Abstract
Nitrogen is a key macronutrient for the quantitative and qualitative yield of grapes; in addition, it influences the development and reproduction of grape pests. The multiple effects of different nitrogen rates were investigated on the red berry cultivar ‘Carignano’ and the grape pest Planococcus ficus in a two-year field trial. Different amounts of ammonium nitrate were compared: 0, 80 and 160 Units ha−1 for mineral nitrogen. The amount of nitrogen fertilization supplied influenced the nitrogen status of vines and increased the pruning weight and leaf area, as well as the overall grape yield, by increasing the cluster weight. However, doubling the nitrogen rate did not generally increase the vegetative and productive parameters of grapevines. At harvest, nitrogen supply did not influence the anthocyanin content, tritatable acidity, and soluble solids, although the latter parameter showed a clear, yet not significant, decreasing trend. Planococcus ficus exhibited higher fecundity, survival and shorter development time on grapevines provided with nitrogen, whereas its fertility was unaffected by nitrogen fertilization. Ultimately, nitrogen had a direct and positive effect on grape yield and vine mealybug development, highlighting the importance of integrated cultural and pest control practices to promote grape production.
Highlights
Accepted: 27 November 2021Soil fertilization is a cultural technique with a great impact on grape yield and quality of must and wine [1]
The aim of the present work was to investigate under field conditions the interdisciplinary implications of nitrogen fertilization by evaluating its influence on both grape yield components and must composition, and the development and fitness of the vine mealybug (VMB)
The consequences of N supply on grape yield were mainly due to differences in cluster weight and, considering that in both years the average berry weight did not vary between treatments, the higher cluster weight was most likely due to a higher number of berries per cluster in the fertilized vines
Summary
Accepted: 27 November 2021Soil fertilization is a cultural technique with a great impact on grape yield and quality of must and wine [1]. Starting from spring, roots absorb this macronutrient mainly in the nitrate form, reaching the maximum adsorption rate from bloom to fruit set [2], whereas its uptake decreases from veraison to leaf fall, when N stored in annual organs is reallocated to woody tissues [3]. Both N deficiency and excess may contribute to reducing yield and fruit quality. Keller et al [7], using pot-grown ‘Cabernet Sauvignon’ vines, reported that moderate nitrogen supplies before bloom favor the synthesis of polyphenols
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