Role of nitrogen form in determining yield of field-grown maize.
1992
Smiciklas K.D. | Below F.E.
Although the maize (Zea mays L.) plant can utilize either NH4-N or NO3-N, many hydroponic studies have shown that mixed-N nutrition (NH4 + NO3) can optimize growth and yield. Results from field studies have been more erratic, however, and may be influenced by genotype. A 2-yr field study was therefore conducted at Urbana, IL, to evaluate five maize genotypes (B73 X LH51, LH74 X LH51, LH74 X LH82, LHE136 X LH82, and LHE136 X LH123) for plant growth, nutrient content, grain yield, and canopy photosynthesis photosythesis (Ps) when N was supplied either as calcium nitrate (NO3 plots) or urea plus a nitrification inhibitor (mixed-N plots). Three of the five genotypes types (B73 X LH51, LH74 X LH51, and LHE136 X LH82) increased grain yield (by 6-8%) when supplied with mixed N, compared with plants supplied with predominantly NO3. However, NO3-grown plants had equivalent or greater rates of canopy Ps (approximately 5-10%) than mixed N plants, and the duration of Ps was unaffected by N-form treatment at photosynthetic photon flux densities of 900 or 1800 micromoles photon m-2 s-1. Furthermore, N-form treatment did not affect the duration of daily canopy Ps. Genotypes responsive to mixed N utilized distinct physiological strategies to achieve increased grain yields. For example, the genotype LHE136 X LH82 increased the partitioning of dry matter to the grain, whereas LH74 X LH51 and B73 X LH51 increased total dry matter production. Mixed-N nutrition decreased the percentage of aborted kernels for the genotype B73 X LH51 and increased anthesis ovule number per earshoot for LH74 X LH82. Plants of the five genotypes supplied with mixed N also increased whole-shoot N content at maturity (by 5-14%). Based on these data, we conclude that mixed-N nutrition can moderately increase grain yield and productivity of certain maize genotypes by altering dry matter accumulation and partitioning, earshoot and ovule development, and N accumulation.
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