Citrus Nematode Alters Carbohydrate Partitioning in the ‘Washington’ Navel Orange
Year: 1985
Type: article
Abstract: Root infection by the citrus nematode ( Tylenchulus semipenetrans Cobb) at population densities above the economic threshold caused altered patterns of root and shoot growth of 20-year-old ‘Washington’ Navel orange trees ( Citrus sinensis L. Osbeck) budded on Troyer citrange rootstock ( Poncirus trifoliata L. Raf. × C. sinensis ), compared with control trees protected from nematode infection by oxamyl (1.1 kg/ha/3 weeks) and permitted to recover from prior nematode infection. Nematode-infected trees initiated new roots every 4–6 weeks, beginning as early as midMarch through as late as mid-January. Each root flush was equal to or greater in magnitude (number of new roots per gram roots) than those observed from oxamyl-treated trees. Oxamyl significantly reduced the population of female nematodes. Oxamyl-treated trees produced 4 relatively small root flushes, typical of healthy trees and exhibited a net increase in root biomass; nematode-infected trees failed to increase root biomass despite repeated root initiation. Oxamyl-treated trees also produced more new shoots and exhibited a greater increase in length per shoot and mean number of leaves per unit shoot length than untreated trees. Measurements of the levels of available glucose, sucrose, and starch provided evidence that nematode-infected trees were carbohydrate depleted. Starch levels were typically 70% higher in the canopy and 96% higher in the roots of oxamyl-treated trees compared to untreated. Root initiation appears to be the first response of the trees penetrated by citrus nematode larvae; repeated root initiation in response to the many generations of larvae that hatch each year is probably a key factor contributing to the depletion of carbohydrate in nematode-infected trees.
Institution: University of California, Riverside
Language: English
Subfield: Plant Science
Domain: Life Sciences
SDG: Zero hunger
Open Access status: hybrid
Estimated APC paid: $3,500
OpenAlex ID: W4289843024