開春以來，一些苗圃地苗木葉片不同程度地發生了黃化現象。據調查，土壤黏重，且以施用化學肥料為主的苗圃發病重；水質鹽堿度高的地塊發病重；種植密度大或是大苗遮擋下的弱小樹體發病重；楊樹平茬苗、柳樹快繁苗和留床苗發病嚴重。另外，在污染嚴重企業周邊，有的樹種也表現出一定的黃化現象，甚至出現死苗。有一處土肥條件較好、規模生產的苗圃地也出現了黃化現象。 　　引起苗木黃化的原因很多，具體到實際情況，主要有以下幾個方面： 　　1.與土壤的pH值過高有關。pH值愈高，土壤的堿性愈大，土壤中的鐵元素在堿性條件下轉化為根系不能吸收利用的不溶性鐵，如氧化鐵或沉淀為氫氧化鐵，鐵的溶解度降低，這時土壤分析并不表現缺鐵，但土壤中的鐵不能被植物利用，而成為無效鐵。施入土壤的無機鐵肥因氧化作用及土壤堿性作用最終會轉化為氫氧化鐵，使作物難以吸收利用。因此，生長在鹽堿土壤上的苗木存在著潛在性缺鐵，并易發生缺鐵失綠癥。當pH值大于8時，黃化癥狀愈加明顯。 　　2.與栽培管理不當有關。苗木抗黃化的能力與苗木綜合栽培管理水平密切相關。栽培管理水平較高，肥水管理得當，黃化現象較輕。前一年種植密度大或其他原因導致光照不足的苗圃，也會影響光合產物的產生，造成樹體養分積累較少、根系發育不良、吸收能力減弱、樹勢不旺，一旦肥水管理不能彌補營養虧缺，也易出現黃化現象。 　　3.與天氣條件影響有關。吳橋縣去年夏季降水過多，一些樹體根系上浮，恰遇今年4月份氣候干旱，根系的吸收活力降低，影響了對鐵和其他養分的吸收，造成黃化。 　　4.與土壤中缺乏鐵元素有關。土壤中鐵元素缺乏，造成植株缺鐵性黃化。
Since the beginning of spring, some viability seedling leaves yellowing phenomenon happened in different degrees. According to the survey, heavy clay soil, and given priority to with applying chemical fertilizer nursery heavy disease; The onset of heavy water of high salinity land plots; Planting density or went under the shade of the weak tree heavy disease; Yang Shuping crop seedlings, willow and MiaoFa micropropagation seedling disease serious. In addition, the polluting enterprises around, some tree species also show some etiolation, appear even dead plants. There is a good soil conditions, scale of production has also appeared in the viability of blanching. Cause a lot of etiolated seedlings, specific to the actual situation, mainly has the following several aspects: 1. Related to the pH of the soil is too high. The more alkaline pH value, the higher the soil, the soil of iron in alkaline conditions into root system unable to absorb insoluble iron, such as iron oxide or precipitation of iron hydroxide, the solubility of iron is reduced, the soil analysis is not lack of iron, but can't be plants use iron in the soil, and become invalid iron. Into the soil inorganic iron fertilizer due to oxidation and alkaline soil will eventually translate into iron hydroxide, the use of crops to absorb. Therefore, grown in saline soil on seedling has the potential iron deficiency, and prone to iron deficiency disease of green. When the pH greater than 8 etiolation symptom more and more obvious. 2. Related to the improper cultivation management. Seedling ability of resistance to yellowing and seedling cultivation management level are closely related. The cultivation management level is higher, water management is proper, blanching is lighter. The year before planting density or other reasons lead to deficiency of nursery, may also affect the production of photosynthetic product, cause less nutrient accumulation of trees, tree root dysplasia, absorbing ability weakened, the potential is not flourishing, once the water management can not make up the nutrition deficiency, also easy to appear yellowing phenomenon. 3. Related to weather conditions. Wuqiao county last summer precipitation too much, some trees root floating body, when drought in April this year, the absorption of root vigor decrease, affect the absorption of iron and other nutrients, cause yellowing. 4. Related to the lack of iron in the soil. Soil fe deficiency, cause plant iron deficiency yellows.