A. Solar, F. Štampar, J. Smole
The degree of heterodichogamy was defined on the basis of 7 year phenological observations in 17 introduced and 3 local walnut cultivars which were planted in the years 1972–75 in Maribor (north-eastern part of 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.

Solar, A., Štampar, F. and Smole, J. (1997). THE DEGREE OF HETERODICHOGAMY OF SOME WALNUT CULTIVARS (JUGLANS REGIA L.) IN SLOVENIA. Acta Hortic. 442, 217-224
DOI: 10.17660/ActaHortic.1997.442.32

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