Abstract:

In a hedgerow intercropping system, root distribution is closely related to interaction relationship between hedgerows and its companion crops. Distribution patterns of thick and fine roots' number, length and biomass of a 6-year hedgerow system, in which mulberry(Morus alba) trees were interplanted within a 0.4 m-wide hedgerow and sweet orange(citrus cinen-trees were grown in the 3.8 m-wide alley, were determined by destruction sampling method. The results indicated that roots of leucaena(Leucaena leucocephala) and mulberry were mainly distributed in soil under hedgerows, while mulberry roots distributed mainly along hedgerow because soil under hedgerow are fertile, and roots of sweet orange trees were mainly distributed in soil around sweet orange trees. 61% of total amount, 66% of total length and 86% of total biomass of leucaena's thick root, and 50% of total amount、49% of total length and 91% of total biomass of mulberry's thick root are distributed in the soil under hedgerow, while 83% of total amount, 83% of total length and 85% of total biomass of orange trees' thick roots were distributed in soil within 0.6 m under them. Fine roots of leucaena and mulberry were mainly distributed in soils under hedgerow and its neighboring two sides, and that of sweet orange trees were almost completely distributed in soil of alley. Percentage of total amount, length, and biomass of fine roots of leucaena in soil under hedgerow upside and downside 0.6 m were 73%, 79% and 72%, and that of mulberry were 70%, 85% and 77%, respectively. Fine roots of leucaena and mulberry were mainly distributed in soils under hedgerow and its neighboring two sides, and almost all those of sweet orange trees were distributed in soil of alley, which implies that the 4 m width of the slopeland contour hedgerow system is reasonable for establishment of sweet orange orchard and minimizing underground interactions and competition for water and nutrients between hedgerows and its companion crops (sweet oranges trees).

Key words: contour hedgerow intercropping, root distribution patterns, agroforesrty, dry valley