Abstract:

The aim of this research was to explore the effects of root separation on aboveground biomass and soil nutrient contents in an oat （Avena sativa）/pea （Pisum sativum） intercropping system. Five treatments were applied in a field experiment： Oat monoculture， pea monoculture， unseparated oat/pea intercropping， oat/pea intercropping with nylon mesh separation， and oat/pea intercropping with plastic film separation. The changes in plant height， aboveground biomass， soil nutrients and root traits after oat/pea intercropping were analyzed. The results showed that the plant height and the aboveground biomass of intercropped oat/pea were reduced by the plastic film separation treatment， with a land equivalent ratio lower than 1， whereas the land equivalent ratios in the nylon mesh separation and unseparated treatment were higher than 1， and intercropping had obvious advantages. The soil organic matter content and available phosphorus content were 14.75%-78.53% lower and 9.31%-29.73% lower in the plastic film separation treatment than in the nylon mesh separation treatment and unseparated treatment， respectively. In the root separation treatments， there was no significant difference in the soil total nitrogen content between the jointing and flowering stages （P>0.05）. Compared with the nylon mesh separation and upseparated treatments， the plastic film separation treatment showed 22.16% and 18.38% lower soil total nitrogen content， respectively， at the grain-filling stage. At the mature stage， the soil total nitrogen content was 10.83% higher in the non-separated treatment than in the plastic film separation treatment （P<0.05）. For pea， the soil organic matter content was significantly higher in the plastic film separation treatment than in the unseparated and nylon mesh separation treatments. In addition， the length of oat roots in the unseparated treatment was 43.03%， 59.02%， and 96.38% higher than that in the nylon mesh separation treatment， single cropping treatment， and plastic film separation treatment， respectively. The surface area of oat roots in the unseparated treatment was 14.84%， 30.20% and 45.55% higher than that in the nylon mesh separation treatment， single cropping treatment， and plastic film separation treatment， respectively. The volume of oat roots in the unseparated treatment was 17.37%， 38.15% and 106.15% higher than that in the nylon mesh separation treatment， single cropping treatment， and plastic film separation treatment， respectively. In conclusion， oat/pea intercropping significantly affected the root characteristics of both crops， and changed the competitiveness of roots for soil nutrients， thus affecting aboveground biomass. The closer the root interaction， the higher the aboveground biomass of oat and pea plants. Plastic film separation without root interaction resulted in poor root growth， lower soil nutrient contents， and the lowest aboveground biomass of both crops.

Key words: oats, peas, root separation, aboveground biomass, physical and chemical properties of soil, root character