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Productivity of Maize (Zea mays L.) in Relation to Morphological and Physiological Characteristics under Varying Amounts of Nitrogen Supply
Author(s) -
Greef J. M.
Publication year - 1994
Publication title -
journal of agronomy and crop science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.095
H-Index - 74
eISSN - 1439-037X
pISSN - 0931-2250
DOI - 10.1111/j.1439-037x.1994.tb00182.x
Subject(s) - photosynthesis , nitrogen , nitrate reductase , chlorophyll , human fertilization , agronomy , zea mays , rubisco , zoology , biology , chemistry , horticulture , botany , organic chemistry
In a field trial located in a northern region of Germany, characterized by a Podzol soil and increasing N fertilization resulted in an enhanced N uptake of the maize ( Zea mays L.) variety “Felix” with increasing N fertilization ranging from 0 kg N ha ‐1 (N1) to 60 kg N ha ‐1 (N2) and to 160 kg N ha ‐1 (N3). The growth conditions reached only nearly optimal temperature for biomass allocation in a short period of July and August 1990. The plant productivity was stimulated due to higher N uptake and N utilization to values of nearly 1600 g ha ‐1 . The N efficiency decreased with increasing N fertilization. A greenhouse experiment was conducted to study the effects of varied nitrogen nutrition on the development of maize plants under standardized growth conditions, comparable to the sub optimal growth conditions of the field experiment. Physiological and anatomical parameters were measured. Within a range of 0.2—1.0 mg N cm ‐2 of leaf nitrogen, the chlorophyll concentration and the CO 2 exchange rate showed a linear relationship with the reduced N in the leaf. Above 1.0 mg N cm ‐2 no further increases in chlorophyll levels or photosynthesis were observed. Nitrate reductase activity was stimulated throughout the N range supplied. The activities of photosynthetic enzymes (PEP carboxylase, N adp malic enzyme, RubP carboxylase) was increased from the low (0.19 g N kg ‐1 soil) to the middle N level (0.37 g N kg ‐1 soil). Under conditions of a high N supply (0.75 g N kg ‐1 soil) the activity decreased, except N adp malic enzyme. This effect was accompanied by alterations of the internal structure of the leaf. Leaf thickness and size of the mesophyll parenchyma were less at the medium nitrate supply. Other anatomical parameters were influenced in proportion to leaf nitrogen status. Stomatal index was not affected by N supply, but lengths and widths of epidermal and stomatal cells as well as the distance between stomata and vascular bundles were increased by high N supply. It is proposed that above an optimal range of leaf nitrogen, maize plants cannot use the potential advantage of the C 4 mechanism and the N utilization shows maximum efficiency in the intermediate N level under the sub optimal growth conditions used in the greenhouse experiment.