纽荷尔脐橙叶脉木栓化症病因诊断

Diagnosis of Suberification in Leaf Venation for Newhall Navel Orange

经矿质营养诊断分析,纽荷尔脐橙叶片Mg含量与叶脉木栓化症的发病率、发病指数,以及病株叶片Mg含量与病株发病等级均呈显著负相关（porb〈0.05）;病树叶片Mg含量0.022%-0.107%,均呈缺乏状态（〈0.2%）,常叶与病叶Mg含量差异（0.12%）极显著（prob〈0.0001）;病叶常伴有缺Mg症黄化,即叶基部绿色区呈“∧”形,病树未见僵果（“石头果”）或果实内有褐色胶状物等缺B症状。据此诊断本研究病例的病因为缺Mg,并表明缺B并非柑橘叶脉木栓化症的唯一病因。

The analysis of mineral nutrients showed significant negative correlation between trace element of Mg content and the incidence and index of the suberification in leaf venation. Furthermore, there was also significant negative correlation between Mg content in diseased plant and diseased grades （porb 〈 0. 05） in Newhall navel orange orchard; Mg content in diseased plant is insufficient （ 〈0. 2% ）, especially Mg content in diseased leaves is only O. 022 -0. 107% ; Mg content is significant different between healthy and diseased leaves （ prob 〈 0. 0001 ） ; The diseased leaves was etiolated, bottom of leaf （ green part） looks like ＂ A ＂, there was no teratogeny - omactivation fruits in diseased plant and no brown jelly in diseased fruits, which the symptoms often appeared in B deficient plant. The reason of suberification in citrus leaf venation is Mg deficiency in our study ; it also showed that B deficiency is not exclusive reason which leads to suberification in citrus leaf venation.