Abstract

The decline of soil fertility due to intensification of agricultural practice can lead to reduced plant performances; the use of organic amendments could be a valuable strategy to overcome this this problem. The aim of the present study was to verify that the application of organic fertilizers may promote root growth to the detriment of the canopy by evaluating the effects of application of organic fertilizer on CO₂ fixation, C partitioning, and plant growth. The experiment was carried out on strawberry (Fragaria × ananassa) plants, potted in 10 L pots. The following treatments were compared, in a complete randomized block design: (1) unfertilized control; (2) mineral fertilization; (3) cow manure (20 g kg⁻¹ soil); (4) compost low rate (20 g kg⁻¹ soil); (5) compost high rate (60 g kg⁻¹ soil). Two months after their application, fertilizers did not affect plant growth; however, the application of compost at the high rate stimulated the ¹³CO₂ assimilation. In the following 2 weeks, plants treated with compost at 60 g kg⁻¹ soil showed a higher amount of ¹³C than the other treatments; however, the ¹³C relative partitioning was not affected by fertilization. Root:canopy ratio was decreased by mineral and compost high rate fertilizations, in response to the increase of root N concentration, indicating that root growth was stimulated by low soil N.

摘要

由于农业实践的集约化，土壤肥力下降会导致植物性能下降；使用有机添加物可能是克服这一问题的重要策略。本研究的目的是通过评估施用有机肥对 CO ₂固定、C 分配和植物生长的影响，验证施用有机肥可能促进根系生长，从而损害冠层。实验在草莓 ( Fragaria × ananassa ) 植物上进行，盆栽在 10 L 盆中。在完全随机区组设计中比较以下处理： (1) 未受精对照；(2)矿物施肥；(3) 牛粪（20 g kg ⁻¹土壤）; (4) 堆肥率低（20 g kg ^-1土壤）；(5) 堆肥率高（60 g kg ^-1土壤）。施肥两个月后，肥料未影响植物生长；然而，以高速率施用堆肥刺激了¹³ CO ₂同化。在接下来的 2 周内，用 60 g kg ^-1土壤堆肥处理的植物显示出比其他处理更高的¹³ C量；然而，¹³ C 相对分配不受施肥的影响。根系：冠层比被矿物和堆肥高比例施肥降低，响应根系 N 浓度的增加，表明根系生长受到低土壤 N 的刺激。