ISHS Acta Horticulturae 721: V International Symposium on Mineral Nutrition of Fruit Plants
FOLIAR NITROGEN COMPOSITION AND APPLICATION TIMING INFLUENCE NITROGEN UPTAKE BY, AS WELL AS PARTITIONING WITHIN, TWO GRAPEVINE CULTIVARS |
| Authors: | D. Porro, C. Dorigatti, M. Stefanini, M. Policarpo, F. Camin, L. Ziller |
| Keywords: | Vitis vinifera, ´Chardonnay´, ´C. Sauvignon´, fertilizer, ammonium, nitrate, SPAD |
| DOI: | 10.17660/ActaHortic.2006.721.33 |
| Abstract:
Foliar spraying of fertilizers is a standard practice used in vineyards and orchards to overcome temporary mineral element deficiencies and improve fruit quality. The authors conducted a field study to compare grapevine uptake and partitioning of foliarly applied nitrogen (N). Three solutions containing equivalent total N amounts of isotopically-labeled N but with varying composition (NH4, NH4+NO3, or NO3) were applied at berry set or at veraison to leaves of mature 'Cabernet Sauvignon' and 'Chardonnay' grapevines. The shoots with the treated leaves were sampled 8 d after application, dissected into leaf, woody stem, and berry cluster components, and analyzed for total and isotopic N contents. The differential N treatments had little effect on shoot growth of either cultivar; however, N uptake from the NH4-containing treatments was higher than from the treatment containing only NO3. The leaves contained substantially greater amounts of N than did the woody stems and berry clusters at both sampling times. The interaction between cultivar and timing of application was significant. 'Chardonnay' woody stems contained higher amounts of labeled N when the N was applied at veraison than at berry set, while 'Cabernet Sauvignon' showed little difference. Leaf green color, measured using a SPAD meter, reflected relative leaf N status. 'Chardonnay' leaves had lower labeled N content and were less green than those of the 'Cabernet Sauvignon' leaves when foliar N was applied at berry set, while they contained more labeled N and were greener than 'Cabernet Sauvignon' leaves following N application at veraison. | |
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