The Effect of Pollen Type of Some Walnut Genotypes on Fruit Set, and Fruit Quantitative and Qualitative Characteristics of MSG15, MKG23 and MKG24 as Seed Parents

Abstract   Background and Objectives To achieve optimal fruit set, economic productivity and targeted crossings in seedlings and grafted walnut orchards, the flowering time of both male and female flowers and their overlapping is important. Since the walnut ovule longevity is limited, fertilization should occur at the shortest possible periods to lead to fruit set. Therefore, the evaluation of effective pollination periods and the needed time for the growth of pollen tube and ovule fertilization are important for successful fertilization. The aim of this study was to investigate the compatibility and the effect of pollen on some selected genotypes of walnut as pollinizers on the fruit set, fruit composition and the quantitative and qualitative characteristics of the progeny derived from MSG15, MKG23 and MKG24 genotypes as maternal parents.   Materials and Methods This research was conducted in 2016-2017 in the research garden of Malayer University in Hamedan province. In this study, female parents including MSG15, MKG23 andMKG24 were pollinated with pollinizers of MKG4, MKG5, MKG10, MKG13, MKG14, MSG15, MKG23 and MKG24. Some of the characteristics of the fruit and the kernel were also evaluated in the offspring resulting from controlled pollination.   Results Based on the results, the cross between female parent genotype of MSG15 with pollinizers of MKG4 (%79.33), MKG5 (%81.67) and MSG15 (%79.67), female parent genotype of MKG23 with pollinizers genotypes of MKG5 (%83.67) and MKG10 (%62.67), female parent of MKG24 with pollinizer genotypes of MKG5 (%81.67) and MKG14 (%81.33) showed the highest fruit set. Also, female parent of MKG15 with pollinizers of MKG13 (%38.33), MKG23 (%37.33) and MKG24 (%38.33), female parent of MKG23 with pollinizer MKG24 (%40.00), female parent of MKG24 with pollinizers MKG10 (%42.33) and MKG23 (%42.33)showed the maximum flower abscission. Moreover, the highest percentage of kernel (%61.9) was found in combination cross of female parent of MSG15 with MKG5 pollinizers. The lowest fruit weight with husk (250 gr) and kernel fresh weight (50.5 gr) was found in combination cross of female parent MKG23 with pollinizer of MKG24. In addition, the lowest percentage of kernel (%28.98) was totally obtained in combination cross of female parent MSG15 with pollinizer of MKG24.   Discussion The highest percentage of fruit was obtained in hybridization of maternal parent MSG15 with pollinizers MK4, MKG5, MSG15, and MKG23 as seed parents with pollinizers MKG5, MKG10, and MKG23 mother's parents with paternal parents MKG5 and MKG10. According to the results of this research, it is possible to use compatible and suitable genotypes introduced in this study in other walnut breeding programs.