect on plant biomass except for the
inflorescence, in which the combination of 100mM+PPV is recommended. Moderate
salt levels (200mM) in conjunction with PPV are recommended for the accumulation of
polyphenolic compounds(antioxidants) except for flavonols, where 100mM is
recommended. It was concluded that moderate salt levels may not promote biomass
accumulation but effective for antioxidant content.
to food production in the future. Increasing agricultural production, therefore,
becomes a challenge to keep up with the increasing population and sustain nutrition
and food security. The Western Cape Province of South Africa has been the most
affected by water scarcity and it has been predicted that in a few years, this province
will be unable to supply water for its agricultural needs. This phenomenon
necessitates the development of more innovative techniques and the cultivation of
halophytes to enhance sustainable crop production. Trachyandra ciliata is a
halophytic plant with limited literature and it belongs to the Asphodelaceae family that
is popular for the medicinal properties of its members. The existing literature suggests
that it is edible but there is no scientific evidence of its biochemical properties and
nutrient content. Hydroponically grown plants use 10 times less water than
conventionally grown plants because in soil-grown plants water quickly leaches to the
soil, while water is collected and circulated again in hydroponic cultivation.
The aim of this study was to determine the influence of salinity and soilless media on
the vegetative growth, phytochemical and antioxidant capacity of hydroponically
grown T. ciliata under a greenhouse environment, in order to determine the growth
protocol for this plant. Four identically constructed Nutrient Film Technique (NFT)
systems were used, with each system on a separate metal mesh steel table (2.5 m
long). NutrifeedTM served as a general hydroponics feed while different salt
concentrations of Sodium chloride (NaCl) (100mM, 200mM, 400mM of NaCl) were used
as treatments added into each sump, while nutrient solution without addition of NaCl
was considered as control. Twenty treatments were evaluated with 10 replicates per
treatment. All nutrient solutions containing NaCl were replaced and the system
flushed every week to avoid the buildup of salts in the medium, pots, gutters, and
reservoirs. The treatments were comprised of 3 different soilless media; Leca clay
(LC), silica sand (SS), and a combination of peat: perlite: vermiculite (PPV) at a 1:1:1
ratio. A standard laboratory scale was used to measure the weight and the shoot
length was manually using a standard measuring tape. The chlorophyll content of the
plants was determined using a SPAD-502 Konica-Minolta meter. Antioxidant content
and capacity of metabolites within the mixture of dried and ground roots and shoots
were assessed by means of assays for total Flavonols, total polyphenols, 2,2'-azinobis(
3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), ferric reducing antioxidant power
(FRAP), and 2,2-diphenyl-1-picrylhydrazyl (DPPH). Salinity significantly (P≤0.05) affected shoots wet weight, root wet weight, shoot dry
weight, and both total wet and dry weight. The highest mean values for shoots wet
weight, root wet weight, and total wet weight were observed at 100 mM salinity level,
while high salinity levels recorded the lowest mean values. Growth media had no
significant effect on biomass accumulation. Both salinity and soilless media showed a
significant effect on shoot length and number of leaves with a combination of
100mM+PPV recording the highest mean values. Both salinity and soilless media
significantly affected the inflorescence weight and the number of flowers with
100mM+PPV interaction recording the highest significant mean values. The
chlorophyll content was significantly affected by salinity while soilless media did not
affect chlorophyll accumulation. 0mM and 100mM recorded the highest SPAD values
although there was no significant effect between the treatments. Salinity-induced
oxidative stress and soilless media are significantly (P≤ 0.05) effective for the
accumulation of polyphenols. The interaction of moderate (20mM) and PPV recorded
the highest significant mean values for polyphenols, FRAP, ABTS and DPPH. The
combination of 100mM+PPV recorded the highest significant mean value for the
accumulation of flavonols. It was concluded that low salt levels (100mM) promote
biomass accumulation while high salt levels (400mM) are toxic and decrease growth
significantly. Soilless media has no significant effect on plant biomass except for the
inflorescence, in which the combination of 100mM+PPV is recommended. Moderate
salt levels (200mM) in conjunction with PPV are recommended for the accumulation of
polyphenolic compounds(antioxidants) except for flavonols, where 100mM is
recommended. It was concluded that moderate salt levels may not promote biomass
accumulation but effective for antioxidant content.
Additional information
Thesis (Master of Horticultural Science)--Cape Peninsula University of Technology, 2020
File(s)![Thumbnail Image]()
Loading...
Name
Sihle_Ngxabi__214217892.pdf
Size
4.85 MB
Format
Adobe PDF
Checksum
(MD5):7a8b0f910f738f9d61e38859112d8cfc