Dissertation
Silicon (Si) is the second most abundant element available in the earth's crust and is
considered as a beneficial element for crop growth especially rice. Si deficiency in the soil
may lead to decline in rice yields. A study was conducted in Mkindo Irrigation Scheme,
Morogoro, Tanzania to assess Si uptake by rice plant grown under the system of rice
intensification and continuous flooding. The experiment was laid out in a randomized
complete block design (RCBD) with two treatments which were two water application
regimes T 1 and T 2 . T 1 was alternate wetting and drying using SRI technology and T 2 was
continuous flooding. The treatments were replicated three times and the rice variety used
was SARO 5 (TXD 306). The experiment was conducted in two seasons from October
2019 to January 2020 and from March 2020 to June 2020. The available Si status in soils
of the experimental site, in rice seeds, grains and in rice plant leaves as well as growth and
yield parameters were assessed according to elemental analysis based on Energy
Dispersive X- Ray Fluorescence and results were analyzed using GENSTAT software.
The soils of the study area had sufficient amount of available Si content which ranged
from 230.58 to 240.42 mg kg -1 . Si content in rice seeds observed prior to the experiment
was within acceptable range between 4-20%. Si content in rice grains was gradually
increasing during reproductive stage and later dropped during harvest. Si content in rice
plant leaves increased from vegetative to ripening stage whereby T 1 gave the highest Si
content (12.37%) while the lowest value (10.15%) was observed in T 2. Similarly, T 1
recorded the highest plant height (147 cm), number of tillers per hill (54), number of
productive tillers per hill (46), number of panicles per hill (31) and grain yield (8 tons ha -1 )
meanwhile T 2 gave the lowest plant height (129 cm), number of tillers per hill (27), number
of productive tillers per hill (22), number of panicles per hill (27) and grain yield (3 tons ha -1 ). It
was concluded that, SRI enhanced adequate uptake of Si which in turn improved significantly crop
growth and rice yield compared to continuous flooding practices.