Open Access173 Calorimetric Evaluation of Metabolic Intensity of Apple Lateral Buds and Roots during the Transition from Para- to Endodormancy
Author(s) -
Jesús Llamas Llamas,
A.A. Gardea,
Jaime Martínez-Téllez,
V. Guerrero-P,
Elizabeth Carvajal-Millán,
Jarma Orozco,
A. Rascon-Chu
Publication year - 2000
Publication title -
hortscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.518
H-Index - 90
eISSN - 2327-9834
pISSN - 0018-5345
DOI - 10.21273/hortsci.35.3.420b
Subject(s) - horticulture , cutting , botany , dry weight , chemistry , biology
Potted 1-year-old `Starking Spur' and `Golden Delicious' trees on MM.106 were used to characterize the metabolic changes in lateral buds and rrots during their transition from para- to endodormancy. Sampling period was from 4 Sept. to 25 Nov. 1999 at 10-day intervals. Well-formed lateral buds were collected from the apical section of current growth; while root samples were white rootlets. Isothermal calorimetry at 25 °C was used to evaluated metabolic activity (q), respiration rate (RCO 2 ), metabolic efficiency (q/RCO 2 ), and growth rate (R SG ·Δ HB ). In both cultivars, q from buds showed significant differences (P ≤ 0.05) among sampling dates; `Starking' rose from 1.8 to 3.7 μW/mg dry weight (dw), while in `Golden' change was from 2.1 to 3.3 μW/mg dw. RCO 2 , q/RCO 2 , and R SG ·Δ HB showed a pattern similar to q. On each sampling date, cuttings were also forced to break and, in all dates, buds broke after 21 days, demonstrating a paradormant condition. MM.106 root tips q behave differently depending on the variety they were grafted on to. When grafted with `Starking', root tips produced a small, but significant, increase in q (from 9.1 to 15.7 μW/mg dw) as the season progressed. RCO 2 and R SG ·Δ HB behaved similarly, increasing from 27.6 to 57.6 mmol CO 2 /mg dw and 3.4 to 8.3 μW/mg dw, respectively. These conditions agreed with a dynamic root growth. A small decrease in q/RCO 2 was observed. However, when grafted with `Golden' root tips metabolic responses did not increase; furthermore, q decreased while RCO 2 , q/RCO 2 , and R SG ·Δ HB did not show a defined pattern. Four complete 2-year-old trees of each variety, kept in 1-m 3 containers, were sampled. The relation of root/wood dry matter was estimated, with difference found between varieties.