1 . This is a report on a preliminary investigation of the causes of insufficient fruit setting in the strawberry variety Jucunda, especially its clone JK3 2. From field experiments in different localities it was concluded : a . that raw weather increases the percentage of malformed fruits (nubbins) in Jucunda, especially in clone JK3, and b . that interplanting with a good pollen variety (Deutsch Evern) may decrease this percentage .
3 . An insufficient pollination may take place in the centre of too closely planted beds . 4. Bees do not improve fruit setting in Jucunda . 5 . Usually the development of good anthers in Jucunda is not abundant, which means that the quantity of pollen produced is not large . 6 . The quality of the pollen, expressed as a percentage of morphologically good pollen, of the bad clone JK3 was sometimes a little lower than that of the good clones of Jucunda . 7 . Meiosis in the anthers of clone JK3 was normal . 8 . The fruit setting of the variety Deutsch Evern was good at all temperatures of the range of 10-26'C, whereas that of Jucunda was only good at 17-26"C . At 14 0 C and lower the fruit setting in Jucunda was reduced to zero . 9 . As the phenomena of this type of unfruitfulness are greatly influenced by the growth conditions of the plants, further investigation of this problem will be carried out under controlled conditions .
1 . INTRODUCTION
In a former article (4) some factors have been discussed which in general can unfavourably influence the fruit setting in strawberries .
Against this background the problem of reduced fertility in the variety Jucunda and especially in its clone JK3, has been studied . As some indications for the best way of further research have been found now, this first orientating phase of our investigations is herewith closed . The results of this preliminary study are reported in the present article .