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作 者 ：王瑛;周治国;陈兵林;孟亚利;束红梅;蒋光华

期 刊 ：应用生态学报 2006年 17卷 12期 页码：2341-2346

关键词：套作；

摘 要 ：在盆栽麦棉套作条件下，于2003～2004年设置麦棉自然根系(麦棉根系和肥水均可相互通过)、麦棉纱网隔根(肥水可相互通过，麦棉根系不能相互通过)和麦棉塑膜隔根(麦棉根系和肥水均不能相互通过)3种麦棉根系处理，运用小麦叶片¹⁵N富积标记法和¹⁵N同位素稀释法，研究麦棉复合根系群体对棉花氮素吸收与分配的影响.结果表明，在麦棉套作群体中，既存在麦棉共处期小麦对棉花根区氮素的竞争，又存在小麦根区及其所吸收氮素向棉花的转移.棉花根系吸收的¹⁵N肥料大多分配到地上部，根系分配的量较少，且麦棉自然根系处理地上部的¹⁵N标记肥料氮的吸收率(NUR)最大，纱网隔根处理次之，塑膜隔根处理最少.在麦棉共处期，麦棉自然根系处理棉花的植株从¹⁵N标记肥料中吸收的氮占其全氮的百分率(Ndff)和NUR均低于隔根处理.至棉花初花期(小麦已收获，秸秆原位埋入土壤中)，麦棉自然根系处理棉花吸收的氮素主要来源于化学肥料而非秸秆降解物.棉株不同器官所分配的¹⁵N标记肥料比例不同，棉花生殖器官中¹⁵N含量明显高于其他器官.麦棉自然根系处理棉株生物量也高于隔根处理.

Abstract:By the methods of ¹⁵N-foliar feeding and ¹⁵N dilution, a pot experiment of
double-cropping wheat and cotton was conducted to study the nitrogen
absorption and allocation in cotton plant under effects of wheat and cotton root
mass. Three treatments were installed, i.e., no separation of wheat and cotton
roots (treatment I), separation with nylon net (treatment II), and separation
with plastic film (treatment III). The results showed that both the competition
of ¹⁵N absorption between wheat and cotton root, and the translocation of
absorbed ¹⁵N from wheat root to cotton were existed in the wheat-cotton
double-cropping system. The absorbed ¹⁵N by cotton root was mostly
allocated in aboveground part, and less in root. The aboveground part of cotton
had the highest N utilization rate (NUR) in treatment I and the lowest one in
treatment III, but the Ndff was lower in treatment I than in treatments II and
III. At the early flowering stage of cotton when wheat was harvested and its
straw was amended in situ, the absorbed nitrogen by cotton was mainly from
the applied ¹⁵N, but not from the amended wheat straw. The allocation of
absorbed ¹⁵N in different organs of cotton was quite different, being much
higher in reproductive organs than in other organs. The biomass of cotton plant
was also higher in treatment I than in treatments II and III.

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