Effects of Compost Water-Extracts on the Germination and Growth of Slickspot Peppergrass (Lepidium papilliferum)

摘要

Compost addition to soil is a common practice, and amendment of soils low in organic content can be used to improve soil fertility. Slickspot peppergrass (Lepidium papilliferum) is a rare plant species of high conservation concern in southwestern Idaho, and grows in depressed soils called slickspots. Slickspot soils are low in organic content and additions of composts may be used to help establish new stands of this rare species. Compost water- extracts (C-WE) contain the portion of organic material that can pass through a 0.45 μm filter membrane and is constituted of an heterogeneous mixture of molecules with different molecular size and complexity, ranging from simple sugars and organic acids to relatively high molecular weight humic colloids. The biological activity of C-WE depends mainly on the type of substrate used for composting and the type and duration of the process. In some cases, however, phytotoxic effects may originate from compost application depending on the plant species type and age and environmental conditions. The aim of this work, which is part of a more extensive research on the restoration of rare plant species, was to evaluate the effects of C-WE from different composts on the germination and growth of slickspot peppergrass, and possibly relate its biological activity to chemical and physico-chemical characteristics of C-WE.