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Functional relationship between sugarcane root biomass and length for cropping system applications

Chopart J.L., Azevedo M.C.B., Le Mezo L., Marion D.. 2010. In : ISSCT. ISSCT 2010: 27th Congress of the International Society of Sugar Cane Technologists Congres, Veracruz, Mexique, 7-11 mars 2010. s.l. : s.n., 8 p.. ISSCT Congress. 27, 2010-03-07/2010-03-11, Veracruz (Mexique).

Sugarcane root length density (RLD, m/m3) and root biomass are key characteristics for respectively determining: (i) the crop nutrient and water uptake capacity, and (ii) carbon partitioning in plants and balance in soil. In previous studies, often only one of these parameters was measured. It is therefore useful to link the RLD and root biomass density (RBD, g/m3) to evaluate one parameter in relation to the other. Relationships between RLD and RBD and specific root length (SRL, m/g) were studied in Côte d'Ivoire and Réunion. Mean SRLs of fine roots were independent of the root location in the soil profile and plant age but higher in Côte d'Ivoire (68 m/g, SD = 19) than in Réunion (35 m/g, SD = 10). The best fit between the RBD and RLD of thick roots was a power function (RLD = 21.3 RBD*0.745; R2 = 0.85). Mean SRL was 7 m/g. When all roots were studied together, the best fit between RBD and RLD was also a power function, with little variation between the two sites or between plant and ratoon sugarcane. The fits calculated with all data except those obtained very close to the plant stem were: RLD = 85.5 RBD*0.742 (R2 = 0.88) and mean SRL = 27 m/g (SD =13). Relationships between root length and biomass were neither fixed nor fully random. Due to SRL variability, it was hard to pinpoint any mechanistic links between root length and biomass. Conversely, for simple field evaluations, a rough and ready RLD estimate can be made on the basis of RBD, and vice-versa.

Mots-clés : saccharum officinarum; réunion; côte d'ivoire; france

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