Examination of photosynthetic nitrogen use efficiency of field- grown sweet corn (Zea mays L var merit) under water and nitrogen stress


The physiological response to drought stress in sweet corn (Zea mays L var merit) is not well understood. Water and nitrogen utilization properties of leaves can play key roles in plant drought tolerance. During the grain-filling period, increasing photosynthesis per unit plant N, namely photosynthetic N-use efficiency (PNUE) is a potential way to increase N-utilization efficiency (NUtE). The objective of this study was to determine whether the PNUE within the canopy is optimized as a method of maximizing canopy productivity under low N conditions and/or wa- ter stress. Sweet corn plants were grown in the field in two consecutive years with three N levels (0, 175, and 225 kg N ha−1) and two water regimes (100 and 60 percent field capacity). Throughout the grain-filling period significant interactions of irrigation regime x nitrogen fertilization on specific leaf N (SLN), net photosynthetic rate (P ), PNUE (calculated as P /SLN), stomatal conductance (gs), transpiration rate (E) and green leaf area (GLA) were measured every 10 d after silking (DAS). Significant differences in SLN, P , gs, E, and PNUE occurred in leaves. Ear FM with- out N (N0) (13.69 and 15.56 Mg ha−1 across 2 yr) was 37% and 45% and 34% and 41% less than the average of N125 and N225 across both years, but physiological NUtE increased by 21% without N. Correspondingly, PNUE at high levels of N was similar to that of the full irrigation, with both of them having smaller PNUE than the lower of N. In conclusion, improved whole-plant NUtE under water stress and with N0 may both contribute to the high degree of physiological acclimation of sweet corn to drought and the overall increase in PNUE in the leaves.


Zea mays, sweet corn, drought, nitrogen use efficiency, photosynthesis

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Maydica - A journal devoted to maize and allied species

ISSN: 2279-8013