PT  - JOURNAL ARTICLE
AU  - Sanliang Gu
AU  - Porter B. Lombard
AU  - Steven F. Price
TI  - Effect of Shading and Nitrogen Source on Growth, Tissue Ammonium and Nitrate Status, and Inflorescence Necrosis in Pinot noir Grapevines
AID  - 10.5344/ajev.1996.47.2.173
DP  - 1996 Jan 01
TA  - American Journal of Enology and Viticulture
PG  - 173--180
VI  - 47
IP  - 2
4099  - http://www.ajevonline.org/content/47/2/173.short
4100  - http://www.ajevonline.org/content/47/2/173.full
SO  - Am J Enol Vitic.1996 Jan 01; 47
AB  - The effect of 60% shading and nitrogen (N) source on growth, tissue NH4+ and NO3- concentrations, and inflorescence necrosis (IN) was investigated in one- and two-year-old potted Pinot noir grapevines. New growth of the vines was significantly reduced by shading and NH4+ feeding resulted in less new growth compared to NO3- feeding. The shaded two-year-old vines developed 26.6% IN compared to only 0.6% on unshaded vines. No IN was induced by either NH4+ or NO3- feeding treatments. Shading increased tissue NH4+ concentration in most tissues of one-year-old vines with few exceptions and in laminas, petioles, and rachis of two-year-old vines. Two-year-old vines fed NH4+ and/or NO3- had a higher rachis, petiole, stem, and young root NH4+ concentration at post-anthesis, compared to the no N control. The NH4+-fed vines had a higher NH4+ concentration than that of NO3##-fed vines only in stems at post-anthesis and young roots pre-anthesis, anthesis, and post-anthesis. Tissue NO3- concentration of laminas, petioles, stems, and young roots was proportional to the amount of NO3--fed to the vines in the root medium. Elevated tissue NH4+ concentration in the rachis of shaded vines and increased incidence of IN suggest that IN is associated with elevated tissue NH4+ levels. NH4+ and/or NO3- in culture media is not a source of elevated NH4+ level for IN development.