Precipitation recorded in the 2021-2022 season was 635.4mm, and while this was the wettest among the study years, precipitation remained below the long-term average precipitation for the region. The hyper-arid conditions across the three study years highlighted the necessity of irrigation water in production regions that were historically dry-farmed and are now affected by substantial changes in precipitation patterns. In the present study, LAI was affected by trellis system and irrigation water amount separately in each year. In the drier study years , trellis systems had negligible effects on LAI while irrigation treatments had statistically significant effects. In the 2020 and 2021 seasons, the 25% ETc treatment exhibited smaller LAI than the 50 and 100% ETc treatments. This aligns with previous work which found that irrigating at 25% ETc produces less leaves and smaller LAI than irrigation at 50 and 100% ETc at the study vineyard with similar vintage climactic conditions . In 2022, the wettest study year, effects due to trellis system effects were observed while effects due to applied irrigation water were negligible. In 2022, when trellis systems demonstrated greater effect on LAI, the VSP60, VSP80, GY and SH trellises had increased LAI values compared to the HQ and VSP trellises. Similar work comparing head-trained caned pruning, California Sprawl and single high wire training systems found that single high wire vines to had greater leaf area per vine than head-trained cane pruned vines .
Additionally, HQ vines at the study vineyard previously demonstrated smaller leaf area than vertically shoot positioned trellis systems . Based on results obtained from that study, plant pots with drainage the authors concluded that HQ resulted in less leaf area and higher crown porosity due to HQ vines continuing to fill up spaces with new growth compared to relatively more established vertically shoot positioned trellis types. Given that the leaf area is a major component of LAI, this continuation of canopy growth could also explain differences observed in LAI values in 2022. Selecting a trellis system is an important decision when establishing a vineyard to ensure proper solar radiation interception and penetration into the canopy to optimize fruit yields and ripening. It has been widely documented that divided trellis systems will produce more yield due to both increased leaf area to support photosynthesis as well as more buds retained per meter of vine row . In the present study, SH vines consistently produced the highest fruit yields per meter of vine row; however, there was a trade-off with cluster mass, as SH vines consistently had the smallest cluster mass in all years. Previous work has demonstrated that trellis systems alter the allocation of carbohydrate resources in the vine . While there was no statistical difference in leaf area to fruit ratio among trellis systems, SH vines often had lower leaf area to fruit ratios . As such, the retention of more buds for vines with sprawling canopies may require the vine to divide limited resources amongst a greater number of fruiting positions, thus resulting in smaller cluster mass. Yield per meter of vine row and cluster mass responded as expected to various applied water amounts. In this present study, yield in all years increased when the applied irrigation water was increased from 25% to 50% ETc. However, yields plateaued when irrigation was increased from 50% to 100% ETc.
Similar yield response to applied irrigation water amounts was observed in Thompson Seedless or Cabernet Sauvignon grapevines in hot climates .Crop water use efficiency for grapevine is defined as the ratio between fruit yield and the amount of water consumptively used to produce that yield. Reducing the amounts of applied irrigation water through regulated deficit irrigation is common in vineyard systems seeking to improve grape quality with minimal reductions in yield. In the present study, WUEc decreased linearly with increasing amount of applied irrigation water. Improvements to WUEc have been observed in hot viticultural regions when the applied irrigation water was reduced from full irrigation to irrigation aiming partial ETc replacement, whether it be through RDI or partial root zone drying . Regarding the trellis systems, in the present study the variations in fruit yield drove changes in WUEc in 2021 and 2022. Improvements in water use efficiency were evident for SH trellises, as these vines produced higher yield with similar irrigation amounts compared to all other trellis systems.Irrigation may be more necessary in the near future, especially in areas that were previously characterized by cool climates and that were historically dry farmed. With natural and legislative restrictions on available water supply for irrigation, wine grape growers will need to implement improved irrigation schedules that maximize WFgreen and minimize WFblue to reduce WFtotal. The WFtotal for vineyards outpaces that of other crops suitable for similar hot and dry environments such as olives and other fruit trees . Previous reports estimate vineyard water footprint as 2400 m3 ·tonne-1 . The total water footprints in the present study ranged from 1016.8 m3 ·tonne-1 to 3528.35 m3 ·tonne-1 , which are in accordance with vineyard water footprint estimates . Variations in WFtotal were due to seasonal precipitation , amounts of applied irrigation water , and trellis system, and were driven primarily by the fruit yield achieved with different trellis systems. Previous work in the Napa Valley quantified the total water footprint and its components on Cabernet Sauvignon on a VSP trellis under varied applied water amounts .
Under the 25 % ETc irrigation treatment, the authors reported a trade-off between WFblue and WFgrey, with higher WFgrey compared to the irrigation treatments at 50% and 100% ETc . In the present study, this trade-off was observed between the amounts of applied irrigation applied water in the study years experiencing severe drought . While decreasing WFblue is an objective for improving vineyard sustainability, D’Ambrosio et al. report the current vineyards’ WFgrey to be unsustainable, as the actual runoff of surface water is unable dilute the pollutant load associated with the diffuse and point sources to values below the maximum acceptable concentration. Subsequently, increases in WFgrey were the contributing component resulting in higher WFtotal among vines irrigated at 25% ETc compared to irrigation treatmenrs at 50% and 100% ETc. Under drought conditions, the WFtotal of the 50% and 100% ETc treatments were comparable. Thus, reducing the amounts of applied irrigation water from 100% to 50% ETc would allow for water conservation in wine grape production vineyards. Previous work reported that irrigating at 50% ETc was sufficient to maintain fruit yields, grape quality, and carbohydrate balance in seasons with scarce precipitation . While previous irrigation recommendations applied to VSP trellis systems, our study provides further evidence to support vineyard irrigation at 50% ETc despite trellis system under drought conditions. The effect of trellis system on water footprint varied depending on vintage, most likely due to variations in seasonal precipitation. In 2020, trellis system differences in WFblue were significant; however not large enough to produce quantifiable improvements to WFtotal. Unlike the trend observed with applied water amounts, there was no observable trade-off between WFblue and WFgrey when comparing water footprints due to trellis systems. In fact, in 2021 when drought was more severe, free sprawling trellis systems like SH and HQ which reduced WFgreen and WFblue also reduced WFgrey and WFtotal. Previous work on Chardonnay in California across multiple vintages reported differences in annual fruit yield as a driver of variation in vine water footprint . Likewise, increased yields in SH and HQ vines drove improvements in WFblue compared to VSP-type trellises, plastic plants pots as higher fruit yields can be produced for a certain amount of applied irrigation water. Additionally, shifting from traditional VSP trellises to SH and HQ trellises provides a solution for improving WFgrey to more sustainable levels, thus reducing the potential for pollution of water bodies due to surface runoff from vineyards . Overall, a reduction in WFtotal, especially in drought conditions, will improve long-term vineyard sustainability. It is important to mention that vine canopies in the SH and HQ trellises not only improve water footprint in drought years, but also provide a method for heat wave mitigation. Cluster temperatures were recorded on the morning and afternoon sides of grapevine canopies irrigated at 50% ETc between 8:00 h and 16:00 h . Compared to VSP and GY trellis systems, VSP60, SH and HQ trellises reduced cluster temperature at 10:00 h on the east side of the canopy . The DT between VSP and SH was 5.1o C. Reductions in cluster temperature were not observed on the west side of the canopy until 16:00 h . SH vines produced clusters will the lowest temperature, while GY vines had clusters with the highest temperature. The DT between GY and SH clusters was 5.2o C. The fig, Ficus carica L., is a classical fruit tree of antiquity associated with the beginning of horticulture in the Mediterranean basin . It is known to have been domesticated from a group of diverse spontaneous figs occurring in the south and east of the Mediterranean region sometime in the Early Neolithic period .
However, large fruited fig trees found in the deciduous forests of the Colchic district of northern Turkey and the Hyrcanic district of Iran and adjacent areas, which often intergrades into the Mediterranean figs, are considered by some botanists as a distinct ecotype of F. carica, and as a separate species, F. colchica Grossh. and F. hyrcanica Grossh., by others . According to Vavilov , Transcaucasia is considered as one of the centers of origin and diversity as one could see all phases of the domestication of fig in the southern Caucasus, where wild, transition, and modern fruit growing still exists. The cultivated fig is gynodioecious, but is functionally dioecious, with pollination facilitated by the mutualisticinteraction of pollinator wasps between the two different fig types, Caprifig and edible fig . The syconium of female fig contains only longstyled pistillate flowers whereas that of the male bears spongy, non-palatable syconia containing both staminate flowers and short-styled female flowers. Caprifig usually bears three crops: over wintering ‘‘mamme’’, numerous ‘‘profichi’’ during spring, and ‘‘mammoni’’ during autumn. Figs are generally classified into Common, Smyrna, San Pedro, and Caprifig types mainly based on the floral biology and pollination behavior. Of the four types, Caprifig, although hermaphroditic, is functionally a male fig and is regarded as primitive while the Common-type, with only pistillate flowers developing into parthenocarpic fruits, is considered advanced and includes most commercial cultivars . Smyrna and San Pedro types represent intermediate forms requiring pollination for normal fruit development with an exception of San Pedro type, which produces an early parthenocarpic crop mainly on older branches . Domestication history and early migration along ancient trade routes have strong bearing on the modern distribution, genetic diversity and structure of fig. The discovery of carbonized figs in an early Neolithic site in the Jordan Valley, dating back 11,400–11,200 years ago, suggests that figs were first domesticated during the early Neolithic Revolution preceding cereal domestication . As fig cultivation spreads to southern Arabia and subsequently into neighboring western Asia including Mesopotamia, Anatolia, Tanscaucasia, Persia, and other Middle-Eastern regions, introgression with local wild figs and landraces, and human selection, especially in Transcaucasia, resulted in recognition of numerous varieties and forms. Further westward migration of fig into Greece, Italy, Spain, Portugal and southward into Egypt added more cultivars. Spanish missionaries introduced fig into the New World in the mid-sixteenth century and North America soon thereafter. Franciscan missionaries were the first to plant figs in California sometime during the mid-ninteenth century and named the cultivar ‘‘Mission’’ . Further introductions of Smyrna and Capri- figs from France and Asia Minor occurred in the latter part of the century and the US Department of Agriculture introduced the pollinator Blastophaga in 1890 to facilitate Smyrna fig production. The long domestication history with numerous cultivars and further exchange and spread into other growing regions of the world has resulted in ambiguity in the description and nomenclature of fig cultivars. Condit listed more than 700 fig cultivars along with their synonyms and classified them into the four types, but a great deal of confusion still exists in the cultivar identification and their relationships. The lax use of cultivar names by growers and commercial nurseries, poor documentation of passport data during germplasm collection, substituting local and regional names for the same clonal cultivars, and existence of variants within cultivars are hindering proper identification and description of fig cultivars.