Impact of sub-optimal macro and micronutrients on Romaine lettuce (Lactuca sativa) and supra-optimal on coffee (Coffea Arabica)
Romaine lettuce (Lactuca sativa) is considered as one of the nutrient-dense lettuce varieties and coffee (Coffea Arabica) is one of the most popular beverage consumed globally. However, inadequate information is available on nutritional status of these crops for optimal quality produce. Therefore, studies were conducted to investigate the impact of 1) sub-optimal macro [nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), sulfur (S)], and micronutrient [iron (Fe), manganese (Mn), zinc (Zn), copper (Cu), boron (B) and molybdenum (Mo)] supply on Romaine lettuce. 2) supra-optimal micronutrient (Fe, Mn, B, Cu, Zn and Mo) supply on coffee plants. For the Romaine lettuce sub-optimal study, the treatments consisted of N, P, K, Ca, Mg, S, Fe, Mn, Zn, Cu or B deprived solutions plus a control with complete modified Hoagland nutrient solution. For supra-optimal micronutrient study, coffee plants were grown in optimal levels of macro (N, P, K, Ca, Mg, and S) and micronutrients (Fe, Mn, B, Cu, Mo and Zn) for control, and elevated micronutrients (B, Fe, Mn, Mo, Cu, and Zn) at five different concentrations (µM) for each element. The number of days to develop nutrient deficiency symptoms is an indication of the sensitivity of Romaine lettuce to a deficient element. The order of sensitivity from most to least is: N deficiency (2 days) > P deficiency (4 days) > K deficiency (5 days) > Fe deficiency (5 days) > B deficiency (5 days) > Ca deficiency (6 days) > S deficiency (6 days) > Mg deficiency (9 days) > Zn deficiency (12 days) > Cu deficiency (20 days) > Mn deficiency (21 days). Nutrient deficiency symptoms developed on the older leaves (N and P deficiency), recently matured leaves (K and Mg deficiency), maturing leaves (Cu, Zn and Mn deficiency) and mostly on the young leaves (Ca, S, Fe and B deficiency). Significant reduction in growth was noted in N, P, K, Ca, Mg, S, Fe, Mn, Zn, Cu and B deprived plants, with dry mass declined by 18%, 3%, 29%, 9%, 16%, 13%, 17%, 29%, 20%, 40% and 18% respectively, compared to normal. SPAD value measurement of N, Mg, S, Fe, Mn, Zn, and Cu deficient plant leaves at different stages of development, leaf position on the plant and physiological age corresponded significantly with the visual nutrient deficiency symptoms of chlorosis except for Ca, K, P and B compared to normal. As for coffee grown under supra-optimal concentrations of Fe, Mn, Cu, Zn, B and Mo, the number of days to develop toxicity symptoms, indicates the sensitivity of coffee to an element of toxicity at a particular concentration. The order of sensitivity from most to least is: Fe toxicity (3 days) > Cu toxicity (3 days) > B toxicity (6 days) > Zn toxicity (11 days) > Mn toxicity (11 days) > Mo toxicity (15 days). Plants treated with 1000 µM Fe, 90 µM Mn, 500 µM Zn, 250 µM Cu, 1000 µM B and 750 µM Mo had ≥50% dry biomass reduction.
"Impact of sub-optimal macro and micronutrients on Romaine lettuce (Lactuca sativa) and supra-optimal on coffee (Coffea Arabica)"
ETD Collection for Tennessee State University.