orchards in Mediterranean areas are Drip Irrigation Elevated Olive Productivity in under rain-fed conditions without Southwest China any form of irrigation (Sofo et al., 2008). However, in modern intensive
1 1 1 1 1 orchards, more trees are planted per Quan Liu , Yan Lan , Feng Tan , Yunbiao Tu , Yingying Sun , hectare than are in traditional or- Gajue Yougu2, Zeshen Yang2, Chunbang Ding3, and Tian Li1,4,5 chards, which leads to decreased wa- ter availability for individual olive trees at a specific area with a relatively ADDITIONAL INDEX WORDS. fruit set, oil content, Olea europaea, perfect flower, shoot stable amount of rainfall (Fernandez growth, yield and Moreno, 1999). As a conse- SUMMARY. Water is essential for crops and plays a vital role in olive (Olea europaea) quence, olive growth, including veg- growth. Three irrigation treatments, rain-fed (CK), flood irrigation (FI), and drip etative growth (the basis for flowering irrigation (DI), were applied from late November to late May in a 2-year study and cropping in the next year), (Nov. 2015 to Oct. 2017) on two olive cultivars, Coratina and Koroneiki. Shoot flower-bud formation, and fruit growth, flower and fruit characteristics, and olive and oil yields were measured. development, could be limited by Compared with CK, FI had significantly higher values of vegetative growth, olive water shortage (Gucci et al., 2009; and oil yields, moisture content, and oil content. Although the fruit weight, pulp rate, and oil content with DI were the lowest, our results support that DI had the Hartmann, 1950; Masmoudi-Charfi greatest positive effects on olive vegetative growth, flowers, fruit set, and olive and and Mechlia, 2008). Studies have oil yields. It is suggested that DI in winter and spring is the best irrigation strategy shown that irrigation during summer for olive productivity in southwest China. and autumn in a Mediterranean cli- mate is an effective way to increase live is commonly used to 1960s (Cheng et al., 2017). After olive productivity (Hijazi et al., 2014; extract olive oil by mechani- decades of exploration, Chinese sci- Proietti and Antognozzi, 1996; Sanz- Ocal means and is mainly entists have reached a consensus that Cortes et al., 2015). In the main grown in Mediterranean coastal areas the most suitable regions for olive growing area in the Jinsha River area (Carrasco-Pancorbo et al., 2015; production in China are two areas: in southwest China, there is almost Vossen, 2007). The global consump- 1) the dry and hot valley zone of no rainfall during winter and spring, tion of olive oil has increased by 63% Jinsha River area (Yongsheng, Yongren, which greatly constrains the vernali- over the past 26 years because of its and Xichang); and 2) the area zation and bloom of olive trees high nutritional value and associated between the south slope of West (Denney et al., 1985; Liu and Sun, health benefits [International Olive Qinling Mountains and the low 2013; Sanz-Cortes et al., 2015). In Council (IOC), 2018]. Accompany- mountain valley of Bailong River recent years, most of the olive trees in ing the global increase in olive oil (Wudu) (Shi et al., 2011; Su et al., Sichuan have been planted in the consumption, improving the produc- 2018). China started to expand its mountains (Guo et al., 2010), and tion of olive oil became a focus issue olive area in the early years of the 21st DI has been applied in the modern for global researchers and producers century and now has 86,000 ha intensive olive orchards to replace (Suematsu et al., 2006). In China, the (IOC, 2016), mainly distributed in traditional FI. However, little is olive oil imports in 2014 were seven southwest (Sichuan, Yunnan, and known about the effects on olive pro- times more than that in 2004 (IOC, Chongqing) and northwest China ductivity of different irrigation strat- 2016, 2018). China started introduc- (Gansu and Shaanxi) (Su et al., egies in China. Therefore, a 2-year ing and planting olive trees in the 2018). Sichuan, especially Xichang field study was conducted 1) to in- [located in Jinsha River area (area vestigate olive productivity under FI Received for publication 29 Oct. 2018. Accepted for 1)], has the best climatic conditions and DI compared with CK during publication 21 Dec. 2018. to develop the olive industry, and oil olive growth and development pe- Published online 15 February 2019. content of olives from this region can riods and 2) to determine a better 1College of Agronomy, Sichuan Agricultural Univer- reach 28% (Xiao et al., 2009). irrigation strategy for improving olive sity, No. 211, Huimin Rd, Wenjiang District, Olive is a drought-resistant production in the main suitable grow- Chengdu City, Sichuan 611130, P.R. China plant. In general, the traditional olive ing area in China. 2Lianshan Zhongze New Technology Development Co., Ltd., Nanhua Tower, Chang’an East Rd, Xichang City, Sichuan 615000, P.R. China 3College of Life Science, Sichuan Agricultural Uni- Units versity, No. 46, Xinkang Road, Yucheng District, To convert U.S. to SI, To convert SI to U.S., Ya’an City, Sichuan 625014, P.R. China multiply by U.S. unit SI unit multiply by 4 College of Water Conservancy and Hydropwer En- 0.4047 acre(s) ha 2.4711 gineering, Sichuan Agricultural University, No. 46, Xinkang Rd, Yucheng District, Ya’an City, Sichuan 0.3048 ft m 3.2808 625014, P.R. China 3.7854 gal L 0.2642
5 2.54 inch(es) cm 0.3937 Corresponding author. E-mail: [email protected]. 25.4 inch(es) mm 0.0394 This is an open access article distributed under the CC 0.4536 lb kg 2.2046 BY-NC-ND license (https://creativecommons.org/ 28.3495 oz g 0.0353 licenses/by-nc-nd/4.0/). 1 ppm mgÁkg–1 1 https://doi.org/10.21273/HORTTECH04211-18 ( F – 32) O 1.8 F C( C · 1.8) + 32
122 • April 2019 29(2) Materials and methods China, Coratina and Koroneiki, were F IELD SAMPLING AND selected for the experiment. The trees MEASUREMENTS. Four branches with FIELD SITE AND EXPERIMENTAL were planted in 2007 at distances of flower buds and new apical shoots MATERIAL. The field trial was con- 4.5 · 4 m (556 trees/ha). The exper- from the four directions (east, south, ducted during two consecutive sea- imental orchard was divided into west, and north) in each sampling tree sons (Nov. 2015 to Oct. 2017) at were labeled at the end of March for Beihe Olive Commercial Orchard three blocks each containing three field survey. The shoot length, num- (lat. 27 44#N, long. 102 14#E, ele- plots, and each plot was 0.3 ha with · ber of shoots with inflorescences, and vation 1590 m) of Liangshan 150 trees (10 rows 15 trees) and florets to inflorescence, were mea- Zhongze New Technology Develop- comprised two equivalent subplots. sured in preselected branches. From ment Co., Ltd., which is located in One subplot was cultivar Coratina, late April to late October, the Xixi village, Xichang City, Sichuan and the other was Koroneiki. Two growth of shoots was measured Province, southwest China. The soil central trees of each cultivar with every month. During the flowering texture of the orchard was red clay flower buds in each subplot were used stage, the number of perfect flowers loam with a pH value of 6.2 (0 to 30 for all field measurements and sam- was recorded. The fruits on the cm depth, 1.85% of organic matter, pling analysis, and the others were branches were counted 60 d after full 110.12 mgÁkg–1 of available nitrogen, considered as guard trees. In Sept. bloom (DAFB). The length of tested 61.29 mgÁkg–1 of available phospho- 2015, a DI system was installed in shoots in each month (from April to rous, and 95.14 mgÁkg–1 of available three plots (one plot in each block) Á –1 October), average number of inflo- potassium K). Meteorological data with two drippers (2.0 L h ) per tree. rescences and flowers per shoot (Fig. 1) were obtained from the Na- The irrigation experimental set up were calculated. The rates of per- tional Meteorological Information was a single factor randomized block fect flowers and fruit set were deter- Center, China (China Meteorological design. Three treatments of different mined based on the total number of Administration, 2017). The climate irrigation strategies, CK (nonirri- flowers. was characterized by dry winter and gated), FI, and DI were applied in Forty olive fruits from each sam- wet summer, and more than 80% of these nine plots. The trees in treat- pling tree were collected randomly at the annual precipitation occurred in ments of FI and DI received the same regular intervals (30 d) by hand at summer and autumn (Fig. 1B). The amount of fresh water three times per a height of greater than 1.5 m outside total annual precipitation, evapo- week from late November to the first of the canopy after the pit hardening transpiration, and sunshine duration notable rainfall (a total daily precipi- stage from June to October (75–195 were 1072.8 mm, 1001.8 mm, and tation of more than 20 mm, usually in DAFB). Twenty olives were weighed 2218.7 h in the first season, whereas late May). During the two seasons and then dried in a forced-air oven at they were 1227.4 mm, 972.6 mm, (2015–16, and 2016–17), the total 105 C for 24 h, and the others were and 2257.4 h the following season, quantities of applied water to each used for weighing the stone. Mois- respectively. The annual average tem- tree were 246 and 228 mm, respec- ture content and pulp rate of fresh perature in the trial period was tively. All other cultivation man- fruit were calculated. The dried olives 17.6 C, with the lowest temperature agement (including fertilization, were crushed and packed in a filter was usually in January (–1.7 C), pruning, and control of weeds, dis- paper bag, then put into a Soxhlet whereas the highest was in May eases, and pests) followed the com- extraction apparatus with petroleum (35.2 C), and the annual lowest mon practices used in the orchard. ether (boiling point: 30 to 60 C) for and highest were 13.1 and 24.3 C, Table 1 presents the applied fertiliza- 8 to 10 h (Bengana et al., 2013). Fruit respectively (Fig. 1A). tion details during two crop seasons oil content was calculated by weigh- EXPERIMENTAL DESIGN. Two (2015–16 and 2016–17) for each ing the paper bag before and after widely distributed olive cultivars in irrigation treatment. extraction. The percentage value of oil content was expressed on a dry weight basis. At the end of October, all fruits in the sampling trees were removed and weighed to calculate the olive yield of each tested tree (including sampling fruits). The oil yield per tree was calculated according to the final sampling moisture and oil contents (195 DAFB). STATISTICAL ANALYSIS. The re- sults were expressed as mean values of six replicates and standard devia- tion. All statistical analysis was per- formed using the JMP 10 statistical Fig. 1. Seasonal trends in climate during two olive crop seasons (2015–16 and software (SAS Institute, Cary, NC). 2016–17): (A) mean daily temperature, daily maximum temperature, and daily Univariate treatments of the data minimum temperature; (B) precipitation, evapotranspiration (ET), and sunshine were analyzed and compared by duration; ( C · 1.8) D 32 = F, 1 mm = 0.0394 inch. one-way analysis of variance by
• April 2019 29(2) 123 RESEARCH REPORTS
Table 1. Applied fertilization details during two olive crop seasons (2015–16 For ‘Koroneiki’, the pulp rates in DI and 2016–17) for each irrigation treatment [rain-fed control (CK), flood were significantly lower than those in irrigation (FI), drip irrigation (DI)]. CK and FI during the middle stages No. Time Fertilizersz (105–165 DAFB), and no significant differences were noted between CK 1 Early Nov. 2015 (and 2016) 2.0 kg of manure per tree were applied to the hole and FI during most of the time of in the soil olive development. 2 Early Mar. 2016 (and 2017) 0.23 kg nitrogen (N), 0.10 kg phosphorus (P) per In contrast, olive fruit moisture tree was applied to the hole in the soil, and 0.2% content (Fig. 3C) decreased during of available boron was sprayed olive development, with an especially 3 Early June 2016 (and 2017) 0.42 kg N, 0.06 kg P, and 0.21 kg potassium per sharp reduction from 75 to 105 tree were applied to the hole in the soil DAFB, after which the decrease rate z 1 kg = 2.2046 lb. slowed gradually. The lowest mois- ture content was detected in CK and was only significantly different from Tukey-Kramer honestly significant characteristics and fruit set rates of those in FI and DI during most of the difference test. Differences were con- the two olive cultivars in DI were olive development period (‘Cora- sidered statistically significant and significantly higher than those in FI. tina’). The moisture content in FI marked with different lowercase let- EFFECTS ON FRESH OLIVE FRUIT and DI showed no significant ters when the probability value was WEIGHT, PULP RATE, MOISTURE difference. less than 0.05. CONTENT, AND DRIED FRUIT OIL Oil content of dried fruit (Fig. CONTENT. The results of fresh fruit 3D) increased with time, reaching the weights of the two cultivars in 2016 Results maximum at the last sampling date. and 2017 followed similar trends of EFFECTS ON OLIVE VEGETATIVE The results of oil content in the three fruit development in all treatments GROWTH. As shown in Fig. 2, the treatments appeared to be close at the (Fig. 3A). Fruit weight increased with shoot increment occurred from April first sampling time, but the content in to October in all treatments, being time; fruit weight in CK and FI FI was significantly higher than those almost linear from April to August, reached the maximum values at 165 in CK and DI (105–195 DAFB). For and leveling off toward October. Ir- DAFB and dropped slightly at har- ‘Coratina’, the oil content in CK was rigation positively affected shoot vest. In contrast, the largest fruit significantly higher than that in DI growth. Shoots increments of ‘Cor- weight of the two olive cultivars in during the last two samplings (165 atina’ and ‘Koroneiki’ starting in late DI was at the last sampling day (195 and 195 DAFB). However, the oil March in FI and DI were significantly DAFB). During the development pe- content of ‘Koroneiki’ in CK were higher than CK. Although the shoot riod, fruit weights of ‘Coratina’ in- significantly lower than those in DI elongation of DI was the highest, no creased by 127.60%, 128.38%, and during the middle samplings (105 statistical differences were found be- 202.90% in CK, FI, and DI, respec- and 135 DAFB). tween FI and DI. It is noteworthy tively. The fruit weights of ‘Koro- E FFECT OF DIFFERENT that the shoot increment in CK from neiki’ at harvest were 1.56, 1.18, IRRIGATION STRATEGIES ON YIELDS OF April to May was less than in FI and and 1.43 times as high as those at 75 OLIVE FRUIT AND OIL. The olive and DI, but then its growth rate became DAFB in CK, FI, and DI, respec- oil yields per tree in the three irriga- similar to shoots in FI and DI from tively. The smallest fruit weight was tion treatments are shown in Table 3. May to October. The shoot elonga- found in DI, which was significantly During the two seasons, compared tions of ‘Coratina’ starting in late different from CK and FI from 75 to with the CK, FI and DI showed March varied from 1.71 to 30.688 165 DAFB. No significant differences significant increases in fruit and oil cm (CK), 4.00 to 34.23 cm (FI), and in fruit weight were observed be- yields, and the yields in DI were 4.74 to 36.28 cm (DI). The shoot tween CK and FI during the fruit significantly higher than those in FI. growth of ‘Koroneiki’ starting in late development of ‘Coratina’. The fruit The maximum olive yields of ‘Cora- March was longer, ranging from 2.91 weights of ‘Koroneiki’ in FI were tina’ and ‘Koroneiki’ were in DI, to 42.55 cm (CK), 5.17 to 46.43 cm significantly smaller than that in CK which increased by 545.58% and (FI), and 5.82 to 47.03 cm (DI). at the last two sampling dates (165 649.16% in contrast to CK and were EFFECTS ON OLIVE FLOWERING and 195 DAFB). There were no sig- 85.55% and 110.54% higher than AND FRUIT SET. Results concerning nificant differences in fruit weights those in FI. The yields of the two the olive flower characteristics in the between DI and FI at harvest. cultivars per tree in FI were 247.93% three irrigation treatments during Similarly to the fresh fruit and 255.82% higher than those in crop years of 2016 and 2017 are weights, olive pulp rates (Fig. 3B) CK. The increment rates of oil pro- shown in Table 2. During the two increased gradually, being linear at duction in DI and FI were close to the seasons, compared with CK, FI, and the early stages (75–165 DAFB) and fruit yields (Table 3). DI caused significant increases of the leveling off toward the harvest stage. numbers of inflorescences and flowers The pulp rates in DI appeared to be Discussion per shoot, and the rates of perfect the lowest, and the highest was in CK, Vegetative growth is the basis for flowers and fruit set. Except for the but no significant differences of olive productivity. In this study, we inflorescence number per shoot ‘Coratina’ were found among CK, FI, found that a low water supply in of ‘Koroneiki’, the other flower and DI (except for the first sampling). winter and spring resulted in
124 • April 2019 29(2) significantly lower shoot growth in especially during the periods of floral inflorescence, and water availability CK (from April to May). The growth bud differentiation, bloom, and fruit is essential to promoting flowers and of new shoots in FI and DI were not oil accumulation (Gucci et al., 2009; fruits (Rapoport et al., 2012). A pre- significantly different. This indicates Hartmann, 1950; Masmoudi-Charfi vious study conducted on young olive that irrigation promotes olive vegeta- and Mechlia, 2008). Olive yield will trees in containers suggested that the tive growth and is not related to be negatively affected by water short- lack of water resulted in incomplete irrigation methods. Our results are ages during these periods. In the flower development and caused a rate similar to findings from studies in Mediterranean basin, the rainfall dur- reduction of perfect flower (Rapoport, other countries, which showed that ing the winter is relatively high and 2014). Another one reported that irrigation during the low rainfall sea- precludes the need to irrigate for olive oil and olive yields can be maximized son in the Mediterranean climate flowering and subsequent fruit set together in the treatment with in- benefited the vegetative growth of (Torres et al., 2017). This is different creased applied water and can be olive trees (Ayoub et al., 2016; Farinelli from the climate in southwestern offset by the reduction in oil con- et al., 2006). China. In Xichang, little rainfall oc- tent (Grattan et al., 2006). Similar In addition to improving shoot curs in winter and spring (Liu and results were found in our study. The growth, water has an important in- Sun, 2013), the critical period for olive yields and oil production were fluence on olive reproductive growth, olive axillary bud to blooming consistent with the numbers of in- florescences, flowers (including per- fect flowers), and fruits among the treatments: the applications of DI and FI showed significant in- crease in production compared with CK, and the production in DI was significantly higher than in FI. It in- dicates that irrigation strategies have a positive effect on olive production. A possible explanation for the higher values of flower number, rate of fruit set, and yields in DI could be due to the lower evaporation rate and higher efficiency of water transportation to the roots than in FI and CK. After that, trees in DI obtained plenty of water to help the differentiation of olive flower bud and reduce the pistil abortion, which contributed to greater potential for olive production. In contrast, FI would be harmful for the root because the air in the soil was squeezed out. During the stage of fruit oil accumulation, we found that olive fresh fruit weight and pulp rate in Fig. 2. Effects of different irrigation strategies (rain-fed control (CK), flood DI were lower than those in CK and irrigation (FI), drip irrigation (DI)] on shoot growth of olive cultivars Coratina FI, which is different from other (left) and Koroneiki (right) during two crop seasons (2015–16 and 2016–17). studies (Garcıa et al., 2014; Proietti Vertical bars indicate SD values, and values with different lowercase letters in the and Antognozzi, 1996). Considering same month are significantly different by Tukey-Kramer honestly significant the highest rates of perfect flower and difference test (P < 0.05); 1 cm = 0.3937 inch. fruit set, the fruit number of trees in
Table 2. Effects of different irrigation strategies on the number of olive inflorescences and flowers per shoot, and the rates of perfect flowers and fruit set of olive cultivars Coratina and Koroneiki during two crop seasons (2015–16 and 2016–17). Inflorescences (no./shoot) Flowers (no./shoot) Rate of perfect flowers (%) Rate of fruit set (%) Cultivar Treatmentz (mean ± SD) Coratina CK 6.27 ± 0.85 cy 69.17 ± 13.26 c 51.18 ± 2.14 c 0.63 ± 0.13 c FI 8.51 ± 0.44 b 120.57 ± 10.25 b 69.36 ± 1.82 b 3.97 ± 0.28 b DI 10.20 ± 0.49 a 143.02 ± 18.71 a 79.06 ± 3.59 a 5.16 ± 0.54 a Koroneiki CK 5.69 ± 0.59 b 82.03 ± 10.93 c 46.42 ± 4.00 c 1.23 ± 0.30 c FI 10.02 ± 1.40 a 123.03 ± 30.09 b 66.13 ± 2.75 b 5.53 ± 0.51 b DI 10.50 ± 1.39 a 159.72 ± 27.68 a 77.87 ± 4.63 a 8.37 ± 1.05 a zCK = rain-fed control, FI = flood irrigation, DI = drip irrigation. yValues with different lowercase letters in the same row are significantly different by Tukey-Kramer honestly significant difference test (P < 0.05).
• April 2019 29(2) 125 RESEARCH REPORTS
DI was expected to be more than those CK, followed by the fruit in FI, climate (Nassar, 2009; Proietti and inCKandFI.Wealsohadtoconsider whereas the lowest growth of single Antognozzi, 1996; Ramos and rainfall without any irrigation starting fruit occurred in DI. The moisture Santos, 2009). The evapotranspira- in late May. Thus, the weight of single content of olives in CK was the low- tion was higher than rainfall from April fruit, which was composed mainly of est, with the same result as irrigation to May in Xichang, causing water pulp, was expected to be the largest in in a dry summer in a Mediterranean shortage for the first fruit growth.
Fig. 3. Effects of different irrigation strategies [rain-fed control (CK), flood irrigation (FI), drip irrigation (DI)] on fruit characteristics of olive cultivars Coratina and Koroneiki during two crop seasons (2015–16 and 2016–17). (A) Fresh fruit weight, (B) pulp rate, (C) moisture content, and (D) oil content. Vertical bars indicate SD values, and values with different lowercase letters at the same days after full bloom are significantly different by Tukey-Kramer honestly significant difference test (P < 0.05); 1 g = 0.0353 oz.
Table 3. Effects of different irrigation strategies on the yields of olive and oil of olive cultivars Coratina and Koroneiki during two crop seasons (2015–16 and 2016–17). Mean Mean Olive yield [mean ± Mean increase increase from Oil yield [mean ± Mean increase increase from Cultivar Treatmentz SD (kg/tree)]y from CK (%) FI (%) SD (kg/tree)] from CK (%) FI (%) Coratina CK 4.71 ± 1.10 cx — — 1.12 ± 0.26 c — — FI 16.37 ± 3.22 b 247.93 — 3.70 ± 0.67 b 231.15 — DI 30.38 ± 5.68 a 545.58 85.55 5.76 ± 1.05 a 414.93 55.50 Koroneiki CK 3.76 ± 0.93 c — — 0.84 ± 0.20 c — — FI 13.39 ± 3.18 b 255.82 — 2.97 ± 0.69 b 253.76 — DI 28.19 ± 5.62 a 649.16 110.54 6.08 ± 1.11 a 624.29 104.74 zCK = rain-fed control, FI = flood irrigation, DI = drip irrigation. y1 kg = 2.2046 lb. xValues with different lowercase letters in the same row are significantly different by Tukey-Kramer honestly significant difference test (P < 0.05).
126 • April 2019 29(2) The oil content was the highest in FI Farinelli, D., P. Proietti, G. Papagni, F. Proietti, P. and E. Antognozzi. 1996. and lowest in DI. Depending on the Famiani, and P. Guelfi. 2006. Effects of Effect of irrigation on fruit quality of table situation of full vegetative growth irrigation on olive and productive activity olives (Olea europaea), cultivar ‘Ascolana since April, the potential amount of and on oil quality in central Italy. Proc. 2nd tenera’. N. Z. J. Expt. Agr. 24:175–181. oil accumulation in FI and DI might Intl. Seminar. Olivebioteq: Biotechnology and quality of olive tree products around Ramos, A.F. and F.L. Santos. 2009. be greater than in CK. It should be the Mediterranean Basin. Marsala-Mazara Water use, transpiration, and crop co- also noted that olive in DI had the del Vallo, Italy, 5–10 Nov. 2006. 2:193– efficients for olives (cv. Cordovil), grown lowest rate of pulp, which perhaps 196. in orchards in southern Portugal. Biosyst. reduced oil accumulation. Eng. 102:321–333. Fernandez, J.E. and F. Moreno. 1999. Conclusion Water use by the olive tree. J. Crop Prod. Rapoport, H.F. 2014. The reproductive 2:101–162. biology of the olive tree and its relation- Olive trees in CK gained the ship to extreme environmental condi- lowest values of yields, vegetable Garcıa, P., C. Romero, and M. Brenes. tions. Acta Hort. 1054:41–50. 2014. Influence of olive tree irrigation growth, flowering and fruit, and Rapoport, H.F., S.B.M. Hammami, P. moisture content. FI also tended to and the preservation system on the fruit characteristics of Hojiblanca black ripe Martins, O. Perez-Priego, and F. Orgaz. improve olive production through 2012. Influence of water deficits at dif- increasing vegetable growth, flower- olives. Lebensm. Wiss. Technol. 55:403– 407. ferent times during olive tree in- ing and fruit, and oil content. Even florescence and flower development. though the fruit weight, pulp rate, Grattan, S.R., M.J. Berenguer, J.H. Environ. Expt. Bot. 77:227–233. and oil content in DI were the lowest, Connell, V.S. Polito, and P.M. Vossen. ı 2006. Olive oil production as influenced Sanz-Cortes, F., J. Mart nez-Calvo, M.L. our results indicate that DI had the Badenes, H. Bleiholder, H. Hack, G. highest values of vegetative growth, by different quantities of applied water. Agr. Water Mgt. 85:133–140. Llacer, and U. Meier. 2015. Phenological flowers, fruit set, and olive and oil growth stages of olive trees (Olea euro- yields, and therefore DI from late Gucci, R., E.M. Lodolini, and H.F. paea). Ann. Appl. Biol. 140:151–157. November to late May was the best Rapoport. 2009. Water deficit-induced changes in mesocarp cellular processes Shi, Z., W. Sun, Z. Qi, Y. Li, and J. Liu. irrigation strategy to elevate olive 2011. On the suitable regions for olive productivity in southwest China. and the relationship between mesocarp Olea europaea and endocarp during olive fruit de- ( ) growing in China. velopment. Tree Physiol. 29:1575–1585. [in Chinese]. Plant Diversity Resources 33:571–579. Literature cited Guo, X., J. Fan, W. Zhu, and D. Yan. Ayoub, S., S. Al-Shdiefat, H. Rawashdeh, 2010. Ecological suitability of olive in Sofo, A., S. Manfreda, M. Fiorentino, B. and I. Bashabsheh. 2016. Utilization of Sichuan Province: Fuzzy comprehensive Dichio, and C. Xiloyannis. 2008. The ol- reclaimed wastewater for olive irrigation: evaluation based on GIS. Shengtaixue ive tree: A paradigm for drought tolerance Effect on soil properties, tree growth, Zazhi 29:586–591. (in Chinese). in Mediterranean climates. Hydrol. Earth yield and oil content. Agr. Water Mgt. Syst. Sci. 4:2811–2835. 176:163–169. Hartmann, H.T. 1950. Olive flower-bud formation: Nutrients essential to tree Su, C.J., J. Sun, W. Zhu, and L. Peng. Bengana, M., A. Bakhouche, J. Lozano- during March and April when flower-buds 2018. History, distribution, and potential Sanchez, Y. Amir, A. Youyou, A. Segura- are forming tests show. Calif. Agr. of the olive industry in China: A Review. Carretero, and A. Fernandez-Gutierrez. 4(11):4–16. Sustainability 10:1426, doi: 10.3390/ 2013. Influence of olive ripeness on su10051426. chemical properties and phenolic com- Hijazi, A., M. Doghoze, N. Jouni, V. Nangia, M. Karrou, and T. Oweis. 2014. Suematsu, M., Y. Wakabayashi, and Y. position of Chemlal extra-virgin olive oil. Ishimura. 2006. Market dynamics and Food Res. Intl. 54:1868–1875. Water Requirement and Water-use effi- ciency for olive trees under different irri- policy reforms in the EU olive oil in- Carrasco-Pancorbo, A., L. Cerretani, A. gation systems. 31 Dec. 2018.
• April 2019 29(2) 127