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The amountof female flowers produced in walnuts is not as high as that of pome and stone fruits, and to produce a good fruits, most of the flowers must be pollinated, so the lack of a suitable pollinator can be very problematic. Therefore, in this study, the phenological characteristics offive selectedpromisinggenotypes (G3, Kz3, K15, 1-88and 2-88), eight genotypes selected as pollinators (3-25, 2-7, 6-21, 3-6, 2-4,4-25,1-8, 7-24and 7-8) of promising genotypes were examined with commercial cultivars of Jamal,Chandler, Pedro and Hartley along with Damavandand Ronde de Montignac (RDM) as pollinatorcontrol cultivars. According to the results, the earliest leafingtime was observed in K15genotype (March 18) and the latest time was observed in RDM(April 18).The earliest time for pollen shedding start was in the Kz3genotype (March 31), and the latesttime was for the cultivar/ genotype of the RDM, 88-1and Hartley, respectively, on 22, 21and 21of March, respectively. In terms of the number of Catkinsper tree, genotypes K15, 7-8and 3-25had the highest number (941, 719and 511, respectively). The longest pollen shedding period with an average of 11days was obtained in K15, 88-25,and 3-25genotypes. The earliest time of female flower receptivity startwasobserved in Genotypes4-25(March 31) and the latest time was observed in Chandler and Hartley cultivars, which female flowers receptivity startedon 3May. The results of overlappingof pollen shedding period withfemale flower receptivityof cultivars and genotypesshowed that there is a favorable overlap between 3-25genotype with late leafing and protogynous genotypes including 88-1and 88-2and also with the chandler and pedrocultivars, it has an average overlap of about 515and can be recommended asa pollinator for these genotypesand cultivars. Due to the fact that 3-25genotype has the desired yield and fruit quality, unlike the existing pollinator cultivars (RDM and franquette), this genotype producedcatkinsin the early years after cultivation (usually the third or fourth year) and thehighvolume of pollen grains producedand due to the relatively long period of pollen shedding, it is recommended as a pollinator for late leaf genotypes. In addition, the88-1and 88-2aslate-leafing and promising genotypesoverlap with lateleafingcommercial and protandreouscultivars (Chandler and Pedro), so these cultivars, in addition to being cultivated as the main cultivar, are pollinators, reciprocally. The other two promising genotypes, Kz3and G3, have high levels of overlap withownpollen grains and often have good fruit setwithout pollinators, but need pollinatorsto form a more desirable fruit. For these genotypes Damavand recommended as a pollinator. In addition, Chandler and Pedro cultivars also cover the final period of their female flowers receptivityand can be pollinated bu these cultivars.Keywords: Walnut, Pollination, Pollen grain, Female flower receptivity
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