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Nodulation response to molybdenum supplementation in alfalfa and its correlation with root and shoot growth in low pH soil

Adhikari, Laxman, Missaoui, Ali M.
Journal of plant nutrition 2017 v.40 no.16 pp. 2290-2302
alfalfa, cultivars, foliar application, genotype, greenhouses, lithium, molybdenum, nitrogen, nitrogen fixation, nodulation, pH, phytomass, roots, shoots, soil
Molybdenum (Mo) is a critical micronutrient for nitrogen (N) fixation in legumes. Low pH limits the availability of Mo, thereby reducing nodulation and N fixation. This study investigates the effect of Mo supplementation on alfalfa nodulation and its correlation with root and shoot biomass in low-pH soil. Three experiments were conducted in the greenhouse, involving 14 genotypes of alfalfa subjected to four different treatments, unlimed low-pH soil (5.2) with Mo applied (lithium (Li) ⁻Mo ⁺), low-pH soil (5.2) without Mo (Li ⁻Mo ⁻), limed soil (pH 7.3) with Mo applied (Li ⁺Mo ⁺), and limed soil (pH 7.3) without Mo (Li ⁺Mo ⁻). Foliar application of Mo resulted in a significant increase in nodule counts in the 14 alfalfa cultivars grown in low-pH soil (5.2) even though to a lesser extent than in limed soil with neutral pH (7.3). The increase in number of nodules correlated positively with plant root weight and upper plant biomass.