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Lanzhou University (2014)

Plant Architecture Plasticity and Its Response to Adverse Stresses in Dryland Triticeae Crops under Artificial Selection Pressure


Titre : Plant Architecture Plasticity and Its Response to Adverse Stresses in Dryland Triticeae Crops under Artificial Selection Pressure

Auteur : 李朴芳;

Grade : Doctoral Dissertation 2014

Université : Lanzhou University

Résumé partiel
Evolvement of plant type in dryland Triticeae crops and its adaptation to adversity is one of the most important fundamental scientific issues. Domestication of Triticeae crops is mostly due to the result of artificial selection, and it is briefly categorized into two types including strong domestication type (mainly refers to as wheat and barley) and weak domestication type (mainly refers to as oat and triticale). In this paper, a group of studies were conducted on the basis of Darwin’s theory of evolution, Vavilov’s homologous variation law and biological metabolism theory using wheats and oats as representative crops. The test materials were chosen from Triticeae crops with genetically evolutionary relationship and various domestication gradients in the combination of experimental verification and meta-analysis methods. A series of eco-physiological and agronomic data were measured and recorded including the parameters of the variation in plant type, water use, yield formation, osmotic adjustment and gas exchange and so on, under adverse stresses including drought, high temperature&low light and high population density. The objectives of this study are to reveal the evolutionary characteristics of crop plant type, reconstruction direction of plant architecture, and the strategies of adaptation to adversity under the pressure of artificial selection. The results would provide new theoretical potential for cultivation management and breeding practice of dryland Triticeae crops. Major results were achieved as follows:1. The results from field experiments showed that plant architecture was evolved towards the tendency from a compact type in diploid wheats to an incompact type in tetraploid wheats, and further to more compact type in hexaploid wheats. Leaf morphological traits tend to become wider and shorter. Field experiment was designed to determine morphological changes in the upper three leaves in three different ploidy wheat species (two diploid MO1and MO4, two tetraploid DM22and DM31, and two hexaploid L8275and Monkhead). The results showed that basal angle, opening angle and cambering angle of three ploidy wheats ranged from22.1°to34.6°,30.0°to66.0°and19.0°to36.4°, respectively. In three ploidy wheats, tetraploid wheats had the highest values among these parameters. The opening angles of hexaploid wheats are greater than diploid wheats, but their basal angles and the cambering angles are lower than those of diploid wheats. Moreover, leaf length-width ratios of leaf, ranged from13.7to26.5, and they increased along with the rise in chromosome sets.2. Field experiments further suggested that source-sink relationship in the evolvement of dryland wheats from wild to modern varieties has undergone two important phases. The first phase was to enhance source dimension, and the second one was to strengthen sink dimension. Yet, leaf net photosynthetic rate has not been improved. With the similarity as the above results, the biomass of leaf, stem, sheath and aboveground biomass all increased significantly from diploid to tetraploid, but there were not significant difference in the transition from tetraploid to hexaploid. From diploid to tetraploid and hexaploid, population yield and harvest index increased, although root biomass decreased gradually. In addition, diploid wheats had the largest net photosynthetic rate, tetraploid wheat was at second place, and hexaploid had the lowest net photosynthetic rate.3. Pot-culture experiment illustrated that biomass allocation pattern experienced an upward shift "from down to up". Upward shift of biomass allocation was observed in three wheat species, in which the dry weight percentages of root, stem, leaf and ear in total biomass were43%,20%,10%and27%in diploid species,21%,34%,16%and29%in tetraploid species and14%,34%,14%and38%in hexaploid species respectively.

Mots clés : Triticeae crops; wheat; oat; plant type; domestication; stress resistance; adaptation strategy;

Présentation (CNKI)

Page publiée le 27 septembre 2017