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近年我们进行橡胶树营养普查时,在东风农场二分场发现种植于冲积性砂壤土上的割胶树(品系为RRIM600)下半年树冠上部发生黄叶,在附近,类似土壤条件的橡胶园约有1000余亩。黄叶树特征是,四月新抽叶稳定老化后,亦可看出树冠上部暴光叶比正常树叶小而色浅(淡绿),到六月叶片退绿愈加明显,其后逐渐变黄。严重时叶尖和叶缘出现褐色枯斑,甚至顶芽嫩稍枯死,但树冠下部荫叶仍为绿色。根据对胶树的叶片和土壤分析,叶片氮磷含量丰富(分别为3.77％和0.27％)镁正常(0.38％)。钾偏低(<0.9％,黄叶树<0.6％)*土壤速效钾含量<50ppm由此认为主要是缺钾引起的。
In recent years, when we conducted the survey of rubber tree nutrition, we found that the upper part of the crown of the plastic tree (RRIM600) planted on alluvial sandy loam soil was yellow leaves in the second half of Dongfeng Farm. In the nearby rubber plantation with similar soil conditions, about 1,000 mu. The characteristics of the yellow leaf tree is that after the new leaf is steadily aged in April, it can also be seen that the upper leaf of the canopy has smaller and lighter light green leaves (light green) than the normal leaves, and becomes more obvious when the leaves are green in June and then turns yellow gradually. Serious brown leaf spot and leaf edge brown spots, and even the top Bud tender slightly dead, but the shade of the shade below the crown is still green. Based on the analysis of leaves and soil of gum trees, leaf N and P rich (3.77% and 0.27%, respectively) were normal to magnesium (0.38%). Potassium is low (<0.9%, yellow tree <0.6%) * Available potassium in soil <50ppm It is mainly caused by potassium deficiency.