Mohamed Ghrab

Institution of Agricultural Research and Higher Education - Tunisia | IRESA · Olive Institute, Tunisia

Temperate trees require low temperatures during winter and subsequent warm conditions in early spring to flower and eventually bear fruit. Many parts of the Mediterranean region feature winters with low and sometimes marginal chill accumulation. To assess historic and future agroclimatic conditions for cultivating temperate trees (including almonds...

La Tunisie a été identifiée comme un 'Hotspot' pour des hausses de températures observées et projetées. Ces changements climatiques ont eu des incidences importantes sur l'agriculture dont le secteur oléicole qui a des retombés socio-économiques importants à échelle nationale et régionale. Dans ce cadre, la phénologie florale connait depuis quelque...

The increase water demand for irrigation is leading to the use of low-quality water resources. The combined impact of drought and salinity on olive production sustainability, yield quality, growth, soil salinity and soil water conditions in arid areas has been little investigated. This study’s purpose was conducted to investigate the effects of the...

In Tunisia, agriculture is vulnerable to climate change with harmful impacts subsequent warming and drying trends. In these regions, olive industry plays a key role at regional and national level. Therefore, the identification of adapted olive tree genotypes has become an urgent need to develop sustainable agriculture in arid lands. This study aime...

The peach (Prunus persica L.) is one of Tunisia’s major commercial fruit crops and is considered one of the biggest water consumers of all crops. In warm and arid areas of southern Tunisia, irrigation is necessary to ensure orchard longevity and high yield and fruit quality. Nevertheless, under water-scarcity conditions and low water quality, water...

In Tunisia, agriculture is vulnerable to climate change with harmful impacts subsequent warming and drying trends. In these regions, olive industry plays a key role at regional and national level. Therefore, the identification of adapted olive tree genotypes has become an urgent need to develop sustainable agriculture in arid lands. This study aime...

The Mediterranean region is facing temperature increases due to climate change. More warm conditions across the fruit and nut growing regions are expected to have a great and negative impact in Tunisian arid regions. Chilling trends among the agricultural production areas and their incidence on flowering and fruiting of typical fruit species were i...

Water scarcity is the main limiting factor for fruit trees in arid regions of Tunisia. In this area, almond is widespread, but severe conditions are a key issue for nuts production and kernel quality. In this study, phenological features and kernel quality of local and foreign almond cultivars irrigated with low water quality were investigated. Loc...

Nowadays, the new tendency for a high-density plantings system for almond requires smaller and more efficient canopies. In this way, appropriate scion-rootstock combination is an important factor in adapting to local conditions and specific training systems. This investigation was dedicated to identify the most suitable scion-rootstock combination...

The oil content, fatty acid compositions of pistachio nut (Pistacia vera L.) samples corresponding to four different varieties (Achouri, Adjmi, Batouri and Mateur), all cultivated in Algeria were determined. The fatty acid profiles of the oil extracted by the Soxhlet apparatus from four main commercial pistachio varieties, were determined by gas ch...

Deficit irrigation strategies are considered as promising irrigation management for water saving. In the arid areas of southern Tunisia, agriculture relies heavily on irrigation. With rainfall scarcity, valuable management of water requires efficient approaches. In this context, the effects of deficit irrigation (CDI) and partial root zone drying (...

Under dry and warm environmental conditions, the main Tunisian pistachio cultivar Mateur does not show a normal ‘On/Off’ cycle with highly variable nut yield, which could be affected by the tree nutritional status. In this context, Potassium (K) is considered a key nutritional element for nut development and for yield. The current study investigate...

Future warming predicted for Tunisia may reduce winter chill and affect the production of tree fruits and nuts, one of the key sectors of the country’s economy. To assess past and future chill availability, we used weather records from 1973 to 2019 to simulate historic and future chill for 20 weather stations (16 from Tunisia, 3 from Algeria and 1...

Tunisia is among the most vulnerable countries to climate change in the future with increasing temperatures and frequencies drought years. In Tunisia, fruit growing is one of the key sectors of the national economy. It occupies 2 million hectares, contributes about 30% to total agricultural production and 60% to agricultural exports. Fruits rich in...

Most of the woody perennial temperate trees require cool and cold temperatures as chilling requirement during winter, followed by warm spring temperatures as heat requirements to break their winter dormancy and to achieve homogeneous and simultaneous flowering and regular yields. Estimating chilling and heat requirements is therefore essential for...

Fruit tree orchards are usually based on a combination of scion and rootstock. The new management trend toward orchard intensification requires rootstocks that reduce tree vigour to control tree size. For stone fruits, newly released dwarfing rootstocks (‘Rootpac® 20’ and ‘Krymsk® 1’) were tested in a high density planting with the well-adapted but...

Recent trends in peach orchards have focused on intensification and high density plantings using different Prunus rootstock species with different vigor traits. This investigation aims to study the physiological behavior of different Prunus rootstocks in order to identify the most suitable rootstock under warm Mediterranean conditions. Field agrono...

Climate changes are expected to have a great and negative impact on agriculture in Mediterranean region. In this region, olive industry plays a key role at regional and national level as in Tunisia. With expected increasing temperature, the impact of climate change on the phonological behavior of the olive cultivars was evaluated in the main produc...

Olive industry plays a key role in the Tunisian agriculture sector and had a significant contribution to the socio-economic activities. Olive tree characterized different agroforestry systems and it is wide spreading from the north to the south. It presents a significant genetic diversity, which allows to this fruit species to survive and produce i...

Temperate deciduous trees can only be productive where winters are cold enough to meet their chilling needs. In the Mediterranean region, chill has traditionally been sufficient for many species, but this may change as temperatures increase. We explored the region’s present and future suitability for temperate trees by quantifying chill for the Sfa...

As the most of woody perennial temperate trees, pistachios enter in dormancy during winter in order to survive to unfavourable conditions and to frost damage. They require cool and cold temperatures as chilling requirement during winter, followed by warm spring temperatures as heat requirements to break their winter dormancy and to achieve homogene...

Des espèces et hybrides de pistachier (Pistacia spp.) de différentes origines ont été évalués durant une période de 12 ans dans les conditions semi-arides du sud-est tunisien en vue d'en sélectionner les plus performants en tant que porte-greffes. Des plants issus de semis ont été plantés en 2002 sous irrigation localisée pendant 2 ans avant d'être...

Fruit and nut orchards make up more than 20% of Tunisia’s agricultural area. Many species grown in these orchards, such as pistachios, almonds and peaches, fall dormant during the cold season and require low winter temperatures to resume growth in spring. Tunisia is one of the world’s warmest regions where such species are commercially grown. It is...

Most temperate fruit and nut trees require fulfillment of chilling and heat requirements during their dormant phase in order to flower regularly and produce economically satisfying yields. Recent and expected temperature increases are cause for concern for many orchard managers, especially in warm growing regions, because they may compromise the tr...

Woody perennial species from temperate regions fall dormant during the cold winter season to avoid unfavourable conditions. To break out of dormancy and eventually flower, they must fulfil cultivar-specific chilling and heat requirements. Phenology analysis can clarify the climatic requirements of tree cultivars and thus provide critical informatio...

Tunisia’s landscape is dominated by fruit and nut orchards, with olives, pistachios, peaches and other species covering more than 20% of the agricultural area. Most of these are temperate-zone species that require cool winters (‘winter chill’) to break their winter dormancy and produce economically sustainable yields. Tunisia is one of the warmest...

With growing water shortages, agriculture faces the challenge of increasing water productivity (WP). In this work, WP of two main crops, peach and olive, is evaluated for different cultivars and deficit irrigation practices. WP in peach was estimated over 4-7 years for three cultivars (early, mid-season and late-maturing), two rootstocks and two de...

The fig tree (Ficus carica L.) is widely cultivated in the Mediterranean region under warm climates. Fig yield is governed by the previous crop load and is strongly dependent on shoot length. Special cultural practices are required to stimulate new vegetative growth that will ensure regular and high productivity. The present study focused on the us...

The agronomic performance and fruit quality traits were evaluated for ten Prunus rootstocks: Garnem, PADAC 150, PADAC 04-03, PADAC 04-01, Rootpac® 70, PM 105 AD, AGAF 0301-04, Krymsk® 1, Krymsk® 86 and PAC 847. These rootstocks were budded with ‘Subirana’ flat peach cultivar in September 2007 and planted in two adjacent plots in northern Tunisia (3...

Introduction. Recent management trends in almond orchards have focused on intensification and high-density plantings using Prunus rootstock cultivars with different vigor traits. This investigation aims to prospect precocious detection of adequate scion-rootstock combination for almond. Materials and methods. Five almond cultivars ('Tuono', 'Lauran...

Productivity of peach cultivars with different ripening seasons was studied under the growers’ conventional conditions of Tunisia. Experiments were performed in northern Tunisia (36° 41ʹ N, 10° 15ʹ E). Performances of Flordastar, Royal Glory, and Carnival as respectively early, mid-season, and late ripening cultivars were evaluated under the grower...

Abstract In Tunisia, the usually used rootstock for pistachio is Pistacia vera. However, some wild pistachio species as P. atlantica and P. terebinthus spread naturally within Tunisia. They seem to be well adapted to the arid zone conditions where pistachio is planted. An experiment was carried out at the experimental station Taous (34°44’26”N, 10°...

Pistachio is an important nut crop well extended in the centre and the south of Tunisia. An important increase of growing area occurred during the last forty years using almost only one variety Mateur, selected in the North of the country. However, the productivity is still very weak under low annual precipitation, warm climate and deficient cultur...

This work aims at testing the capacity of scion-rootstock combination and irrigation scheduling techniques to improve water management under situations of water scarcity. A field experiment was carried out in northern Tunisia on two drip irrigated peach varieties 'Early May Crest' and 'Royal Glory' grafted on two rootstocks, GF677 and Cadaman. Two...

Performance of fruit species from Prunus is highly dependent on rootstock. This study focused on evaluating the field performance of several Prunus rootstocks in the main fruit irrigated production area in Tunisia. Nine new rootstocks: PADAC 150 AD, PADAC 04-03, PADAC 04-01, ROOTPAC 70, PAC 941, AP1, Krymsk-1, PAC 0301-04 and PM 105 AD were tested...

Long-term effects of partial root-zone drying (PRD) irrigation technique using saline water (6.7 mS cm(-1)) on olive yield and olive oil composition were investigated. Three irrigation levels were considered: (i) full irrigation (control); (ii) PRD15 and PRD30 irrigated with 50% of water of the control applied on one side and switched every 15 and...

Biological effects of contrasting chill accumulation on scion-rootstock combinations of peach were investigated using field observations during 2006–2010. Early and mid-season ripening peach cultivars (Early May Crest and Royal Glory, respectively) grafted on GF677 and Cadaman rootstocks were monitored over a five year period in the region of Morna...

Water status of trees is affected by evaporative demand, soil water availability and hydraulic conductance of the root system. The objective of this work is to test the possibility of improving water status of peach trees by the choice of the rootstock for variable levels of deficit irrigation. A field experiment was carried out in 2006 and 2008 at...

Climate change characterized by global warming is expected to have an incidence on fruit trees’ development and production. The severity of these effects depends on lack of chilling. The current study focused on the research of an optimal dose of hydrogen cyanamide (Dormex) treatment which can advance the bud break of female pistachio trees (Pistac...

Knowledge of seasonal dynamics of macronutrients in mature trees is an important component of mineral nutrition management of pistachio. The objective of the present work was to determine the dynamic changes of nitrogen (N), phosphorus (P) and potassium (K) in leaves and shoots of fruiting and non-fruiting branches of 40-year-old 'Mateur' pistachio...

This work aims to assess the reproductive traits of nineteen, 40-year-old, trees of male pistachio (Pistacia vera L.) genotypes. The successive stages of flower cluster development were described. Structural composition of the inflorescence was studied for a total number of 30 clusters originating from ten genotypes (3 clusters per genotype) to det...

Nut trees must fulfill a chilling requirement to break their dormancy. In Tunisia, pistachio is wide spread in the center and south of the country and Mateur is the most cultivated pistachio cultivar. However, little information is available for its chilling and heat requirements for breaking dormancy and flowering. The present research was carried...

Peach production will eventually suffer from the temperature changes initiated by global warming. This study investigates the response of peach cultivars to exceptional warm winter conditions. Fifteen peach cultivars from three production areas in the north and the centre of Tunisia were surveyed during 2006 and 2007. Flowering date and period, veg...

Adequate choice of variety, rootstock and irrigation techniques could be, together, sources of improvement of water use. A field experiment was carried out in northern Tunisia on two drip irrigated peach varieties grafted on two rootstocks. Two deficit levels, mild DI1 and severe DI2, were applied. Phenological survey allowed determination of the c...

Key message After applying disbudding treatments, removal of fifty percent of flower bud each year improves dry matter accumulation in fruiting and non-fruiting branches of pistachio trees, which could mini-mize alternate bearing. Abstract Dry matter accumulation and distribution within branches of pistachio trees were investigated during 2005-2008...

ABSTRACT: This review highlights the current status of Tunisian olive production, challenges facing the sector and opportunities available. Olive, a fruit tree native to Mediterranean countries, is the subject of increased international interest for olive oil production for the global food market. Olive and olive oil production in Tunisia are of gr...

Besides hop, Hop stunt viroid (HpSVd) infects many woody species including grapevine, citrus, peach, plum, apricot, almond, pomegranate, mulberry and jujube. Here, we report the first detection of HpSVd in pistachio (Pistacia vera L.). Samples corresponding to 16 pistachio cultivars were obtained from a nearby almond collection. From these samples,...

Increasing water scarcity has changed the primary objective of farmers from seeking maximum yields to preservation of the agricultural system. Deficit irrigation may be used to reduce water use; however, the adoption of this technique requires precise knowledge of tree water status and the implementation of specific irrigation skills to reduce the...

Long-term effects of deficit irrigation on yield and water productivity of peach trees (Prunus persica L., cv. Carnival) grown in a semi-arid climate in northern Tunisia (36841’N, 10815’E) were investigated. Continuous deficit irrigation (Di I-II-III) was compared with the grower’s irrigation programme (Control). The effects of Di I-II-III on yield...

Background and aims – Pistachio (Pistacia vera L.) is an interesting crop for arid areas, well adapted to marginal lands and to drought conditions. Traditional production areas of Tunisia harbor an interesting diversity of pistachio germplasm. In order to identify and describe this diversity, a field study was conducted in the traditional pistachio...

Some biochemical pistachio nut traits were investigated to characterize pistachio germplasm. Local and foreign cultivars and ecotypes from three localities were surveyed. Kernel samples were collected during two years. Chlorophyll content, oil content and fatty acid composition were assessed. Chlorophyll content, fat content and fatty acid composi...

This study was carried out in the south of Tunisia. The region was characterized by high evaporative demand and severe water deficit. Responses of pistachio cultivars to water deficit were evaluated. Physiological behavior was assessed by means of the following parameters: net carbon assimilation, stomatal conductance, transpiration, photosynthetic...

In Tunisia, the almond tree (Prunus amygdalus Batsch) dates back to ancient times and has been known since the Carthaginian era. About 90% of the almond production is in the semi-arid central and southern part of the country. In the north, Bizerte presents a very specific ecosystem, with cultivars practically resistant to strong wind and high humid...

Pistachio germoplasm cultivated in traditional areas of Tunisia presented an interesting genetic diversity. The study was conducted to assess desirable biochemical characteristics from the rich local germoplasm in pistachio ecotypes. Kernel samples of the widely cultivated Mateur cultivar and 89 ecotypes from Sfax and El Guetar localities were coll...

Aflatoxins (AFs) are potent sources of health risks to both humans and animals. Among them, AFB1 is the most hazardously toxic and the most frequent in various food commodities, including pistachio nuts. In this survey, the effect of the storage period on AFB1 accumulation on pistachio nuts was investigated. A total of 49 samples collected during t...

A research program is focus on protecting local genetic resources of pistachio and almond. The main traditional zones of pistachio crop in the centre and the south of Tunisia were prospected. Many specimens of Pistacia vera and Pistacia atlantica were investigated. Subsequently, local and foreign cultivars from collection were studied. Flowering ti...

In Tunisia, olive and pistachio trees are mainly conducted under rainfed conditions and subjected to water and nutrient deficits. An experiment was established in semi arid region to study the response of olive and pistachio trees to potassium mineral nutrition using potassium sulphate in reference to control. Potassium was supplied by foliar spray...

The experiment was made in 2006 using 15-year-old trees in commercial plum and peach orchards in which standard horticultural practices of commercial production were being carried out. The plum cultivar grown was "Black Star" grafted on Mariana rootstocks, with tree planting spaced at 3 x 5 m. For the peach experiment, the mid-season cultivar "Roya...

Introduction The fruit tree industry is one of the most important agricultural sectors in Tunisia, with more than 2 million hectares planted mainly with olive (1.5 million ha), almond (257,000 ha), pistachio (44,000 ha) and palm date (26,000 ha). Citrus and stone fruits are also economically important crops (Table 1). Owing to water scarcity, the s...

– During the 1999-2002 period olive growing faced a very severe drought in Tunisia. The rainfall deficit reached in some regions more than 50% of the normal amount. In order to quantify the drought effects, a severity scale was established. This scale was based on plant status and has three levels which are: 1-normal state, 2-growth halt without va...

SUMMARY - Research has been developed on tree species and genotypes presenting adaptive mechanisms to drought. Almond and pistachio were considered as very drought tolerant crops. The ability to endure high water deficits was related to efficiency in valorising marginal soils under conditions of high evaporative demand and chronic water shortages....