在柑桔叶片上喷尿素对柑桔植株能提供速效氮源。可是,某些商业性肥料中的缩二脲对柑桔具有植物毒性,因而易导致柑桔“叶尖黄化病”。对脐橙和伏令夏橙植株喷尿素溶液的试验表明:从4月25日开始,于中午时分,用0.5％尿素溶液对植株进行喷布处理,每周处理一次,连续三周。在高温、相对湿度低和强烈的 Spraying urea on citrus leaves provides a viable nitrogen source for citrus plants. However, the biuret in some commercial fertilizers is phytotoxic to citrus, which can easily lead to “yellow leaf tip disease” in citrus. Experiments on the urea solution of navel orange and valerian summer orange plants showed that from April 25, noon urea solution was sprayed on the plants at noon and treated once a week for three weeks. At high temperature, low relative humidity and intense