Chemical constituents of <i>Cinnamomum septentrionale</i> leaf litter and its allelopathic activity on the growth of maize (<i>Zea mays</i>)

<p>A pot experiment was conducted to study the effect of decomposing <i>Cinnamomum septentrionale</i> leaf litter on the growth of maize. In this study, the morphological traits of maize were significantly inhibited when the leaf litter amount reached or exceeded 40 g per pot; Furthermore, during the early growth stage or with a large amount of litter addition, the pigment contents were inhibited by <i>C. septentrionale</i> leaf litter. Gas chromatography–mass spectrometry was used to determine the volatile substances of leaf litter and 34 compounds were identified, several of which were reported to be phytotoxic. In conclusion, the leaf litter of <i>C. septentrionale</i> showed a strong allelopathic effect on the growth of maize. Thus, it is better to avoid the growing of maize under or near the <i>C. septentrionale</i> plantation unless the leaf litter could be eliminated in time or other effective leaf litter processing methods could be implemented.</p

Allelopathic activity and chemical constituents of walnut (<i>Juglans regia</i>) leaf litter in walnut–winter vegetable agroforestry system

<div><p>Walnut agroforestry systems have many ecological and economic benefits when intercropped with cool-season species. However, decomposing leaf litter is one of the main sources of allelochemicals in such systems. In this study, lettuce (<i>Lactuca sativa</i> var. <i>angustata</i>) was grown in the soil incorporated with walnut leaf litter to assess its allelopathic activity. Lettuce growth and physiological processes were inhibited by walnut leaf litter, especially during early growth stage (1–2 euphylla period) or with large amount of litter addition. The plants treated by small amount of leaf litter recovered their growth afterwards, while the inhibition for 180 g leaf litter persisted until harvest. Twenty-eight compounds were identified in the leaf litter, and several of them were reported to be phytotoxic, which may be responsible for the stress induced by walnut leaf litter. Thus, for highest economic value of vegetables such as lettuce, excessive incorporation of leaf litter should be discouraged.</p></div