Assessment of germination stimulants from non-host leguminous crops for control of striga asiatica (L.) Kuntze in semi - arid areas of Tanzania.
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Date
2005
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Publisher
Sokoine University of Agriculture
Abstract
Sin^u asiatica is one of the mosl deslructix e parasitic weed species in the Semi And
Zone of Tanzania
In an efibrt to come out with an appropriate and sustainable
method of conlrolling lhe weed species, two 1 aboralor\7screen house and one field
experiments were conducted to identify leguminous crop species/cullivars that are
suitable for use as trap crops in lhe control of Stnga asiatica. Eflectiveness of root
exudates of 56 cultixars from six leguminous species on germination of S. asiatica
seeds were assessed in vitro using Pein Dish (PD) technique. A split plot design
replicaied four times was used.
The second laboratory experiment, aimed at
exaluating lhe effect of seed coat colour and different plant pans oT selected
leguminous species/cullivars on stimulating germination of the parasitic weed seeds
was done
used.
A Completely Randomised Design (CRD) with four replications was
Both experiments were repealed three limes.
In addition, a 2-\ears field
experiment was conducled to exaiuate lhe efficacy in situ of the species/ cultivars
identified in vitro A Completely Randomised Block Design (CRBD) was used and
lhe experiment w as replicated four times. Results indicated that effectiveness of root
exudates depends on Striga seed population. and cultivars \\ ithin species differed in
lheir capacity to stimulate gennination of S. asiatica seeds. Pigeon pea cultivars
ICEAP 00020 and ICEAP 00040; groundnut ex-Bukene: cowpeas white black eyed;
barnbara groundnut cultivars Nyandani spotted cream and Red ex- Makutupora were
round lo stimulate significantly (P < 0 ()01) higher germination percentages of S.
usianca seeds compared lo lhe other tested cultivars within their respect!\e species.
hence were selected for further evaluation in field. Seed exudates from black seeded
bambara groundnut stimulated 66.8% germination of S. asiatica seeds, which was
significant!} (P < ()001) higher compared to percent germination induced by the
positixe control (41 3%). Genninaiion of Sfn^a seeds exposed lo exudates from
dilTerent plant pans (roots, shoots and seeds) of bambara groundnuts, cowpeas and
groundnut ranged from 15% lo 63.4%. which was significantly higher compared to
percent germination induced by the negative control (2.4%). Rotating legume trap
crops with sorghum resulted into 3X - 48% reduction of Stnga seeds in the soil as
well as reduction of Sirica inlesiaiion by 50% compared to continuous sorghum
cropping and w eed free fallow 一 sorghum rotation. Yields of sorghum grow n after
legumes ranged between ().75 — 2 28 tons/ha. while \ ields from sorghum after weed-
free fallow and sorghum continuous cropping were 0.53 tons/ha and 0.61 tons/ha
respeclixely Except lor cowpeas, all other legume - sorghum rotations resulted into
significant^ (P < () 0()1) higher yields compared with the weed free fallow and
continuous sorghum cropping
It is concluded that crop rotation with pigeon pea
cultivars ICEAP ()0020 and ICEAP 00040: groundnut ex-Bukene; and bambara
groundnul cultivars Nyandani spoiled cream and red ex- Makutupora can serve as
efTectixe trap crops which would reduce S. asiatica seed bank and iniestations. By
inference, rotating sorghum with any of these legumes would boost yields, thereby
sparing farmers limited resources, which would have otherw ise been spent for other
expensixe Stn^a conirol measures.
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Thesis
Keywords
Germination stimulants, Leguminous crops, Semi - arid areas, Tanzania, Kuntze