Field Evaluations of Yield, Iron-Manganese Relationship, and Chlorophyll Meter Readings in Soybean Genotypes as Affected by Iron-Ethylenediamine Di-o-hydroxyphenylacetic Acid in a Calcareous Soil

ABSTRACT

Iron (Fe)-deficiency chlorosis is a common constraint when soybean (Glycine max L.) is grown on calcareous soils. Considerable differences exist among soybean genotypes for susceptibility to Fe chlorosis. In order to evaluate the effectiveness of iron-ethylenediamine di-o-hydroxyphenylacetic acid (Fe-EDDHA) for three soybean genotypes (A3237, Black hack, and Wells), field studies were conducted for the years 2001 and 2002 in a calcareous soil. Although, available Fe of the studied soils was either lower than critical level or in marginal range, application of Fe-EDDHA did not result in a significant increase in soybean yield probably, due to the antagonistic relationships between Fe and manganese (Mn). It appears that Fe soil test as the only criterion for Fe fertilizers recommendation is not appropriate and soil test for Mn is also recommended. Significant quadratic equations were obtained between chlorophyll meter readings (CMR) in growth stage 3 (GS3) with seed yield (SY) of A3237 and Black hack. However, SY of Wells showed close relationships with CMR in growth stage 4 (GS4). A tentative conclusion is that the chlorophyll meter is a reliable and non-destructive tool for the prediction of SY for the studied soybean genotypes in GS3 or GS4.

Due to the fact that use of Fe fertilizer might cause nutritional disorder, use of Fe-efficient genotypes remains as an effective and economic sound practice. However, positive responses to Fe-chelate treatments are expected for genotypes with shoot Fe: Mn ratio less than 0.4 when both nutrients are in the sufficiency range. Obviously, such a requirement limits the utilization of Fe-chelate to post-emergence fertilization.

Keywords:

• calcareous soil
• chlorophyll meter readings
• Fe-EDDHA
• manganese
• soybean

ACKNOWLEDGMENT

The authors would like to appreciate Shiraz University for providing research facilities.

Notes

*For each year, means in each row or column followed by the same lower case are not significantly different (p < 0.05) by Duncan's Multiple Range Test.

*For each year, means in each row or column followed by the same lower case are not significantly different (p < 0.05) by Duncan's Multiple Range Test.

*For each year, means in each row or column followed by the same lower case are not significantly different (p < 0.05) by Duncan's Multiple Range Test.

*Means in each row or column (in each stage) followed by the same lower case are not significantly different (p < 0.05) by Duncan's Multiple Range Test.