Allelopathic effects of leaf litter from Cinnamomum japonicum on vegetative and reproductive growth of Impatiens balsamina

We studied the performance of Impatiens balsamina in soil incorporated with the leaf litter of Cinnamomum japonicum. The application of 40 or 80 g litter in 8 kg soil, significantly inhibited the vegetative growth and photosynthetic rate of I. balsamina. These treatments also changed the normal blooming pattern of the receptor plant. Though the fruit and seed yield per plant of I. balsamina was not influenced by C. japonicum leaf litter, but the seed yield per fruit was increased at the highest dose. Incorporation of boiled leaf litter to soil did not affect the growth of I. balsamina, which indicated that the allelochemicals of C. japonicum were neutralized by boiling i.e. high emperature. Eight compounds (terpenoids, aldehyde and esters, which are Dihydrocoumarin, 1,8-Cineole, Cinnamaldehyde, trans-Caryophyllene, alpha-Terpineol, (+)-Spathulenol, Caryophyllene oxide and Borneol L.), were found in C. japonicum leaf litter. These may be potential allelochemical candidates. In conclusion, C. japonicum leaf litter during its decomposition was allelopathic to I. balsamina. The allelopathic effects inhibited the carbon-fixation ability, thereby reduced the vegetative growth and flower production of I. balsamina.