Allelopathic effects of decomposed leaf litter from intercropped trees on rape

Abstract

The allelopathic effect of decomposed litter from trees interplanted with crops is a key problem in the intercrop agroforestry business that could influence the economic benefits and sustainable development of ecoagriculture. In our study, the litter from 12 common intercropped tree species was collected from the Guanzhong Plain (Shaanxi Province, China) and mixed with soil, incubated to allow decomposition for 120 days, and then extracted using water. The water extracts at different concentrations were used for filter paper-dish cultivation of rape (Brassica napus) seeds. Indicators of the germination and growth of seedlings were measured to investigate the allelopathic effects of decomposed litter on rape. The results showed that in rape the most sensitive indicators of harmful allelochemicals derived from decomposed litter were the germination speed index and catalase activity of seedlings. Moreover, extracts of decomposed medium (soil) containing litter from Paulownia fortunei, Acer truncatum, Zanthoxylum bungeanum, Juglans regia, Diospyros kaki, Prunus persica, Prunus armeniaca, and Ziziphus jujube were beneficial to the germination and seedling growth of rape at all concentrations examined, and thus these trees could be safely interplanted with rape. Extracts from Eucommia ulmoides, Populus canadensis, and Malus pumila inhibited the germination and seedling growth of rape, and thus the use of these trees in intercropping should be reduced. Extracts from Pyrus bretschneideri showed growth promotion at lower concentrations (10 and 20 mg mL -1 ) but were growth inhibitive at a high concentration (40 mg mL -1 ); thus, it could be intercropped with rape but at a low density.

Litter addition decreases plant diversity by suppressing seeding in a semiarid grassland, Northern China

“…However, soil temperature and radiation were not the major factors regulating seedling recruitment in this study. Furthermore, study has evident that plant litter addition had direct negative effects on seedling recruitment by allelopathy (Ruprecht et al, ; Zhang et al, ) and mechanical interference (Li & Ma, ; Li, Jia, Long, & Zerbe, ; Mitschunas, Filser, & Wagner, ). These effects may be the main reason for litter addition can directly and significantly inhibit seedling recruitment in this study (Figure a).…”

Allelopathic Effects of Aqueous Extracts of Alternanthera philoxeroides on the Growth of Zoysia matrella

“…Allelopathy has been considered to play a vital role in successful invasions by alien species [8][9]. Certain plant species secrete allelochemicals, which exert positive or negative effects on neighboring plants or microorganisms in the environment [10]. The allelochemical isolated from Ficus microcarpa inhibits the growth of Chlorella pyrenoidosa and the primary active fraction was identified as 2-propyl phenol [11].…”

Allelopathic effects of humus forest soil of Hippophae rhamnoides, Caragana korshinskii and Amorpha fruticosa on medicinal plants

“…Nevertheless, in this study, the humus soil from C. korshinskii inhibited the seed germination of Glycyrrhiza uralensis, which is not in line with the findings of Sun et al (2008), who reported that C. korshinskii roots leaf water extract caused significantly inhibition on the seed germination of Glycyrrhiza uralensis. Based on these differences it shows that the allelochemicals obtained from different sources (living leave water extract/ soil) were different, because allelochemicals may be decomposed or transformed in the soil, which resulted in altering the activities or structure of allelochemicals (Zhang et al, 2015).…”

“…The mixture of 5 ml of supernatant liquor and 5 ml of hydrogen peroxid was incubated in a 20°C water bath for 5 min, at the same time add 5 ml sulfuric acid to steady all the undecomposed of hydrogen peroxide, then added 1 ml potassium iodide, 3 drops of ammonium molybdate and 5 drops of starch indicator, at last titrated with a 0.01 mol L -1 sodium thiosulfate solution until the blue disappeared. (Gao, 2000;Chi, 2011;Zhang et al, 2015).…”

“…However, most of these researches used water extract to deal with the receptor plants. In fact, which cannot completely simulate the actual situation in the field; because allelochemicals are firstly released into the environment through foliar leachates, root exudation, leaf litter or other-residue decomposition, or volatilization (Inderjit, 2005); and then affected by the microorganisms and nutrients in the soil, allelochemicals might be decomposed or resynthesis, the activities might be inhibited or simulated (Zhang et al, 2015). Considering the above facts and observation, it is better to use the soil as the source of allelochemicals and the aim of present study is to evaluate the allelopathic effect of humus soil of three typical shrubs deciduous tree species (Hippophae rhamnoides, Caragana korshinskii and Amorpha fruticosa) on seed germination and seedling growth of 11 species of local common medicinal plants.…”