NUCIS number 12. September 2004. 52 pages (full ... - IAMZ - ciheam

Table 1. Pistachio production in Tunisia (2002).Surface Number Yield Yield Density(ha) of trees (t) (kg/tree) (trees/ha)Irrigated crop 1.065 135.500 148,3 1,1 125Rainfed crop 41.983 2.888.618 1.029,5 0,4 70(Source: DGPA, 2002)Figure 2. Repartition of Pistachio growing area in TunisiaFigure 1. Geographical distribution of Tunisianpistachio growing area706050% of total area% of total productioncenter and the south of the country (Fig.1). Gafsa, Sidi Bouzid, Kasserine andSfax are the most important producing regionswith respectively 19.800 ha, 9.188ha, 7.668 ha and 3.290 ha.Despite this acreage increase the productionis still very weak reaching only1.170 t with important differences betweenirrigated and rainfed orchard and alsoregions (table 1). The north region representsless than 1% of the growing surfaceproducing more than 16% of the nationalyield (fig. 2).To understand this weak yield and characterizethe current situation of pistachiocrop in Tunisia, a survey was carried outin the important Tunisian pistachio growingzones (Ghrab et al., 2002b). Themost important observations were:• Inappropriate distribution of male andfemale trees on the orchard. Different ratiosof male to female varying from 2% to90% were observed reducing the profitabilityof the orchard.• Inadequate planted material that is supposedto be ‘Mateur’ as female and malesA40 and A25 cultivars. However the observationsmade revealed significant phenotypicdifferences between trees.• A shift of the flowering periods betweenA25 and A40 male cultivars and ‘Mateur’inducing an inefficient pollination. Thosecultivars were selected on the north ofthe country for their production, qualityand overlapping flowering period howeverunder the central and southern climaticconditions the flowering period of themale cultivars does not overlap with theblooming period of Mateur.• Since pistachio tree needs more thanfive years to bear under the central andsouthern semi-arid conditions, some growersopted for other species and quittheir orchards without any management.• For some pistachio growers, managementoperations such as fertilization, pruningand pest and disease control were%403020100Northignored and considered without any benefitfor this crop.CULTIVARS AND ROOTSTOCKSThe most commonly cultivated variety inTunisia is ‘Mateur’ (Fig. 3), selected in theNorth as well as two corresponding pollinatorsA40 and A25 (Mlika, 1980). Almostall the development of the pistachio industryin Tunisia is based on this cultivar.Few other local varieties are cultivated insome specific localities from which it tookits names as ‘Meknassy’ cultivars in the regionof Meknassy (Sidi Bouzid), ‘El Guettar’from the region of El Guettar (Gafsa) and‘Nouri’ and ‘Thyna’ from Sfax region.As rootstock, P. vera is almost the onlyused by growers for its good germinationrate. P. atlantica and P. terebinthus, inspite of their good characteristics asrootstock are barely used because oftheir seed germination difficulty.CULTURAL CONSIDERATIONPropagationT-budding is the most common propagationmethod. The budding is performed inJuly at the nursery on seedling of P. vera.The following winter trees are planted inthe orchard.PruningThe training system used for pistachio isusually the open vase, however a lot oforchards were grown without any training.CentreGrowing AreaSouthThe annual pruning is also rarely made. Ifit is made it is mainly to remove dried, diseased,infected, pest damaged, andnon-fruiting old shoots.PollinationPistachio trees are dioecious, with maleand female flowers borne on separatetrees. The designed orchard should ensurean adequate pollination. Male trees areoften planted in the center of a 3m x 3msquare of females, yielding an 8:1 ratio(Jacquy, 1973). Additional male trees aresometimes planted in border rows. Naturally,wind transports pollen from maleflowers to female flowers. Efficient pollinationwas assured when the floweringperiods of males is long enough to overlapwith the female flowering. But underTunisian conditions, a high percent ofblack fruit is obtained, and natural windpollination is proved inefficient and artificialpollination was widely adopted(Mlika, 1974). The male panicle is harvestedand kept on a dry, shaded place.The pollen is collected and mixed withtalc (1/9 ratio) and sprayed on the femalepanicle early in the morning. Three to foursprays are made during the female floweringperiod to insure a good pollinationrate.Pest and diseasePest and disease decrease quality andquantity of pistachio crop through their directand indirect damages. Few important20 FAO-CIHEAM - Nucis-Newsletter, Number 12 September 2004