ISHS Acta Horticulturae 465: IV International Peach Symposium
TAKING INTO ACCOUNT RELATIONSHIPS BETWEEN ECOPHYSIOLOGICAL PROCESSES IN THE BREEDING FOR PEACH TREE CHARACTERISTICS |
| Authors: | J. Kervella, F. Pfeiffer, L. Pagès, M. Génard, V. Serra |
| Keywords: | tree habit, mechanical resistance, hydraulic conductivity, sylleptic branching, genetics |
| Abstract:
Tree characteristics are determined by interrelated ecophysiological processes. Taking into account these relations through models allows to define more reliable and relevant selection criteria and to better characterise genotypes. We illustrate this approach by two examples. The data are taken from experiments designed to evaluate genetic variations in tree growth and development characteristics between standard cultivars. These experiments also aimed to define early selection criteria for those characteristics on one-year-old trees. Thickness is an important parameter of mechanical resistance and hydraulic conductivity of branches. Evaluation of branch thickness on trees at the end of their first growing season is more reliable if the relation between length and diameter of branches, rather than the diameter alone, is considered. It reduces the bias due to variations in the distribution of branch lengths between genotypes. Some genotypes with a high average diameter on axillary branches produce longer branches than other genotypes, but their shoots are actually thinner when branches of similar length are compared. Sylleptic branching (i.e. growth of axillary meristems into branches as the bearing shoot is growing) is more often observed on vigorous shoots. Branching capacity is therefore better evaluated when growth rate is taken into account. Thus, in our experiments, 'M1339' branched more frequently than 'Silvergem' but grew faster. Modelling sylleptic branching in relation to growth rate emphasised that, conversely, for similar growth rates, sylleptic branching occurred more often in 'Silvergem'. In both cases, the modelling of interrelations allowed to better exploit the available data. | |
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