Self-incompatibility in Spanish clones of apricot (Prunus armeniaca L.) tree
The present study is about some aspects of the reproduction physiology of twenty apricot clones ( Prunus armeniaca L.) grown in Abarán (Murcia, Spain). Self incompatibility of these clones was determined not only in field conditions in terms of the fruit set by means of self fertilization and free pollination, but also in laboratory conditions, by means of fluorescence microscopy of pollen germination on the stigma and of the growth of the pollen tube towards the egg. The only clone with signs of self incompatibility was ‘Moniquí Azaraque’. The clone with the lowest fertilization time was ‘Chicanos Archena’.
Cross-(in)compatibility in apricot (Prunus armeniaca L.)
Summary Eight apricot (Prunus armeniaca L.) cultivars and selections were self- and cross-pollinated in order to determine their pollen and stylar compatibility. Overall, 40 pollination combinations were examined. Pollen-tube growth in pistils pollinated in the laboratory was analysed using fluorescence microscopy. Three inter-incompatiblity groups of cultivars were found, of which two had not been described previously, while an existing group was expanded with one additional cultivar. The first group consisted of three Hungarian cultivars (‘Ligeti Orias’, ‘Cegledi Orias’, and ‘Szegedi Mammut’) and a Moldavian cultivar (‘Kostjuzhenskyi’). The second group consisted of two American cultivars (‘Stark Early Orange’ and ‘Nugget’). The third group consisted of two Serbian selections (‘Novi Sad Early’ and ‘Frushka Gora Early’). In the incompatible cultivar combinations, pollen-tube growth stopped in the style with the formation of the characteristic swelling. In the compatible combinations, the pollen tubes reached the ovary in the majority of the pistils examined.
A microscopical research on the incompatibility in the crossRhododendron impeditum × R. Williamsianum
SummaryA microscopical investigation has been carried out to find the causes of the failure of the species cross between scaled and unscaled Rhododendrons species. It was found that pollen germination on the stigma and pollen tube growth in the style proceed normally, but that difficulties occur when the pollen tubes reach the ovary. A small number of pollen tubes enters an ovule, but only in a few cases is seed setting effected (2–4 seeds per fruit). The majority of the tubes do not reach an ovule; the tubes have often thickened tips or, when they continue growth, they start to coil without penetrating into an ovule.SamenvattingKruisingen tussen geschubde en ongeschubde rhododendronsoorten, een microscopisch onderzoek
 Door middel van een microscopisch onderzoek is nagegaan waarom de kruisingen tussen geschubde en ongeschubde rhododendronsoorten mislukken.Gebleken is dat de kieming van de stuifmeelkorrels op de stempel evenals de groei van de pollenbuizen in de stijl normaal verlopen, maar dat de moeilijkheden optreden, wanneer de pollenbuizen het vruchtbeginsel bereiken. Een gering aantal pollenbuizen dringt in een zaadknop, hetgeen slechts in enkele gevallen (2–4 zaden per vrucht) tot zaadvorming leidt. Het merendeel blijft steken vóór de zaadknop; het buiseinde is vaak verdikt of er vormt zich een kluwen van de doorgegroeide maar niet in de zaadknop binnendringende pollenbuis.