Arnon Dag

Agricultural Research Organization ARO | aro · Institute of Plant Sciences

The olive tree (Olea europaea L. subsp. europaea var. europaea) is one of the most important crops across the Mediterranean, particularly the southern Levant. Its regional economic importance dates at least to the Early Bronze Age (~3600 BCE) and its cultivation contributed significantly to the culture and heritage of ancient civilizations in the r...

Olive trees are known for their capability to endure and recover from low stem water potentials (Ψstem <-6 MPa) and even maintain substantial gas exchange under such conditions. In the current experiment, we tested the physiological responses of mature olive trees in-situ while enduring such Ψstem under field conditions for seven months of rainless...

Recent economic, environmental, and regulative concerns force farmers to precise their fertilization practices. Yet, a critical knowledge gap concerning the temporal variability in perennials’ nutritional requirements renders most fertilization applications inefficient. While mass balance studies could illustrate the dynamics of crops’ mineral upta...

Olive (Olea europaea L.) trees can reach a very old age and still bear fruit. Although traditional groves are planted at low density and are rainfed, many newer groves are planted at higher densities and irrigated. As expected, initial yields per area are larger in high density plantations, yet some farmers claim they experience a reduction in prod...

With climate change, spring heatwaves have become frequent in the Mediterranean region. High temperatures combined with wind and low humidity are problematic for subtropical crops adapted to high humidity and mild climate. Avocado is a valuable crop—nutritionally and economically—and many new orchards are planted in Mediterranean areas. Spring heat...

Background: Intensive olive (Olea europaea L.) orchards are fertilized, mostly with the macronutrients nitrogen (N), phosphorus (P) and potassium (K). The effect of different application levels of these nutrients on olive oil composition and quality was studied over 6 years in a commercial intensively cultivated 'Barnea' olive orchard in Israel....

Proceeding of the IX International Symposium on Mineral Nutrition of Fruit Crops

Olive (Olea europaea) trees in the arid Negev Desert of southern Israel are important relicts on the ancient agricultural landscape. Among them are a cluster of several trees located in Wadi Zetan, at the heart of the Shivta horticulture terroir, with its abundant agricultural runoff remains. Two isolated olive bearing trees stand in a sheltered be...

Avocado is an edible crop with increasing economic significance. ‘Hass’ is the primary avocado cultivar, gaining high popularity among consumers and dominating the world industry. ‘Hass’ cultivation areas expand each year, but growers consistently report issues of irregular bearing and low yields. Leaf mineral analyses revealed that leaf boron (B)...

The first exploited and domesticated olive forms are still unknown. The exceptionally wellpreserved stones from the submerged Hishuley Carmel site (Israel), dating from the middle of the 7th millennium BP, offer us the opportunity to study the oldest table olives discovered so far. We apply a geometrical morphometric analysis in reference to a coll...

Jojoba (Simmondsia chinensis (Link) Schneider) wax is used for various dermatological and pharmaceutical applications. Several reports have previously shown beneficial properties of Jojoba wax and extracts, including antimicrobial activity. The current research aimed to elucidate the impact of Jojoba wax on skin residential bacterial (Staphylococcu...

Jojoba (Simmondsia chinensis (Link) Schneider) holds high industrial value and an extended cultivation trend. Despite its increased importance, there is a lack of fundamental information about its metabolic reserves and development. Our objective was to characterise metabolite allocation and fluctuations in the carbohydrate and nutrient balance of...

The physiological traits that set the tradeoff between productivity and drought adaptation in plants are still under debate. To reveal these traits, we compared the water relations of two olive (Olea europaea) cultivars: 'Barnea'- a highly productive modern cultivar; and 'Souri'- a drought-adapted traditional cultivar. We hypothesized that Souri ha...

Phosphorus (P) availability significantly impacts olive tree reproductive development and consequential fruit production. However, the importance of P fertilization in olive cultivation is not clear, and P application is usually recommended only after P deficiency is identified. In order to determine the long-term impacts of continuous P fertilizat...

Commercial avocado orchards typically consist of composite trees. Avocado is salt-sensitive, suffering from substantial growth and production depreciation when exposed to high sodium and chloride levels. Salt ions penetrate the roots and are subsequently transferred to the foliage. Hence, understanding distinct physiological responses of grafted av...

Salt stress is a major limiting factor in avocado (Persea americana) cultivation, exacerbated by global trends towards scarcity of high-quality water for irrigation. Israeli avocado orchards have been irrigated with relatively high-salinity recycled municipal wastewater for over three dec-ades, over which time rootstocks were selected for salt-tole...

Jojoba (Simmondsia chinensis) is a wax crop cultivated mainly in arid and semi-arid regions. This crop has been described as an alternate-bearing plant, meaning that it has a high-yield year (“on-year”) followed by a low-yield year (“off-year”). We investigated the effect of fruit load on jojoba’s vegetative and reproductive development. For two co...

The controlled application of olive mill wastewater (OMW) as a by-product of the olive oil extraction process is widespread in olive oil-producing countries. Therefore, a sustainable approach necessarily targets the positive effects of soil resilience between successive annual applications to exclude possible accumulations of negative consequences....

'Manzanilla', today's main table olive cultivar, is traditionally harvested manually. However, manual harvesting is becoming less economically feasible due to increasing labor costs and a shortage of workers. Consequently, we examined options for mechanical harvesting of these table olives. The 'Manzanilla' fruit skin is sensitive to bruising and d...

Precise phosphorus (P) application requires a mechanistic understanding of mineral effects on crops' biology and physiology. Photosynthates assimilation, metabolism, and transport require phosphorylation, and we postulated that P is critical for the bloom and fruit-set of almond trees that rely on stored carbohydrate reserves. Hence, we studied the...

We present here the earliest evidence for large-scale table olive production from the mid-7th millennium BP inundated site of Hishuley Carmel on the northern Mediterranean coast of Israel. Olive pit size and fragmentation patterns, pollen as well as the architecture of installations associated with pits from this site, were compared to finds from t...

Commercial pruning practice in jojoba plantations is traditionally dictated by maintenance requirements only. It enables machine movement between the plants and efficient harvest but is not designed to maximize long-term productivity. In this study, mechanical and manual pruning approaches were tested in two cultivars in a mature jojoba plantation,...

Profits from olive oil production are expected to benefit from regulated deficit irrigation (RDI) regimes designed to optimize yield and oil quality with minimal inputs of water. We evaluated a number of potential strategies for implementing RDI including choosing phenological periods for reduced irrigation, use of midday stem water potential (SWP)...

Roots are the first plant organ to encounter, sense, and respond to soil salinity. Like for many moderately salt tolerant species, roots of olive (Olea eurpaea) trees are the principal players in salt tolerance. We studied roots of mature olive trees in order to illuminate the yet vague mechanism(s) of root salt exclusion. Root structural traits we...

Pomegranate cultivation has expanded significantly in the last two decades. However, there is limited information on its fertilization requirements and the effect of macronutrient availability on its reproductive development. Two commercial pomegranate cultivars—“Wonderful” and “Emek”—were grown in 500-L containers for 3 years, using a fertigation...

Lipids have a key role in a variety of physiological functions in insects including energy, reproduction, growth and development. Whereas most of the required fatty acids can be synthesized endogenously, omega-3 and omega-6 polyunsaturated fatty acids (PUFA) are essential fatty acids that must be acquired through nutrition. Honey bees (Apis mellife...

The global avocado industry is growing, and farmers are seeking to expand their plantations. However, many lands suitable for avocado planting were previously cultivated with hosts of the soil-borne fungal pathogen Verticillium dahliae, which is the causal agent of Verticillium wilt (VW). VW can seriously impair avocado orchards, and therefore, pla...

Quantification of actual plant consumption of nitrogen (N) is necessary to optimize fertilization efficiency and minimize contamination of earth resources. We examined the performance of fruit-bearing pomegranate trees grown in soilless media and exposed to eight N-fertigation treatments, from 5 to 200 mg N L−1. Reproductive and vegetative indices...

Intensification of olive orchard management entails increased use of fertilizers, especially nitrogen, phosphorus, and potassium. In this review, plant responses to nutritional aspects, as well as environmental considerations, are discussed. Nutrient deficiency impairs production, whereas over-fertilization may reduce yields and oil quality, and in...

Rangelands are a dominant anthropogenic land use and a main driver of natural habitat loss worldwide. Land sharing, the integration of agricultural production and biodiversity conservation, may provide a platform for managing rangelands to fulfill multiple ecosystem services. However, livestock grazing can greatly affect biodiversity and little is...

Background: Nitrogen (N) fertilization influences plant growth and yield, and may also affect fruit quality. For two consecutive seasons, we examined the effects of different N-fertilization levels-5 to 200 mg L-1 -on pomegranate fruit, aril and juice quality. Evaluations included fruit and aril weight, size and color, appearance of peel blemishes...

Summer and autumn in Israel are highly arid with not enough plants in bloom offering nectar and pollen to support the local apiary. This leads to decline in colony health and honey production. To increase food sources for honeybees, we initiated a project to clone elite Eucalyptus trees exhibiting constant and rich blooming from late summer to earl...

To test the influence of avocado rootstocks on the scion leaf ionome, the nutritional status of avocado cultivars Hass and Ettinger grafted onto 15 rootstocks was compared over 3 years. The rootstocks were of different genetic origins (West Indian or Mexican) and were clonally or reproductively propagated. The trees were grown in a high-density orc...

The olive growing sector is transitioning from traditional to intensive irrigated cultivation, dictating a need to reconsider orchard management practices including fertilization. Potassium (K) is an essential nutrient, typically found in high concentrations in plants. Orchard K fertilization requirements are commonly derived from the disparity bet...

Background: Irrigation of olives increases fruit and oil yields. Due to scarcity of fresh water, low-quality water including recycled wastewater (RWW) is utilized in orchards. Here, effects of irrigation with RWW and of fertilization on the composition and quality of olive oil were studied. Results: Long-term RWW irrigation of 'Barnea' and 'Lecc...

Plants of Eruca sativa Mill. (Brassicaceae) from desert and Mediterranean populations in Israel differ in flower color and size. In the desert habitat, the population has higher abundance of flowers with cream color and longer petals, whereas in the Mediterranean habitat, the population has higher abundance of flowers with yellow and shorter petals...

Utilization of reclaimed wastewater (RWW) presents an alternative to irrigation of agricultural crops with fresh water (Fr), especially in dry areas characterized by water scarcity. While RWW often contains considerable amounts of valuable plant nutrients, it is also typically characterized by high salt content, which can impair agricultural yields...

Current trends of intensification of olive cultivation including irrigation and fertigation have dictated a need to reconsider fertilization management practices. We evaluated the long-term effect of nitrogen (N) fertilization level on the productivity of field grown olive trees in an intensively cultivated orchard in order to optimize N fertilizat...

Demand for olive oil has grown dramatically over the past decades. The accompanying increase in production has been largely due to improvement in horticultural practices by means of intensification. Modern intensive olive orchards are characterized by high yielding cultivars, high tree density, mechanization, and micro-irrigation enabling the appli...

Avocado (Persea americana) has synchronously protogynous flowers: flowers open first in female phase before closing and opening the next day in male phase. Cultivars are grouped based on whether the flowers typically first open in female phase in the morning (type A), or in the afternoon (type B). However, it is known that environmental factors can...

BACKGROUND Olive oil, a functional food, is increasingly produced from trees irrigated with water containing high concentrations of salts. We studied effects of irrigation‐induced salinity on quality and health‐related compounds in olive oil. Trees (cv Barnea) were grown in lysimeters with continuous control and monitoring of root zone salinity. Sa...

Floral pollen is a major source of honey bee nutrition that provides them with micro- and macro-nutrients, including proteins, fatty acids, vitamins, and minerals. Different pollens vary in composition, including in the essential fatty acids, alpha-linolenic acid (omega-3) and linoleic acid (omega-6). Monocultures, prevalent in modern agriculture,...

Honey bee colonies require adequate pollen for maintenance and growth. Pollens vary in nutritional value, and a balanced diet is achieved by mixing pollens with complementary essential nutrients. We tested subjective evaluation of pollens by foragers in colonies deprived of one of two essential fatty acids (eFAs), alpha-linolenic acid (omega-3) or...

Several studies cautioned against potential negative effects of controlled olive mill wastewater (OMW) application on soil physical properties that could be associated with the possible adverse effects of K on soil structure stability. The objective of the study was to examine the effects of annual application of OMW over several years on selected...

Expansion of irrigated olives, combined with prevalence of water containing dissolved salts, leads to irrigation induced exposure of olive trees to salinity. Root zone salinity can rise either as a function of increasing input irrigation water salinity (ECi) or relative reductions in water for leaching. We investigated five ECi levels from 0.5 to 1...

This paper presents and discusses the results of residue analysis conducted on 78 ceramic lamps found in archaeological excavations in ancient Jerusalem, in an attempt to identify the types of oils used and the reasons for their preferential choice. The oil lamps chosen for the study were taken from a variety of contexts, which represent the differ...

BackgroundA previous multi-locus lineage (MLL) analysis of SSR-microsatellite data of old olive trees in the southeast Mediterranean area had shown the predominance of the Souri cultivar (MLL1) among grafted trees. The MLL analysis had also identified an MLL (MLL7) that was more common among rootstocks than other MLLs. We here present a comparison...

Background and aimsIrrigated olives are increasingly exposed to conditions of high salinity. Salt tolerance of olives is commonly attributed to ion exclusion. Our objective was to advance understanding of salt stress response of olive roots. Methods Nine levels of root zone salinity originating from either irrigation water salinity or leaching leve...

Background Naturally growing populations of olive trees are found in the Mediterranean garrigue and maquis in Israel. Here, we used the Simple Sequence Repeat (SSR) genetic marker technique to investigate whether these represent wild var. sylvestris. Leaf samples were collected from a total of 205 trees at six sites of naturally growing olive popul...

The olive tree is generally characterized by relatively low final fruit set consequential to a significant rate of undeveloped pistils, pistil abortion, and flower and fruitlet abscission. These processes are acknowledged to be governed by competition for resources between the developing vegetative and reproductive organs. To study the role of phos...

In modern oil olive orchards, mechanical harvesting technologies have significantly accelerated harvesting outputs, thereby allowing for careful planning of harvest timing. While optimizing harvest time may have profound effects on oil yield and quality, the necessary tools to precisely determine the best date are rather scarce. For instance, the c...

Cultivated since ancient times, the olive tree is native to Israel and the Palestinian Authority. Around 375 olive mills in the region are operated by a three phase continuous centrifugation process which yields pomace, olive oil and olive mill wastewater (OMW). The Project “Wastewater from Olive Oil Mills in Israel and Palestine: Interactions with...