Effects of Seasonal Deficit Irrigation, Potassium Fertilization and Bunch Thinning on Growth, Yield and Quality of Flame Seedless Grapes | ||||
| Alexandria Journal of Agricultural Sciences | ||||
| Article 1, Volume 62, Issue 1, January and February 2017, Page 11-30 | ||||
| Document Type: Original Article | ||||
| DOI: 10.21608/alexja.2017.5755 | ||||
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| Author | ||||
| Diaa El-Ansary* | ||||
| Department of Pomology, Faculty of Agriculture (El-Shatby), University of Alexandria, 21545, Egypt | ||||
| Abstract | ||||
| Impacts of deficit irrigation levels, potassium fertilization, and bunch thinning on grapevine vegetative growth, yield and quality of Flame Seedless table grapes were investigated during 2012 and 2013 seasons. Vines were subjected to seasonal irrigation treatments from bud swell to dormancy including: Standard irrigation (100 % of crop evapotranspiration [ETc]), moderate deficit (80 % of ETc), and sever deficit (60 % of ETc). Effects of two levels of potassium fertilization (0 and 0.58 kg as K2O per vine per season) and bunch thinning (40 and 30 bunch per vine) were also investigated. Results showed that vine petiole potassium concentration was significantly dependent upon applied irrigation level and was highest in standard irrigated potassium fertilized vines. Shoot length, leaf area and pruning weight responded negatively to irrigation deficit, while bunch thinning increased leaf area in both seasons and pruning weight in the second season with no effect on shoot length, whereas potassium had no effects on vegetative growth. Vine yield, bunch weight and berry diameter increased significantly with increasing irrigation level and with potassium fertilization. Bunch thinning significantly decreased yield in first season only while increased bunch weight and berry diameter. Crop load (yield/pruning) significantly increased by potassium and decreased by thinning with no effect for irrigation. Water use efficiency (yield/irrigation) significantly increased by increasing irrigation level and by potassium fertilization while decreased in first season by thinning. Increasing deficit irrigation level resulted in increased berry juice total soluble solids (TSS) and declined titratable acidity (TA), decreased berry firmness, increased skin anthocyanin and total phenolics, and reduced skin color characteristics values of lightness (L*), chroma(C*) and hue angle(h°). Bunch thinning increased berry TSS in first season, did not affect TA and fruit firmness, and increased berry skin anthocyanin and total phenolics, while decreased skin L* in the first season, C* and h°. Potassium fertilization increased berry TSS, TA, anthocyanin, total phenolics, did not affect firmness with no consistent effect on skin color characteristics. | ||||
| Keywords | ||||
| Evapotranspiration; crop load; water use efficiency; Color; Anthocyanin; Total Phenolics; firmness | ||||
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