洋葱氮、磷、钾养分吸收与分配规律的研究

田间试验研究了秋栽洋葱生长特性及对氮、磷、钾的吸收分配规律。结果表明，洋葱幼苗期生长极为缓慢，干物质积累量较少，对氮磷钾的吸收速率较低，吸收量仅占全生育期的4%左右；发棵期植株生长迅速，氮（N）、磷（P2O5）、钾（K2O）的吸收速率分别达 22.03、8.60和15.65 mg/(plant·d)，吸收量分别占全生育期的 92.74%、91.01%和71.79%；鳞茎膨大期氮、磷吸收速率迅速降低，而钾仍高达 7.23 mg/(plant·d)。洋葱全生育期对氮磷钾的吸收比例为1:0.40:0.92；但随着生长的进行，磷钾吸收比例升高，在鳞茎膨大期达1:0.92:9.04。洋葱幼苗期吸收的氮磷钾主要分配在叶片中，发棵期则以鳞茎和叶片分配率较高，鳞茎膨大期则主要分配在鳞茎中，在这一时期分配率分别达75.88%、87.77%和71.81%。在本试验条件下，每生产1000 kg鳞茎，约分别吸收N、P2O5、K2O为2.93、1.16和2.69 kg。

Absorption and distribution of nitrogen,phosphorus and potassium in onion

The growing characteristics of onion planted in autumn and its absorption and distribution rule on nitrogen, phosphorus and potassium were studied. The results showed that dry matter accumulation in onion at the seedling stage was very slow and absorption speed of the nitrogen, phosphorus and potassium was very low, which only accounted for about 4% of the whole nutrient. At plant vigorous growth stage, the uptake rates of N, P₂O₅, K₂O were 22.03, 8.60 and 15.65 mg/(plant·d), accounted for 92.74%, 91.01%, 71.79% of nutrient uptake during the whole growing stages. At the bulb expanding stage, the uptake rate of N and P₂O₅ decreased rapidly, but the rate of K₂O was still kept at 7.23 mg/(plant·d). The proportion of onion absorption to N, P₂O₅ and K₂O was 1:0.40:0.92 taking the whole growing stages into consideration. The absorption rate of phosphorus and potassium increased with onion growing, and reached 1:0.92:9.04 at the bulb expanding stage. Nitrogen, phosphorus and potassium were mainly distributed in leaf at the seedling stage, in bulb and leaf at the plant vigorous growth stage and in bulb at the bulb expanding stage, with distribution rate being 75.88%, 87.7% and 71.81%, respectively. The demands for N, P₂O₅ and K₂O were about 2.93, 1.16 and 2.69 kg for every 1000 kg bulb product, respectively.