PISTILLATE FLOWER ABSCISSION OF WALNUT GENOTYPES

In walnut cultivars and genotypes there is a kind of abnormal pistillate flower abscission (PFA) that is different from the abscission of non pollinated flowers. One of the causes of this disorder is reported as high pollen load during pollination. This study, in 1997-1998, was conducted to determine the PFA susceptibility of 60 walnut genotypes in 20 half- sib (hs) families. The evaluation of flower number before and after abscission together with branch diameter and fruit number was done on three branches in each genotype. There were great differences between different hs families and genotypes. The maximum and minimum abscission (two year means) were belong to families: k66 and k22 with 24% and 76% respectively. Meanwhile the least and highest abscission on genotypes were 11% and 92% in k66/2 and k22/2. There were also significant differences on flower density (no. of flowers /branch cross sectional area cm²). So that the families Kl04 and K39 with 4.55 and 0.56 and the genotypes K104/2 and K13/3 respectively with 6.6 and 0.27 showed the maximum and minimum of FD. Narrow sense heritability of PFA and FD 0.55 and 0.34 were estimated respectively.