Wheat straw placement effects on total phenolic compounds in soil and corn seedling growth

Opoku, G., Vyn, T. J. and Voroney, R. P. 1997. Wheat straw placement effects on total phenolic compounds In soil and corn seedling growth. Can. J. Plant Sci. 77: 301-305. The effects of placement of wheat (Triricum aestivum L.) straw on the release of phenolic compounds potentially phytotoxic to corn (Zen mays L.) seedling growth were examined in plastic pots under controlled conditions in growth cabinets. The treatments were soil only (control), soil with straw only in the top 2.5 cm, and soil with mixed straw. Each of these treatments was either sown or not sown with corn. Corn radicle leneth and seedline biomass were sienificantl) reduced. rclstl\c 1 ~ 1 uthcr trraments, uhsn $3 1hc.11 htr:t\\ ~ 3 % present only in the top I.~!cr of soil \\'3tcr c\trdcts from ,011 w ~ t h s~rface ,rrd\\ h .4 h ~ ~ h c r amount. of total plirnolic r..lmpounds than the othcr truoncnrr it sxch o f ~ h s \3mplln: rimes. The concenrratlon oiphcnol~c ~(~mpoundc in reased wlth rmc. a . ~ t h a\craes amount.: at 14 and 28 d hems 53 and 7-''0. rc~~ect~vcly. of the concentration at 42 d. he presence of corn reduced the amount of phenolic compounds at 14 and 42 d compared with whin corn was absent (P = 0.01). Water extracts prepared from soil afler 42 d from all the treatments were used to investigate germination of corn seeds. Germination of corn seeds and radicle extension were inhibited by water extracts from all the above soils at 42 d compared with the control (deionized water). Coleoptile length was inhibited when concentration of phenolic compounds exceeded I0 ppm. Soil NO,-N differences among the treatments were insignificant at the various sampling times. This indicated that the observed corn growth differences were mainly due to the presence of phenolic compounds.