DEBOTTLENECKING FIBER PRODUCTION: FIELD EVALUATION OF LOW-LIGNIN POPLAR VARIETIES FOR PULP INDUSTRIES

?We aim to test the field performance of edited poplar varieties and the pulping efficiency of their wood harvesting outdoors in Southern US. Whether it is worth promoting our poplar varieties to stakeholders depends on the answers to these three questions. 1. Can our elite poplar varieties handle the stresses in the plantation in Southern US, outside the controlled greenhouse environment? 2. Can the wood from our elite poplar varieties consistently maintain its improved pulp yield performance through the recurring cycles of growth and dormancy and environmental stresses in the plantation? 3. Does agroforestry system using our elite poplar varieties gain more productivity, profitability, and sustainability merits in the southeast US? All three questions will be experimentally tested via field trials, laboratory analyses, and in silico modeling. The specific objectives of this A1701 Integrated standard project proposal are:1. Establish the short-rotation plantation of CRISPR-edited poplar varieties. Our plantation will be established in three steps: (1) Propagation of Edited Poplar Seedlings: Initially, we will propagate the edited poplar seedlings using tissue culture. (2) Cultivation in Greenhouse: Following propagation, the seedlings will be carefully cultivated in a greenhouse to attain a specific size. (3) Transplantation into the field: Finally, the well-grown seedlings will be transplanted into the field for further growth and development. Through these processes, we assessed the suitability of our CRISPR-edited poplar plants, propagated from tissue culture, for adaptability and their capacity to thrive in the Southern US agroforestry lands. These evaluations offer insights into the effect of our genetic edits on seedling development and tree survival outdoors.2. Evaluate growth and resilience related traits of the CRISPR-edited elite poplar varieties in the field trials. To better evaluate the growth and resilience performance of the edited poplar varieties in the Southern US field trial, we will monitor several physiological traits. 1. For the tree productivity, tree heights, basal diameters, aboveground biomass, photosynthetic and respiration phenotypes are monitored. 2. For tree resilience, xylem specific conductivity, water use efficiency, and relative water content of stem are investigated. 3. For tree tolerance to pathogen, we will score rust infection and insect damage according to the observation. By comparatively measuring these traits between our edited varieties and wild-type poplars in the field trial we will evaluate not only the productivity, profitability, resilience, and sustainability of our poplar varieties but will also provide guidelines for our stakeholders who will utilize our varieties for pulpwood production. Poplar varieties displaying strong fitness and robust growth during the field trial will be chosen for further tests of their wood's pulping yield and properties.3. Assess the cell wall properties and pulp yield efficiency of wood sourced from field-grown elite poplar varieties. The wood harvested from the chosen poplar varieties, as well as the control group, will undergo analysis to assess their wood cell wall properties, including lignin content and composition. These properties serve as potential indicators for the suitability of these woods for various industries. Subsequently, micro kraft pulping will be conducted to assess how well the modified poplar trees accommodate wood samples. Taken together, the implementation of these practices and the subsequent analysis of the results hold the potential to provide comprehensive and actionable insights for forest landowners and mills regarding the optimization of our modified poplar resources. This information includes comprehensive insights into optimizing harvesting cycles, identifying industries poised to reap the benefits of these unique wood varieties, and recommending adjustments to current procedures. This empowers stakeholders to make well-informed choices that not only maximize economic gains but also enhance environmental sustainability through these innovative poplar resources.4. Disseminate training and outreach materials and technical support for Extension agents, landowners, pulp mill managers, dealers, nursery managers, focused on forest growth and pulpwood production for a climate-smart agroforestry. This program includes face-to-face workshops, landowner workshops, and an online forum facilitated by AU's College of Forestry and Wildlife Sciences. Stakeholders can connect with researchers, consultants, and others in the agroforestry and pulp production community, applying knowledge gained during field-testing. Small landowners may conduct their own trials or participate in larger ones with pulp industries. A forum will facilitate knowledge exchange, fostering sustainable impact in the region, with continuous technical support provided by the co-PIs.