TY - JOUR
T1 - The number of bacteria in the rhizosphere during plant development: relating colony-forming units to different reference units
AU - Duineveld, B.M.
AU - Van Veen, J.A.
N1 - Reporting year: 1999
Metis note: 2561; CTE; TME ; ME file:///L:/Endnotedatabases/NIOOPUB/pdfs/Pdfs1999/Duineveld_ea_2561.pdf
PY - 1999
Y1 - 1999
N2 - The number of bacteria was determined during the growth of chrysanthemum plants on young (tip) and old (base) root parts. We assessed if the same conclusions could be drawn on the dynamics of bacterial populations during plant development when different reference units were used to express the bacterial counts. The results indicated that the total number of bacteria on the base decreased significantly during plant development, when expressed per root length, per root fresh weight or per root surface. The number of bacteria on the tip only decreased significantly when expressed per root length. Using the unit of dry weight of adhering soil, contradictory results were obtained for both base and tip; in general, the number of bacteria increased significantly during plant development. Thus, different reference units may lead to different conclusions. Root surface seemed to be the best unit to use, but the use of this unit requires time-consuming measurements. Regression analyses indicated that the reference unit "root surface" was highly correlated with root fresh weight (R-2=93%). Thus, once this relation is determined, the less time-consuming unit can be measured in the experimental work. To analyse the data, the colony-forming units should be expressed per root surface. Besides bacterial numbers during plant development, we assessed whether the bacterial populations collected showed different growth rates on agar plates. The growth rates of bacteria from the tip and base and different development stages of the plants showed differences, indicating differences in the metabolic state of the collected populations. [KEYWORDS: chrysanthemum; rhizosphere; rhizobacteria; root age; reference unit]
AB - The number of bacteria was determined during the growth of chrysanthemum plants on young (tip) and old (base) root parts. We assessed if the same conclusions could be drawn on the dynamics of bacterial populations during plant development when different reference units were used to express the bacterial counts. The results indicated that the total number of bacteria on the base decreased significantly during plant development, when expressed per root length, per root fresh weight or per root surface. The number of bacteria on the tip only decreased significantly when expressed per root length. Using the unit of dry weight of adhering soil, contradictory results were obtained for both base and tip; in general, the number of bacteria increased significantly during plant development. Thus, different reference units may lead to different conclusions. Root surface seemed to be the best unit to use, but the use of this unit requires time-consuming measurements. Regression analyses indicated that the reference unit "root surface" was highly correlated with root fresh weight (R-2=93%). Thus, once this relation is determined, the less time-consuming unit can be measured in the experimental work. To analyse the data, the colony-forming units should be expressed per root surface. Besides bacterial numbers during plant development, we assessed whether the bacterial populations collected showed different growth rates on agar plates. The growth rates of bacteria from the tip and base and different development stages of the plants showed differences, indicating differences in the metabolic state of the collected populations. [KEYWORDS: chrysanthemum; rhizosphere; rhizobacteria; root age; reference unit]
U2 - 10.1007/s003740050495
DO - 10.1007/s003740050495
M3 - Article
SN - 0178-2762
VL - 28
SP - 285
EP - 291
JO - Biology and Fertility of Soils
JF - Biology and Fertility of Soils
IS - 3
ER -