Soybean (Glycine max) Cultivar Response to Iron Deficiency Chlorosis.

Iron is an essential micronutrient for soybean growth and development and is often abundant in the soil. However, plants may have trouble absorbing this nutrient in adequate amounts, particularly when cultivated in high pH soils. Plants deficient in iron will appear yellow with interveinal chlorosis of the upper leaves. This is due to the correlation between iron and chlorophyll formation. Lack of available iron can cause substantial crop loss in sensitive crops such as soybean. Due to the sporadic nature of IDC during the growing season or even within a single field, proper cultivar selection may be the most economical and minimally labor-intensive management method, given that certain soybean cultivars may be more sensitive to this issue than others. The objective of this research was to evaluate soybean cultivar response to IDC across commercially available maturity group IV and V soybean.

Experiments were conducted at two locations during the 2018 growing season in Monroe County and Lowndes County, MS. A total of 98 cultivars were screened for tolerance to IDC. At each location, cultivars were separated into three experiments representing relative maturity 4.5 to 4.6 (mid-maturity group (MG) IV), 4.7 to 4.9 (late-MG IV), or 5.0 to 5.9 (MG V). Of these, 27 cultivars were included in the mid-MG IV experiment, 39 cultivars in the late-MG IV experiment, and 32 cultivars in the MG V experiment. Treatments consisted of a single cultivar planted in plots measuring 1.1 by 4.6 meters with 3 replications at each location. Visual ratings for IDC tolerance were recorded on a 1 to 10 scale and soybean yield was measured in kilograms per hectare. These data indicate tremendous differences in tolerance to IDC among the cultivars evaluated and will ultimately offer soybean producers an additional source of information for cultivar selection and management of IDC.