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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 trees’ ability to fulfill their climatic needs. To explore temperature responses across different cultivars, we applied Partial Least Squares (PLS) regression to correlate bloom dates of 12 local and 25 foreign almond ( Prunus dulcis Mill.) cultivars in Sfax, Tunisia with daily chill and heat accumulation based on more than 30 years of phenology records from 1981 to 2014 and long-term daily minimum and maximum temperatures between 1973 and 2016. We used three chilling models (the Chilling Hours, Utah and Dynamic Models) and one forcing model (Growing Degree Hours; GDH) to quantify climatic needs. Chilling and forcing phases derived from the PLS outputs appeared discontinuous for all almond cultivars and were shorter for the local almond cultivars than for the foreign cultivars. The Dynamic Model provided the most precise estimates of chilling requirements but still appeared to have some shortcomings. According to the Chilling Hours Model, chilling needs were very low, but still higher than for the Utah Model, where the negative chill contributions by high temperatures implied negative chilling requirements. The Chilling Hours and Utah Models therefore do not seem suitable for the climate of the Sfax region. For local almond cultivars, chilling requirements were estimated at between 3.4 and 15.5 Chill Portions (CP) and heat needs between 3962 and 8873 GDH. For foreign cultivars, chilling requirements varied from 6.7 to 22.6 CP and heat needs from 2894 to 10,504 GDH. High temperatures during the chilling phase showed a significant bloom-delaying effect on most of the local and the foreign almond cultivars.

28 Pags.- 1 Fig.- 3 Tabls. The definitive version is available at: https://www.tandfonline.com/toc/lpla20/current, 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 agronomic performance and foliar nutrient content of the flat peach cultivar ‘Subirana’ grafted on ten different Prunus rootstocks were studied on calcareous soil typical of the Mediterranean area. Ten rootstocks: ‘ADAGAF 04-03’, ‘AGAF 0301-04’, ‘Garnem’, ‘Krymsk® 1’, ‘Krymsk® 86’, ‘PAC 847’, ‘PADAC 04-01’, ‘PADAC 150’, ‘PM 105 AD’, and ‘Rootpac® 70’, were considered. Vegetative growth, chlorophyll SPAD index, leaf mineral status and deviation from the optimum percentage (DOP) index were determined. Leaf chlorophyll content varied depending on the rootstock. ‘PADAC 04-01’ and ‘ADAGAF 04-03’ showed higher chlorophyll index. The lowest SPAD values were observed for the most dwarfing rootstock ‘Krymsk® 1’, which showed visual chlorosis symptoms, and lower leaf mineral contents compared to the other rootstocks. Peach trees on Prunus rootstocks showed differences in leaf macronutrient and micronutrient content. ‘Rootpac® 70’, ‘ADAGAF 04-03’ and ‘PADAC 04-01’ had better adaptation under warm Tunisian conditions but high ΣDOP index. The most invigorating ‘Garnem’ had the highest imbalanced nutritional status, but continues to perform well under warm conditions. Interesting results were obtained with ‘Rootpac® 70’ showing one of the best balanced nutritional values (average ΣDOP index). However, the most dwarfing rootstock ‘Krymsk® 1’ presented the worst adaptation to the studied warm Mediterranean conditions., This research was supported by the Tunisian Ministry of Higher Education and Scientific Research (LR17AGR01, LR16IO02) and by the Bi-lateral Cooperation Project between Tunisia and Spain ‘Compatibilité des porte-greffes Prunus avec les espèces fruitières à noyau’ (Ref. A/5525/06) funded by the Agencia Española de Cooperación Internacional (AECI).

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 deficit irrigation strategies. In terms of yield/total water supply, the late maturing cultivar subjected to mild deficit irrigation, gave the highest WP (4.1 kg m-3), compared to the mid-season (3.0 kg m-3) and early cultivar (1.9 kg m-3). Full irrigation reduced slightly the performance of the most productive cultivar (3.7 kg m-3). Performances of early and mid-season cultivars were affected by rootstock. Interaction between mild deficit irrigation and vigorous rootstock induced better WP. Experimental work in olives targeted WP under contrasted environments. In northern Tunisia (450 mm annual rainfall), average yield for three cultivars ('Picholine', 'Chetoui' and 'Mansanille') planted at 6×6 m spacing on a clay soil, varied between 3.9-4.7 and 4.7-6.1 t ha-1, respectively when irrigation was increased from 100 to 200 mm. Under these restrictive conditions, the highest WP values were obtained for 'Picholine', respectively 0.77 and 0.86 kg m-3. However, in southern Tunisia (200 mm rainfall), the 'Chemlali' cultivar, conducted under intensive planting (4×4 m) on sandy soils, showed a drastic increase in production. With irrigation water supply of 200-400 mm, average yield reached 10-12 t ha-1, and WP 2.1 kg m-3. Adaptation to water scarcity is discussed on the basis of the obtained results.

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. Speci...

36 Pags.- 4 Figs.- 5 Tabls. The definitive version is available at: http://www.sciencedirect.com/science/journal/03044238, 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 (36°41′N, 10°15′E) on a heavy and calcareous soil typical of the Mediterranean area. Tree mortality, vegetative growth, rate of bud failure and fruit quality were assessed. Significant differences were found among rootstocks for the agronomic and fruit quality traits. Growing conditions generated varying levels of tree mortality, the highest with Krymsk® 1 rootstock. In contrast, all trees on PADAC 04-03 and PADAC 04-01 survived well. The lowest vigor was induced by Krymsk® 1 with a reduction of 90% in trunk cross-sectional area (TCSA) and canopy volume as compared to Garnem. PADAC 150 also expressed a low vigor. The highest canopy volume was found on Rootpac® 70 as similarly for Garnem. The remaining rootstocks induced a medium vigor level. Trees on vigorous rootstocks as Rootpac® 70 showed the lowest rate of bud failure, while dwarfing rootstocks induced the highest buds abscission. Yield was higher for AGAF 0301-04 in 2011 and 2012 as compared to the rest of rootstocks. The highest yield efficiency was recorded on PM 105 AD and AGAF 0301-04 rootstocks. Rootpac® 70 presented the highest fruit weight and fruit diameter. The highest level of soluble solids content (SSC) was recorded on Krymsk® 1, and the lowest on Garnem, although differences were not significant when compared to the other rootstocks. The less vigorous rootstocks seem to induce a better fruit quality of peach based on fruit sugar content. This study provides information that new Prunus rootstocks for peach can lead to a better agronomic performance than Garnem, mainly in vigor and in productive parameters. The peach-plum hybrid PADAC 04-03 induced good yield, with large fruit size and acceptable efficiency with significant smaller trees than Garnem., This research was partially supported by the Bi-lateral Cooperation Project between Tunisia and Spain ‘Compatibilité des portes greffes Prunus avec les espèces fruitières à noyau’ (Ref. A/5525/06) and funded by the Agencia Española de Cooperación Internacional (AECI).

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’, ‘Lauranne’, ‘Soleta’, ‘Belona’ and ‘Guara’) grafted on three peach and plum based rootstocks of different degrees of vigor (‘Garnem’, ‘Rootpac-40’ and ‘Rootpac-20’) were trained in super high-density planting in an experimental orchard. Tree vigor, tree water status, leaf chlorophyll content and quantum yield of photosynthesis system II (PSII) were monitored over two budding seasons. Results and discussion. ‘Garnem’ and ‘Rootpac-40’ were respectively the most and the medium vigorous rootstocks and induced the best tree water status, chlorophyll content and quantum yield of PSII for the tested almond cultivars. Scions grafted on ‘Garnem’ had the highest values of trunk cross-sectional area (TCSA), and almond scions were higher on ‘Garnem’, intermediate on ‘Rootpac-40’ and lower on ‘Rootpac-20’. Scions grafted on ‘Rootpac-20’ seemed to be the most dwarf phenotype. Moreover, ‘Rootpac-20’ performed the lowest values of stem water potential and showed various visual symptoms of chlorosis. Conclusion. Overall, ‘Rootpac-40’ exhibited a medium capacity to control tree vigor and well adapted to Mediterranean soil conditions.

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’s conventional irrigation programs. Fruit growth, yield, water supply, and water productivity were determined through four years. For the three cultivars, Flordastar, Royal Glory, and Carnival, fruit maturity was achieved at 650, 1100, and 2200 GDD, respectively. Average yields were 17.4, 29.8, and 41.1 t ha–1 and mean values of water productivity were 1.9, 3.1, and 3.6 kg fresh yield m–3 for early, mid-season, and late cultivars, respectively. Results of agronomic performances evaluation at the farm scale provided a reference on the behavior of early, mid-season, and late cultivars of peach in irrigated orchards in semi-arid conditions.

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 production region in central Tunisia (34°56′08″N, 10°36′54″E) during 2005–2015.The relationships between the budburst and flowering dates and climatic variations were investigated for the main local (Chemlali, Chemchali, Oueslati and Chetoui) and foreign (Koroneiki and Arbequina) olive cultivars to state their adaptability to warm area climate. Chilling was computed as chill portions (CP) from October to budburst using Dynamic Model, whereas heat accumulation was quantified as growing degree hours (GDH) from budburst to the beginning of flowering. As a result, variable budburst and flowering dates of olive cultivars were obtained related to the climatic conditions occurring each year. ‘Chemlali’ and ‘Arbequina’ seemed to be the precocious cultivars with an average budburst date of DOY-71 (March-12), whereas ‘Chemchali’ and ‘Koroneiki’ were the most late with an average budburst dates of DOY-80 and DOY-81 (March21-22). The beginning of flowering occurred from DOY-93 (3-April) to DOY-126 (6-May), where ‘Chemchali’ seemed, also, to be the latest one. Winter chill impacted significantly olive flowering with a positive correlation between flowering date and chill accumulation. A tendency for advancing flowering of local and foreign olive cultivars occurred subsequent a lack of winter chill. Trends for increasing heat accumulation with increasing chilling were observed in exponential manner to achieve flowering of olive cultivars. Moreover, winter temperature, appeared to be one of the most important variables in determining flowering time of olive cultivars mainly when quarterly and monthly mean temperatures were considered. In conclusion, this investigation is the first database concerning olive cultivars originated from different geographical areas and grown in a warm area. It revealed that olive cultivars behaved differently with contrasting chilling and heat accumulations and in years with extreme climatic conditions. It will be more interesting to consider the important genetic diversity of olive tree to mitigate the harmful effect of increasing temperature in the future.

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 Mornag in northern Tunisia (36°41′N, 10°15′E). Flowering date, flowering duration and double fruits rate were observed over the entire experimental period. The phenological behavior, expressed as fruit set and flower buds abscission, was also surveyed. At harvest, yield, fruit size and number of commercial fruits were determined. Trends of chilling accumulation were characterized over twenty years using two chilling hours models (0–7.2 °C model, CH and Crossa-Raynaud model, CH CR ), Utah and Dynamic models. Correlations among chilling models showed that the Dynamic model is more appropriate to estimate chilling accumulation in our warm production area. Climatic conditions during the five experimental years were variable, with chill accumulation in the range 127–421 CH, 82–294 CH CR , 298–860 chill units (CU) and 19–50 chilling portions (CP). Exceptionally warm conditions were observed in winter 2006–2007 and 2009–2010 with significant drop of chill accumulation to levels less than 50% of average chill accumulation. Flowering and fruiting of both early and mid-season maturing commercial cultivars were affected by chill accumulation variability. Warmer winter delayed flowering, extended flowering duration, increased bud abscission and affected fruit set. A chill accumulation less than threshold values of 25 CP, 200 CH, 100 CH CR , and 350 CU resulted in substantial decrease of yield and fruit quality. Cultivar responses to chilling conditions in term of flowering date and yield seemed to be rootstocks dependant. Adoption of appropriate scion-rootstock combination and cultural practices based on chill accumulation could be used in peach industry as means to adapt to increasing frequency of warm winters.

Fruit trees need to store reserves to allow their survival during winter and for bud flush and leaf growth in the following spring. The current study investigated the effects of alternate bearing and flower buds removal on seasonal starch storage and mobilization in leaves, current shoot and one-year-old wood of fruiting and non-fruiting branches of ‘Mateur’ pistachio (Pistacia vera L.) trees in arid land. Four treatments were applied; T0: untreated trees, T1: removal of all flower buds for one year, T2: removal of all flower buds for two successive years and T3: removal of 50% of flower buds for each year. Annual starch storage and mobilization in fruiting and non-fruiting branches of pistachio trees appeared to be driven by crop load, nut development stage and carbohydrate demands. Starch concentrations in leaves, current shoot and one-year-old wood increased slightly in non-fruiting than in fruiting branches of pistachio. In ‘on’ trees (T0 and T3), one-year-old wood starch increased after the initial growth flush, but is mobilized during kernel fill and continued to decrease after nut harvest. Starch mobilization from current shoots of ‘on’ trees during the high demand period of stage III corresponded to the period of flower bud abscission. These results suggested that branch wood starch concentrations represent the overall balance between source and sinks. Subsequent flower buds removal (T1 and T2), leaves accumulated starch during the first and the third stage of nut growth, whereas, gradually increase of starch concentration occurred over the growing season for the current shoots and one-year-old wood. Starch deficiency in current shoots of ‘on’ trees could be responsible for bud drop and finally for alternate bearing. The yield patterns of pistachio trees cv. Mateur have not shown real evidence of alternate bearing in the experimental site. Flower buds removal (T1 and T2) allowed pistachio trees to achieve higher yield potential, while, these two treatments performed the lowest cumulated yield. Removal of 50% of flower buds (T3) did not cause a significant change in yield, compared to untreated trees, in each of the first three years, as well as in the total yield accumulation. When focusing on 2008, this treatment caused a significant increase in yield, compared to other treatments including the control. Current shoot starch status was also higher in 2008 in the 50% fruit removal treatment. If we isolate and focus on the results obtained in 2008, it appears that this treatment can cause more stable yields, possibly through an increase in current shoot starch content. Consequently, under severe climatic conditions of arid land, the annual pruning could be applied to equilibrate flower buds number and to improve the tree starch status.

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 minimize alternate bearing.

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 impact of stress. The present work investigates the water status of peach in relation to water supply under high evaporative demand with the objective of developing practical methods for deficit irrigation scheduling. A field experiment was carried out in 2006 and 2008 at the research station of INAT-Mornag in northern Tunisia. Drip-irrigated mid-season cultivar Royal Glory grafted on GF677 was used. Total water applied during the dry season was in the range 50–100 mm in 2006 and 200–300 mm in 2008. Predawn ( Ψ PD ), midday ( Ψ m ), and stem ( Ψ stem ) water potentials, weather factors, irrigation and soil moisture were monitored. Results show that ET c was 524 and 603 mm for 2006 and 2008, respectively, under ET o of 1171 and 1180 mm. With highly variable quantity and distribution of precipitation, the contribution of soil reservoir water is essential to regulate evapotranspiration of trees. In 2006, applied water covered 0.35–0.50 ET c during the initial-mid season period and 0.60–0.65 ET c in postharvest. Irrigation was adjusted in 2008 to cover 0.55–0.75 ET c during vegetative and fruit growth and 0.50–0.65 ET c during postharvest. Water supply indices were defined as ratios between cumulated water supply ( I + P ) and ET o over different periods of time. Seasonal ( K s ), 30-days ( K 30 ), 15-days ( K 15 ), and 7-days ( K 7 ) were calculated over the cropping season starting in October. Tree water status and fraction of available water (FAW) was relatively high early in the season but declined to extremely low values during the high evaporative demand period and during the periods without irrigation. Extreme low values of −1.28, −2.13 and −2.51 MPa, respectively for Ψ PD , Ψ m and Ψ stem were observed during the high evaporative demand period. Relationships were significant between Ψ stem and Ψ PD and Ψ m . A good correlation was also observed between FAW and Ψ PD , Ψ m and Ψ stem . Analysis of the relationships between water supply indices ( K 7 , K 15 , K 30 and K s ) and tree water potential shows a high correlation between Ψ stem and K s . Upper and lower limits of 0.8 and 0.5 could be adopted for K s in order to maintain water status of peach trees within acceptable level corresponding to moderate and severe water deficit.

a b s t r a c t Pistachios (Pistacia vera L.) are widely grown in the arid rainfed areas of Tunisia. However, pistachio production is still low with important variation between years. This study investigated the responses of pistachio trees to variable winter chilling and annual precipitation. It was carried out in an experimental orchard of Mateur, the most important Tunisian cultivar in central Tunisia (34◦94� 11�� , 10◦60� 82�� ) for a period of twelve years from 1997 to 2008. Yield correlated poorly with precipitation (varying on the range of 80-300 mm/year during the 12 years) and showed a moderate alternate bearing index of 0.63. However, flowering and nut yield of pistachio trees was a function of chill accumulation computed as chilling hours (CH), chill units (CU) or chilling portions (CP) depending on using Crossa-Raynaud, Utah or Dynamic models, respectively. For Mateur cultivar, the threshold chilling accumulation appeared to be 206 CH, 539 CU or 36 CP depending on the model used. Under this level, pistachio production was clearly affected. Warm winters with low chilling caused erratic floral bud break, delayed flowering, sparse foliage and decreased yield. With inadequate winter chilling, chemical treatments with hydrogen cyanamide (Dormex) at 2 and 4% increased floral bud break, advanced flowering period and improved vegetative growth of pistachio trees in comparison to the untreated control. As a conclusion, better prediction of chill accumulation must be achieved in the warm production region of Tunisia. To that effect, the Dynamic model showed the lowest coefficient of variation compared to the chilling hours and Utah models and seemed to better reflect what is happening on the field under our warm winter regions. © 2013 Elsevier B.V. All rights reserved.

Water scarcity and the increasing water demand for irrigation in olive orchards are leading to adopt deficit irrigation approaches and the use of saline water. Field experiment was conducted on nine-year-old olive trees ( Olea europaea L. cv. Chemlali) grown on sandy deep soil and drip irrigated with saline water (EC 6.7 ms cm −1 ) under arid Mediterranean climate in southern Tunisia during 2003–2006. Three irrigation treatments (i) Control: full irrigated, (ii) DRY: rain-fed and (iii) PRD: partial root-zone drying were applied. PRD 30 and PRD 15 supplied 50% of the Control with an alternate irrigation switched every 30 and 15 days, respectively. PRD achieved significantly better soil water status in comparison to DRY and less than 30% of soil moisture level under the Control. Soil salinity levels were significantly lower during wet season than that of the summer period. PRD reduced the quantity of salt incorporated in the root-zone. Predawn ( Ψ PD ) and stem ( Ψ stem ) water potentials across all irrigation treatments diverged progressively from one another throughout summer season. Minimum values of −0.9, −1.3, −1.2 and −1.3 MPa for Ψ PD and −2.2, −2.4, −2.4 and −2.9 MPa for Ψ stem were measured during the summer for the Control, PRD 30 , PRD 15 and DRY, respectively. PRD showed statistically comparable values of water potentials to the Control which seemed to prevent an excessive drop in tree water status by modulating stomatal closure. High correlations of Ψ stem with Ψ PD and soil water potential indicated that Ψ stem could be used for the control of water supply in olive orchards. An improvement of olive yield was achieved by irrigation with saline water. PRD 30 achieved a slight cumulative yield reduction (11%) compared to the Control while applying half of irrigation quantity. The oil content showed an improvement with increasing deficits. PRD 30 seems to realize a good compromise between yield, quality and environmental impact and could be recommended for irrigation of olive trees under similar situations of water quality, soil and precipitation regimes.

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 (36°41'N, 10°15'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 and fruit quality were analysed. The benefit of deficit irrigation strategy in terms of water saving and agricultural water productivity (Wp) were estimated. Different relationships were investigated between yield, fruit quality, and Wp, and irrigation and total water supply. In reference to the high water needs of late cultivar Carnival for irrigation, Di I-II-III led to an important water saving (33%) with a yield reduction of 14%. Yield and fruit quality seemed to be related to watering regimes. Fruit dry matter (DM) decreased linearly with irrigation water supply for both Control and Di I-II-III. Unlike yield, Di I-II-III improved the dry weight of fruit. C...

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 information to ensure the future viability of orchards in warm growing regions, where warmer winters are expected as a result of climate change. We used Partial Least Squares (PLS) regression to correlate first bloom dates of 4 local and 3 foreign pistachio ( Pistacia vera L.) cultivars with daily chill and heat accumulation (quantified with the Dynamic Model and Growing Degree Hours Model, respectively) for 18-year records (1997–2016) from Sfax, Tunisia. PLS outputs allowed delineation of the chilling phase, during which high chill accumulation was correlated to early bloom, and the forcing phase, when this was true for high heat accumulation. Both phases showed discontinuities. During September and October, high heat accumulation appeared to first have a bloom-delaying effect, followed by a bloom-advancing effect, indicating that temperature during dormancy induction may affect bloom dates. Chilling requirements were estimated between 32.1 ± 2.3 and 33.3 ± 2.2 Chill Portions and heat requirements between 9974 ± 198 and 12,738 ± 235 Growing Degree Hours. This study revealed limitations of the Dynamic Model, which is often considered the most accurate among commonly used models, in the warm Tunisian climate. High temperatures during the chilling phase had a significant bloom-delaying effect on all pistachio cultivars. Low chill accumulation was related to very low yields and associated with zero production in 1995, 2001 and 2007. Low flowering percentage, high bud fall percentage, long and inhomogeneous bloom, and co-occurrence of several phenological stages on the same branch were symptoms of lack of chill in 2016.

Southern Tunisia is characterized by high evaporative demand and severe water deficit. Responses of pistachio cultivars to water deficit were evaluated. Physiological behavior was assessed using the following measures: net carbon assimilation, stomatal conductance, transpiration, photosynthetic efficiency, water use efficiency, and chlorophyll concentration. The local cultivars ‘Meknassy’, ‘Nouri’ and ‘Mateur’ achieved the best compromise between photosynthesis and transpiration, which maximized water use efficiency. In contrast, the foreign variety ‘Libye Rouge’ had lower net carbon assimilation, stomatal conductance, and photosynthetic efficiency. Chlorophyll concentration varied among local and foreign cultivars. Local cultivar ‘Thyna 1’ had the most chlorophyll at 0.17 mg/cm2.

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 collected during 2 years. Oil content and fatty acid composition were assessed. Fat content and fatty acid composition differed significantly among local ecotypes. The mean fat content of pistachio ecotypes ranged from 56 to 78%. Palmitic acid content varied between 7.1 and 12.9%. In addition, stearic acid was found as a minor saturated fatty acid in pistachio kernels; levels varied from 0.7 to 2.8%. Oleic acid content ranged from 56.1 to 80.7% with a significant difference over the different ecotypes. Linoleic acid varied between 8.2 and 29.7%. Mateur cultivar showed slight variations of fat content and fatty acid composition in the localities investigated. Certain ecotypes, such as Loby7 (fat content 78.5%), Sridique1 (80% Oleic, 9% linoleic), Ibala3 (76.8% oleic, 9.5% linoleic) from Sfax, and EPE2 (80% oleic, 8.2% linoleic), BMS3 (79.4% oleic, 9% linoleic), HAB3 (78.6% oleic, 9.9% linoleic), AMMS4 (78% oleic, 11.2% linoleic), and ABT2 (76.8% oleic, 12.1 linoleic) from El Guetar oasis, were distinguished by the interesting oil quality compared with Mateur and foreign cultivars. These results offer opportunities for further genetic improvement of pistachio oil quality.

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 the crop year of 2005 from the most cultivated pistachio cultivars in Tunisia were rapidly screened by enzyme-linked immunosorbent assay (ELISA) combined with an immunoaffinity step. The obtained results showed that the contamination of pistachio nuts has occurred clearly after two years of storage for all the tested cultivars except the case of Mateur variety and Thyna ecotypes. In this study, the cultivar Mateur was found to be the most susceptible cultivar to contamination by AFB1. After 4 years of storage, the average contamination levels in nut samples ranged from 2.7 ± 0.3 to 12.7 ± 2.2 µg/kg for AFB1, according to the cultivar. These levels exceeded the maximum permitted limit of 2 µg/kg set by the European Commission in nuts.

Effects of atmospheric pollution on three local grapevines, Asli, Jerbi and Tounsi, growing in the vicinity of a phosphate fertiliser factory, consist of an exhibition of characteristic necrosis on leaves and fruits. Analysis of necrotic leaf areas allowed us to distribute local vines into sensitivity classes. The follow-up, in function of time and space, of stomatal conductance and leaf fluoride content during the different seasons allowed us to reveal some offensive strategies allowing these vines to escape from pollutants toxicity and maintaining its vitality. Therefore, giving that fluorine is strange to its metabolism, grapevine tends to accumulate it, thanks to an external concentration mechanism, in the tips and leaf margins. Necrotic areas are delimited by a narrow brown border line. Thus, allowing the plant not only to avoid F- toxicity, but also to keep a big assimilation surface. In addition, possibilities as F- excluding, F- vacuol partitioning, temporary closing of stoma, F- trapping as CaF2, SiF4 are also to be considered.By another way, our results seem to show that full mature grapevine leaves may constitute an efficient tool to assess fluorine pollution impact. Berries contamination seems to be affected directly by the factory smoke, there is no endogenous supply. Likewise, by its characteristic necrosis in the leaf boundaries, grapevine may be considered as a bioindicator variety of fluorine pollution which can be used in mapping polluted areas.

6 Pags.- 3 Tabls.- 2 Figs. From: Proceedings VIIIth Intl. Peach Symposium, 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 of comparison to the most widely used rootstock (Garnem). The performance of a flat nectarine variety ‘Subirana’ budded onto these rootstocks was evaluated. Phenological stages, rate of bud failure, vegetative growth and chlorophyll index were monitored. The results of the evaluated Prunus rootstocks revealed contrasting effects on the nectarine variety depending on the vigor of the rootstocks. The PADAC 04-03 induced an important vigor identical to that of trees on Garnem, whereas Krymsk-1 produced the lowest tree vigor. Krymsk-1 and PAC 941 induced an early development of floral buds, while the other rootstocks delayed flowering by few days. The nectarine variety ‘Subirana’ showed SPAD chlorophyll index values above the threshold with all rootstocks, which seems to have good nitrogen nutrition. PAC 0301-04 and Garnem obtained the highest yields.