Effects of striga asiatica (L.) Kuntzc and Rhaniphicarpa fistulosa (Hochst) Benth. seed densities on physiology and yielding ability of rice (Oryza sativa L.)
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Date
2014
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Publisher
Sokoine University of Agriculture
Abstract
Striga asiatica and Rhamphicarpa fistulosa greatly affects rice productivity in
infested fields. To address this problem, two screen house experiments were
conducted at Sokoine University of Agriculture during September, 2012 to February,
2013 to study the effects of parasitic weed seed densities of S. asiatica and R.
fistulosa on physiology and yielding aptitude of rice. In one of the experiments eight
S. asiatica densities were planted with single host rice (variety IAC 165) while in the
second experiment, seven R. fistulosa densities were planted with single host rice
(variety IR64). Both experiments were laid out in a Completely Randomized Block
Design (CRBD) with five replicataions. In addition, a supplementary experiment was
conducted to study the intra specific competition between R.jistulosa plants under
monoculture where six R.fistulosa seed densities (31, 62, 125, 250, 500 and 1000
seeds/pot) were sown without host. In the S. asiatica density experiment, the highest
value on stomatal conductance was recorded in the parasite free pots (205.8
mmol/ni2 s) while the lowest was recorded in the plants with the highest S. asiatica
infestation densities (21 mmol/(m2s). At 60 DAS there was a significant difference
(P<0.05) between the treatment means chlorophyll content from 20.8 in highest S.
asiatica density (47 840 seeds/pot) to 34.1 in S. asiatica free pots. The highest
average total rice biomass was recorded in non-infested pots (2.5 g/pot) while the
lowest was recorded in the highest S. asiatica infestation density (0.5 g/pot). In R.
fistulosa density experiment there was significant difference in stomatal conductance
(P<0.05) at 60 DAS i.e. (202.8 mmol/(m2,s) from R. fistulosa free plants and (143.6
mniol/(m2 s) from lowest R. fistulosa infestation density. At 60 DAS, the highest
average value of chlorophyll fluorescence (0.66) was recorded in R. fistulosa free
plants while the lowest (0.413) was recorded from plants in the highest R. fistulosa
infestation density (1000 R. fistulosa seeds/pot). The highest rice biomass was
obtained from R. fistulosa free plants (5.42 g/pot) while the lowest was recorded in
the highest R. fistulosa infection levels (0.68 g/pot). On the basis of these results, it
was concluded that S. asiatica and R. fistulosa affect rice physiology and yielding
ability.
Description
Dissertation
Keywords
Parasitic weed, Rice seed, Seed Sowing