RESPONSE OF ´FLAME SEEDLESS´ GRAPEVINES TO SOME NITRIFICATION INHIBITORS

A field study was conducted to determine the effects of three nitrification inhibitors on ‘Flame Seedless’ grapevines grown in a sandy loam soil.
The nitrification inhibitors (NIs) were: nitrapyrin at rates of 2.5, 5 and 10 mg L^-1; 8-Hydroxyquinolin (8-HQ) and carbon disulphide (CS₂) at rates of 10, 20 and 40 mg L^-1. The data indicated that, nitrapyrin at all rates tested and CS₂ at 20 or 40 mgL^-1 significantly increased vegetative growth (shoot length, leaf area and pruning weight) as compared to the control.
Furthermore, 8-HQ at 20 or 40 mg L^-1 markedly increased shoot length but only slightly increased leaf area and pruning weight. Nitrapyrin at 5 or 10 mg L^-1 and CS₂ at 40 mg L^-1 caused a significant increase in the number of clusters vine^-1 and yield, meanwhile 8-HQ at all rates caused a slight increase in yield and number of clusters vine^-1. Nitrapyrin and CS₂ at the medium and high rates and 8-HQ at 20 mg L^-1 markedly increased cluster weight, juice volume of 100 berries, total soluble solids and vitamin C contents.
None of the NI rates significantly affected juice acidity.
Leaf N, Fe, Mn, Zn and Cu contents significantly increased as a result of the NI applications.
Leaf P, K and Ca contents decreased, especially with high NI rates.
Generally, the addition of NIs significantly increased soil NH₄⁺-N and decreased both soil NO₃–N and soluble N. Moreover, the nitrification rate (NR) markedly decreased due to NI applications.
The inhibition of nitrification expressed as a percent of the control and ammonium recovery ratio increased with increasing NI rates with the effect of nitrapyrin more superior compared with the other nitrification inhibitors.

VII International Symposium on Grapevine Physiology and Biotechnology

S.M. El-Shazly

´Flame Seedless´, mineral nutrition, nitrification, nitrate, ammonia

https://doi.org/10.17660/ActaHortic.2005.689.8