Study on growth performance of Stevia rebaudiana by chemical fertilizer and green manure on BRIS soil

BRIS soil is the problematic soil in Malaysia because it retain a high sandy
texture, low fertility and low water holding capacity. The application of chemical
fertilizer and sesbania grandiflora as green manure is to increase the fertility of
BRIS soil towards the crop production. This study was carried out to estimate the
fertility of BRIS soil by determine the growth performance of Stevia rebaudiana
under three different media, which is BRIS soil as control soil, BRIS soil + Chemical
Fertilizer and BRIS soil + Green Manure with two light condition, 30% and 50%
light intensities. The parameters that evaluated were growth performance (height of
plants, number of branches, number of leaves, diameter of stem and length of roots)
and biomass production. Results indicate that the highest mean average in number of
leaves (4.17) in lighting 50% and number of branches (91.2) at lighting 30% by
adding the chemical fertilizer. Results the number of branches showed that the three
media (BRIS soil, BRIS soil + Chemical Fertilizer and BRIS soil + Green Manure)
have the highest mean average in lighting 30% compared to in lighting 50% which is
BRIS soil (6.72), BRIS soil + Chemical Fertilizer (4.32) and BRIS soil + Green
Manure (2.97). The diameter of stem showed that the highest mean average (2.1 mm)
and the height of plants (17.77 cm) at BRIS soil in lighting 50%. The fresh and dry
weight biomass production of the roots of Stevia rebaudiana plants were highest in
the BRIS soil at lighting 30% which is 7.9925b and 3.2475c respectively. While in
lighting 50%, the fresh weight and dry weight were highest in BRIS soil + Green
Manure, which is 3.8300c and 1.2250b. But the fresh and dry weight biomass
production of the stem of Stevia rebaudiana plants were highest in the BRIS soil +
Cemical Fertilizer at lighting 30% which is 6.1400c and 1.9950b. While in lighting
50%, the fresh weight and dry weight were highest in BRIS soil + Green Manure,
which is 7.2975c and 2.6150b respectively. By adding the chemical fertilizer, it
might be affected by the reduction in photosynthesis and subsequent growth and it
also can be cause by the nitrogen content in the chemical fertilizer that increase the
number of leaves and number of branches. Light plays an important factor that can
inflence the growth performance of Stevia rebaudiana, therefore this result suggested
that adding the chemical fertilizer to BRIS soil under 30% lighting intensity should
be used in crop production.