Effects of Furrow and Subsurface Drip Irrigation Systems on Water Productivity of Vineyard in Bowed trellis and Creeping Plantation Systems

Grapes are planted throughout the world and are used to produce dried fruit (raisins), grapes for fresh market (table grapes) and juice. Development of effective methods to improve water productivity in Agriculture is necessary due to the shortage of water resources. Water productivity is a momentous index to assess water saving and to gain more turnover for each unit of water used. Improving water productivity in irrigated agriculture decreases the demand for additional water sources and is thus a solution to the shortage of water resources. One of the efficient methods to improve water productivity is to use micro irrigation systems, which may help to reduce water used to increase yield. Subsurface drip irrigation (SDI) has been used in various countries for over 30 years especially in the regions encountering water scarcity. The results of the implementation of this method were identified in terms of increasing yield, reducing applied water, fertilizer and weed control costs, improve crop quality and water productivity. This study was conducted with the aim of evaluation of water productivity of grapes in two different plantation systems under SDI and furrow irrigation systems.

In order to evaluate the effects of a Subsurface Drip Irrigation (SDI) on two varieties of grapevine; Sultani and Fakhri, this experiment was carried out based on completely randomized design with three replications during 2019 growing season in two vineyards with Bowed trellis (A) and Creeping (B) plantation systems. In vineyard A, laterals of SDI system were installed 50 cm below the soil surface and 50 cm from the grapes rows and in vineyard B, 30 cm below the soil surface and 60 cm from the grapes rows. Irrigation water requirement was calculated by P.M.E to meet full grapes water requirement using daily weather information data collected at Malekan weather station. Irrigation management of the furrow irrigated rows in both vineyards were controlled by the owner of the orchard. Except for the difference in irrigation, the vineyard’s grown vines were established and treated similarly (row spacing, training, pest control, canopy management, fertilization and pruning).

At the end of the growing season Water productivity, Yield and some physiological traits such as: number of clusters in tree, berry weight, number of berries in cluster, length of cluster were measured. Analysis of variance showed significant difference (at 1% level) between water productivity of different irrigation methods in both vineyards. The SDI method in vineyard A and furrow method in vineyard B had the highest water productivity (5.39 kg/m^3 and 3.7 kg/m^3, respectively). The comparison of interaction effects between irrigation methods and cultivars in vineyard A showed that the water productivity of Sultani variety under SDI irrigation (7.23 kg/m^3) was higher than other treatments and in vineyard B water productivity of Sultani variety under furrow method (5.17 kg/m^3) was higher than other treatments. SDI treatment in vineyard B, which was previously furrow irrigated and therefor roots had spreaded out into a larger volume of soil than that wetted by the SDI system, wasn’t capable to adequately supply Crop water requirement which manifested in crop yield reduction.

The SDI system in Bowed trellis plantation was able to adequately replenish Crop water requirement which enhanced crop yield. Implementation of the SDI system in vineyard A increased yield (28.4% in soltani variety and 32.4% in fakhri variety) and water productivity (42% in soltani variety and 47% in fakhri variety). Studies indicate that in Creeping plantation due to lack of proper distribution of moisture in the root zone, needs further investigation. In order to increase yield and water productivity of vineyards with bowed trellis systems, the installation of SDI system is recommended.