RESUMO
Temperate deciduous fruit trees survive winter temperatures by entering a dormant phase in their aerial meristematic organs. Release from bud dormancy occurs after chill requirements (CR) have been satisfied, whereas bud burst/flowering follows heat requirement (HR) fulfillment. The physiological basis behind these metrics remains elusive. In this study, we are presenting the first multidisciplinary dormancy progression analysis in northern Patagonia, linking (1) forcing/field phenology, (2) bud anatomical development, and (3) soluble sugar (sucrose, glucose, and fructose) dynamics in Juglans regia L. CR and HR were determined for 'Chandler' and 'Franquette,' two walnut cultivars with markedly different CR, in artificial chill/forced heat trials (three seasons) and in-field chill/forced heat tests (five seasons) using excised twigs either with or without apical buds (non-decapitated and decapitated). The soluble sugar dynamics of 'Chandler' (high-performance liquid chromatography) and the anatomical changes of the buds (light microscopy) of the two cultivars were analyzed during endo-ecodormancy progression in one and two seasons, respectively. The CR defined by artificial chill tests proved to be an overestimation compared to the field determinations. Moreover, HR was the main driver in the phenology dynamics, as expected for a high-chill region. 'Chandler' showed an average of 10.3 field chill portions (CP) and 2,163 Growing Degree Hours (GDH°C) less than 'Franquette' for dormancy release and bud burst, respectively. These results were consistent with the transition of the shoot apex from the vegetative to the reproductive phase and the soluble sugar profile. The decrease in sucrose between 15 and 30 days after CR fulfillment could be a reliable biological marker for endodormancy release in walnut, while the increase in fructose and glucose is likely an osmolyte and cellulosic carbon source in pre-sprouting. In addition, we discuss the effect of paradormancy thanks to our apical bud experiment (with or without). Our results improve the current understanding of endo-ecodormancy progression in walnut and provide insightful results for walnut production (i.e., cultivation practices such as pruning) as well as for further application in dormancy modeling, to infer the ideotypes that should be bred for future climate conditions.
RESUMO
Agricultural expansion requires the deployment of stress-tolerant crops like safflower (Carthamus tinctorius L.). In safflower breeding, oil improvement in early generations requires indirect selection through simply inherited traits. The oil quality is mostly related to the fatty acid profile, which is determined by the OL locus. The aim of this research was to identify simple easy-to-measure traits that indirectly explain oil content variation and its interaction with yield components, and also to generate an effective tool for genotyping the OL locus. A field experiment with F5 and pure lines was carried out to correlate the oil content with 18 traits including yield components, and phenological and morphological characteristics. KASP technology using primers designed according to the ctFAD2-1 gene sequence was applied for OL locus genotyping and validated through fatty acids phenotyping. Hull content, the length:width ratio of the grain, and plant height were identified as the most promising selection tools for increasing oil content, and grains per capitulum was the best yield component for increasing yield without decreasing the oil content. KASP genotyping successfully worked as a MAS tool, identifying oleic and linoleic genotypes. These tools enhance options for improving oil content and quality for safflower breeding.
