ARS | Publication request: Source of Boron in Curcuma for Burn Symptoms at Leaf Margins

Submitted to: Journal of Plant Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 30, 2009
Publication Date: July 13, 2009
Citation: Roh, M.S., and Lawson, R. 2009. Source of boron in Curcuma for burn symptoms at leaf margins. J. Plant Nutrition. 32:798-808.

Interpretive Summary: Genotypes of Curcuma spp. native to tropical Asia, have been cultivated as ornamentals because they have large, showy, concave or hooded bracts. Older leaves often exhibit burn symptom at the margin of the leaves (‘LMB’) and this could be correlated to high concentrations of boron (B), iron (Fe) and manganese (Mn). These symptoms were observed in older leaves of ‘CMU Pride’ with broad leaves, but the ‘LMB’ symptoms were not observed in young leaves of ‘CMU Pride’ or C. alismatifolia with narrow leaves. It has not been investigated whether the source of B responsible for ‘LMB’ observed in old leaves of Curcuma species with broad leaves is responsible for ‘LMB’ and whether B is supplied from the growing medium, rhizomes, or resulting from guttation. The objectives of this study were (a) to investigate the source of accumulated B in the affected part of the leaves and (b) determine the relationship between ‘Leaf margin-burn’ (‘LMB’) and nutrient element content of leaf tissue. B accumulated in the outer region of the old leaves following evaporation of gutatted water droplets containing dissolved B. High levels of B in the edge of the old leaves may not be transported from the rhizomes.

Technical Abstract: This study was initiated to investigate the source of boron (B) accumulated in margins of leaves of Curcuma ‘Chiangmai University Pride (‘CMU Pride’). Nutrient elements were analyzed from different rhizome locations before potting, and from whole rhizomes and different leaf locations at harvest after forcing in soilless medium. Plants were fertilized with solutions lacking B during the forcing period. Leaf-margin burn, (‘LMB’) symptoms in old leaves of ‘CMU Pride’ could result from the combination of high levels of B and low total N levels. High levels of manganese (Mn) may not be involved in ‘LMB’ symptoms. B accumulated in the outer region of the old leaves following evaporation of gutatted water droplets containing dissolved B. High levels of B in the edge of the old leaves may not be transported from the rhizomes.