Journal of Energy Bioscience 2024, Vol.15, No.6, 337-348 http://bioscipublisher.com/index.php/jeb 342 leguminous crops (such as Canavalia ensiformis and Phaseolus lunatus) significantly improves the photosynthetically active radiation utilization efficiency (RUE) and crop water productivity (CWP) by increasing the leaf area index (LAI) and light interception rate of the composite population (Figure 2) (Gitari et al., 2018; Nyawade et al., 2019). This planting system also improves the field microclimate environment and maintains soil temperature and humidity conditions that are conducive to photosynthetic carbon assimilation. In terms of canopy structure optimization, directional pruning and plant shaping technology can adjust the leaf inclination distribution so that light energy is more evenly distributed inside the canopy. This regulation not only avoids the waste of light saturation of the upper leaves, but also alleviates the light limitation of the lower leaves, thereby improving the photosynthetic efficiency of the population as a whole. Relevant agronomic measures provide a practical basis for building an efficient photosynthetic production system. Figure 2 Canopy overlap by potato grown alone (Adopted from Nyawade et al., 2019) Image caption: (a) and intercropped with lima bean (b) and dolichos (c). Photos taken in the upper midland agro-ecology at vegetative growth of potato (Adopted from Nyawade et al., 2019) 4.4 Role of biostimulants and growth regulators in photosynthesis efficiency Biological stimulants and plant growth regulators are novel regulatory methods for enhancing the photosynthetic efficiency of potatoes, exerting their effects through multiple physiological mechanisms. This type of active substance includes natural extracts (such as seaweed polysaccharides, amino acid complexes) and synthetic compounds. Its mechanism of action mainly includes: (1) promoting chloroplast development and increasing chlorophyll content per unit leaf area; (2) Enhance root morphology and expand nutrient absorption surface area; (3) Activate the antioxidant defense system to alleviate damage to photosystem II caused by environmental stress. Research has shown that treatment with seaweed extract can increase the maximum photochemical efficiency (Fv/Fm) of PSII in potato leaves by 12% to 15%, while promoting the transport of carbohydrates to tubers (Tiwari et al., 2020). In terms of plant hormone regulation, cytokinins (such as 6-BA) maintain photosynthetic activity by delaying leaf senescence, while gibberellins (GA3) enhance light harvesting ability by expanding leaf area. When combined with precision irrigation, optimized intercropping systems, and other agronomic measures, these bioactive substances can form a synergistic effect, increasing the population photosynthetic rate by 18% to 22%. This integrated strategy of "physiological regulation agronomic optimization" provides a new technological approach for achieving resource efficient potato production. 5 Case Study: Enhancing Photosynthesis Efficiency through Chloroplast Engineering 5.1 Overview of chloroplast-targeted modifications Chloroplasts, as the core organelles for energy conversion in photosynthetic eukaryotic cells, directly affect the carbon assimilation ability of plants in terms of their efficiency in converting light energy into chemical energy. Modern genetic engineering technology has achieved precise modification of chloroplasts at multiple levels: (1) by introducing efficient Rubisco variants of purple non sulfur bacteria (Rhodospirillum rubrum), carbon fixation efficiency comparable to the wild type can be maintained under CO2 enrichment conditions, while significantly improving carboxylation reaction rates (Manning et al., 2023); (2) The potato chloroplast proteome map constructed based on high-throughput mass spectrometry technology revealed key targets including electron transfer chain complex regulatory proteins and redox modification sites, providing a molecular basis for
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