坡耕地等高固氮植物篱复合经营系统根系分布格局研究

Distribution Patterns of Root System under Contour Hedgerow Intercropping on Slopeland in Dry Valley of the Jinsha River

研究根系的数量、长度和生物量在植物篱 -桑树 -脐橙坡地复合经营系统中不同位置和层次的分布。结果表明 :植物篱树种新银合欢根系主要在植物篱带垂直分布 ,深度超过 1 0m ,分布于植物篱带的≥ 1mm粗根数量、根长密度和生物量分别占该树种粗根总数量、总长度和总生物量的 6 2 %、6 6 %和 86 % ;套种在植物篱中的桑树的根系沿植物篱带分布 ,≥ 1mm粗根数量、长度和生物量分别占粗根总数、总长度和总生物量的 5 0 %、4 9%和91% ;脐橙根系较浅 ,主要分布在作物种植带中间上下 0 6m的范围内 ,深度不足 0 6m ,分布于作物带中央上下 0 6m范围的≥ 1mm粗根数量、长度和生物量占总量的 83%、83%和 85 % ;新银合欢 <1mm细根主要在植物篱带及其两侧 0 6m内 ,分布于该范围的细根数量、长度和生物量分别占相应总量的 73%、79%和 72 % ;桑树 <1mm细根分布与新银合欢类似 ,分布于该范围的数量、长度和生物量分别占相应总量 70 %、85 %和 77% ;脐橙 <1mm细根主要分布在其植株周围 0 6m范围 ,其数量、长度和生物量分别占相应总量的 70 %、6 3%和 6 4 %。该农林复合经营系统中新银合欢植物篱和套种在其中的桑树根系分布重叠 ,有利于桑树充分利用新银合欢根系提供的养分 ;

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).