Abstract
Several instances of nutrient deficiency symptoms observed in citrus trees growing in some orchards in Osaka prefecture were collected for investigation.
The information obtained from these instances are found to be useful for nutritional diagnosis of plant and soil test.
The results were as follows.
1) Magnesium deficiency: Magnesium deficiency symptom appeared in the old leaves lowing Mg concentration less than 0.13%. The content of exchangeable Mg in such a soil was less than 21 mg/100g.
2) Iron deficiency: Interveinal chlorosis was observed in leaves of low Fe concentration. The trees having such leaves were grown in the soil where pH and exchangeable Fe were low, but exchangeable Mn and available P2O5 were very high.
3) Manganese deficiency : Mn deficiency symptom appeared in the leaves having Mn concentration less than 16 ppm. This deficiency was markedly decreased by foliar application of 0.3% MnSO4 solution.
In such a soil pH (H2O) was higher than 6, CaO was generally high, but exchangeable Mn was lower than 3 ppm.
4) Zinc deficiency: Zn deficiency symptom appeared in the leaves having Zn concentration as low as 16 ppm, and their young leaves turned light green, or yellow mottling appeared between the veins. The pH (H2O) of such a soil was higher than 7.3, and the content of exchangeable Zn and 2 N MgCl2-extractable Zn were markedly low.
5) Boron deficiency; Boron deficiency symptoms on leaves or inside of fruits occurred when B concentration in the leaves lowered in a range 9-16 ppm.
