ISHS Acta Horticulturae 785: International Symposium on Grape Production and Processing
NUTRIENT MANAGEMENT IN TABLE AND WINE GRAPES BY FERTIGATION |
| Author: | B. Bravdo |
| Keywords: | drip fertigation, mineral nutrition, leaf analysis, phosphorous application, mineral distribution |
| Abstract:
The introduction of drip irrigation in the early sixties has opened new avenues for the control of root environment and thereby the vegetative and reproductive growth of the whole plant. The dense rootlet system that develops under the drip emitters is spread in an onion shaped limited volume of soil. A gradient of soil water potentials that varies between saturation in the pooling area under the drippers to wilting point at the edges of the wetted soil exist under frequent irrigation regimes. An opposite gradient of aeration consisting of high aeration at the peripheral of the wetted soil to almost zero aeration under the drippers enables to maintain simultaneous high water availability without interference with root aeration. Soluble mineral application by fertigation through the drip emitters results in concentration gradients of the various elements according to their mobility in the wetted soil. Element such as K and P are slow movers and tend to concentrate near the pooling area whereas nitrates and chlorides move fast and tend to concentrate at the edges of the wetted zone. The ability of individual roots to exchange water and minerals enables root growth and extension beyond the wetted soil zone, develop supporting roots and provide nutrients to all the roots regardless of their exposure to mineral concentrations and soil water potential. Drip systems enable efficient use of the concentration approach instead of the traditional kg/ha in regard to mineral fertilization since mineral uptake by roots are a function of concentration rather than of amounts per hectare. Composition and concentration of the soil solution can be monitored and controlled by the use of soil extractors and field kits for rapid analyses. Blade and petiole mineral analyses made at full bloom and before harvest serve as an efficient tool for optimizing production and quality. Petiole analyses better reflect the mineral status of the vines. Control of NPK fertigation by means of soil extractors, blade and petiole analyses and water availability significantly affected fruit bud fertility, sugar, pH, maturation time and fruit flavor. | |
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