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The study was conducted to evaluate the primary production variables of Brachiaria grass cultivars in semi arid regions of Eastern Kenya. Brachiaria cultivars B. decumbens cv. Basilisk, Brachiaria hybrid Mulato II, four Brachiaria brizantha cultivars Marandu, Xaraes, Piata, MG4 and Brachiaria humidicola cv Llanero were assessed with reference to their field establishment and growth rates. Chloris gayana cv. KATR3 and P. pupureum cv. Kakamega I were included as controls. Plant numbers, heights, spread, plant tiller number and plant cover were monitored for the initial 16 weeks following seedling emergence. A standardization cut was done on all the plots at week 16 and dry matter yields determined. All growth parameters measured varied significantly (p<0.05) among the cultivars. Chloris gayana cv. KATR3 recorded the highest plant numbers (48plants/m2). Llanero recorded highest plant spread (146.9 cm) and tiller number (31tillers/plant). Napier had the highest plant height (103.8cm), cover (94.9%) and average dry matter yields (5430kg /ha). The results demonstrate that Brachiaria grasses are capable of establishing themselves in the semi arid regions of Eastern Kenya. It is recommended that the experiment be conducted for a longer period of time to determine their growth capacity during dry spells and pests and diseases that can hinder establishment and production.
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Tropical and Subtropical Agroecosystems, 19 (2016): 29 - 39
29
PRIMARY PRODUCTION VARIABLES OF Brachiaria GRASS CULTIVARS
IN KENYA DRYLANDS
[VARIABLES DE PRODUCCIÓN PRIMARIA DE CULTIVARES DE PASTO
BRACHIARIA EN ZONAS ARIDAS DE KENIA]
Susan A. Nguku1*, Donald N. Njarui2, Nashon K.R. Musimba1,
Dorothy Amwata1 and Eric M. Kaindi1.
1South Eastern Kenya University, P.O. Box 170-90200 Kitui, Kenya
2Kenya Agriculture and Livestock Research Organisation, Katumani, P.O. Box 340,
Machakos, Kenya,
* Corresponding author
SUMMARY
The study was conducted to evaluate the primary
production variables of Brachiaria grass cultivars in
semi arid regions of Eastern Kenya. Brachiaria
cultivars B. decumbens cv. Basilisk, Brachiaria
hybrid Mulato II, four Brachiaria brizantha cultivars
Marandu, Xaraes, Piata, MG4 and Brachiaria
humidicola cv Llanero were assessed with reference
to their field establishment and growth rates. Chloris
gayana cv. KATR3 and P. pupureum cv. Kakamega I
were included as controls. Plant numbers, heights,
spread, plant tiller number and plant cover were
monitored for the initial 16 weeks following seedling
emergence. A standardization cut was done on all the
plots at week 16 and dry matter yields determined.
All growth parameters measured varied significantly
(p<0.05) among the cultivars. Chloris gayana cv.
KATR3 recorded the highest plant numbers
(48plants/m2). Llanero recorded highest plant spread
(146.9 cm) and tiller number (31tillers/plant). Napier
had the highest plant height (103.8cm), cover (94.9%)
and average dry matter yields (5430kg /ha). The
results demonstrate that Brachiaria grasses are
capable of establishing themselves in the semi arid
regions of Eastern Kenya. It is recommended that the
experiment be conducted for a longer period of time
to determine their growth capacity during dry spells
and pests and diseases that can hinder establishment
and production.
Keywords: Brachiaria; grass; Livestock production;
Climate change; Forages; Establishment.
RESUMEN
El estudio se realizó para evaluar las variables de
producción primaria de cultivares de pasto Brachiaria
en las regiones semiáridas de Kenia Oriental. Los
cultivares B. decumbens cv. Basilisk, Brachiaria
híbrido Mulato II, cuatro cultivares de Brachiaria
brizantha Marandu, Xaraes, Piata, MG4 y Brachiaria
humidicola cv Llanero fueron evaluados con
referencia a su establecimiento de campo y las tasas
de crecimiento. Chloris gayana cv. KATR3 y P.
pupureum cv. Kakamega se incluyeron como
controles. Número de plantas, altura, propagación, el
número de hijos de las plantas y la cubierta vegetal
fueron controlados durante los primeros 16 semanas
siguientes emergencia de las plántulas. Un corte de
normalización se realizó en todas las parcelas en la
semana 16 y los rendimientos de materia seca fueron
determinados. Todos los parámetros de crecimiento
medidos variaron (p <0.05) entre los cultivares.
Chloris gayana cv. KATR3 registró el número de
plantas más altas (48 plantas / m2). Llanero registró la
mayor propagación (146.9 cm) y el número de hijos
(31 hijuelos/planta). Napier registró la mayor altura
(103.8cm), cobertura (94.9%) y rendimiento de
materia seca (5430 kg/ha). Los resultados demuestran
que los pastos Brachiaria son capaces de establecerse
en las regiones semiáridas de Kenia Oriental. Se
recomienda que el experimento se lleve a cabo
durante un período de tiempo más largo para
determinar su capacidad de crecimiento durante los
períodos secos y las plagas y enfermedades que
pueden obstaculizar la producción y establecimiento.
Palabras clave: Brachiaria; pasto; producción
ganadera; cambio climático; establecimiento.
Nguku et al., 2016
30
INTRODUCTION
Livestock form an important avenue for rural
development and provide the bulk of meat consumed
in Kenya. One of the most important constraints on
livestock production is nutrition, especially during the
dry season when forage quality and quantity is low
(Orodho, 2007). Grazing systems are most affected
by climate change because of their dependence on
climatic conditions, their natural resource base and
their limited adaptation opportunities (Aydinalp and
Cressor, 2008). Climatic impacts are expected to be
more severe in arid and semi arid grazing systems at
low latitudes where higher temperatures and lower
rainfall are expected to reduce yields on rangelands
and increase land degradation (Thornton, 2010).
Current weather projections for East Africa indicate
that temperature will increase between 1.3oC and
2.10C depending on climate models by 2050
(Waithaka et al., 2013). The rise in temperature will
increase evaporation and cause loss of soil moisture
hence increasing the plant moisture requirements
(Waithaka et al., 2013). Impacts on livestock
production systems include productivity losses due to
temperature increase, change in water availability and
alteration in fodder quality and quantity. Prolonged
droughts often leave many livestock keepers poorer
and unsure of reliable livestock feed source. A
drought experienced in 2008/9 in the country affected
approximately 10 million people; a third of the
country’s population with massive losses in livestock
occurring in the Northern Frontier (Gullet et al.,
2011).
Grass is one of the most important sources of
nutrients for domesticated ruminants during a large
part of the year (Taweel et al., 2005) and is more
easily accessible, better in taste and quicker in
digestion than shrubs and trees (Quraishi, 1999).
Animals do not compete with humans for grasses as
food and they are therefore a cheap and economical
feed source. According to Herrera (2004), pasture
turn out to be an appropriate source of food for
ruminants, mainly in countries of tropical climate
such as Cuba due to the high number of species that
can be used and the possibility of cultivating them
throughout the year. The developmental morphology
of plants defines their architectural organization,
influences their palatability and accessibility to
herbivores, and affects their ability to grow following
defoliation (Briske, 1986). Tillers increase the chance
of survival and the available forage resource of
grasses and tiller numbers are an indicator of resource
use efficiency by different grass species (Laidlaw,
2005).The weight of a plant’s tillers will determine its
productivity (Nelson and Zarrough, 1981). Plant
cover on the other hand is important because it
chokes weeds and also serves to protect the soil from
erosion agents. Pasture species which grow fast and
tall are more efficient in use of resources and
therefore, are more competitive. Such species
eventually shade out the other species if planted in
mixed stands thereby, suppressing their growth
(Opiyo, 2007; Mganga, 2009; Ogillo, 2010).
There is a great potential to improve pastures through
breeding by increasing diversity through germplasm
introductions to the Kenyan environment to boost the
forage resource base for livestock (Orodho, 2007).
Forage grasses commonly found growing in the semi
arid regions of Kenya include Buffel grass (Cenchrus
ciliaries), Rhodes grass (Chloris gayana), Panicum
maximum, Masai love grass (Eragrostis superba),
Horse tail (Chloris roxbhurgiana) and Enteropogon
machrostachys (Orodho, 2007). These grasses’
nutritional and yield status decline with changing
climatic conditions in the year making them incapable
of meeting the needs of livestock (Gitunu et al.,
2003). Napier grass which is the most commonly
grown fodder grass by dairy farmers has been
encountering disease and pest attacks that are
rendering it vulnerable (Orodho, 2006). The
Brachiaria grass spp. is a perennial grass native to
East and Central Africa and has been introduced into
humid tropical regions of Latin America, Southeast
Asia, and northern Australia where it has
revolutionized grassland farming and animal
production. Whereas their potential in their native
land remains largely unexploited, in their adopted
homes in South America and Asia, there have been
several research and development efforts to improve
the productivity, nutritive values and other agronomic
characteristics of these grasses (Ndikumana and de
Leeuw, 1996).
The study sought to examine the primary production
variables of seven Brachiaria grass cultivars in Semi
arid Kenya. These included four Brachiaria brizantha
cultivars namely; MG4, Xaraes, Piata and Marandu;
Brachiaria hybrid cv. Mulato II; Brachiaria
humidicola cv. Llanero and Brachiaria decumbens
cv. Basilisk. Chloris gayana cv KATR3 and Napier
grass (Kakamega I) were grown alongside these
cultivars to serve as controls.
MATERIALS AND METHODS
Site
The study was conducted at the KARI (Kenya
Agriculture Research Institute) now KALRO (Kenya
Agriculture and Livestock Research Organisation
(KALRO) Katumani- Machakos, Kenya (10 58´S,
370 28´E). Elevation is 1600m above sea level and
the mean temperature is19.60C (Njarui et al., 2003).
The soils are Luvisols, low in nitrogen and
Tropical and Subtropical Agroecosystems, 19 (2016): 29 - 39
31
phosphorus with a PH of 6.5 (Aore and Gitahi,
1991). The mean annual rainfall is 717 mm, with a
bimodal pattern, the long rains (LR) occurring from
March-May and the short rains (SR) from October-
December with two dry seasons (June-September;
January-February). During the time of the
experiment, the total rainfall recorded was 571 mm.
This figure includes rainfall data collected in
February and March, 2014. Average temperature
ranged between 15.30C -26.20C.
Experimental design and treatment
The experiment was run within the period of October,
2013 at the onset of the short rainy season to March
2014 at the onset of the long rainy season. Site
selection and laying of plots was done in October
whereas sowing of seed was done on 11th November,
2013. Data collection begun at 4 weeks post seedling
emergence and ended at 16 weeks post seedling
emergence. Brachiaria brizantha cv. Marandu, B.
brizantha cv. Xaraes, B. brizantha cv. Piata, B.
brizantha cv. MG4, B. decumbens cv. Basilisk, B.
humidicola cv. Llanero, Brachiaria hybrid cv. Mulato
II, C.gayana cv. KATR3 and Napier grass were tested
for field establishment, growth and thereafter for dry
matter yields. The experimental design was a
randomized complete block design with 4
replications. Individual plot sizes were 5m x 4m with
a 1m path between plots and 1m path between the
blocks. The seeds were drilled in furrows of about
2cm deep on a well prepared seedbed at an inter row
spacing of 0.5m, giving 10 rows in each plot. Triple
super phosphate (TSP, 46 % P) fertilizer was applied
to the soil prior to sowing of the seed at the rate of
50.8kg P/ha in the planting rows. Sowing was done
manually by placing the seeds in the furrows and
covering them with a thin layer of soil. The grass seed
was sown at rates of 5kg/ha. For Napier grass 3 splits
were planted at intervals of 1m apart in holes dug
15cm deep after adding TSP at the rates of 50.8kg
P/ha. The trials were kept weed free throughout the
experiment by hand weeding and slashing inter row
spaces to reduce weed competition within the
replications. Standardization cuts were carried out in
the sixteenth week at the onset of the long rains and
dry matter yields established.
Data collection
Plant attributes (Plant height, plant counts, tiller
numbers, plot cover and plant spread) were recorded
at week 4, 8, 12 and 16 after seedling germination. A
standard cut was done at week sixteen at the onset of
the long rainy season (March-May) and dry matter
yields established.
Plant counts: Number of plants was determined by
counting plants in a 1m x 1m fixed quadrat placed
over two rows.
Plot cover: Percentage plot cover was established by
using a quadrat of 1m x1m subdivided into 25 squares
of 0.2m x 0.2m as described by (Njarui and Wandera,
2004). The percent canopy cover of Napier grass was
determined using the dot method as described by
(Sarrantonio, 1991).
Plant spread: For spread, the plant diameter was
measured from one edge to the other of each of 4
randomly selected and tagged plants. This was done
using a metre ruler.
Plant height: Plant height was measured on the
primary shoot from the soil surface to the base of the
top-most leaf using a metre rule as described by
(Rayburn and Lozier, 2007).This was done on the
same four plants tagged.
Number of tillers: The number of tillers for the same
4 tagged plants was counted and recorded. Total tiller
number per tuft on each measurement occasion was
defined as the sum of total tiller number at previous
measurement and number of tillers formed after
previous measurement.
Standardization: The onset of the long rainy season
(March-May, 2014) marked the end of the
establishment and primary production period. This
was at week16 post seedling emergence. After
recording plant counts, plant cover, plant height, tiller
numbers and plant spread, the grasses were cut to a
stubble height of 5cm in a randomly selected area of
4m2 within the plots as described by (Tarawali et al.,
1995). A fresh weight of all the harvested material
was recorded after which sub samples of these were
weighed and recorded. The sub samples were dried in
an oven for 72 hours at temperatures of 650C after
which the dried sample weights were recorded. The
oven-dry weights were used to calculate dry matter
(DM) yield per plot which was then extrapolated to
kg/ha. These oven dried samples included the leaves
and stems harvested at 5cm stubble height.
Statistical analyses
Data on agronomic parameters and dry matter yields
of forage samples were subjected to ANOVA based
on the model designed for a randomized complete
block design (RCBD) according to (Gomez and
Gomez, 1984).To compare significant differences in
response variables, ANOVA analysis was done using
SAS package (SAS, 2001). Duncan’s Multiple Range
Test was carried out for subsequent comparison of
means as described by (Steel and Torrie, 1986).
Nguku et al., 2016
32
RESULTS
Climatic data
Figure 1 below shows the rainfall data for the site
recorded during the period of January 2012June
2014 presenting 5 rainy seasons: long rains (March
May), short rains (OctoberDecember), short dry
season (JanuaryFebruary) and long dry season
(JuneSeptember). Rainfall for the long rains in 2014
is given for 3 months, March May. During the short
rainy season of 2013, maximum rainfall was
experienced in the month of December. During the
long rainy season of 2014, maximum rains were
experienced in March which was also above the Short
Term Average (STA). The months of April and May
recorded lower rainfall which was also below the
short term average. The temperatures in almost all
months were similar to the short term average (Fig.2).
Plant population
Changes in plant numbers over time are shown in
table 1. Plant population means for all the cultivars
were significantly (p<0.05) different. At week 16,
Chloris gayana (Kat R3) recorded highest plant
numbers at 48.5plants/m2. MG4 (27.3 plants/m2),
Mulato II (23.8 plants/m2), Marandu (20.8plants/m2)
and Basilisk (24 plants/m2) recorded similar plant
population. Plant population for Xaraes (12
plants/m2), Piata (8.3 plants/m2) and Llanero (16
plants/m2) were lowest but similar (p>0.05).
Plant spread
Table 2 shows the mean values for spread for the
cultivars. Mean plant spread for the cultivars were
significantly different (p<0.05) and increased
progressively from week 4 (4.1 cm) to week 16 (65.8
cm). At week 16 Plant spread for Llanero was highest
at 146.9cm and lowest for Mulato II at 40.7cm.
Napier (72.2cm) recorded second highest mean plant
spread which was similar to mean plant spread for
MG4 (58.6cm), Basilisk (60.4cm) and C.gayana
KATR3 (60cm). Initially at week 4, Marandu showed
highest mean spread at 10cm but by week 12 it was
among the lowest in spread. Mulato II maintained the
lowest mean plant spread throughout this period (2.3 -
40.7cm).
Plant cover
Plot cover generally increased for all the cultivars as
shown in Table 3. Cover means were significantly
different for the cultivars (p<0.05) during this period.
All the cultivars except Piata and Xaraes recorded
high and similar plot cover at week 16. Only Piata
had less than 50% plot cover at week 16.
Figure1: Monthly rainfall recorded data at experimental site from January, 2012 to June, 2014
Tropical and Subtropical Agroecosystems, 19 (2016): 29 - 39
33
Figure 2: Mean monthly temperature at experimental site from January 2012 to June 2014
Table 1: Mean plant population (plants/ m2) of the grass cultivars during field establishment and growth
Cultivar
Week 8
Week 12
Llanero
17ced
17cbd
MG4
27.3b
27.3b
Marandu
20.8cbd
21.8cb
Piata
8.3fe
8.3ed
Xaraes
11.8fed
12ced
Mulato II
23.8cb
23.8b
Basilisk
19.5cbd
24.0b
Kat R3
48.5a
48.5a
Napier
4f
4e
Mean
20.1
20.7
SE
±1.0
±1.2
Column means with similar superscripts are not significant (p<0.05)
Table 2: Mean plant spread (cm) of the grass cultivars during field establishment and growth
Cultivar
Week4
Week 8
Week 12
Week 16
Llanero
3.6b
49.4a
107.7a
146.9a
MG4
4.8b
16.3b
38.1cb
58.6cb
Marandu
10.0a
12.1b
29.2cb
49.7cd
Piata
3.0b
10.0b
31.2cb
56.4c
Xaraes
3.6b
12.1b
29.4cb
47.4cd
Mulato II
2.3b
9.8b
24.5c
40.7d
Basilisk
3.2b
10.1b
36.6cb
60.4cb
Kat R3
2.3b
13.5b
34.7cb
60.0cb
Napier
-
16.3b
47.1b
72.2b
Mean
4.1
16.6
42.1
65.8
SEM
±0.6
±0.8
±2.1
±1.5
Column means with the same superscript are not significantly different (p<0.05).
Nguku et al., 2016
34
Table 3: Mean Plant cover (%) of the grass cultivars during field establishment and growth
Cultivar
Week4
Week 8
Week 12
Week 16
Llanero
8.0bc
25.0bac
71.5a
81.0ba
MG4
13.0a
32.0ba
51.3ba
74.0ba
Marandu
10.0ba
19.0bac
47.0bc
74.0ba
Piata
5.0bc
16.0c
34.0bc
49.0c
Xaraes
8.0bc
25.0bac
39.0bc
62.0bc
Mulato II
8.0bc
18.0bc
45.0bc
70.0ba
Basilisk
13.0a
33.0a
31.0bc
71.0ba
Kat R3
9.0b
13.0c
44.0bc
69.0ba
Napier
-
15.8c
24.5c
84.9a
Mean
9.3
21.9
43.0
70.5
SEM
±0.4
±1.5
±2.6
±2.0
Column means with the same superscript are not significantly different (p<0.05)
Plant tiller number
Mean tiller number increased progressively for all
cultivars and there were significant differences
among the cultivars (p<0.05) as shown in Table 4.
The Brachiaria spp recorded generally higher tiller
numbers than both C.gayana and Napier throughout
the growth period. Mean tiller numbers were highest
for Marandu, MG4 and Basilisk at week 4. At week
16, Llanero (30.5tillers/plant) recorded highest tiller
numbers but Marandu (16.8 tillers/plant) was among
the lowest in tiller recruitment. MG4
(24.5tillers/plant), Piata (25.5tillers/plant), Xaraes
(25.5tillers/plant), Mulato II (23.8tillers/plant) and
Basilisk (20.5tillers/plant) also recorded high and
similar tiller numbers with Llanero at week 16.
Plant height
Mean plant heights for the cultivars generally
increased and were significantly different (p<0.05)
throughout the growth period as shown in Table 5
below. At week 16, Napier recorded the highest mean
plant heights (103.8cm) and Llanero lowest at 6cm.
Among the Brachiaria cultivars MG4 (63.4cm)
recorded higher plant heights and although second
after Napier (103.8cm), it’s height was not
significantly different (p>0.05) from C.gayana cv.
Kat R3 (52.8cm).
Dry matter yields
Figure 3 shows the dry matter yields of the cultivars
at week 16. Dry matter yields at week 16 represented
primary production There were significant differences
(p<0.05) between the cultivars for dry matter yields.
Napier (5430KgDM/ha) recorded highest dry matter
yields followed by MG4 (4583.4 Kg DM/Ha) and
Mulato II (4050.2 Kg DM/Ha). The lowest yields
were recorded for Llanero at 2282 Kg DM/Ha though
this value was similar to that of C.gayana KATR3
(2741 Kg DM/Ha), Marandu (2596 Kg DM/Ha) and
Xaraes (2335 Kg DM/Ha).
Table 4: Mean plant tiller number of the grass cultivars during field establishment and growth
Cultivar
Week4
Week 8
Week 12
Week 16
Llanero
3.5b
9.5ba
16.5ba
30.5a
MG4
4.8a
12.3a
16.8a
24.5ba
Marandu
4.8a
8.0bc
11.8bc
16.8bc
Piata
2.0c
5.5c
12.8bac
25.5ba
Xaraes
3.3b
9.3ba
14.3ba
25.5ba
Mulato II
3.2b
8.5bc
14.8ba
23.8ba
Basilisk
4.0ba
7.8bc
12.3bac
20.5bac
Kat R3
3.4b
6.8bc
11.8bc
17.8bc
Napier
-
8.0bc
8.3c
10.6c
Mean
3.6
8.4
13.2
21.7
SEM
±0.1
±0.4
±0.5
±1.2
Column means with the same superscript are not significantly different (p<0.05).
Tropical and Subtropical Agroecosystems, 19 (2016): 29 - 39
35
Table 5: Mean Height (cm) of the grass cultivars during field establishment and growth
Cultivar
Week4
Week 8
Week 12
Week 16
Llanero
2.3c
3.3b
3.9d
6.0f
MG4
5.0a
4.5b
37.3b
63.4b
Marandu
4ba
3.4b
10.2dc
20.4de
Piata
2.9bc
3.3b
14.6c
29.8dc
Xaraes
3.9ba
4.3b
12.6dc
24.9dce
Mulato II
2.1c
3.0b
7.9dc
14.3fe
Basilisk
4.6a
3.7b
12.8c
34.9c
Kat R3
2c
2.3b
7.3dc
52.8b
Napier
-
44.4a
67.3a
103.8a
Mean
3.3
8.0
19.3
38.9
SEM
±0.1
±0.4
±0.9
±1.4
Column means with the same superscript are not significantly different (p<0.05).
Figure 3: Dry matter yields in Kg/ha at primary production
DISCUSSION
The study demonstrated considerable variation in
establishment of the grass cultivars. The differences
in plant population can be attributed to species
differences in seed germination rates, seedling
establishment and survival. Plant numbers were
highest for C. gayana KATR3. According to (Cook et
al., 2005), Chloris gayana is likely to have the
greatest number of seed (7 250 000 to 9 500 000 per
kg of seed). This explains the higher plant counts for
C.gayana as compared to the other cultivars. Seed
proportion of C.gayana has been shown to have a
significant effect on agronomic traits (Yisehak,
2008). Higher plant populations for Brachiaria
brizantha cultivars MG4 and Marandu, can be
explained by their higher germination percentages
and accompanying seedling vigour (Nguku, 2015).
Vegetative growth (height, spread and tiller number)
generally increased for all the cultivars and can be
attributed to the morphological and physiological
differences among the cultivars. The rapid spread of
the cultivars indicates that they can play an important
role in quick soil stabilization for erosion control and
can be utilized in the stabilization of terrace banks in
semi-arid areas. Plant spread can be attributed to
individual growth habits of the cultivars. Brachiaria
humidicola is a strongly stoloniferous and
rhizomatous perennial grass, forming a dense ground
cover and B. decumbens has good ground cover,
aggressive growth and decumbent habit as reported
Nguku et al., 2016
36
by ook et al (2005). Napier being a fodder crop and
gigantic in nature would naturally out do the other
grasses when it comes to spread. Cook et al (2005)
further report that the ability of C .gayana to spread is
because it produces stolons which creep over the
ground, developing roots at the nodes and that
Marandu has some allelopathic effect which even
reduces seedling recruitment of its own seed. This can
explain the initial high spread of Marandu and the
decreased vigour in this attribute relative to other
cultivars by week 16.
MG4 and Napier were taller than the other plants and
also produced high dry matter yields at week 16.
Studies by Tessema et al (2003) concur that
increasing foliage height in Napier grass increased
biomass yield. Chloris gayana KATR3 on the other
hand has a higher proportion of stem relative to leaf
by week sixteen which could be the reason for lower
dry matter yields. The vertical growth habit of
Napier, MG4 and C. gayana cv. KATR3 explain why
they are tallest by week 16 relative to other cultivars.
(Opiyo, 2007; Mganga, 2009 and Ogilo, 2010) report
that, pasture species which grow fast and tall are
more efficient in use of resources and therefore, are
more competitive. Such species eventually shade out
the other species if planted in mixed stands thereby,
suppressing their growth. Brachiaria humidicola cv.
Llanero’s decumbent habit explains why it is the
shortest at week 16.
All cultivars but Piata attained over 50% plant cover
by week 16. The high plant cover for both B.
brizantha and B. decumbens cultivars could be
attributed to their growth habits. Brachiaria brizantha
is more tufted in terms of growth habit and
Brachiaria decumbens more decumbent and this
makes them form a dense plant cover (Cook et al.,
2005). Mulato II on the other hand produces vigorous
cylindrical stems, some with a semi-prostrate habit
capable of forming roots at the nodes when they come
into contact with the soil (Vendramini et al., 2011)
making them attain high plot cover (70%). Studies in
Honduras indicate that Mulato II establishes rapidly,
and was able to achieve 85% ground cover at 2
months (Cook et al., 2005). Cook et al (2005) further
report that Llanero has a strongly stoloniferous
growth habit and this causes it to have good ground
cover. Napier on the other hand is a tall, tufted,
rhizomatous perennial, very coarse and robust, in
dense clumps. Its giant nature naturally makes it
occupy a larger area relative to the other grasses
hence the higher plot cover (Bogdan, 1977). Chloris
gayana is a tufted perennial that also has a
stoloniferous growth habit making it have a high plot
cover. It produces stolons which creep over the
ground, rooting at the nodes, and also produces
abundant seed to give rise to new plants (Cook et al.,
2005).
Llanero, MG4, Mulato II, Piata, Basilisk and Xaraes
had higher tillering ability than the rest of the
cultivars. This is an indication of the ability of the
cultivars to recover faster after defoliation. Hiernaux
et al (1994) found that plant tillering early in the life
of the stand compensated for low plant density that
resulted from drought or intense grazing. Marandu
was not able to maintain a high tiller recruitment
which could be attributed to allelopathic effect
exhibited by the cultivar (Cook et al., 2005). Cook et
al (2005) further reports that tillering in Llanero can
be attributed to its growth habit. According to Halim
et al (2013) taller varieties of Napier tend to have
fewer tillers but produce higher DM yields compared
with shorter varieties which recruit higher tiller
numbers and have higher nutritive values.
There were differences in dry matter yields among
the grasses which can be attributed to their genotypic
and phenotypic differences. Despite low plant
numbers in some cultivars all the grasses persisted
during the duration of study. On the basis of dry
matter yield the best is Napier grass whereas the most
promising among the Brachiaria cultivars is MG4.
Napier out yielded the other grasses confirming
studies by Humphreys (1994) and Skerman and
Riveros (1990) of its potential for high dry matter
yields relative to other tropical grasses. Herbage yield
of Napier grass may however be affected by the
harvesting day after planting. Generally, as grass
ages, herbage yield is increased due to the rapid
increase in the tissues of the plant (Minson, 1990).
Mulato II was second to MG4 among the Brachiaria
grass cultivar in dry matter yields. Dry matter yields
for Mulato II can be largely attributed to its large size
leaves (15-2" long) and thick stems (1-1.5" width)
(Guiot and Meléndez, 2003). Mean primary dry
matter yields for C. gayana though low were found to
be similar to Brachiaria cultivars Piata and Basilisk
which ranked third and fourth respectively in primary
production. Although Marandu had high
establishment rates this did not parallel its dry matter
yields at primary production as reported by studies by
Rao et al (1998) of rapid establishment accompanied
by high DM production.
A longer period of study is recommended for
evaluation of the Brachiaria cultivars for age at
senescence and subsequent productivity.
CONCLUSION
The grass cultivars depended solely on the short rains
with no irrigation water added. All the species
established and persisted for the duration of the study.
Tropical and Subtropical Agroecosystems, 19 (2016): 29 - 39
37
Although C. gayana KATR3 is superior in terms of
plant population and Napier grass superior in plant
cover and height, the Brachiaria species perform
better in terms of spread, plant cover, plant tiller
number and even height and The Brachiaria species
performed better in plant attributes like spread
(Llanero), plant cover (MG4, Xaraes, Llanero) and
tiller recruitment (MG4 and Xaraes). Napier and
MG4 are both tall varieties and also produced
comparatively higher dry matter yields compared to
the other cultivars demonstrating their potential to
utilize available plant resources. The tillering and
spreading ability of Llanero is an added advantage for
soil cover and protection as well as being an animal
feed. This is also true for all the Brachiaria cultivars
in this study.
Acknowledgement
This study is a collaborative undertaking between
KARI and Bioscience for eastern and Central Africa/
International Livestock Research Institute
(BecA/ILRI) and was funded by Swedish
International Development Agency (Sida). We also
want to appreciate the cooperation from various
KALRO-Katumani and KALRO- Muguga staff for
their support and team work during project execution.
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Submitted November 09, 2015 Accepted December 16, 2015
... El incremento del rendimiento con la edad de rebrote en el periodo lluvioso (Tabla 3) se puede atribuir entre otros factores, al aumento del proceso fotosintético y la síntesis de metabolitos necesarios para el crecimiento y desarrollo de las plantas, lo que trae consigo acumulación de materia seca (Del Pozo et al., 2001;Ramírez et al., 2010). Otro estudio en el trópico reflejó rendimientos superiores a los notificados en este trabajo, estos autores reportaron valores superiores a las siete toneladas a los 56 días de rebrote, lo que sin duda estuvo influenciado por las condiciones climáticas (Nguku et al., 2016). Sin embargo, Reyes-Pérez et al. (2018), señaló valores inferiores de rendimiento (1.18 t MS ha -1 ) al estudiar la Brachiaria decumbens a los 63 días de rebrote en condiciones climáticas del oriente de Cuba. ...
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This study evaluated the effects of organic and inorganic soil fertilization on forage grass (Brachiaria brizantha cv. xaraes) yields, soil N availability, and soil greenhouse gas (GHG) emissions in Central Kenya. A field experiment was conducted at the International Livestock Research Institute (ILRI) farm in Nairobi, Central Kenya. A completely randomized block design was set up with three replications in blocks (20 m × 15 m) approximately 50 m apart from each other, each containing six plots (4 m × 2 m) with Brachiaria brizantha cv. xaraes. Treatments included one inorganic and four organic soil fertilizers, namely NPK fertilizer, farm-yard cattle manure (FYM), FYM plus biochar (FYM-BC), FYM converted to bioslurry via anaerobic digestion, legume intercropping with Lablab (Lablab purpureus), and control (zero fertilizer amendment). Greenhouse gas emissions (N2O, CO2 and CH4) were measured using the static chamber approach for a period of eight months. In addition, soil samples were taken for determination of mineral N concentrations in the forms of nitrate (NO3-) and ammonium (NH4+). Plant biomass sampling for Brachiaria brizantha cv. xaraes grass yields was conducted every ten weeks and above-ground plant dry matter was determined. All fertilizer types were applied at a rate of 45 kg N ha-1 one week after each harvest, except for Lablab intercropping, which relied solely on biological nitrogen fixation via the legume (rate not determined in this study). The study was conducted between October 2018 and August 2019 comprising of four harvest seasons of 10 weeks each: short rains (SR, October 2018 to January 2019), hot dry season (HD, January 2019 to March 2019), long rains (LR, March 2019 to June 2019), and short rain 2; cold dry season (CD, June 2019 to August 2019). Treatment and season significantly influenced daily CH4 uptakes (p <0.01 and p = 0.009) but did not show significant interaction (p = 0.093). Methane uptake was similar across all the treatments following the order of Control > Lablab > FYM > FYM-BC > NPK, except for Bioslurry which exhibited significantly lower (-2.69±4.47) CH4 uptake (p< 0.01). Within the seasons, significantly lower (-11.43±4.42) and higher (-21.23±1.11) CH4 uptakes were recorded during the HD and CD seasons, respectively while SR and LR seasons had similar CH4 uptake. Treatment and season had significant (p < 0.01 two-way ANOVA) effect on CO2 emissions. CO2 emissions in FYM-BC and FYM alone were on average lower by 61.6% compared to the control which had the highest (94.76±19.32). Seasonal CO2 emissions followed the order of CD>HD>LR>SR seasons, respectively. Treatment and season also interacted significantly (p<0.01 two-way ANOVA) to influence CO2 emissions. Lower (44.33±15.67) emissions occurred under FYM alone during the HD season while the highest (157.54±2.77) CO2 emissions was recorded under the control treatment during the SR season. FYM-BC and FYM alone had significantly (p < 0.01 two-way ANOVA) lower (6.70±14.48 and 8.20±15.67 respectively) N2O emissions compared to the control which had the highest (12.95±3.61). Significantly higher N2O emissions were recorded during the SR season while HD, LR and CD seasons had similar emission rates. Significant (p < 0.01 two-way ANOVA) interaction between treatment and season was also observed with NPK recording the lowest (4.21±0.83) emissions during the second season relative to control which had the highest (27.16±0.90) N2O emissions during the first season. Furthermore, fertilizer treatments significantly influenced NH4+ and NO3- availability in the soil (p < 0.001). The highest NH4+ concentration was recorded in the NPK treatment 14 days after fertilization (21.20±27.01 µg g-1 DM), while the lowest NH4+ concentration was recorded in the Lablab treatment (6.62±8.02 µg g-1 DM). 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