Handbook of Plant and Crop Physiology

of N per person per day is excreted in urine by humans who eat a typical Western diet [182]. Along with this, however, nearly 18 ...

William Knott, Biomedical Office, Kennedy Space Center for his support and encouragement in this pro- ject. This research was su ...

FJM Maathuis, D Sanders. Mechanisms of potassium absorption by higher plant roots. Physiol Plant 96:158–168, 1996. DW Rains, E ...

CPL Grof, M Johnston, PF Brownell. Effect of sodium nutrition on the ultrastructure of chloroplasts of C 4 plants. Plant Physio ...

FA Smith, JA Raven. Intracellular pH and its regulation. Annu Rev Plant Physiol 30:289–311, 1979. RB Lee, RG Ratcliffe. Phospho ...

T Murata, T Akazawa. Enzymatic mechanism of starch synthesis in sweet potato root. I. Rquirement of potas- sium ions for starch ...

DW Rush, E Epstein. Comparative studies on the sodium, potassium, and chloride relations of a wild halo- phytic and a domestic ...

18 Nitrogen Metabolism and Crop Productivity Fred E. Below University of Illinois, Urbana, Illinois 385 I. INTRODUCTION Among th ...

II. NITROGEN ACQUISITION BY CROP PLANTS A. Nitrogen Availability Under natural conditions, N enters the soil environment as the ...

established procedure to document crop N status. These tests involve measuring organic N (also called reduced N) in the leaves [ ...

Although the process of NH 4 uptake is not completely understood, it is clear that passive and active uptake must occur by diffe ...

[74,91,92]. The limitation in NH 4 uptake at low pH can lead to N stress and a decrease in growth when NH 4 is the only form of ...

duced ferredoxin as the electron donor [61]. Nitrite reduction in the root occurs in a plastid, which is anal- ogous to a chloro ...

More extensive early-season N uptake may also be the result of a larger supply of N in the soil, be- cause available soil N ofte ...

Thus, as leaves age and senesce, their capacity for photosynthesis declines, with a correspondingly neg- ative effect on assimil ...

workers have suggested that the deposition and/or accumulation of storage protein by the kernel is a factor regulating grain dev ...

dition, source-sink alteration experiments have indicated that C- and N-storage processes in cereal ker- nels seem to operate au ...

Mg, respectively). In contrast, the fourth 67-kg increment increased yield by only 0.1 Mg, which would not be considered economi ...

after flowering. However, these types might also be more susceptible to N deficiency early in the grow- ing season and less like ...

crops is beneficial under production conditions [242–247]. Several reports [243,246,247] have shown moderate yield increases of ...