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Characteristics of Ammonia Volatilization from Spring Wheat
Author(s) -
Morgan Jack A.,
Parton William J.
Publication year - 1989
Publication title -
crop science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.76
H-Index - 147
eISSN - 1435-0653
pISSN - 0011-183X
DOI - 10.2135/cropsci1989.0011183x002900030038x
Subject(s) - photorespiration , volatilisation , ammonia , shoot , biology , agronomy , nitrogen , ecophysiology , ammonia volatilization from urea , botany , raceme , photosynthesis , horticulture , chemistry , fertilizer , inflorescence , biochemistry , organic chemistry
The gaseous exchange of NH 3 between plants and the atmosphere is important in the N budgets of agricultural cropping systems, yet the physiological bases underlying plant NH 3 fluxes remain obscure. The objective of this study is to describe NH 3 fluxes from shoots of well fertilized growth‐chamber grown wheat ( Triticum aestivum L.) plants from early vegetative growth through maturity. Effects of developmental stage and photorespiration on shoot NH 3 and CO 2 exchange were investigated with a steady‐state, whole‐plant gas exchange cuvette. Ammonia compensation points were also determined during the grain‐filling period. Volatilization (loss) of NH 3 from wheat shoots at ambient [NH 3 ] was consistantly observed throughout the study. Plant CO 3 exchange rates and NH 3 volatilization rates were strongly influenced by leaf area, although trends for exchange of the two gases were dissimilar when expressed on a leaf area basis. Photorespiration was only modestly associated with level of NH 3 volatilization. The highest rates of NH 3 volatilization occurred during grain filling, with two bursts of high activity after anthesis and prior to maturity. Ammonia compensation points rose as plants approached maturity. Increased potential for NH 3 volatilization during later developmental stages is attributed to ontogenetic changes in plant N metabolism that elevate tissue [NH + 4 ] from concentrations occurring in younger, vegetative tissue.