Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: July 1, 2004
Publication Date: N/A
Technical Abstract: This study examined the interactions of P deficiency and CO2 enrichment on partitioning to roots obtained from barley seedlings [Hordeum vulgare (L.) cv. Brant]. Plants were grown from single seeds in controlled environment chambers provided with ambient (36 Pa) or elevated (100 Pa) CO2 and with either sufficient (1 mM) or moderately deficient (0.05 mM) P. Root growth, metabolites and minerals were then measured between 9 and 17 days after sowing. Root growth was decreased by P deficiency, although root growth of both P sufficient and P deficient plants was increased by CO2 enrichment. Root P levels were unaffected by enhanced CO2 but were about 10-fold greater in P sufficient compared to P deficient plants. Inorganic NO3- levels also were unaffected by CO2 enrichment but were 9% greater in P deficient compared to P sufficient roots. Under P sufficient conditions root Suc, Glc and Fru were increased up to 35% by CO2 enrichment. Similar increases of soluble sugars in roots were observed when plants were grown under P deficiency. Consequently, soluble sugar levels were minimal in P sufficient roots of ambient CO2 grown plants and were greatest in CO2 enriched plants with P deficiency. Root hexose-P levels were decreased by P deficiency, but adenylates (ATP + ADP) were unaffected by this treatment. Interestingly, the root adenylate pool was increased 32% by CO2 enrichment, whereas root hexose-P levels were similar in the ambient and elevated CO2 treatments. Glu and Gln were both decreased by P deficiency and Glu was unaffected but Gln was increased by enhanced CO2. The above results indicated that both P deficiency and CO2 enrichment impacted photosynthate partitioning to roots by altering the source to sink balance of barley seedlings.