Assessment of organic and conventional soil fertility practices and cultivar selection on mineral nutrient accumulation in field-grown lettuce

ABSTRACT

Depleted soil fertility and high-yielding cultivars have been associated with low mineral nutrient contents in vegetables. This study explored if mineral nutrient concentrations of lettuce (Lactuca sativa L.) can be increased though selection of cultivars and management of soil fertility. Cultivars including butterhead, romaine, and loose-leaf phenotypes of heritage and modern origins were studied. Conventional, compost, and organic regimes were assessed. Elements in whole heads were determined. Heritage cultivars had about 7% higher magnesium, sulfur, copper, and iron (Mg, S, Cu, and Fe) concentrations than modern cultivars with no differences occurring for phosphorus, potassium, calcium, sodium, zinc, manganese and boron (P, K, Ca, Na, Zn, Mn, and B). Differences for each element occurred among phenotypes and fertilization but with no consistent trends. Head weight had only minor effects on nutrient concentrations, but total accumulation increased with head size. Some cultivars had nearly twice the accumulation of nutrients as others. This work suggests that cultivars can be selected for production of nutrient-rich lettuce.

KEYWORDS:

• Lactuca sativa
• heirloom lettuce
• modern lettuce
• lettuce phenotypes
• dietary nutrients

Funding

This publication is based on research supported by the National Institute of Food and Agriculture, U.S. Department of Agriculture, the Massachusetts Agricultural Experiment Station, and the Stockbridge School of Agriculture under Projects No. MAS 00459, 00963, and 00981 and is paper number 3500 in the journal series of the Experiment Station.