Crop Science and Production Collection

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Browsing Crop Science and Production Collection by Author "Constantine, John"

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    Effects of striga asiatica (L.) Kuntzc and Rhaniphicarpa fistulosa (Hochst) Benth. seed densities on physiology and yielding ability of rice (Oryza sativa L.)
    (Sokoine University of Agriculture, 2014) Constantine, John
    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.