Flowering and Pollination Biology of Walnut

Abstract

Common walnut (Juglans regia L.) is a monoecious, herkogamous, anemophilous, heterodichogamous and autofertile plant. Study of the sexual cycle of the walnut is hindered by the presence of a relatively long juvenile period and high genetic diversity, so that many questions in the field of reproductive biology of the walnut still remained unresolved. This paper gives an overview of current knowledge regarding the sexual process of walnut, with the focus on the morphology of staminate and pistillate flowers, the dynamics of their opening, as well as ecological and physiological aspects of dichogamy, pollen transfer, stigmas receptivity, pollen germination, pollen tube growth in the pistil, singamia, apomixis and pistillate flower abortion.

Obični orah (Juglans regia L.) je monoecijska, herkogama, anemofilna, heterodihogama i autofertilna biljka. Proučavanje polnog ciklusa oraha otežano je usled prisustva relativno dugog juvenilnog perioda i velike genetske raznolikosti, pa su mnoga pitanja iz oblasti reproduktivne biologije oraha ostala i dalje nerazjašnjena. U radu je dat prikaz dosadašnjih saznanja u vezi sa polnim procesom oraha, pri čemu je težište stavljeno na građu muških i ženskih cvetova, dinamiku njihovog otvaranja, kao i ekološke i fiziološke aspekte dihogamije, transfera polena, receptivnosti žigova, klijanja polena, rasta polenove cevi u tučku, singamije, apomiksisa i abortiranja ženskih cvetova.