Changes in Chlorophyll and Protein Contents of Vigna unguiculata, Glycine max, Zea mays and Sorghum bicolor Raised in Soil Incorporated with the Shoots of Tithonia rotundifolia

Tithonia. rotundifolia is an allelopathic weed that grows in association with cultivated crops in Nigeria. Allelopathy is a phenomenon of plant releasing allelochemicals into the environment that can inhibit or stimulate the growth of other plants and microorganisms. This study aimed to evaluate the effects of soil incorporated with the fresh shoots of T. rotundifolia on chlorophyll and protein accumulation of Vigna unguiculata L. Glycine max L., Zea mays L. and Sorghum bicolor L. 250 g of fresh shoots of T. rotundifolia were worked into each plot of 2 m2 dimension and the test crops were sown in the plots. Plots with no T. rotundifolia shoots were included as control plots. The experiment was performed in completely randomized block design (CRBD). The parameters measured were chlorophyll a, chlorophyll b total chlorophyll and protein content. The results showed a stimulation in chlorophyll contents in the test crops except inhibition in chl b and total chlorophyll in Zea mays L. Also, there was a stimulation of protein in Zea mays L. and Sorghum bicolor L. The study suggests that incorporation of shoots of Tithonia rotundifolia could imparts stimulatory allelopathic effects.