SDI in grapes

 

Irrigation using subsurface drip irrigation (SDI) has been shown to be productive when applied to a number of different irrigated crops such as alfalfa21, corn18 and cotton18. SDI is applicable in row crops and permanent crops and SDI emitters may last over 20 years in a given field21.

It is hypothesized that trees and vines could profit from SDI since soil compaction due to machinery being inserted into wet fields is decreased. It would be beneficial to examine the effects of SDI in vineyards, for as a potentially water saving and crop improving method, it would be invaluable to grape growers.

 

The experiment

A study evaluating the effects of SDI and deficit irrigation on vines grafted to Freedom rootstock was conducted in a Sauvignon Blanc vineyard in California. The vines received one of four irrigation treatments:

 

The study also examined other parameters such as minimal pruning, the trellis system and more, but these results are omitted from this website as they do not fit in with the general theme. The complete study can be viewed at: http://cati.csufresno.edu/VERC/rese/98/980401/index.html

 

The measurements

The measurements were carried out on five vines in the middle of each row21. 100 berries were randomly selected from these vines before harvest and stored at 34°F for not longer than two days21. The berry juice was analyzed for titratable acidity and pH. At harvest time, the yield and the number of clustered were obtained for each of the five vines21.

 

The results

Effect of SDI on yield:

The irrigation method influenced the number of clusters per vine, but not the yield per vine or the cluster weights. The yield per vine was highest in plots irrigated with 0.8 ETc regardless of the irrigation method21. The number of clusters per vine was highest in the plot irrigated with 0.8 ETc using drip irrigation, however cluster weights were equal for both the 0.8 ETc irrigated plots- surface drip irrigated and SDI21. The berry weights and the number of berries per cluster were similar in all the vine plots21.

Effect of SDI on fruit composition

The amount of soluble solids was highest in the plot receiving 0.8 ETc via SDI, and lowest in the plot subjected to drip irrigation at a rate of 0.8 ETc21. The highest juice pH was obtained in SDI plots receiving 0.6 and 0.4 ETc while the lowest juice pH was produced in berries from 0.8 ETc drip irrigated vines. Finally, the titratable acidity of the juice was not influenced by the irrigation method21.

Effect of SDI on vine growth

No significant differences in vine growth were observed between the irrigation treatments21. Further studies should be done to back this finding, maybe placing the surface irrigation emitters on the soil surface and not 18 inches above it and assessing the differences between the results.

 

Conclusion

It can be drawn that when irrigation drops below 0.8 ETc, the yield is reduced. Since crop yield does not seem to be negatively affected by SDI, compared to surface irrigation, it would be beneficial to growers to employ this irrigation method, thus allowing them to take advantage of the positive qualities SDI has to offer, such as less evaporation of irrigation water, low maintenance requirements21 and a long life span21, without harming crop production. Drip emitters placed above the ground may be damaged during machine harvesting, while SDI emitters are less susceptible to such machines22; positioning emitters under the soil protects them from harm caused by harvesting, pruning or coyotes22. Furthermore, emitters at a depth of 18-24 inches below the surface in the middle of the row are productive for weed growth suppression, while emitters situated closer to the top allow the moisture to reach the surface and help crop growth22..

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