Selection for iron efficiency of soybean in nutrient-solution and field tests

A nutrient-solution system has been developed that may be useful for selection of iron (Fe) efficiency among soybean [Glycine max (L.) Merr.) plants in a greenhouse throughout the year. The objective of our research was to determine the effectiveness of the nutrient-solution system for single-plant selection of Fe efficiency compared with single-plant selection among plants grown on calcareous soil in the field. Selection for Fe efficiency was practiced among F₃ plants from six single-cross populations in the field on calcareous Harps soil (fine-loamy, mesic Typic Calciaquoll) during 1985 and 1986 and in nutrient solution during 1985. The progenies of the F₃ plants were evaluated for Fe efficiency in the field on calcareous soil in replicated tests during 1986 and 1987. The heritability of Fe efficiency on a single-plant basis as determined by parent-offspring regression averaged 16% for selection in the field during 1986 and 14% for selection in nutrient solution. Heritability of Fe efficiency based on variance component estimates of random lines evaluated in the field during 1986 and 1987, was 17% on a plot basis and 55% on an entry-mean basis. The results suggest that single-plant selection in populations derived from crosses between parents with moderate Fe efficiency is of limited value with either field or nutrient-solution evaluation. With such populations, selection among lines in replicated tests would be most appropriate.