外源碘在森林土壤中的残留及对山野菜植物的施用效果

Residual of exogenous iodine in forest soils and its effect on some wild-vegetable plants.

以培育富碘山野菜为目标.在东北森林暗棕壤上进行了5种山野菜施碘试验.碘肥种类为碘化钾(KI),施碘剂量为1.00、3.33、10.00、16.67和50.00 mg·kg-1.结果表明,土壤施碘是培育富碘山野菜的有效途径,从低施用量到高施用量,不同山野菜植物的含碘量可达对照的2～40倍,但外源碘在土壤中的当年残留率并不高,仅有40％～5％残留,并且随着施入量增加而迅速降低;植物对碘的积累也并非总是随着施入量的增加而增加,施碘量达到10.00 mg·kg-1时,大部分植物的碘积累量趋于稳定.从施碘条件下外源碘的土壤残留率、植物碘积累特征及施用成本等方面综合考虑,适宜的施碘量上限大约为10 mg·kg-1.土壤因素显著影响施碘效果,栽培地应选择土质细腻、肥沃的中上坡地段.砂砾质土壤和易形成水分潜流的下坡土壤都不利于肥料碘的保持和植物吸收.

To cultivate iodine-enriched forest vegetables in the mountainous regions of northeast China, a series of iodine application experiments were conducted. Iodine fertilizer (potassium iodide, KI) was added to the forest soils supporting a variety of wild-vegetable plants, with a dosage gradient of 1.00 ,3.33 ,10.00 , 16.67 and 50.00 mg· kg-1. The results showed that iodine application was an effective approach to obtain iodine-rich vegetable materials, and the iodine contents in treated plants could be 2 ~ 40 times higher than control. But, the residual of added iodine in soil was generally not high, only occupying 40% ~5% of the application dosage. The accumulation of iodine in plants did not consistently increase with the dosage, which tended to slow down when the application amount increased to 10.00 mg·kg-1.In a comprehensive consideration of soil iodine residual, plant iodine accumulation and application cost, the proper iodine dosage should be approximately 10 mg· kg-1. Soil conditions had significant influence on the efficiency of iodine application, and the cultivated lands should be chosen at fine-textured, fertile, and upper-sloped sites, while sandy soils and down-sloped sites were unfavorable to the preservation of added iodine and to plant absorption.