| dc.description.abstract | Sunflower contributes about 40% of total national cooking oil requirement in Tanzania, ranking
as one of the most important cooking oil with very high nutritional value. However, its
production per unit area ranges between 800 and 1100 kg/ha, the average of which is below the
potential production of 1200 to 2000 kg/ha in most African countries. The low sunflower
productivity is partly attributed to low soil fertility. A field experiment was therefore conducted
during the 2013/2014 long and short rains season at the Sokoine University of Agriculture soil
science experimental sites to determine the effect of fertilizers; farmyard manure (FYM) and
inorganic nitrogen fertilizers on sunflower growth, yield and seed oil content. The treatments
consisted of: control (no nitrogen fertiliser, no farmyard manure); 2 t farmyard manure (FYM)/ha
applied at planting; 5 t FYM/ha applied at planting; 10 t FYM/ha at planting; 20 kg N/ha applied
as UREA at 30 days after planting; 40 kg N/ha applied as UREA at 30 days after planting; 60 kg
N/ha applied as UREA at 30 days after planting; 2 t FYM/ha at planting + 20 kg N/ha applied as
UREA at 30 days after planting; 5 t FYM/ha at planting + 40 kg N/ha applied as UREA at 30
days after planting and 10 t FYM/ha applied at planting + 60 kg N/ha applied as UREA at 30
days after planting. The treatments were laid out in a randomized complete block design and
replicated three times. Sunflower variety record was used as a test variety. Data collected
included: plant height and number of leaves at 15, 30, 45, 60 and 75 days after planting (DAP);
Head diameter, biomass yield, total seed yield per hectare, weight of 1000 seeds, seed oil content
and total seed oil yield per hactare. All data were subjected to analysis of variance (ANOVA)
using General Statistical Package (GENSTAT) and means were separated using the least
significant difference (LSD) test at P = 0.05.
The results showed that plots supplied with farmyard manure alone or in combination with
inorganic N- fertilizers had significantly taller sunflower plants than the no fertilizer control
plots. Application of FYM at the rate of 10 t/ha increased plant height, biomass formation, and
oil content. The application of 10 t FYM/ha and 60 kg N/ha significantly increased seed yield
and weight of 1000 seeds. Application of 60 kg N/ha increased plant height at 60 days after
planting during the long rains season and number of leaves at 45 DAP and 60 DAP in both
seasons of the experiment. Application of inorganic nitrogen fertilizers at rates lower than 60 kg
N/ha did not significantly increase sunflower crop performance relative to control.
It was concluded that application of fertilizers had positive impacts on crop growth, yield, yield
components and percentage oil content as of sunflower. However unlike the other parameters, oil
content was only increased by 10 t FYM/ha and control had higher oil content than some other
treatments in both seasons. The evidence from crop performance in terms of height, head
diameter, yield and yield components suggested that a combination of FYM and inorganic
nitrogen fertilizers at rates of 40 kg N /ha + 5 t FYM/ha and 60 kg N /ha +10 t FYM/ha are the
most promising soil fertility management practice followed by FYM alone especially to small
scale farmers who cannot afford the high costs of inorganic fertilizers. It was also concluded that
application of inorganic nitrogen fertilizers at rates 20 kg N/ha and 40 kg N/ha showed no
significant effect on sunflower crop yields.
It was therefore recommended that farmers in Morogoro to consider application of fertilizers in
sunflower crop production, especially 10 t FYM/ha alone and/or combination of 60 kg N/ha + 10
t FYM/ha as an important farm management practice to obtain seed yield of more than 1 t/ha. | |
