| dc.description.abstract | Allelopathy is a common among plants. Allelopathic substances affect seed
germination, plant growth and development or even affect chlorophyll
synthesis by the plant leaves. Tithonia diversifolia contains allelochemicals
that inhibit growth of many agricultural crops. A study was conducted at
Maseno University (Kenya) to investigate the allelopathic effects of T.
diversifolia on the germination of seeds, growth and synthesis of chlorophyll
of seedlings of cowpea (Vigna sinensis). Cowpeas seeds and seedlings were
subjected to four different concentrations of the fresh shoot aqueous extracts
which comprised of 0 (tap water), 25%, 50%, 75%, and 100%. Twenty Seeds
of cowpeas were germinated in sterilized petri dishes lined with a layer of
filter paper whatman no. 1, moistened with 10ml of each extract concentration
and tap water respectively. Germination percentage, plumule and coleoptiles
length were determined at the end of the study. Individual cowpeas seedlings
were planted in 4.5 litres plastic pots containing soil and irrigated with the
various shoot extracts concentrations and tap water using 500ml respectively.
The treatments were replicated five times and the pots laid out as completely
randomized design in the glasshouse. Data on shoot height; number of leaves
per plant was recorded on weekly basis. Leaf area, shoot and root dry weights
and leaf total chlorophyll, chlorophyll a and b concentration were determined
at the end of the experiment. Data collected was subjected to analysis of
variance (ANOVA) using SAS statistical package. Treatment means were
compared using the least significant difference (LSD) at (P<0.05). The results
revealed that fresh shoot aqueous extracts of T. diversifolia have both
inhibitory and stimulatory effects on V. sinensis. Seed germination increased
with increasing concentration of shoot extracts from 25%, 50% to 100% even
though there were no significance differences among treatments. Plumule and
radicle lengths reduced significantly among treatments. Shoot heights, leaf
number, leaf area, shoot and root dry weights, total chlorophyll and
chlorophyll a and b concentrations increased significantly with increasing
shoot extract except at 100% treatment where all these parameters were
inhibited. | en_US |
