The olive tree has anatomical-morphological and physiological adaptations which enable it to cope well with dry conditions and water deficits. However, if water shortage occurs during the development phases (shoot growth, flower bud development, bloom, fruit set, cell division and enlargement and oil accumulation), which are the most susceptible to stress, it can also have a negative effect on the growth and productivity of olive trees. The Slovenian Istria is facing with increased risk of drought. Due to increased occurrence and intensity of agricultural droughts controlled deficit irrigation will become an inevitable element of agricultural practice in Slovene Istria.
B.06 Other
COBISS.SI-ID: 1537961924The olive tree has anatomical-morphological and physiological adaptations which enable it to cope well with dry conditions and water deficits. However, if water shortage occurs during the development phases (shoot growth, flower bud development, bloom, fruit set, cell division and enlargement and oil accumulation), which are the most susceptible to stress, it can also have a negative effect on the growth and productivity of olive trees. The Slovenian Istria is facing with increased risk of drought. Due to increased occurrence and intensity of agricultural droughts controlled deficit irrigation will become an inevitable element of agricultural practice in Slovene Istria.
B.06 Other
COBISS.SI-ID: 1538121668Olive trees have been traditionally cultivated under rainfall conditions, as they are well known to be resistant to drought. In high-density, irrigated olive orchard, greater yields and reduced alternate bearing behaviour are recorded. However, since most olives are grown in areas subjected to water scarcity, regulated deficit irrigation is a promising technique for achieving quality yield with lower water consumption. In an intensive olive orchard (Olea europaea L., cv. ‘istrska belica’) in south east Slovenia (Slovenian Istria), soil water conditions under three continuous deficit irrigation treatments (15% crop evapotranspiration (ETc), 33% ETc, 40% ETc) were compared to full irrigation (100% ETc) and rain-fed conditions. Soil water content was measured by using TDR (Time Domain Reflectometry) probes, and in this paper soil water conditions from May throught September in 2015 were evaluated. Soil water storage under rain-fed conditions was depleted at the beginning of the study season. Full irrigation (100% ETc) provided optimum soil water conditions, under this treatment soil water content remained in the range of field capacity throughout the season (between 28 and 32 %). Under deficit treatments, 40% ETc and 33% ETc, soil water conditions remained on the lower end of plant available water (around 25 %), intermittently reaching water content of permanent wilting point (18 %). Soil water content under 15% ETc treatment and rain-fed conditions remained between 20 and 10%, which is close to or below permanent wilting point. Amount of water, added with irrigation in the studied period varied between individual tree rows. This indicates at the influence of orchard structure on water demand.
B.03 Paper at an international scientific conference
COBISS.SI-ID: 1538833092Northern Mediterranean region’s vulnerability to climate change has been highlighted by the increased occurrence and intensity of agriculture droughts in recent years. Consequently, there has been an enormous increase in the interest in "deficit irrigation" approach to irrigation, where water supply is reduced below maximum levels and mild stress is allowed with minimal effects on yield. In order to determine the vegetative and productive response of local variety 'Istrska belica' to variable water quantities applied during the extreme drought season, an experiment was set in a 17 year old olive grove located at Slovenian Istria (southwestern Slovenia). Four irrigation treatments were applied during extreme drought growing season, with applied water in the amount of 15% ETc (crop evapotranspiration), 33% ETc, 40% ETc, 100% ETc and rain fed conditions. Irrigation regime significantly affected the shoot length, fruit set, a number of fruit per shoot and olive production. This finding was also confirmed by further ANOVA analysis, which showed a statistically significant difference (shoot growth F (4, 190) = 4.84, P = 0.00095; fruit set F (4, 190) = 2.27, P = 0.06; number of fruit per shoot F (4, 190) = 4.64, P = 0.0134 and crop yield F (4, 35) = 5.02, P = 0.002) between irrigation treatments. Although the rain-fed treatment resulted in the smallest yield, the shoot growth of trees under rain-fed conditions was greater (6.05 cm) than that of trees receiving 15% ETc (4.45 cm), 33% ETc (4.35 cm), 40% ETc (3.39 cm) and 100% ETc (2.10 cm) irrigation treatments. Results showed that flowering was not significantly affected by water supply.
B.03 Paper at an international scientific conference
COBISS.SI-ID: 1538805700In the last years the Slovenian olive growers and producers have faced problems to achieve constant yields and quality of olive oil due to the extreme weather conditions, especially because of the more frequent occurrence of the drought. A technically accomplished pilot automatic irrigation system of olive trees was established. In 2015, the impact of different irrigation treatments (0% ETc (crop evapotranspiration), 15% ETc, 33% ETc, 40% ETc and 100% ETc) on olive variety 'Istrska belica' were studied to determine the minimum amount of added water that has positive effect on the yield and quality of the produced extra virgin olive oil. The study results showed that the quantity of applied water equal to 100% ETc had a significant effect on yield of olive fruits. The average fruit mass of the trees grown under full irrigation (100% ETc) was significantly higher than those given rain-fed and deficit irrigation treatments (15% ETc, 33% ETc, 40% ETc), between no significant differences were found. The fatty acid composition showed the highest amount of oleic acid (75.61%) at 100% ETc and the lowest amount (74.69%) at 15% ETc, while the highest amount of linoleic acid (6.52%) was determined at 15% ETc, the lowest (5.98%) at 100% ETc. Total biophenol content and biophenol compostion was determined. The 40% ETc irrigation system showed the highest amount of total biophenols, total oleuropein and total ligstroside derivatives (1076 mg/kg, 562 mg/kg and 388 mg/kg, respectively), while the lowest results (883 mg/kg, 477 mg/kg and 299 mg/kg, respectively) were determined in control system (0% ETc). The organoleptic assessment of the olive samples showed that the positive sensory attributes of fruity, bitter and pungent were more intensive at 33% ETc and highest graded.Olive oil from non-irrigated trees (0% ETc) received the lowest sensory score.
B.03 Paper at an international scientific conference
COBISS.SI-ID: 1538806212