ISHS Acta Horticulturae 396: Hydroponics and Transplant Production
STUDIES ON NFT CULTURE OF 'KYOHO' GRAPES: WATER STRESS SYMPTOMS AND FRUIT QUALITY OF GRAPEVINES SUPPLIED AMMONIUM NITROGEN AT LOW PH AFTER VERAISON |
| Authors: | H. Motosugi, K. Beppu, A. Sugiura |
| Keywords: | NFT (nutrient film technique), ABA (abscisic acid), Water stress, Ammonium nitrogen, Grapevine, Fruit quality |
| Abstract:
'Kyoho' grapevines on 'SO4' rootstock were cultured on nutrient film technique (NFT) beds. The nutrient solution used as standard was 1/5 strength Hoagland's No.2 solution (nitrogen supplied as nitrate to ammonium at a 14:1 ratio) and the pH adjusted to 5.5. After the onset of veraison, the grapevines were subjected to four treatments comprising of a combination of two nitrogen sources (standard or ammonium nitrogen alone) and two pH levels (standard pH or low pH). In low pH treatments, the pH was adjusted every day to 3.0–3.5. These treatments were continued for two weeks. With ammonium treatment at low pH, all the fine roots gradually died, which caused water stress in the grapevines. Transpiration rate and leaf water potential also decreased and stomatal resistance increased during the period in those vines. Upon returning to the standard solution, new roots grew vigorously and the vines almost completely overcame the stress by harvest. With ammonium nitrogen at low pH, abscisic acid levels in leaf and berry skin increased significantly during the treatment period and the anthocyanins in the berry skin also increased in the following two weeks. Berry size and concentrations of glucose and fructose in the juice were not affected by the treatments. | |
Download Adobe Acrobat Reader (free software to read PDF files) | |
