根外追肥的特点是:简单易行,用肥量小,发挥作用快,且不受养分分配中心影响,可及时满足果树急需,并可避免某些元素在土壤中化学的或生物的固定作用。 根外追肥最适温度为18～25℃,温度较大些效果好。因而喷布时间于夏季最好在上午10时以前和下午4时以后,以免气温高、溶液很快浓缩,既影响吸收,又易发生药害。目前,兰州地区常采用以下几种根外追肥方法。 1.花期喷布0.1％～0.2％的 Root top dressing is characterized by: easy to use, with a small amount of fertilizer, play a role fast, and not affected by the nutrient distribution center, timely to meet the urgent need of fruit trees, and avoid certain elements in the soil chemical or biological fixation . Root top dressing temperature optimum temperature is 18 ~ 25 ℃, the temperature of some good effect. Therefore, spraying time in summer is best before 10 o’clock and after 4 o’clock in the afternoon, so as to avoid high temperature, the solution quickly concentrated, both affect the absorption, but also prone to injury. At present, Lanzhou often use the following methods of root top dressing. 1. Flowering spray 0.1% ~ 0.2%