THE DEGREE OF HETERODICHOGAMY OF SOME WALNUT CULTIVARS (JUGLANS REGIA L.) IN SLOVENIA

We defined 9 protandric and 11 protoginic cultivars. The average flowering interval of female flowers is 10.8 days in protandric cultivars and 12.4 days in protoginic cultivars. Out of 14 early leafing cultivars 9 have protoginic flowering pattern.

The degree of dichogamy varies a lot in all cultivars. Cultivars Esterhazy-II and Hartley are absolutely dichogamous. High average level of dichogamy was found also in cvs. G-1239 (91.7%) and G-120 (90%), and also in Franquette, Parisienne and Cheinovo (81.8 %). Those cultivars are followed by cvs. Mayette, MB-24, Plovdivski and Drenovo (between 63.6% and 53.9%). Cvs. G-26, Elit, Killinger, Concord, Dzinovski and G-139 show a more homogamous flowering (degree of dichogamy - DD is between 35.7% and 25%). Flowering was the most homogamous in the 7 years' time period in G-1247, Petovio and Batchovski (DD is between 23.1% and 15.4%).

The relationship between the degree of dichogamy and weather conditions was discovered. In the extremely late year 1984 the late leafing cultivars Franquette, Parisienne, G-26 and MB-24 preserved protandric pattern of flowering, but their time advantage over female blossoms was much smaller than in the extremely early year of 1990.

Out of 20 cultivars only 4 did not have the same dichogamic pattern of flowering in all 7 years of our research. Deviations were minimal and present only in one or another extreme year.

On the basis of the discovered patterns of protandric-protoginic dimorphism adequate pollinators were selected for 7 walnut cultivars, suitable for growing in Slovenia.

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