| dc.description.abstract | Safflower (Carthamus tinctorius L.) is a versatile crop used for edible oil, vegetable, cut flower
production, colouring foods, cosmetics, pharmaceuticals, livestock feed, biofuels, textile, and
medicinal purposes. Soil fertility is one of the factors that limit crop production in Botswana.
The objective of this study was to evaluate the influence of N and P fertilizer application on
the growth, seed yield, and oil content of safflower. The experimental design was a split-plot
laid down in randomized complete blocks with three replications. The treatments were N
application at 0, 40, 80 and 120 kg/ha allocated to main-plots and P application at 0, 25, 50 and
50 kg/ha allocated to sub-plots. The results revealed that N and P significantly (P < 0.05)
influenced vegetative growth, yield components, seed yield, and oil content of safflower.
Application of 40 N + 50 P kg/ha to safflower plants produced maximum first branching height,
leaf area, and chlorophyll content. Maximum safflower plant dry matter was obtained from
plants applied with 120 N + 75 P kg/ha. While N and P independently significantly (P < 0.05)
increased plant height (40 N, 50 P kg/ha), primary branch number (80 N, 50 P kg/ha) and stem
diameter (40 N, 75 P kg/ha) compared to control plants. The interaction of N and P also
significantly (P < 0.05) affected NUpE, NUtE, NUE, PUpE, PUtE, and PUE in both summer
and winter. Application of 40 N + 50 P and 40 N + 25 P kg/ha, optimised NUpE, NUtE and
NUE, and PUpE, PUtE and PUE, respectively. The interaction of N and P significantly (P <
0.05) influenced safflower yield components. Maximum capitula number/plant, capitula
diameter, seed number/capitulum, and 1000-seed weight were produced by safflower plants
applied with 40 N + 50 P and 40 N + 25 P kg/ha, respectively. Application of 40 N + 50 P and
80 N + 75 P kg/ha to safflower plants significantly (P < 0.0001) increased the seed yield to
1356 and 3528 kg/ha in summer and winter, respectively. There was no significant interaction
of N and P on seed oil content in summer, but the application of N and P independently
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significantly (P < 0.05) increased safflower seed oil content with a maximum oil content of
46.4 and 46.1% obtained through the application of 120 and 25 kg/ha of N and P, respectively.
In winter, N and P significantly (P < 0.0001) interacted at 0 kg N/ha + 25 kg P/ha to produce
the maximum oil content of 71.8%. The results revealed that winter grown safflower produced
seed with high oil content than summer grown safflower. From the results based on the
performance of safflower as N and P influenced vegetative, yield components, seed yield, and
seed oil content it was concluded that application of 40 N + 50 P kg/ha was recommended to
maximize safflower production. However, it was also recommended that this study be repeated
in Southern Botswana for confirmation of the current results. Also, fertilizer trials to be done
in other parts of the country where farmers are currently growing safflower. | en_US |
