Apoplastic infusion of sucrose into stem internodes during female flowering does not increase grain yield in maize plants grown under nitrogen-limiting conditions.
Nitrogen (N) limitation reduces leaf growth and photosynthetic rates of maize (Zea mays), and constrains photosynthate translocation to developing ears. Additionally, the period from about 1 week before to 2 weeks after silking is critical for establishing the reproductive sink capacity necessary to attain maximum yield. To investigate the influence of carbohydrate availability in plants of differing N status, a greenhouse study was performed in which exogenous sucrose (Suc) was infused around the time of silking into maize stems grown under different N regimes. N deficiency significantly reduced leaf area, leaf longevity, leaf chlorophyll content and photosynthetic rate. High N-delayed leaf senescence, particularly of the six uppermost leaves, compared to the other two N treatments. While N application increased ear leaf soluble protein concentration, it did not influence glucose and suc concentrations. Interestingly, ear leaf starch concentration decreased with increasing N application. Infusion of exogenous suc tended to increase non-structural carbohydrate concentrations in the developing ears of all N treatments at silking and 6 days after silking. However, leaf photosynthetic rates were not affected by suc infusion, and suc infusion failed to increase grain yield in any N treatment. The lack of an effect of suc infusion on ear growth and the high ear leaf starch concentration of N-deficient maize, suggest that yield reduction under N deficiency may not be due to insufficient photosynthate availability to the developing ear during silking, and that yield reduction under N deficiency may be determined at an earlier growth stage.
The Key Laboratory of Plant-Soil Interactions, Ministry of Education, Center for Resources, Environment and Food Security, China Agricultural University, Beijing, 100193, China.
Yunfeng
Y
Peng
Chunjian
C
Li
Felix B
FB
Fritschi
D018533:Biomass; D050260:Carbohydrate Metabolism / Q000187:drug effects; D002734:Chlorophyll / Q000378:metabolism; D005308:Fertilizers; D035264:Flowers / Q000187:drug effects / Q000502:physiology*; D009584:Nitrogen / Q000172:deficiency* / Q000494:pharmacology; D010788:Photosynthesis / Q000187:drug effects; D018515:Plant Leaves / Q000033:anatomy & histology / Q000187:drug effects / Q000502:physiology; D010940:Plant Proteins / Q000378:metabolism; D018547:Plant Stems / Q000187:drug effects / Q000502:physiology*; D012639:Seeds / Q000187:drug effects / Q000254:growth & development*; D012995:Solubility / Q000187:drug effects; D013395:Sucrose / Q000494:pharmacology*; D003313:Zea mays / Q000187:drug effects / Q000254:growth & development* / Q000502:physiology*
D005308:Fertilizers; D010940:Plant Proteins; D002734:Chlorophyll; D013395:Sucrose; D009584:Nitrogen