Screen house experiments were carried out to examine the effects of aqueous leaf extracts of Tithonia diversifolia (Ti) and Vernonia amygdalina (Ve), as well as NPK fertilizer (15-15-15) on the germination, growth and development of maize. Fresh leaves were collected, washed with tap water, chopped and pounded, soaked in distilled water and filtered. The two filtrates were used to prepare extracts at 50 and 100% w/v. Four maize seeds were placed in Petri dishes laid out in a completely randomized design with five replicates. In every Petri dish 10 ml of extract per treatment was added. A control experiment with distilled water was also set up. Also, in a completely randomized design with four replicates, 4-week-old potted maize plants were treated with 500 ml of each extract as well as with 1.52 g of NPK fertilizer. The results showed that the germination percentage of the seeds followed the order Ti 50 -Control -Ve 50 . The seeds treated with aqueous extracts of T. diversifolia and V. amygdalina at 100% w/v produced lower but equal germination percentage. The seedling radicle growth was significantly inhibited by the aqueous extracts of Ti 100 , Ve 50 and Ve 100 (p≤0.05). The inhibition was dose-dependent and more pronounced in seeds treated with extracts of V. amygdalina. The aqueous extract of T. diversifolia (50% w/v) and control influenced radicle growth substantially. All the extracts inhibited the plumule development compared to the control. On the other hand, growth, development and yield were not significantly affected by the plant extracts.

The effects of decaying leaf litter of Tithonia diversifolia and Vernonia amygdalina as organic fertilizer, inorganic fertilizer and their combination effects on the growth and development of maize were studied in a screen house. Twenty-four experimental bags filled with 20 kg of loamy soil were laid out in a completely randomized design with six treatments and four replications for each treatment which included: 250 g of decaying leaves of T. diversifolia as mulch (T 1 ), 250 g of decaying leaves of V. amygdalina (T 2 ), 1.52 g of NPK (inorganic) fertilizer (T 3 ), a mixture of 250 g of decaying leaves of T. diversifolia and 1.52 g of NPK 15-15-15 fertilizer (T 4 ), a mixture of V. amygdalina and 1.52 g of NPK 15-15-15 fertilizer (T 5 ) and control (T 6 ). The significant growth as well as maize yields were obtained from T 3 treated maize seedlings, and this was closely followed by T 4 treated seedlings. The study showed that the decaying leaf litter as an organic fertilizer in maize production in a screen house conditions did not give better yield than NPK treatment alone.

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