Seed yield and quality of Cenchrus ciliaris cv. Biloela under various agronomic practices in sub-humid eastern zone of Tanzania
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Date
2015
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Sokoine University of Agriculture
Abstract
Livestock production especially ruminants, is one of the major agricultural activities
in Tanzania. Both traditional and improved livestock production depend on natural
and improved forages which are inadequate due to land use pressures from other
users which sometimes result in resource use conflicts. Land ownership to intensify
livestock farming is shown to be one of the steps for increased livestock productivity,
improved degraded grazing land and for resolving conflicts associated with land use
pressures. Pasture establishment is an alternative solution to improve owned land and
hence increased livestock productivity, despite inadequate availability of good
quality planting material especially grass pasture seeds. Cenchrus Ciliaris cv.Biloela
(buffel grass) is among those adapted promising grass species promoted for
establishment for its desirable drought tolerant characteristics, Inadequacy and poor
viability of the buffel grass seeds seem to be the hindrance. Available information
showed that, low fertility of soils and high risks of diseases are among the major
factors affecting viability of buffel grass seeds in wet season. There is also limited
information on production of seeds and forage biomass of this grass in dry season
under irrigation, its response to different fertilizer application rates, rows spacing,
cutting heights and the overall biomass productivity under field conditions.
Therefore, there was a need to conduct a study to gain a practical experience on how
to compromise facts on seed quality and forage biomass production under field
conditions in sub humid agro-ecological zone of Tanzania. The main objective of the
study was to evaluate the effects of various agronomic practices on seed yield and
quality of Cenchrus ciliaris cv. Biloela in the sub-humid eastern zone of Tanzania.
In order to achieve the main objective of the study, a field survey of three pasture
seed farms was done, followed by field trials at Magadu dairy farm of Sokoine
university of Agriculture to evaluate different agronomic practices including
fertilizer levels and row spacing under two cutting heights on how they affect seed
yield, quality and forage biomass production in wet and dry season. The three seed
farms were Mazimbu in Morogoro, Vikuge pasture seed production farm in Kibaha
and TALIRI, Tanga. A laboratory experiment was conducted to assess viability
status of sampled Cenchrus ciliaris seeds from the visited farms and those produced
from the field trial. Soil samples were also taken from visited farms so as to assess
current fertility status of these seed farms. The results showed that spikelet
germination percentage was 8.33% for Mazimbu, 0.25% for Vikuge and 1.83% for
Tanga farms. Total soil Nitrogen was observed to be at very low to low levels i.e.
0.08%, 0.13% and 0.12% for Vikuge, Tanga and Mazimbu farms, respectively. From
this study it could be concluded that old age sward produced low quality seeds in
terms of viability, and this could be further exacerbated by low soil fertility. In order
to improve an understanding of grass seed production, additional studies on fertilizer
rates, irrigation during dry season, rows spacing, cutting height on how they affect
seed yield and quality were conducted in the similar agro-ecological zone. For
specific objective 2 and 3, study two was conducted at Sokoine University of
Agriculture farm to assess the effects of different levels of Nitrogen and Phosphorus
0 KgN/ha 0KgP/ha, 40KgN/ha 20KgP/ha, 60KgN/ha 30KgN/ha P abbreviated as
(0N 0P, 40N 20P, 60N 30P) , row spacing (25, 75 and 100 cm) under two cutting
heights (15 cm and ground cut) under rain fed and irrigation in wet and dry seasons
on seed yield and vegetation characteristics of Cenchrus ciliaris cv.Biloela. The
study was done in two consecutive years 2012 and 2013 (March – June and June-
September) for long rains and dry seasons, respectively. It was observed that, seed
yields were higher at higher rates of nitrogen and phosphorus at ground cutting (77.5
kg/ha) than at 15 cm cutting height (56.7 kg/ha) with a trend of decreased seed yields
in the second year (77.5 to 38.4 kg/ha) and (56.7 to 35.5 kg/ha) at the same levels of
nitrogen and phosphorus. Row spacing of 100cm showed slightly higher seed yield
(70 kg/ha) as compared to other two row spacing (25 cm and 75cm) that gave 67.2
and 69.3 kg/ha, respectively. Higher seed yields were observed in dry than wet
season for two consecutive years under all cutting heights (66.7 and 37.8 kg/ha 15
cm cutting for dry and wet season, respectively). Higher levels of nitrogen and
phosphorus yielded significantly (p<0.05) higher forage biomass (13.2 and 11.1 t
DM/ha) from 15cm and ground cutting respectively as compared to 10.0 and 8.6 t
DM/ha for low level of nitrogen and phosphorus rates. High plant density at 25 cm
row spacing yielded higher biomass (12.2 t DM/ha) than low plant density at 100 cm
row spacing (11.4 t DM/ha). It was concluded that, ground cutting could be
beneficial management practice for rhizomatous grass so as to obtain higher seed
yields since it allows healthier ground tillers from rhizomes than profuse aerial tillers
produced at higher cutting heights. Irrigation during dry season was the best option
for Cenchrus ciliaris cv. Biloela seed production when row spacings of 75 cm and
100 cm are used at ground cutting height with proper rates of nitrogen and
phosphorus. However, strategies for bird scaring during dry period (offseason) were
highly emphasized from blooming stage to seed maturity to maximize seed yield.
Study two (specific objective three) was done to investigate the effect of fertilizer
levels and row spacing under two cutting heights on seed quality of Cenchrus
ciliaris cv. Biloela in wet and dry season using irrigation. In this study, four
parameters of seed quality namely; caryopsis index, spikelet germination, seed
colour and physical grain qualities (good and damaged) were assessed for first and
second harvest. The findings showed significantly high (p≤ 0.05) caryopsis index for
seeds produced in dry and wet season (37.9 and 24.3%) respectively. The interaction
of fertilizer levels within seasons marked a clear variation on caryopsis index and
germination potential in dry season seeds for seeds of first harvest than second
harvest. The colour of seeds produced during the wet season indicated a vivid sign of
fungal infection. The age of vegetation also significantly (p<0.05) affected the
germination of seeds in both year one and year two from 20.4 to 30.0% and 12.9 to
22.8%, respectively. It was also observed that, old age vegetation produced low
viable seeds than younger vegetation. Viability improved with time of storage,
however only six months were tested. These results suggest that dry season and
higher rates of nitrogen and phosphorus fertilizer be taken into consideration to
improve production of quality grass pasture seeds, however proper fertilizer rates
depends on soil fertility status of the site. Harvest time had a significant (p < 0.05)
effect on quality of batches of seeds produced. The first harvested seeds were
significantly (p < 0.05) higher in viability than second harvest thus were good for
commercial purposes. For specific objective 4, the third study was conducted to
evaluate profitability of both seed and forage biomass production of buffel grass
(Cenchrus ciliaris cv.Biloela) based on irrigation in dry season and wet season
under different levels of Nitrogen and phosphorus using Urea and Triple Super
Phosphate (TSP) fertilizers. The study was carried out at Magadu Dairy farm of
Sokoine University of Agriculture, Morogoro, Tanzania. Two seasons (wet and dry)
were involved with three treatments:- without fertilizer (0KgN/ha 0KgP/ha),
combined fertilizers (40KgN/ha 20 KgP/ha) and (60KgN/ha 30KgP/ha). All the fixed
and variable costs were recorded and computed for cost benefit analysis during the
trial and supplemented with secondary information from other input suppliers and
farms. The results of this study showed that higher level of fertilizer significantly
(p<0.05) led into more seed yield and biomass than when lower levels were applied.
Economically, break even level was reached in wet season for revenues from both
seeds and forage in year 1 and 2. However, only one level of fertilizer (60KgN/ha
30KgP/ha) was profitable by (TZS 81,011.75) during the year 1 in dry season due to
costs incurred for irrigation and planting materials. The profit in dry season was
realized in second year. Trend of seed and forage production was profitable in year
two for both seasons as no costs were incurred for establishment for perennial
species where planting materials costs are only incurred in first year. It was learnt
that it was profitable to produce forage biomass in wet season than dry season
however, seed production showed vice versa trend and hence relatively profitable to
produce seeds in dry season. It is therefore recommended that the use of irrigation
and proper fertilizer rates for grass pasture seed production can be a potential option
for improved quality and quantity of grass seed production to meet demands of
livestock producers.
Description
PhD Thesis
Keywords
Seed yield, Cenchrus ciliaris cv. Biloela, Agronomic practices, Sub-humid, Eastern zone, Tanzania